Before the Dinosaurs: The TRUE Story of PREHISTORIC REPTILES ! Earth History DOCUMENTARY

Have you ever dreamed of traveling through the ages to discover the true masters of our planet? How did creatures with gleaming scales managed to conquer all of Earth's environments long before the appearance of mammals or even dinosaurs? Welcome to the incredible saga of reptiles. These extraordinary survivors who have traversed more than 300 million years of history. From the early reptilia mororphs timidly emerging from primordial waters to the impressive crocodiles that still rule our marshes today and the venomous snakes and lizards with astonishing adaptations. We will dive into the fascinating epic of these masters of adaptation

who have conquered burning deserts, lush forests, and deep oceans thanks to their revolutionary evolutionary innovations. But before embarking on a new adventure, don't forget to like the video and subscribe to the channel so you won't miss a thing. Thank you and have a nice [Music] [Music] trip. We all know the simplified story of evolution. Fish gave rise to tetropods. Tetropods became amphibians and amphibians evolved into reptiles. This very simplified version is useful for explaining the essentials even if it doesn't reflect all the complexity of evolution. In reality, fish, tetropods, amphibians, and reptiles coexisted for millions

of years. Terrestrial vertebrates appeared in the Deonian over 400 million years ago. Over 248 million years in the form of amphibians known as Stegoalians. Closely tied to water bodies, they reproduced exclusively in water and lived near it, where terrestrial vegetation was found. Occupying areas far from water sources required major adaptations. Protection against drying out, breathing air, locomotion on solid surfaces, reproduction out of water, and adapted behaviors. These adaptations allowed for the emergence of a new qualitatively distinct animal group. These characteristics were first fully developed in reptiles. Towards the end of the Carboniferous about 300 million

years ago, about 186 million years, significant environmental changes occurred, including climatic diversification, the development of varied vegetation, the expansion of plants far from water bodies, and the widespread distribution of tracheal breathing arthropods. These becoming food sources also spread across waterheds. However, the reptile link is particularly essential for specialists in prehistoric life because it's from these ancestral reptiles that dinosaurs, terosaurs, and marine reptiles of the Mesazoic era descended. But what exactly is a reptile? [Music] Biologists define reptiles primarily by their ability to lay hardshelled eggs on land unlike amphibians which must lay soft permeable eggs in

water. This characteristic allows reptiles to move away from water for reproduction. In addition, reptiles have scaly or armored skin which protects them from dehydration, a beneficial adaptation for terrestrial life. Compared to amphibians, reptiles also have more developed and muscular limbs, a slightly larger brain, and more efficient lungs for respiration. Though unlike mammals, they do not have a diaphragm, an innovation that appeared later in evolution. These adaptations allowed them to conquer various environments and become the ancestors of the fascinating groups that include dinosaurs and other giant reptiles of the past. About 320 million years ago during

the Carboniferous period, Earth presented favorable conditions that shaped the evolution of life, notably the emergence of the first reptiles. Indeed, the Carboniferous is marked by an initially warm and humid climate that favored the expansion of vast tropical forests. Average temperatures were around 20 cigarasis or 68°, creating ideal conditions for lush vegetation. This abundant plant life led to a significant increase in atmospheric oxygen concentration reaching up to 35% well above the current 21%. Meanwhile, carbon dioxide levels were high at the beginning of the carboniferous estimated at 1500 parts per million or almost four times today's levels

contributing to a pronounced greenhouse effect and higher global temperatures. During this time, land masses were in constant motion, gradually coming together to form the superc continent pangia. This tectonic process led to the formation of major mountain chains such as the Hercinian range, whose weathering contributed to a decrease in atmospheric CO2. This reduction in CO2 initiated a gradual climate cooling leading to the perocarbonous glaciation. On the other hand, the warm and humid conditions of the early carboniferous allowed the development of vast swamps and forests, notably of giant treelike ferns. The incomplete decomposition of this dense vegetation

due to the absence of efficient lagnant decomposers led to the formation of thick coal deposits, hence the name carbonifpherous. These vegetationrich environments also favored the evolution and diversification of terrestrial fauna, including the appearance of the first reptiles. [Music] Towards the end of the Carboniferous, the climate underwent a notable transition. The continued absorption of CO2 by rock weathering and organic sedimentation led to a decrease in greenhouse gases, causing a global cooling. This climate change led to the formation of ice caps in the southern hemisphere marking the beginning of the Permo Carboniferous glaciation which extended over several

million years. During the Carboniferous, the transition from amphibians to the first reptiles marked an essential step in the evolution of terrestrial vertebrates. This evolution was facilitated by significant morphological and physiological adaptations, allowing the first reptiles to free themselves from aquatic environments and colonize new terrestrial habitats. The transition from amphibians to reptiles did not occur overnight. It was a gradual process spread over millions of years during which populations of amphibians gradually acquired adaptations allowing them to survive and reproduce in increasingly dry terrestrial environments. These changes were favored by the selective pressures of the time, notably the

competition for resources and climatic fluctuations, which pushed certain species to explore and establish themselves in new ecological niches. Fossils of intermediate species bear witness to this evolutionary transition. Among them, Seoria is often cited as an example of a tetropod exhibiting both amphibian and reptilian characteristics. Traditionally, it is considered that all reptiles descend from a unique permean genus, Simoria, which exhibits intermediate characteristics between stegoians and reptiles. As a result, simoria occupies a pivotal position between amphibians and reptiles to the extent that experts still debate its precise classification. Although primarily terrestrial, Samoria retained anatomical features reminiscent of

its aquatic ancestors, illustrating an intermediate step in the evolution towards reptiles fully adapted to terrestrial life. Their vertebrae offered a unique combination of flexibility and robustness to their spine, which gave them a significant advantage. The first two cervical vertebrae had evolved into the atlas and axis, allowing better mobility of the head. This adaptation was particularly useful for terrestrial animals, enabling them to better orient themselves, hunt mobile prey, and defend against predators. Their skeleton, notably that of the limbs and girdles, was completely oified, giving them a solid structure. They had long bony ribs, although these did

not yet form a closed rib cage. Their limbs, more robust than those of their Steigoshalian ancestors, allowed them to hold their bodies above the ground. The skulls of these animals had an occipital condile, an articulation contributing to the mobility of the head. Some species like samoria still retained structures such as branchial arches, suggesting a link with their original aquatic environment. These species probably lived near bodies of water and could still have aquatic laral stages. One of the major adaptations of the first reptiles is their skin covered with keratinized scales. This thick, horny epidermal structure significantly

reduces water loss through evaporation, providing effective protection against dehydration in terrestrial environments. Unlike amphibians, whose permeable skin requires humid habitats, the scales of reptiles provide a physical barrier against external aggressions and climatic variations. Another innovation is the development of the amniotic egg. Unlike amphibian eggs which require a moist environment to avoid desiccation, the amniotic egg has a protective shell and several internal membranes such as the amnon which create an aquous environment for the embryo. This configuration allows reptiles to lay their eggs on land without dependence on an aquatic environment for reproduction. Indeed, the amniotic egg

protects the embryo from desiccation, provides nutrients, and eliminates waste, thus facilitating embryionic development in a terrestrial environment. Additionally, the first reptiles developed lungs more efficient than those of their amphibian ancestors, adapted to exclusively aerial respiration. This improvement allowed them to better exploit terrestrial habitats. As ectothermic animals, their body temperature depended on the external environment. This characteristic made them particularly sensitive to climate variations influencing their behavior and geographical distribution. The first reptiles presented distinctive skeletal adaptations such as a single occipital condile connecting the skull to the spine offering greater mobility of the head. Their robust spine

and limbs positioned laterally under the body improved their terrestrial locomotion giving them a more efficient gate to move on land. These characteristics allowed the first reptiles to free themselves from the constraints of aquatic environments, paving the way for successful diversification and colonization of terrestrial ecosystems. The evolution of reptiles spans nearly 320 million years during which several distinct lineages have developed. Williston's proposed classification establishes these lineages based on the number and position of temporal fenistry on the skull. First, the enapsid skull characterized by the absence of temporal fenistray is found in turtles and primitive reptiles such

as the cotillosaurs. Next, the diapsid skull with two temporal fenistray is typical of the majority of reptiles including dinosaurs, terasaurs, and lepidosaurs which have given rise to modern lizards and snakes. Additionally, the urapsid skull, also called parapsid, features a small high-positioned temporal finestra and is found in messoic aquatic reptiles such as plesiosaurs, mosasaurs, and ichthyossaurs. Finally, the synapsid skull with a single lowition temporal finestra is typical of mamalian reptiles. [Music] It was thought that The earliest reptiles had a solid skull without lateral openings except for the nostrils, eyes, and spinal cord. This type of skull

is called a napsid, as we have just seen, and it is considered a primitive characteristic of the earliest reptiles. About 315 million years ago, a series of fossilized footprints discovered in Nova Scotia offers us a fascinating glimpse into the earliest land reptiles. These footprints featuring typically reptilian toes and scale marks are attributed to Hilonamus. Considered the oldest indisputably known reptile, Hilonamus was a small animal resembling a lizard measuring between 20 and 30 cm or 8 and 12 in long. Its morphology indicated a perfect adaptation to terrestrial life with an elongated body and skin covered in

scales offering protection against dehydration. Its many sharp teeth suggest an insectiverous diet, meaning it fed mainly on insects which were abundant at that time. These fossil footprints bear witness to the evolution of reptiles, marking an essential step in the transition from amphibians to reptiles, fully adapted to life on land. Other examples of early reptiles include West Lothiana and Paleothyus, which share a similar constitution and probably comparable habits. Although West Lothiana is sometimes considered a stem amniote rather than a true amniote, these species illustrate well the intermediate stages in reptile [Music] evolution. During the carbonifpherous and

perian periods, three major families of reptiles emerged. The evolution of these groups followed different paths. The first to separate from the ancestral lineage were the synapsids. Reptiles having lower temporal openings bounded by the zygomatic schemosal and postorbital bones. From the late carbonifpherous, this group became dominant among the early amniotes. The enapsids like hilonamus had a solid skull with no opening for jaw muscles which limited their bite strength. The last lineage the diapsids possessed two openings on each side of their skull. These additional holes lightened the skull and allowed for the attachment of powerful muscles making

their jaw more efficient. This lightweight and versatile skull structure of the diapsids proved highly advantageous for evolution. It allowed for greater diversification and adaptation to different lifestyles, paving the way for a wide variety of reptiles, including dinosaurs and marine reptiles. These differences in skull structure played a key role in reptile evolution, influencing their success and dominance in the ecosystems of the time. The anapsid, synapsid, and diapsid reptiles followed very different evolutionary paths at the beginning of the messoic era. Today, land and aquatic turtles are the only living descendants of anapsids, although the exact link between

