When India Was An Island

stay tuned for the end of the episode for a mammoth announcement we need to talk about the biggest breakup of all time the breakup of the supercontinent Pangia around 200 million years ago the ground split open and the crack grew until it reached all the way across the supercontinent eventually flooding with seawater this Seaway connected two ancient oceans together separating laasia in the north from gandana in the South and it also separated all the plants and animals that lived on each this was a major fork in the road of evolution life became divided into two

different groups but they didn't lose touch forever the subcontinent of India became a sort of Island messenger between the two halves of the globe breaking away from gondwana and traveling 9,000 kilometers across the sea to collide with laasia this journey took 35 million years but the plants and animals that went along for the ride when Indi became an island eventually reunited with their long lost Northern relatives kind of because a lot can happen over that much time and ultimately when India smashed back into Asia it really just traded one form of evolutionary isolation for another

when the breakup started gondwana was made up of what is now South America Africa India Antarctica and Australia Africa Madagascar and India were one neighbors that is until sometime around 120 to 100 million years ago when a rift formed breaking India and Madagascar away from Africa and isolating all the gondwanan plants and animals living there then around 90 million years ago Madagascar split off and India was basically on its own now we know that Island isolation often leads to Unique Evolution think of the galpagos or Madagascar itself for that matter this is alop Patrick's speciation

where a physical barrier creates a separation that leads to new species and during the Cretaceous Period the island of India was home to a bunch of animals that were suddenly cut off from the rest of the world everything from frogs lizards