these reptiles is still debated among paleontologists. The synapsids, on the other hand, gave rise to two major lineages. The first is that of the pelicosaurs, now extinct, whose most famous representative is Demetradon. The second lineage, that of therapids, gave birth to the first mammals during the triacic period. The pelicosaurs in particular were close to the kotillosaurs. Their fossils discovered in North America and Europe reveal animals resembling lizards measuring between 1 and 2 m or 3 and 7 ft with by concave vertebrae and well-developed abdominal ribs. Their teeth lodged in alvoli showed slight differentiation. [Music] In

the middle perian, the pelicosaurs were replaced by therapids called theodons or beast teeth animals which are more evolved. D. Their teeth were clearly differentiated. A secondary bony pallet formed and the skulls articulation with the spine changed to improve mobility. Their lower jaw was mainly composed of the dentary bone. The position of their limbs changed with elbows directed backward and knees forward, placing the limbs under the body as in mammals rather than on the sides like reptiles. The diapsids were the next group to separate from the anapsid cotyosaurs. Their skull has two temporal openings located above

and below the post orbital bone. At the end of the Paleozoic, specifically in the perian, the diapsids experienced great diversification, giving rise to many groups and species, among which are extinct forms and current reptiles. Two main subgroups emerged among the dipids, the lepitosaurs and the arosaurs. Paleontologists are not certain which of these subgroups appeared first, but they followed distinct evolutionary trajectories. Leitosaurs include current reptiles like the touitaras, lizards, snakes, and chameleons, as well as their extinct ancestors. The touitara, which today lives on small islands off the coast of New Zealand, descends from primitive lizards with

wedge-shaped teeth, common in the middle of the Mesazoic. Primitive lizards were distinguished by wedge-shaped teeth on the jaws and pallet and by vertebrae concave on both sides reminiscent of those of amphibians. Today, lizards, snakes, and chameleons form the order of squamates, one of the most diversified among reptiles. Lizards present since the late perian share several similarities with the sphenodon such as widely spaced limbs and an undulating spine. Snakes appeared later in the Cretaceous, while chameleons, a more specialized group, appeared in the Cenazoic between the Paleocene and the Meioene. Arasaurs are among the most fascinating reptiles

that have ever existed, including crocodiles, terosaurs, and dinosaurs. Today, only crocodiles have survived from this group. Emerging at the end of the Triacic, the first species of crocodiles were quite different from modern crocodiles. For example, those from the Jurassic did not have a true bony pallet. Their internal nostrils opening between the palatal bones and their vertebrae were concave on both sides. Modern crocodiles with a secondary bony pallet and well-developed procolus vertebrae descend from ancient arosaurs called pseudosukians present since the end of the triacic. While most lived in freshwater, some marine species are also known among

Jurassic forms. These evolutions allowed a great diversification of reptiles, enabling them to conquer various habitats and dominate ecosystems for millions of years. One of the earliest well-known reptiles is Msosaurus, a genus from the early Perian, remarkable for having returned to aquatic life. It was long thought that Mesosaurus was one of the first marine reptiles. Unlike the majority of its terrestrial contemporaries, Mesosaurus had adapted to water and primarily fed on fish, showing early diversity in the lifestyles of reptiles. [Music] During this period, the earliest reptiles were largely overshadowed by much larger labberthodont amphibians such as Cockiosaurus.

These amphibians dominated the ecosystems of the time, restricting the ecological niche of reptiles to a small discrete part of the fauna. It was only after the small glacial period at the end of the Carboniferous that reptiles began to diversify and occupy a more significant place in ecosystems, laying the groundwork for their future dominance on land. Towards the end of the Carboniferous, terrestrial labyrinthodons were still present, but a new player was emerging, the synapsids. These gave rise to the first large fully terrestrial vertebrates, the pelicosaurs, among which adaposaurus is one of the best known. It was

a herbivorous reptile measuring over 3.5 m or 11 ft long with a short low skull and blunt conical teeth which lived in North America and Europe in the early perian. These imposing animals characterized by a distinctive dorsal sail were well adapted to their terrestrial environment. In the middle of the perian, the climate became drier causing upheaval in the fauna of the time. Primitive pelicosaurs which had dominated until then were gradually replaced by therapids, more advanced synapsids. Therapids are the ancestors of modern mammals and began to show traits that foreshadowed this evolution. Meanwhile, anapsid reptiles recognizable

by their massive skulls lacking post orbital holes continued to thrive. Among them, the parasaurs. Robust herbivores reached gigantic proportions before disappearing at the end of the perian. These largest reptiles of the Perian had a length varying from 60 to 300 cm or 24 to 118 in. And some species could weigh over 1,000 kg or 2,25 labes and played an essential role in the ecosystems of the time. During the Perian period, Pereasaurs, a group of partiles, are considered the closest ancestors of turtles. They were covered with hard armor-like plates, and their slow and awkward gate is

reminiscent of modern turtles. Contrary to what one might think, parasaurs were not dinosaurs. They belong to a distinct branch of reptilian evolution. Their extinction later allowed dinosaurs to thrive. However, how the first ancestors of turtles appeared at the end of the triacic remains a subject of research for scientists seeking to understand this interesting transition. Meanwhile, Dapsid reptiles featuring two temporal openings in their skull began to diversify towards the end of the Perian. They split into two major lineages. The arcosaurs, which would give rise to crocodiles and dinosaurs, and the lepidosaurs, precursors of modern touittas, lizards,

and snakes. [Music] At this time, arosaurs and lepodosaurs remain relatively small and inconspicuous, resembling lizards and occupying specific ecological niches. Scientists have recently discovered a new species of ancient reptile that fills a major gap in the history of dinosaur ancestors. This reptile named Tilio Cretier was a carnivore measuring between 2 and 3 m 7 and 10 ft long with a long tail and an elongated neck. It moved on four sturdy legs and lived about 245 million years ago at the beginning of the dinosaur era. Scientists have proven that Tilio Crater belongs to the Arasaur group.

This discovery is essential because Tio Crater appears just after the split of arosaurs into two lineages. one leading to birds and dinosaurs, the other to crocodiles. This reptile sits on the bird branch and has features that help understand what the early ancestors of dinosaurs looked like. Unlike other smaller and bipeedal ancestors, Teliorater was larger with a flexible ankle joint similar to that of crocodiles. It also had jaw musculature and rapid growth similar to that of dinosaurs. The fossils of Telia Crater have allowed paleontologists to better understand its role in dinosaur evolution, revealing that some dinosaur

characteristics were actually present long before their appearance. This period of transition marked a turning point in the evolution of terrestrial vertebrates, laying the groundwork for the explosion of reptilian diversity that would follow, notably with the rise of dinosaurs during subsequent geological eras. However, the end of the Perian period was marked by the largest mass extinction ever recorded. While scientists continue to debate the causes, they agree on a major suspect. Intense volcanic activity. For a million years, the heart of present-day Siberia was the scene of powerful volcanic eruptions spewing colossal amounts of lava reaching a thickness

of 3,000 m, 9,43 ft. These eruptions filled the atmosphere and oceans with toxic gases, possibly accompanied by acid rains, causing major ecological disasters. Earth's temperature soared, depriving the oceans of oxygen and leading to the extinction of 70% of terrestrial species and 95% of marine life. The vast sheets of solidified lava known as traps attest to the scale of these eruptions covering Siberia with up to 4 million cubic km 966,000 cubic miles of lava. At that time the planet was dominated by a superc continent pangia and an immense ocean [Music] panthalasa around 235 million years ago.

The evolution of arosaurs led to the emergence of terasaurs, crocodilians, and dinosaurs, marking a major diversification among reptiles. Arasaurs, originally made up of theodons, separated from the eosukians towards the end of the perian and reached their peak in the triacic. This group of lizard-like creatures measured between 15 cementers or 6 in and 5 m or 16 feet in length. Most lived on land with hinded limbs often longer than the front limbs, allowing them to move efficiently on solid ground. At the same time, another branch of theodons adopted a semi-aquatic lifestyle, giving rise to crocodiles at

the end of the triacic. These crocodiles diversified during the Jurassic and Cretaceous periods, occupying various aquatic habitats. Dinosaurs appeared in the fossil record as early as the middle of the triacic, becoming the largest and most diverse group of reptiles ever to live on Earth. They included species of all sizes, ranging from small animals measuring less than 1 m or 3 ft long to enormous creatures reaching nearly 30 m or 98 ft. Some dinosaurs moved solely on their hind legs, while others walked on all fours. Some had feathers, horns, or enormous claws. Dinosaurs were present on

almost every continent, occupying a wide variety of environments. They lived in deserts, forests, and swamps, and some even adopted a semi-aquatic lifestyle. It is undeniable that during the Mesazoic, this group of reptiles dominated the earth. The appearance of dinosaurs was very varied, but they shared certain common traits. For example, their heads were relatively small compared to their bodies. Another interesting characteristic is that in the sacral region of their spinal cord, there was a local expansion, often more voluminous than their brain. Dinosaurs are the only reptiles to have an upright posture, meaning that their legs are

positioned under their body, unlike modern reptiles like crocodiles or lizards, which have their limbs on the sides. Although there are other skeletal differences between dinosaurs and other reptiles, they are less obvious. However, one particular bone called the fcula is easy to spot. The fcula known among birds as the wishbone is actually the result of the fusion of the clavicles. For a long time, it was believed that this bone was unique to birds, but today we know it already existed in some dinosaurs, notably therapods. This shows that birds simply inherited this bone from their dinosaur ancestors,

proving their kinship with them. [Laughter] [Music] Heat. Heat. [Music] [Laughter] [Music] [Music] From the beginning of their evolution, dinosaurs split into two main groups that evolved in parallel. This distinction is based mainly on the structure of their pelvic girdle which led to their classification into two categories. The sarishians or lizardhipped and the ornithyscians or birdhipped. The sarishians were originally relatively small predators. Their hind legs allowed them to propel themselves quickly while their shorter front legs were mainly used for grasping food. A long, sturdy tail provided essential balance, helping them stabilize during their movements. Over time,

this group evolved to include impressive herbivorous forms walking on all fours. Among these giants were some of the largest vertebrates ever to have lived on Earth. The brontosaurus, for example, reached a length of about 20 m or 66 ft, while the Diplodocus could measure up to 26 m or 85 ft. These immense creatures likely lived in terrestrial environments, feeding on the abundant vegetation found in marshes and near bodies of water. Their massive size allowed them to defend against predators and adapt to a primarily plant-based diet. On the other hand, the ornithysians or bird-hipped dinosaurs derived

their name from the shape of their pelvis reminiscent of modern birds. Initially, these dinosaurs moved on long hind legs, but over the course of evolution, many developed proportionally adapted front limbs, allowing them to walk on all fours. Unlike the Sarishians, ornithysians were exclusively herbivorous, specializing in various types of vegetation. Notable representatives of the Ornithysians include the iguanadon, which could move on its hind legs and reach a height of 9 m or 30 ft. Another fascinating species is the Triceratops, similar to a rhinoceros with a small horn at the tip of the snout and two large

horns above the eyes. Its size could reach 8 m or 26 ft long. And these horns were probably used for defense and territorial combat. The Stegosaurus, on the other hand, was distinguished by its relatively small head compared to its body and its two rows of high bony plates adorning its back. This dinosaur measured about 5 m or 16 ft long. The Stegosaurus' plates, often interpreted as means of thermal regulation or defense, added a spectacular dimension to its appearance. These two groups, the Sorishians and the Ornithysians, illustrate the incredible diversity of dinosaurs and their adaptation to

different lifestyles over the millions of years during which they dominated the Earth. [Music] The earliest fossil traces of dinosaurs found in South America are Sarishians, a group that includes species like Saturnelia, Herrerasaurus, Stricosaurus, Eraptor, and Alwalkaria, having lived between 220 and 232 million years ago during the early late triacic. These dinosaurs were bipeedal carnivores measuring up to 5 m or 16 ft long. They were the first representatives of their group and their morphological characteristics distinguish them from other reptiles of the time. These oldest dinosaurs had vertical limbs, a posture that offered them superior mobility compared

to quadripedal crocodilians with lateral limbs. This increased mobility allowed them to better hunt and escape from predators. Their warm-blooded metabolism also favored a more active life. These advantages might explain their rapid proliferation during the Mesazoic. The classification of these primitive dinosaurs is complex. It is only with the dinosaurs of the late triacic that scientists can clearly differentiate two major subgroups, the theropods and the sorapottomorphs. [Music] Therapods are primarily carnivorous and are characterized by hollow bones and three fingers at the ends of their limbs. They were mainly bipedal, giving them great mobility. Although often associated with

large predators like the famous Tyrannosaurus Rex or Velociaptor, a study conducted by American paleontologists revealed that the majority of therapods were actually herbivorous. Out of 90 species analyzed, many showed anatomical adaptations related to a vegetarian diet, such as a toothless beak. The size of therapods varied considerably. Some like Ankoris measured about 30 cm or 12 in long and weighed 110 g or 4 o while others such as Spinosaurus could reach lengths exceeding 15 m or 49 ft. This diversity in size reflects a variety of lifestyles and ecological niches occupied by therapods. Moreover, therapods also showed

great diversity in their dietary habits. While the earliest representatives were mostly carnivorous, some groups evolved towards omnivorous, insectiviverous, herbivorous or paciviverous diets. For example, Spinosaurus specialized in fishing while others like Manoraptorra had a more varied diet. A notable feature of theropods is the presence of feathers or similar structures in several genre, suggesting a close relationship with modern birds. This hypothesis is reinforced by shared traits such as the three-toed foot, fcula, and hollow bones. These similarities indicate that current birds are the direct descendants of some small therapods from the late Jurassic. Meanwhile, serapotamorphs are a cate

of sorishian dinosaurs that appeared at the end of the upper triacic around 230 million years ago. They are distinguished by several notable anatomical features. Their head was relatively small compared to the rest of the body positioned at the end of a long neck composed of 10 or more cervical vertebrae. This configuration allowed them to reach vegetation at height, offering them a unique ecological niche among the herbivores of their time. Their dentition was adapted to a herbivorous diet with leafshaped or spoon-shaped teeth. Instead of chewing their food, they used gastroliths or swallowed stones to grind plant

fibers in their stomach, thus facilitating digestion. [Music] The first soropotamorphs such as Saturnelia were small, measuring about 1.5 m or 5 ft long. Over time, some members of this cate evolved to become the largest terrestrial animals to have ever existed, reaching lengths of 30 m or 98 ft or more and masses exceeding 60 tons or 66 tons. Initially bipedal, soropotamorphs gradually adopted quadrupal locomotion as their size increased, developing a gate adapted to their massive size. Their long tails served as a counterbalance to their elongated neck, thus ensuring their balance. Fossils indicate that some soropotamorphs lived

in groups, suggesting gregarious behavior. This herd life could have offered protection against predators and facilitated access to food resources. These primitive dinosaurs nevertheless bore resemblances to another major group of dinosaurs, the ornithatians. Even though their skeletons had notable differences, particularly in the pelvis and skull areas. Ornithacians like Triceratops and Stegosaurus had a pelvis different from serishians often adapted to a herbivorous diet. After the establishment of the major families of dinosaurs in the early Jurassic, evolution followed its natural course. However, recent research shows that by the end of the Cretaceous, the rate of dinosaur adaptation had

significantly [Music] slowed. At that time, dinosaurs were mostly related to existing families, and their rates of speciation and diversification had decreased. This reduction in diversity may have made them particularly vulnerable to the mass extinction at the end of the Cretaceous known as the Cretaceous tertiary extinction or crisis. Most messoic reptiles were highly specialized and their survival depended on very specific living conditions. This extreme and unilateral specialization likely contributed to their extinction. Although extinctions occurred throughout the Mesazoic, the phenomenon became particularly pronounced at the end of the Cretaceous when the majority of these reptiles disappeared in

a relatively short period of time. If the messoic is often called the age of reptiles, the end of this era could just as well be named the age of the Great Extinction. 65 million years ago, a massive meteorite crashed into the Yucatan Peninsula. This explosion generated gigantic clouds of ash blocking sunlight which led to the disappearance of the majority of plants. At the end of the Cretaceous, intense volcanic activity resulted from the collision between India and Asia. The significant reduction in vegetation led to the extinction of herbivores followed by that of carnivorous dinosaurs. This massive

extinction coincides with major climatic and geological changes. The Cretaceous saw significant redistributions of land and sea accompanied by movements of the Earth's crust that led to vast mountain forming phenomena known as the alpine phase. At the same time, the messoic flora dominated by conifers and psychicheads was replaced by angioperms, a new type of flowering plants. Genetic changes in the reptiles themselves cannot be ruled out. These transformations affected the survival capacity of species, particularly those that were highly specialized. Ironically, just as the Peran Triacic extinction paved the way for the emergence of dinosaurs, the Cretaceous tertiary

extinction paved the way for the rise of mammals. These, which coexisted with dinosaurs as small mousel-like creatures, were then able to evolve and occupy new ecological niches left vacant by the disappearance of dinosaurs. [Music] 400 million years ago during the Deonian period, lobefinned fishes made an evolutionary leap by colonizing ing the land in the form of amphibians. Their descendants then spread across all continents and even conquered the sky. However, some chose to return to their original environment, the water, thus becoming secondarily aquatic animals. They had to readapt to aquatic life independently of each other. They

developed similar adaptations as the sea, their new habitat, imposed universal constraints. The first to return to the sea were reptiles, reaching their peak in the Mesazoic era. Climatic upheavalss and the disappearance of many competing species following the Peran Triacic crisis offered reptiles a unique opportunity to thrive in the oceans. The vast marine expanses of the Triacic, emptied of their biodiversity, turned into attractive ecological niches, prompting some terrestrial species to return to the sea. Reptiles were the first to seize this opportunity, notably thanks to the extinction of plaaderms, those armored fish with powerful jaws. In the

immense ocean surrounding Pangia and the Tethus, its inner sea, many marine predators appeared. Among these newcomers, two major groups diversified from the beginning of the Triacic. The echiosaurs, also called fish reptiles, whose fossils reveal sizes ranging from less than 3 feet to over 66 feet. And the soropterians or thin lizards. [Music] These two groups thrived in the seas until the mid cretaceous, playing an essential role in the marine ecosystems of their time. In just a few million years, these marine reptiles adapted to the demands of aquatic life, developing streamlined bodies, transforming their limbs into swimming

paddles, and adjusting to salinity and diving conditions. Within these revitalized marine ecosystems, these reptiles coexisted with a diverse fauna, including fish, sharks, seephopods, echinoderms, and balves. Meanwhile, on land, another group of reptiles was on the rise, colonizing the ground and the skies. Ichthyossaurs were the first pelagic reptiles, fully adapted to life in the open sea far beyond the shores of pangia. The first ichthyosaurs appeared in the early triacic around 250 million years ago and quickly spread across the globe. The triacic marks the period of greatest ecological diversity for these creatures, ranging from fish hunters to

benthic feeders. During the Jurassic, pelagic species evolved, becoming capable of fast swimming and diving to great depths. Thyiosaurs were typical pelagic predators, inhabiting the vast marine expanses. Their fossils have been discovered all over the world, notably in the vulga region in Russia, where interesting specimens have been found. Ichthyosaurs were the marine equivalents of today's citations during the Mesazoic. Over the course of their evolution, ichthyossaurs took on various forms, but all shared common characteristics adapted to predation in the open sea. Their body became streamlined, their skeleton less dense, and their snout elongated. They hunted fish, marine

reptiles, and seephalopods like ammonites. Their streamlined body, large eyes adapted for underwater vision, and their metabolism are notable examples. They swam by undulating their bodies, especially the tail, while their fins were used for steering. Their resemblance to dolphins is striking. A streamlined body, an elongated snout, and a large fin with two loes. Their limbs transformed into fins while their hind legs and pelvis diminished. Their fingers had numerous felanges, and some ichthyossaurs had up to six fingers. Their skin was smooth. Being endothermic, meaning warm-blooded, they could maintain a stable body temperature, allowing them to hunt in

cold waters without relying on the sun to warm them. Their eyes, which could reach 25 cm or 10 in in diameter, provided excellent vision in the dark depths. Ichthyossaurs also had a crescent-shaped tail fin and a fleshy dorsal fin reminiscent of modern citations. However, they are not related to dolphins which descended from terrestrial mammals. Unlike many reptiles, ichthyossaurs were viviperous, meaning they gave birth to live young rather than laying eggs. This adaptation was necessary because their bodies did not allow them to return to land to lay eggs. Depending on their size, they occupy different ecological

niches. The majority fed on small fish and seephalopods with their teeth being long, thin, and pointed. [Music] During the Triacic, certain species specialized in benthic animals, mainly mollisks. From the Jurassic onwards, ichthyossaurs with broad, straight teeth appeared, capable of hunting large fish and other marine reptiles. Their natural enemies included sharks, plyosaurs, and crocodilamorphs. During the Cretaceous, the diversity of ichthyiosaurs declined with only a few large predators remaining until their extinction after the Cenomanian Terrronian crisis 94 million years ago. Their disappearance could be due to competition with other marine predators and environmental changes in the upper

Cretaceous. Furthermore, plesiosaurs are an order of marine reptiles belonging to the soropterigians. The first fossils of plesiosaurs date back to the upper triacic about 203 million years ago. This group thrived during the Jurassic with a great diversity of forms. Plesiosaurs are distinguished by a broad barrel-shaped body with flippers and a short tail. Their skin was smooth without visible scales, but had folds and wrinkles. One of their defining characteristics is their long neck and small head. The elongation of the neck was due to the number of vertebrae rather than their size as in the giraffe. The

elasmosaurus holds the record with 76 cervical vertebrae. The neck of plesiosaurs was rigid and did not allow for swan-like bending. Contrary to some earlier reconstructions, the size of plesiosaurs ranged from 1.5 m or 5 ft to over 12 m or 39 ft with the elasmosaurus reaching up to 15 m or 49 ft. Plesiosaurs frequented both coastal waters and the open sea and were present in all regions, including polar waters. In the past, some theories suggested they laid eggs on land, but recent discoveries instead support vivy parody. The newborns were large, generally one or two per

litter, and it is possible that plesiosaurs exhibited a form of parental care in their early stages. Their diet consisted of fish and sephalopods. Their long neck may have helped to conceal their approach to a school of fish, as the small size of their head was not perceived as a threat. Plesiosaurs are also known for the presence of gastroliths in their stomachs. Stones used as ballast or to grind the shells of [Music] molllesks. In the Cretaceous, giant species like the Alasmosaurus appeared, but the order began to decline. The few species that survived the Cenamomanian Terrronian extinction

94 million years ago had to face strong competition from mosasaurs. Plesiosaurs eventually disappeared at the end of the Cretaceous. Furthermore, pleosaurs are a group of plesiosaurs characterized by a short neck and a large elongated head. They do not form a single taxin but group representatives of different families sharing this distinctive morphoype. Like all plesiosaurs, pleosaurs had a robust body, limbs transformed into flippers, and a short tail. What sets them apart is their shortened neck and massive head. For example, the Chronosaurus had a skull 2.8 m or 9 ft long, representing 1/4 of its total length

of 12 m or 39 ft. Pleosaurs use the same underwater swimming technique as plesiosaurs, but their more compact body due to the shortened neck increased their speed. When they attacked, the powerful and synchronized movement of their four flippers allowed them to propel rapidly towards their target. The analysis of their bone structures suggests they could dive to considerable depths to hunt. Pleosaurs were as widespread as plesiosaurs, but unlike the latter, they were super predators at the top of the food chain. Their large conical teeth and powerful jaws were designed to tear muscles and crush bones. [Music]

At the end of the Cretaceous, mosasaurs in rivalry with sharks became the main marine predators. The first mosasaurs measured up to 1.5 m or 5 ft, while species like Mosasaurus Hoffmani could reach 17 m or 56 ft. Mosasaurs had a long streamlined body similar to that of a monitor lizard but with a proportionally larger head. Their limbs transformed into flippers were short and later species had a long tail with a forked fin. Initially mosasaurs swam by undulating their bodies side to side like traditional reptiles. With evolution they adopted a more effective swimming style for fast-moving

sea dwellers thanks to powerful tail strokes more flattened with a fin. Although they could achieve speeds higher than plyosaurs, they remained slower than ichthyossaurs. They could dive deep but preferred shallow waters. These marine reptiles occupied niches of large and medium-sized predators living in the shallow coastal seas worldwide. Their diet included sharks, large fish, sea turtles, other reptiles, and occasionally ammonites and bellonites. However, the catastrophic changes in the biosphere at the end of the Cretaceous led to the destruction of marine food chains leading to their extinction as well as that of other large predators. The lotattosuchians

or marine crocodiles are the only arosaurs aside from marine birds to have fully adopted an aquatic lifestyle. This group includes two families, the tieiosaurs and the mitriorinkus which descended from them. Marine crocodiles lived mainly in the shallow seas of western Europe, although fossils have been found in Argentina and Madagascar. They became extinct in early Cretaceous, just like the ichthyossaurs. Tiosaurs were less adapted to aquatic life, retaining a crocodilian appearance. They had a carrapase made of bony plates covering their back and belly, limbs still resembling legs with webbing between the toes, and a long robust tail.

Their size generally ranged from 3 to 4 m or 10 to 13 ft reaching up to 7 m or 23 feet. However, Mitriorhenkis were entirely adapted to aquatic life having lost their carropace transformed their legs into flippers and developed a codle fin. Their sizes ranged from 1.5 to 6 m or 5 to 20 ft. Tiosaur swam using their legs and undulating their bodies with the tail playing the main role in propulsion. They might still have been able to move on land for short periods. In contrast, Mitriorinkis had completely abandoned terrestrial living, using their tail and

fin for propulsion and their flippers for steering. Their long, narrow jaws and pointed teeth indicate they primarily fed on small fish. Teosaurs had not yet completely severed their link with the land and could still lay their eggs there, while Metriorhinkus were presumably viviperous. Marine turtles include several families of turtles not directly related but all having adopted an aquatic lifestyle. Most current marine turtles belong to the Cheloniti family while the Dermacalles family represented by a single species includes leatherback turtles. The protostigiti family closely related to leatherback turtles and some other families are now extinct. The first

marine turtles appeared at the end of the Jurassic and experienced significant diversification during the Cretaceous. The Cretaceous Paleogene extinction event 66 million years ago had little impact on them, perhaps due to their feeding habits and long reproductive cycles which helped them survive this difficult period. Marine turtles retain a major trait of their terrestrial ancestors, the shell. In chaloniid, it is streamlined, oval or heart-shaped. In contrast, in protogy and leatherbacks, the shell is greatly reduced, composed of bony plates forming ridges and covered with thick skin instead of the horned scales. Their limbs and large heads are

not hidden under the shell. The size of marine turtles varies, most measuring about 1 m or 3 ft long, although the largest, like the leatherback turtle, reaches up to 2.5 m or 8 ft. Archelon, an extinct species, was even more imposing, measuring 4.6 m or 15 ft long and weighing about 2 tons or 4,49 LOBs. Marine turtles mainly use their long front flippers for movement, allowing them to perform motions similar to flying birds. Their rear flippers act as rudders. Although their speed is moderate, they are very maneuverable. These turtles can spend extended periods underwater, staying

active for up to an hour underwater and diving 4 to 7 hours during sleep. Their diet is omnivorous, primarily composed of algae, mollisks, crustaceans, ainoderms, kenteritates, and sometimes sponges. The leatherback turtle mainly feeds on jellyfish, but may eat other animals. Extinct turtles like Archelon had similar diets. The main threats to these turtles come from sharks and formerly marine reptiles such as mosasaurs or plyiosaurs. Among all the marine reptiles of the messoic, turtles have proven to be the most resilient in the long term. [Music] Around the middle of the triacic period, terasaurs or flying lizards evolved

from theodons. Scientists consider scaramoclas to be the ancestor of terasaurs. The slender reptile about 18 semi peters or 7 in long with a thin body had long legs. It spent a lot of time in the trees and was capable of walking on two or four legs and jumping. It is possible that it had a membrane similar to that of a flying squirrel. Terasaurs spread widely during the Jurassic and Cretaceous periods, colonizing the skies with a great diversity of species. These winged reptiles are a fascinating example of the specialization of reptiles during the Mesazoic era. These

flying creatures had a unique structure. Their wings were formed by folds of skin stretched between the sides of the body and an extremely elongated fourth finger on their forlims. This configuration is one of the most unique adaptations in the animal kingdom for flight. Their sternum was wide and featured a well-developed keel similar to that of birds, serving as an attachment point for the powerful flight muscles. Many bones in their skeleton were pneumatic or hollow to lighten their weight while ensuring the necessary strength for flight. The jaws of terasaurs were often elongated and equipped with teeth,

although there were variants with a toothless beak. The flying reptiles of the early triacic and jurassic periods are traditionally classified under the name Ramferhinkcoidia. Unlike the more advanced pterodactyloids of the Cretaceous, Ramur Hinkcoids largely retain the characteristics of their non-flying ancestors with low skeletal pneumaticity, toothy mouths, long tails, and generally the absence of headcrests. Their wingspan relatively short, usually measured less than 2.5 m or 8 ft. Their bodies were covered with hairlike pike fibers suggesting a warm-blooded metabolism. In the middle of the Jurassic period, ramper hinkcoids diversified forming three distinct types of ecosystems. The first

type, probably the most archaic, includes terrestrial and aerial predators like dormorphodon. These terosaurs spent a lot of time on the ground on branches or in rocks. They were able to climb easily and run after their prey, and they had large, short wings as well as robust jaws and teeth. Their diet included various small animals, ranging from insects to amphibians, lizards, and mammals. The second type encompasses hunters of flying insects, capturing their prey in flight. Although they were not particularly fast, they were very agile. Among them were the Anurnathy, roundheaded terasaurs with large eyes that primarily

hunted at night. The third type consists of paciferous creatures living near the shores of water bodies. These graceful terasaurs like the genus Ramperhinkus had long wings, narrow jaws, and needle-shaped teeth. They captured fish and sephalopods by snatching them at the surface of the water or diving into the depths. From the middle of the Jurassic period, the ramper hingedai began their decline and by the end of the Cretaceous period, only a few residual species survived. At this time, the pterodactyloids were already in direct competition with birds. The latter could not be completely ruled out, but the

birds did not hesitate to occupy the niches left vacant by the reptiles. The terasaurs then began to increase in size. This size difference allowed them to coexist in the same ecosystems without directly competing. Throughout the Cretaceous, a wingspan of 2 m or 7 ft constituted the upper limit for birds and the lower limit for most terasaurs. This shift towards larger sizes also triggered changes in their environment. Terasaurs specialized in fishing survived but were now hunted by pterodactaloids with a wingspan of 5 to 7 m or 16 to 23 ft. Pteranodons by folding their long wings

dove at high speed into the marine depths. Nichtosaurus sporting a crest 1 m or 3 ft long captured fish at the water's surface with their fine teeth. These paciviverous terasaurs were common inhabitants of coastal areas in inland waters living alongside seabirds like Ichthyornis and Hesperornis. The group of land air predators also experienced significant changes. These terasaurs now active in open spaces hunted on the ground and near bodies of water. Some like the tsunaripteriday fed on mollisks and crustaceans in the coastal area crushing their shells with their powerful teeth, a rare feature among pterodactyloids. Others like

the estioactil flew in groups searching for kerrion like vultures. There were even filter feeders like flamingos feeding on small crustaceans and plankton. But most notably, the terasaurs of the azdar family stood tall as giants. At the end of the Cretaceous period, they reached extreme sizes for flying creatures. Specimens like qualatlas and hatsopterics, the largest of the family, had a wingspan of 10 to 12 m or 33 to 39 ft. With their long necks, enormous heads, and pointed beaks, they spent almost more time on the ground than in the air. Qualcolas, with a wingspan of 9.6

6 m or 31 ft and a length of 8 m or 26 ft from head to hind leg appeared like a winged giraffe when on the ground. Like giant horn bills, they roamed the fern savanas and in case of danger deployed their great leathery wings to take off. In summary, it can be said that the anatomy, biomechanics, and aerodynamics of terasaurs were all aimed at a single goal, flight. Despite their evolutionary success, terasaurs gradually declined with the arrival of birds which seem to have occupied similar ecological niches. This decline led to their extinction at the

end of the Cretaceous along with non-avian dinosaurs. It is important to note that terasaurs and birds followed independent evolutionary trajectories although they share ancestors among the various families of picodons. [Music] [Music] The Perian Unatosaurus, considered the ancestor of turtles, was a small lizard-like animal with short and very wide ribs, forming a sort of dorsal shield, but lacking an abdominal shield and possessing teeth. Mesazoic turtles were initially terrestrial and probably burrowing before some groups adopted an aquatic lifestyle, leading to a partial reduction of their bony and horny shells. Since the Triacic, turtles have retained their main

features, surviving challenges that eliminated most reptiles and remain as prosperous today as in the Mesazoic. Modern crypto diaries and plurdiaries largely preserve the primitive appearance of triacic terrestrial turtles while marine and softshelled turtles appeared at the end of the messoic. Modern reptiles except for turtles often referred to as anapsids are primarily dapsids. A group characterized by two temporal cavities in their skull. A lower one for synapsids, an upper one for pariles and urapsids and two for diapsids. The enapsided group includes a variety of reptiles including the lepitosauromorphs, a subgroup that gave rise to toueras and

squamates. The lepitosaurs, a specific subset within the vast cate of lepitosauramomorphs, have a very fragmented fossil record with few wellpreserved fossils between their estimated origin around 260 million years ago or 161 million years ago and the end of the Jurassic around 150 million years ago or 93 million years ago. This knowledge gap represents one of the greatest enigmas of vertebrae evolution. It leaves us with almost no clue about the origin of these reptiles which play a major role in current and past terrestrial ecosystems. However, a recent discovery in Argentina has allowed paleontologists to find the

most primitive known lepitosaur to date called titalura. This fossil represents a transitional form between early reptiles and modern lepidosaurs. Tetalura is considered the ancestor of the two main groups of lepidosaurs. the squamates like lizards and snakes and the sphenodonians like touittaraas. Analyses show that the bodies of early lepitosaurs resembled more closely primitive spenodontians while squamates evolved more diversely. This diversity may have contributed to the evolutionary success of lizards and snakes compared to spenodontians. Interestingly, all known fossils of squamates, spinodons, and their close relatives have been discovered primarily in Europe, while Tedura was found in Argentina.

This suggests that primitive lepitosaurs migrated over great distances, crossing the vast expanse of Panga. They coexisted with the first true lizards and spenodons for about 20 million years or 12 million years, indicating a more complex evolutionary history than expected. By the end of the perian, squamates, a group including lizards and later snakes, had separated from primitive diapsids. They began to diversify during the Jurassic between 200 and 146 million years ago, or between 124 and 91 million years ago. This group experienced great diversity and rapid expansion, especially in the Cretaceous. Early snakes evolved from lizards during

the middle Jurassic around 174 to 163 million years ago or 108 to 101 million years ago. The golden age of squamates occurred during the Cenozoic where they became the dominant reptile group now representing the majority of living reptiles. This development of lepitosomorphs, particularly of squamates, marked an important step in reptile evolution, leading to the great diversity we observe today. These adaptations enabled them to adjust to various environments from arid deserts to tropical forests, contributing to their persistent evolutionary success. By the end of the Cretaceous, two new classes of warm-blooded vertebrates had already emerged, mammals and

birds. The large specialized reptiles that had survived until this time, failed to adapt to changing living conditions. The increasing competition with birds and mammals, smaller but more active, also contributed to their extinction. These new vertebrates, with their warm blood, high metabolism, and more complex behavior, quickly gained importance. They adapted efficiently to changing landscapes, conquered new habitats, exploited new food sources, and exerted increased competitive pressure on less active reptiles. The Cenazoic era that followed saw birds and mammals dominate the terrestrial fauna. Among reptiles, only a few groups survived. The squamates, lizards, and snakes, relatively small and

mobile. turtles protected by their shells and a small group of aquatic arcosaurs, the crocodiles. Today, reptiles include various groups such as turtles, crocodilians, snakes, and lizards with about 10,000 identified species. Turtles number about 340 species, crocodilians 23, snakes nearly 3,000, and lizards over 4,000. These reptiles play an essential role in ecosystems. They regulate prey populations, control pests, participate in pollination and seed dispersion, and serve as indicators of ecosystem health. [Music] Previously we saw While the Paleozoic meaning ancient, then the Mesazoic meaning middle. Now we come to the Cenazoic which could be defined as recent. This

period which continues to this day began in the aftermath of the dinosaurs some 66 million years ago. Cenazoic meaning recent life or new life comes from the Greek chinos new and zo life. This gives you an idea of the new departure in biodiversity during this period. The cenazoic is divided into two major systems. The first is called the paleog gene and includes the paleocine, eosene and oligosine. Next comes the neoene which comprises four periods. the meiosene, the piocene and finally the quadinarya which includes the pletosene and the [Music] holosene. Geographically speaking things have changed and

had a major impact on climate and by extension flora and fauna. Pangia is no more and continental drift continues. Gondana land is increasingly fragmented, cracking on both sides. Australia drifted northwards while Antarctica took its place at the South Pole. The detachment of Australia and Antarctica and the creation of the Drake Passage led to a significant cooling of our planet. As a result, the climate is noticeably colder in some places while in others it is warmer and wetter. Towards the end of the paleo gene during the oligosene, sea currents also changed particularly near South America and

the Antarctic. Indeed, when these two continents were joined, warm currents bathed the sides of Antarctica. These currents provided a warm climate for a rich jungle to flourish. But when the Antarctic broke away, it offered a passageway to the colder marine currents. The Antarctic circumpolar current is born. It brings Antarctica's deep, cold waters to the surface. Little by little, 33 million years ago, it became a veritable continent of ice. To sum things up, at the beginning of the Cenazoic, some continents broke away, others gradually dried up, and new land masses appeared, notably in Northern Africa and

Europe, which were once archipelos. During the Eioene, India and Eurasia collided, closing the Tethus Sea. Elsewhere on our planet, geological upheavalss [Music] continue. The Atlantic Ocean, for example, has settled comfortably between Europe and North America. The subduction of the Pacific plate beneath the Americas is causing the Sierra Nevada and the Andes to rise. These changes are not insignificant. Biodiversity is closely linked to geological and climatic factors. Continental migrations, ocean closures and openings, and other tectonic upheavalss have consequences for climate. The planet is warming. It's getting warmer, but it's also getting wetter. If the milder temperatures

of the Paleocene allow plants to develop and expand their territory, like our famous ferns we met earlier, the humid tropical climate of the Eosene is a real springboard for the development and diversification of [Music] vegetation. Interestingly, the diversification of these plants can be compared with that of mammals. [Music] To give an order of magnitude, there are around 31 species of mammal at the beginning of the [Music] paleocene. These animals took advantage of their strengths to survive, but also of the ecological niches left vacant after the disappearance of the dinosaurs. These are not surviving species that

simply escaped the global catastrophe, but new species. New leaf eaters that didn't exist before and are gradually taking over. By the end of the eosene, there were almost 120 species of mammal, four times as many as just a few thousand years earlier. Even flying mammals such as bats were present. The ascent is therefore [Music] meteoric. The main stay of this ascent is plants. As soon as they diversify, they open up new evolutionary opportunities, unexplored ecological [Music] niches. In the space of 700,000 years, a tiny period of time on the scale of life on Earth, flora

grew exponentially and above all diversified. Flowering plants, seeds, nuts, legumes, and even the first vegetables provided a varied diet that enabled many species to specialize. Some mammal species even went from weighing less than 600 g to over 50 kg or 110 lb in the same period. When we speak of the Mesazoic, we mean the era of the dinosaurs. The Cenazoic era on the other hand could be seen as the era of mammals as they managed to find their place on our planet during this period. However, it should not be assumed that mammals were the only

species living on planet Earth during this pivotal period. Reptiles as well as birds and giant birds in particular were also major groups to populate the land during this same period. [Music] The Cenazoic is divided into three major systems. Paleogene, Neoene, and quatinary. A few years ago, the Paleogene and Neoene were grouped together under the term tertiary era. But in view of recent discoveries, this has fallen into disuse and remains less appropriate than the Paleogene and Neoene, which stand for old genus and new genus, [Music] respectively. Let's begin our journey in Paleogene territory. The era stretches

from 66 million years ago to around 23 million years ago. This era is itself divided into sub periods so that we can better grasp the different evolutions over the 40 million years it defines. We speak of the Paleocene, then the Eioene, and finally the oligosine. Welcome to the very first period of the Paleo gene, the Paleocene. [Music] The vegetation of this period is quite similar to that of a tropical rainforest. Made up of giant trees 40 m or 88 ft tall. This forest is home to sassifras walnut and even tropical chestnut and seoia trees which

are colonizing more and more territory. Beneath these giants are smaller trees and shrubs such as ficus, palms, and of course our famous tree ferns. The ground was covered with ferns such as this asplenium, providing shelter for many species, but also allowing many insects to proliferate. In the marshy areas bordering the lake, the vegetation is a little different with tyas, reeds, and waterlies, for example. There are also a few tall trees such as cyprress and nisa. In other more aid zones, the first cacti make their first appearance. Plant cover diversifies according to climatic conditions and geographical

zones. Little by little, new species take the place of plants less able to survive and develop. But like any self-respecting ecosystem, climate, flora, and fauna are closely linked. So, it's only natural that fauna should adapt, specialize, and diversify as plants [Music] evolve. Of course, many mammals were present in the Paleo gene. In fact, they were the dominant group in the Cenazoic despite the large number of birds and insects. [Music] In fact, the Cenazoic is often referred to as the golden age of mammals or the golden age of the term mammal is wellknown, but theion is

less so. It defines and groups together the three main types of mammal found on our planet. We speak of etherans for placental mammals, mththerans for marsupials, and prototherans for monotreams. The monotreams, like the platypus, are the most unusual mammals in the Theion group. It's a mammal, but strangely enough, it lays eggs. Let's take a look at some placental mammals first. They come in all shapes and sizes. As you'll see, there are small quadripeds like this propelliotherium ancestor the horse barely 60 cm or 24 in at the withers, as well as large mammals like this one,

which weighs in at around 2 tons and is almost 4 m or 13 ft long. It's an uentthetherum. If uenttherum has generous measurements to say the least, this animal of the dinosera group, also known as uenttheres, was originally much more modest in its lineage. Early species measured just 175 kilos or 390 lb. That's a lot, but not much compared with the 4,000 kilos or 8,800 lb of muscle it now [Music] displaces. At that time, you could also have met a phenotus. It's probably one of the oldest undulates known today, about the same size as our

present-day tappers. But we'll come back to the undulate group a little later. First, let's look at the mammal group in the broadest sense. There are three types of mammals. Placentals, marsupials, and monotreams. From the Paleocene onwards, the rise of mammals has been quite meteoric. Two lineages quickly emerge within the group. the creodants which generally led to carnivores and the condolarres which led to herbivores and omnivores. Fenicotus which we've just seen is one of the condolarres. Its teeth are adapted to chewing plants. If you take a closer look at its feet, you'll see that it has

five toes on both front and hind legs, each fitted with a small hoof during the same period, but not sharing the same environment. You could have come face to face with a corifodon if you adventured into the marshes of Europe, China, or even North America. It feeds on aquatic plants. The corifodon is very impressive, yet it too is a herbivore. Its musculature and jaw are impressive. 500 kilos or,00 lb for 2.5 m or 8 ft in length. Are such prey safe with such an imposing body mass? No, not necessarily. It all depends on the predator

and its capabilities. A carnivore 14 m or 46 feet long, 80 cm or 31 in wide, weighing up to 1.5 tons with a 40 cm or 16in cranium, and razor sharp teeth could take on such prey. Titanoboa Sarah Jonensis meets all these requirements. Unfortunately for our corifodon, living near rivers in present-day Colombia, it is the most imposing snake the world has ever known, feeding on giant freshwater turtles and even nearby crocodiles. [Music] That's not to say that the only real predators worthy of the name were reptiles. In the paleo scene, there were many other dangers

faced by terrestrial herbivores. While many mammals are still veget, granavores, or insecttovores, there are some pretty impressive carnivores in their group, too. Arctic Scion is a fine example of the transition between these two regimes. The size of a large dog, it weighed up to 50 kg or around 110 lb. Equipped with robust mullers for crushing and powerful masticatory muscles, it is able to tear off leaves and chew efficiently. Yet, it has impressive tusks visible on the mouth side. Are they canines? Nothing is less certain, but scientists believe that this rather unspecialized animal probably had an

omnivorous diet. And it is assumed that it was in the process of switching from a carnivorous to a vegetarian diet. Other mammals with a similar silhouette had a meatonly diet. These are the Mesanakians. They are nicknamed hoofed wolves. Their nickname is very telling. They have the silhouette of a wolf, but are equipped with five fingers. Then, as they evolve with four fingers ending in small hooves, they were very good runners and walked on their [Music] fingers. Native to Asia, they quickly established themselves as formidable predators. Dacus, a genus descended from the Mesanakians, gradually spread to

Europe and even North America. Another genus, Ankolagon, ventured as far as New Mexico and was the size of a bear. Dicactus was closer to the size of a jackal. Like the other genera of the Messikian group, his dentic became increasingly differentiated and efficient. It has modified mers for shearing, slender lower mers for shredding, and sharp teeth for slicing. Andrew Sarcus Mongoliansis can also be found on the plains, weighing 400 kilos or 880 lb and measuring around 4 m or 13 ft long and nearly 2 m or 7 ft at the withers. It was a very

impressive predator. Later, Magistotherium osteoplastus, a member of the group that appeared in the Meioene, was even more charismatic and dangerous, weighing up to 800 kilos or 1,800 lb depending on the source. Mammals adopt different diets, morphologies, and environments. Their diversity is great. As early as the beginning of the eosene, the second period of the paleo gene, we can even see flying mammals. The bat in question is via sigay. Taking advantage of caves for shelter, it fed on insects. What's really interesting about this bat is its ability to maneuver in flight. While far from being able

to perform the feats of some of today's birds or even bats, it was nonetheless very gifted for a group of recently flying mammals. Paleo gene birds, on the other hand, were not always gods of the skies. On the contrary, some enjoyed the land far more than the air. Mammals may have diversified greatly and are quite numerous in the continent, but they are far from being the only tenants of our planet. Giant birds, some of them also known as terrible birds or terror birds, have largely earned their place on Earth. Just a few million years ago,

terasaurs dominated the skies. The Cretaceous Paleogene biological crisis having passed, things have changed quite a bit since then. With flying reptiles gone, an ecological niche remained. It was the dinosaur avens who would evolve into birds that would fill the gap. Many of them took to the skies, but a few preferred life on the ground. [Music] birds underwent an incredible radiation during the Cenazoic. Several groups and families underwent a meteoric rise. First of all, there are the gastronithids which we'll talk about in greater detail later on which are large land birds. Then there are the platopteri

which are large seabirds. Then there are what we might define as primitive penguins, but also pelagronithids, bronithids, and forest rids. It's the latter that will be nicknamed the terror birds. While some birds are herbivores, forest rids are not. They are even reputed to be super predators. Unable to fly, they measure up to 3 m or 10 feet in height and can weigh up to 200 kilos or 440 lb. These terror birds live in South America. One of the largest is Titanis Weri, but it arrived on Earth a little later in the Neoene. [Music] These birds

established themselves slowly but surely during the first part of the Cenazoic, but it was during the second part that they were at their most fearsome. Before reigning terror in South America, these flightless super carnivores were found elsewhere in the world. The oldest known forest rid lavocatavas is thought to have been found in Africa. Scientists are still investigating the reasons for this possible migration. Eluththeronus, also relatively large, could reach 1.5 m or 5 ft in height and was found in Europe, notably in France and Switzerland. [Music] Let's take a look at two other very characteristic birds

of the period which don't belong to the forest rasid group but to the gastronith. The first is a giant bird called gasttoris while the second is datrima. Gasttoris is very tall around 2 m or 7 ft. It doesn't fly, but it runs. Its diet has long been the subject of debate. It has to be said that given its silhouette, scientists were keen to count it among the predators. And yet, its morphology left a few doubts. In the end, it was Deline Angst and Eric Buffet, two specialists in paleontology, who succeeded in demonstrating through their various

studies that it was indeed a [Music] planteater. As for the second data, you're probably thinking that they're eerily close in physical terms. Well, you're absolutely right. To tell you the truth, they're even the same animal. In fact, back when prehistoric animals were first discovered in the 1800s and 1900s, on more than one occasion, two different scientists described and named similar [Music] dinosaurs. Sometimes they were closely related dinosaurs, but of different species. For others like Gastronis and Datrima, they were indeed the same animal species. Over the years, the name Gastronis has stuck. Let's leave the birds

for a moment and get back to some reptiles. Apart from our famous Titanoboa, others also crisscrossed the world's continents and waters during the Paleocene. [Music] Many reptiles disappeared after the Cretaceous, including flying and marine reptiles. But a few groups managed to establish themselves more permanently. These include crocodiles, snakes, lizards, and turtles. Here in this paleogene region close to bodies of water, we can admire animals such as this diploinodon, part of the illegator family, or this eoconstrictor snake. At the end of the paleocene, temperature soared. We're talking an extra 8° C or 14° F. This is

enormous. Many species will not survive this turnaround. This fracture will lead to a so-called minor extinction. Although not on the scale of the end of the Cretaceous, for example, it nevertheless marked a new turning point for flora and fauna. This episode marks the end of the Paleocene and the beginning of the eosene. Temperatures fell again for most of the rest of the Cenazoic, even leading to an ice age at the end of the period. During the Paleo gene, the seas continued to recede and new land appears again and again. When we look at the planosphere,

we see that the position and shape of the continents increasingly resemble what we know today. India comes into contact with the Eurasian plane and the Tephus Ocean is partly closed. This marks the beginning of the Himalayas, one of our highest and most beautiful mountain ranges. Further north, Greenland also broke away from Europe. Other animals appeared during the eosene and oligosine. Predatory mammals like Andrew sarcus mongoliansis. It is one of the largest carnivores of the eosene plains. It can grow to 4 m or 13 ft and weigh around 400 kg or 880 lb. Other bats have

also joined the family such as the archonic terrace lasedon undoubtedly a carnivore. And then there are groups that were already present but which managed to conquer an everexpanding territory at the expense of other species such as [Music] rodents. In the living world, it's all a question of adaptation and survival. When a species fails to adapt, it becomes extinct. This is what undoubtedly happened to the multi-tuberculates and what served the cause of the first rodents to become established. These small mammals, like those of the cryptobatar genus, hopped about like gerbles. They were omnivorous and had teeth

quite similar to rodents. Scientists believe that the disappearance of the multi-tuberccullets is linked to their competition with rodents. Both groups occupied the same ecological niche. As rodents are equipped with hyped and chisel-like incizers, they seem to have fared better than multi-tuberccullets. Without this key evolution, multi-tuberccullets would have disappeared from the landscape. Apart from rodents, we're also seeing more and more lagamorphs, i.e. rabbits and [Music] hairs. But the great revolution of the eosene was undoubtedly the appearance of the primate lineage. They were quite similar to our present-day lemurs. The canopy has become much richer and more

diverse over the last few thousand years. There are more and more deciduous trees, but also flowering trees and above all fruit trees. And yes, let's not forget that angioperms, i.e. flowering plants have developed considerably and expanded their territory. All this food is a godsend for these primates who make their home high up in the trees. The first mammals capable of climbing trees had to come down to feed. But there are plenty of predators down there. To offset the danger, some mammals developed finer motor skills in the trees, but also found food in them to increase

their chances of survival. Their vision becomes sharper. Their legs become hands. An opposable thumb appears. They gain balance. In short, they colonize the trees and offer themselves an impregnable kingdom in the heights thanks to new physical abilities. As far as we know, Purgatorius is probably one of the oldest representatives of our primate ancestors. This small animal lives in North America. The one hanging over our heads is a Darwinius Masile. It belongs to the Notharkai family and comes to us from Europe in Germany. Notice the opposable thumb. As you can see, their morphology is quite similar

to that of today's lemurs. Slender, slender, and agile. Eocene primates found in Asia, Africa, and North America already display most of the group's typical features. Prehensile feet, binocular vision, and nails instead of claws. Most eosene primates, especially those from Eurasia and North America, belong to several groups. The most important being the notharki and omo midi. Many primates will disappear after the eosene. At least most of the taxa native to North America and Europe. The surviving taxa will be of Asian and African origin. Some eosene mammals are particularly important for the rest of our history. Pacetus,

for example, is probably a distant ancestor of whales. Yes, despite what you might think, the ancestor of this enormous aquatic animal actually lived on land, not in the ocean. Hierrotherum is also an emblematic animal of the eosene, whose genealogy led to animals we still know well today. Hitherium is thought to be one of the most distant ancestors of the horse. Propalia and Paleoththerium followed our would be related to our present-day elephants. Although I agree that it looks a lot like rhinoceros. The distant relative of rhinoceroses would be this one, Megazeraps, a brontoerin. In the same

group, the brontothereroids also include embeotherium with its nasal horn and 2.5 m withers. Both belong to the parasidactyl, i.e. undulates with an odd number of digits such as horses, rhinoceroses, and tappers. Conversely, those with an even number of digits include bovids, servids, giraffes, camelids, and incredible as it may seem, citations. Megaserops, on the other hand, has an odd number of toes and is therefore a parasidactyl like horses and tappers. Speaking of tappers, here's a member of the Tapira, Loiodonte, whose typical representative is Loiodon, a close relative of today's tappers. During the Aligga scene, grasses became

increasingly abundant and a few small meadows appeared on the horizon. This was an environment that had not previously existed on Earth. Unulates or hoofed mammals were the first to colonize this new ecological niche. Several species of rhinocerati, aquidi, and chilicaphariaday are found in Europe, Asia, and even North America. In Europe, these are mainly chelicapharia day such as chelictherarium. It measures around 2.5 m or 8 ft in length and weighs no less than 350 kg or 770 lb. In North America, it's the ecquids that are evolving quite marketkedly. New forms are appearing such as messahippus which

is becoming increasingly similar to today's horse. We can see that not only its silhouette has evolved but also its skeleton. The preolars are molar form. This makes it easier to crush even tough leaves. In Asia, rhinoceratids are particularly abundant. Heracaserium, for example, is one of the species that took up residence in Asia during the illegene. These large herbivores are beginning to reach some pretty impressive sizes. This one reaching 5 m or 16 ft in height and no less than 15 tons. Not all of them have such dimensions, however, and there are many smaller rhinoceratids developing

in the [Music] region. The development of grasslands and the expansion of flowering plants also served another animal group, [Music] insects. By the cretaceous, numerous groups had already emerged. Beetles such as beetles and ladybugs could already be observed at this time. There were also dip terra which we often like a little less because of their sting as in the case of the [Music] mosquito. The last to arrive were the himoptera, including bees and wasps. This little world is about to welcome newcomers. the lepidopodoptera which includes [Music] butterflies. During the oligosene, we meet up with our pacetus

again. Well, not quite. We're going to meet one of its descendants. And as you can see, this one has already returned to the water. We're talking about Ambilisetus. His name means the walking whale. This gives you an idea of some of its present and future characteristics. Ambilisetus like Himalayas and Indoetus is able to take advantage of both terrestrial and aquatic environments as was once the case for certain amphibians. This evolutionary perspective may have its origins in the emergence of new land masses and the gradual retreat of the sea in these Eurasian regions. A little further

out to sea, we may also come across a cotillar. The kotilloar is a type of dolphin that is physically very similar to our modern-day dolphins. In fact, according to scientists, kotillocars like them were probably capable of echolocation. But these marine mammals aren't the only ones in the water. There are large predators to be wary [Music] of in the waters of the Paleo gene. Over a period of almost 25 million years, condrifians, cartilagenous fish like the shark dominated the world's waters. With the great diversity of actinopterigians, i.e. Rafe and fish. These great predators were spoiled for

choice when it came to their menu. Food galore. Hunters inevitably thrive and sharks find themselves at the very top of the food chain. But that doesn't stop the few marine mammals that thrive beneath the waves. Descendants of Ambilisetus and other primitive whale congeners for example continue to evolve. Towards the end of the iligosine basillosaurus appeared. He belongs to the archioet group. Far from the image we have of a marine mammal. It was once considered a reptile. Scientists named it Basillosaurus Sorus referring to its reptilian condition. It has to be said that its silhouette is almost

identical to that of a snake. Yet many years after its discovery in 1834, study of its skeleton showed not only multi-rooted teeth and a single jawbone characteristic of mammals. What really confirms the diagnosis, however, are its forlims, which truly characterize it as a marine mammal on a par with whales. In fact, it is a descendant of pacetus, an ambulacetus. This 20 m or 65 ft long citation is a much feared predator in the area. It has sharp deadly teeth. In the marine world, there are much smaller forms of life, particularly those belonging to the framina

family are also developing, completing the food chain. Framina Farera include numulotide and alvolinade. Now it's time to leave the paleog gene and see what awaits us after the neo [Music] gene. As we have just seen, the paleocene was marked by many changes both geographically and biologically. The end of the Paleocene marked the beginning of a new era for terrestrial flora and fauna. The Neoene begins on the Mayio scene. A number of geological changes continued. The face of the earth gradually changed. Even though this new geographical facet began several million years ago, the planet continued to

cool and the Antarctic continent became covered in ice. At the end of the pio scene, pack ice even appeared at the North Pole. Then during the Neoene, land routes began to take shape, inexraably impacting biodiversity. These routes brought South America into contact with North America through the ismas of Panama, Eurasia with Africa, the closing of the Tethus Ocean, which later became the Mediterranean Sea, and the appearance of the Strait of Gibralar. These new contacts led to migrations, but also to competition. Yet another minor biological crisis was already on the horizon. At the end of the

neoene, some species become extinct, unable to adapt to new territories or to compete, while others diversify and expand their territories. Marsupials and placentalss will be the big winners in this new adaptation. These changes combined with the isolation of certain continents apart from Europe and Asia which remain united led to the development of environments, fauna and flora specific to each continent. In South America, predators are limited to animals belonging to the marsupial or giant bird groups. Primates thought to have originated in Africa are also present in North America. The evolution of ecids continues a pace from

the first horse to the only surviving genus Ecquis. Height at the withers increases progressively. Another evolutionary characteristic of ecids is their feet. At first, only three of the four toes were preserved. Then a single toe became the hoof. At first, they eat soft food such as buds or young leaves. Then their teeth evolve to better crush grasses and rougher leaves. Let's go back 23 million years to the very beginning of the Neoene to understand why this period of history was so enriching for biodiversity both on land and at sea. [Music] Still in the Cenazoic era,

after having traversed the Paleo gene, we now continue our journey into a new era, the Neoene. It began 23 million years ago and ended 2.5 million years ago. Like the Paleo gene before it, this system is also subdivided into different periods to better understand the 21 million years it defines. The meioene the first period of the Neoene corresponds to the major part of this period spanning the first 18 million years. It is divided into six stages. The following 3 million years correspond to the pioene with two [Music] stages. Many other surprising and impressive animals await

us during the Neoene. Before meeting them, let's take a look at their environment and the characteristics in which they [Music] evolved. Continents broke away from each other. New lands emerged and temperatures dropped throughout the period. Depending on the geographical zone, warmer and wetter environments appear while others are colder. Geographically speaking, with less than 23 million years separating us from our present era, the position of the continent seems very close to the usual continental configuration we are all familiar with. If we're a little more observant, we can see that there are still a few small points

that are far from settled. Greenland, for example, is not yet covered by its Neoene ice mantle, nor are the continents of South America and North America yet connected. After this brief geological and climatic overview, let's take a look at how flora and fauna evolve during the [Music] Neoene. After taking a dip in the ocean, here is the landscape you might have discovered during the Meioene, the first period of the Neoene. Although some species differ, you'll no doubt recognize the large families that live here around you. There are corals and sponges, algae, mollisks, arthropods, and lots

and lots of fish. As we saw during the paleo gene, rayfinn fish diversified greatly, providing an important ecological niche for many predators. Since the beginning of the cenazoic, marine reptiles have no longer been the main beneficiaries, but condrithians, cartilagenous fish, and in particular, primitive sharks. They were already present in the ocean 300 million years earlier as early as the Deonian for the oldest and the perian for the so-called modern sharks i.e. well before the dinosaurs. However, they were not in a position of strength and face stiff competition. first with large arthropods such as uripids, then

with messoic marine reptiles, veritable sea monsters. During the Cenazoic, however, competition diminished, if not to say became virtually non-existent. They can evolve at will, and it's not the most impressive of them all, having inspired cinema's greatest sea terror, who will say otherwise. Is it worth introducing the monstrous megalodon? The otudus megalodon shark is a member of the Ottoant family. This impressive and intriguing family emerged after the Cretaceous crisis. It is therefore very recent yet no less evolved and specialized. Megalodon live in shallow marine areas and warm waters. Other species, notably pinnipedomorphs such as this an

alios are also making their grand entrance into the marine fauna. It could be the origin of the pinniped genus. It had a short tail, developed muscular limbs, and webbed feet for swimming. It was already well adapted to the aquatic environment with vibration sensitive whiskers, an inner ear capable of hearing underwater, and large eyes. However, this carnivore probably had to consume its meal on the surface, as its dentic, notably its sharp carnivorous teeth, did not allow it to do so in the water. So, it went to the beach to enjoy the fruits of its hunt. [Music]

Apart from the megalodon, these animals could come across other predators just as frightening as they were impressive. But they weren't out of the woods yet. Another large predator sailed here and there in search of prey to sink its teeth into. Leviatin Melvelli is a sperm whale measuring around 15 m or 50 feet in length with a skull alone measuring 3 m or 10 ft in length. Apart from its impressive length, you can see that its skull is heavily armed with a battery of teeth over 30 cm or 12 in long. Enough to make any prey

that crosses its path shutter. Unlike today's sperm whales, which gobble up giant squid, the livatin devoured whales. During the Paleogene era, we mention another family, the citations. By the time we left, this family was slowly but surely evolving. So what happened to them afterwards? To give you a little clue, scientists often refer to the citation era when they talk about the meioene. As you can imagine, this was an extremely positive time for this group. Like the mammals before them, the citation order underwent such a rapid growth in species that two lineages were soon established. On

the one hand the adonttocetis the tooth sitations and on the other mysticetes the boline whales. The adonttoacetis or tooththed whales include dolphins, sperm whales and orcas which feed on fish, birds and even a few mollisks. Mysticetis with their filtered bell plates have a more restricted menu generally limited to krill. The first mysticetis however are more likely to have teeth than boline plates even if a lineage differentiation is already apparent. This is the case of lanocatidi, etioetidi and even janisetus which date from the iligosine. During the meiosene eelene optera could be observed but it was in

piscoelina that the boline plates were most clearly visible as well as in titanicetus. Now, it's time to go back up to the surface to see how vegetation and fauna have continued to [Music] evolve. The Paleocene was also a pivotal period in the history of mammals. In a short space of time, they diversified and specialized, growing from a few grams to several hundred kilos. Some even went from being vegetarians to omnivores or carnivores. Initially, it was plants among other things that provided the springboard for such evolutionary radiation. Although their presence on the planet is still very

important at this precise time, they are not alone. In addition to birds, they include numerous reptiles and a host of insects of all kinds. This new diversity in the world of plants and insects further encouraged the diversification of certain existing paleo gene groups, notably the herbivorous, grivorous, and frugorous mammals of the heights with a great period of evolutionary radiation in monkeys and bats. On land too, mammals still have the monopoly. The biggest predators apart from the terror birds of South America are mostly [Music] mammals. Some of them can be quite surprising. The wthogs we know

are generally more prey than predator. However, in the Mayio scene, it wouldn't have been a good idea to come across Antilodante. With its imposing size, it could rival a bull in terms of mass and power. The largest of its kind, Antelodon Magnus, could reach 2 m or 7 ft at the withers and was probably close to a ton of muscle. But its most impressive feature was its jaw. Like all mammals, its dentition is differentiated. So it has an armada of teeth in its mouth, enabling it to take on any prey in its hunting territory. It

is tall on its feet and reputed to be a good runner. Scientists are unsure whether he was a carnivorous hunter, a scavenger, or a bit of both. In view of his build, power, and sharp teeth, we're tempted to think of him as an outstanding predator and the perfect [Music] hunter. However, some scientists are more inclined towards the opportunistic scavenger hypothesis. It's true that some of its teeth are perfectly shaped for crushing bones, making it the ideal scavenger. In any case, it remains an impressive predator. Just a few meters away lives the hyenodon, which isn't very

friendly either, to be honest. As for its diet, this time the scientists are positive. It's a carnivore and a very good predator at that. Weighing up to 500 kg or,00 lb, it is muscular with powerful legs and five toes. Armed with sharp claws, the long narrow jaws were powerful and used for biting, neck breaking, crushing, and crushing. With its eight razor sharp teeth, it rarely lost a fight with its prey. Other lesser predators were just as agile and powerful in Europe and Asia. Sansanos smileus, for example, is a member of the Barbarara Feladay family, weighing

around 80 kilos or 180 lb with relatively short but powerful and muscular legs. Homothetherum was a member of the saber-tooth feline family made famous in prehistoric films and cartoons. Saber-tooth felines are known as mccera dantine. Weighing up to 250 kg or 550 lb and reaching 1.8 m or 6 ft at the withers, these felines were quite powerful and impressive. The incizers and lower canines formed a powerful piercing device. Once the prey was caught in the predator's powerful jaws, there was no chance of escape. It also has long slender legs and it seems a very large

nasal opening. This means it had a fast and efficient oxygen supply and its legs were formidable when running. Elsewhere on the globe, predators were of a very different kind. In South America, marsupials and terror birds still have a monopoly on the [Applause] territory. Among carnivorous marsupials, bore hyena comes to mind. With its long, powerful neck and jaw with sharp, jagged teeth, it was an impressive hunter. Its name echoes the hyena, as the front of its body, notably the head and long neck, are reminiscent of this opportunistic African predator. Ostello hyena, also a member of the

sporacodont group, had a short snout, strong canines, and mullers for crushing. It was one of the largest predators in its environment, weighing up to 70 kilos or 155 lbs. It must have been able to break bones just like hyenas. Yopsis lureroscerus can also be mentioned in the same [Music] genus. Among giant birds, we can turn to Forest Racos to learn more about this group. He is considered one of the largest predatory birds ever to have existed. He belongs to the group known as terror birds which also includes Titanis and Kolen. Cororus Rakos measures around 2.5

m or 8 ft in height and can weigh up to 150 kg or 330 lb. The most striking feature is its beak. It's huge and above all hooked. To help him in his hunt, he also had a pair of claws on his wings and long legs that enabled him to run, according to scientific estimates, at up to 65 kmh or 40 mph. Kolen was even bigger, reaching a height of 3 m or 10 ft. His head alone was 7 cm or 3 in long. He had the same physical prowess as his fellow Forus Rakraos, namely

the speed and weapons to take on prey such as rodents, reptiles, and even small mammals. As we have already seen with the end of the paleo gene and the beginning of the Neo gene, flora and fauna became increasingly differentiated according to region and location. climate, but also the isolation of certain continents plays a part in this specialization. And these different [Music] radiations traveling around lakes and forests during the Mayio scene, here are some of the animals you might have come face to face with. Some are calm and peaceful, others fierce predators. Several members of the

rhinocereted family lived in the Bosnia Herziggoina region including Brachaporum brachipus, lettotherum sanseni, placia kerthetherum volcanicum and hispanothetherum. A little koala can be seen high in the forest in Australia. Towards the end of the meioene, as we shall see, some land masses dried up. Eucalyptus forests, on the other hand, expanded. This is undoubtedly what led one of the genera to specialize its diet with these trees in particular. Still in Australia, what could be likened to a muskrat also lived. This was a culta, a strict carnivore unless it was omnivorous. A few fossilized remains do not allow

us to define its diet with any certainty. Another forest animal, Plyopythecus. Plyopythecus is a monkey, a type of primate physically quite similar to the gibbons. Unlike gibbons, however, it had a very short tail. It is found in Asia but also extensively in Europe. According to some studies on fossils found, our plyopythecus may have been able to swing from tree to tree thanks to its long arms rather than relying solely on the dexterity of its hands and opposable thumbs. When an animal uses this tree to tree swinging technique, it is said to be able to branch

out. This is a major turning point for primates as they become increasingly agile at heights and can thus protect themselves from terror birds and other ferocious predators below. [Music] Speaking of canopies and tree climbing prowess, another animal, this time from South America, lived in the river plains close to the forests. We're talking about the giant sloth. In view of its size and weight, it was probably not, as today's sloths are, capable of living in trees. Several species of giant sloth lived in South America during the meioene. Megalonics is one of them. It had powerful claws

for clinging to trees and above all pulling food towards itself. Meggathereum was over 6 m or 20 ft long and probably weighed almost 3 tons. The advantage of his claws, but above all of his height, was the food he could reach. Very few vegetarians could reach such a height. So, he could occupy an ecological niche without worrying too much about competition. A little less tall, but just as impressive, is Aramtherium Laurelardi. It measured 2 m or 7 feet at the withers. But when it stood on its hind legs in search of food, it displayed 5

m or 7 ft of robust muscle and bone structure. Still among the predators, but a little more generous in size this time. We can also observe in North America, Europe, and even Asia. Macarotus, a saber-tooth feline, echtherium, which belongs to the hyenas, and Amphicion. Amphicon is a subtle cross between a bear and a dog. Probably omnivorous, it had powerful paws and a thick neck like a bear, but a broad tail and wolf-like teeth. It could reach 600 kg or,300 ft making it a predator high up on the food chain. In Eurasia, it was able to

prey on species such as dicroseras, a small servid measuring 70 cm or 28 in at the withers. It is the oldest known antelid servid. On the plains of Africa, certain mammals began to grow in size, especially the genus Probosidians. Dinotherium is one of them. It is considered to be the largest land mammal ever to have walked the Earth. According to sources and descriptions, Dinotherium could have measured around 3.7 m or 12 ft in height and weighed between 10 and 14 tons for the largest males. One of the main differences between dinothereum and our modern elephants

is its trunk which is shorter and its tusks which are not attached to the maxill as is the case with elephants today but to the mandible i.e. the lower jaw. In Europe and North Africa archabelladon was a genus of probacidians smaller than our elephants. Even so, it weighed between 2.5 and 3.5 tons. Closest to the water is a hexaprodon. This genus groups together a large number of extinct species of hippopotamus. The main common feature that gave the genus its name is the jaw. These animals have three pairs of fairly pronounced incizers, not to be confused

with the rhinocerated species we encountered earlier, which could also share the same environment, notably swampy forests and somewhat drier open plains. In the fresh waters, it was not uncommon to see an esceris. This freshwater dolphin belongs to the Platinest family, the river dolphins. Our little tour of the different environments of the meioene is coming to an [Music] end. Why subdivide the Neoene into two parts given that one of them was only 3 million years old? Even though it's relatively short, it's still very important. To begin with, we need to look at the Earth's temperature and

dryness. The climate became colder and colder, and forests gradually gave way to savas and grasslands. This process had already begun during the Maya scene, but became much more pronounced during the pioene. This drastic change in the landscape had a significant impact on the fauna. The drying up of the land is very violent. The Tethus ocean, for example, disappeared completely, replaced by a white desert of salt. The sea loses up to 1 meter per year with all the direct and indirect consequences this entails. This episode is known as the Masonian salinity crisis. In addition to these

climatic and geological upheavalss, there's the evolution of particular group and above all the emergence of a new genus during the plyio scene that is of great importance to mankind. Who are we talking about? If I answer to my does that give you any idea? Around 7 million years ago, a primate close to the origin of the human lineage was discovered. Measuring 1 meter or 3 ft in height, it was bipedal and belonged to the homminid family. It shares many of the characteristics of the hominins i.e. the subtribe comprising the homminids and the genus homo. If

we study dentition carefully, we can see that tooth enamel thickness is between that of the pang genus i.e. chimpanzees and that ofcus. Another important fact in the evolution of this new lineage is bipedalism. According to its skeleton, in the presence of the fammen magnum, the spinal column was upright implying possible locomotion on the two hind legs. Evolution towards the Oroalopithesine Kenyanthropus and then towards the homogeneous is underway. Humanity is in the process of being born here in Chad. Tomi took his first steps on two legs here on the outskirts of Tauros Manala in the Jorab

desert 7 million years ago. Though the landscape was very different from the one you see today in this part of Africa, a forest had grown up around the edge of the lake. In this forest, you could find tall trees, shrubs, and leguminous plants. Nearby, a savannah landscape could also be seen. Probaccidians, unulates such as giraffids or ecquids and bovids enjoyed the area when saber-tooth felines such as macarotus or hyenids were not around. To understand the appearance of tomi we need to go back in time. 16 million years ago in the meioene the pon the Asian

lineage of orangutang separated from the homminina the euroaffrican lineage of gorillas chimpanzees and humans. Less than 10 million years later, Tumi upset the established order of the hommin. The latter diverged into two new lineages, the Panin or chimpanzee lineage and the hommin or human lineage. [Music] Sahalanthropus Chedenzis led the lineage to Orurin Taganis, a hominin aged 5.9 million years. Then a little later to Artipythecus Kadaba, aged 5.8 to 5.5 million years. The lineage continued to evolve over the millennia. Around 4.2 2 million years ago oralopythecosines made their appearance with oralopythecus animensis the oldest known of

the genus. Then 3.2 million years ago in present-day Ethiopia Lucy entered the human story. This oralopythecus apherensis turned the scientific world upside down and shook all the beliefs we had previously held about this lineage. Based on in-depth analysis of the fossil remains, it would appear that Lucy was 25 years old. The fossil is quite complete with around 40% of the bones recovered. This provides a sufficiently precise picture of the genus to which she belongs. The discovery was made by a project involving some 30 Ethiopian, American, and French researchers, co-directed by paleoanthropologist Donald Johansson. He was

accompanied by geologist Maurice Taib, artist and paleontologist Claude Gilamott, paleontologist Coppins, and student Tom Gray. A few years later, just 4 km away, drowned in the Aash River, the skeleton of a three-year-old child named Salam, meaning peace, was also unearthed. These lived in present-day Africa 3.2 million years ago at the end of the pioene. Lucy evolved in this savannah environment, able to live both on the ground and in the trees. She was also able to move into the rainforest so necessary for feeding. Grasses, succulents, insects, and perhaps even a few small animals completed her daily

menu. It is possible that one of these oralopythecus species was the origin of the homogeneous which appeared in Africa between 3 and 2 million years ago. Studies and research are continuing on this subject. Our journey ends on this African landscape and the new hope of the name Lucy. The rest is just the beginning of a new page for mankind and the story of a new journey. [Music]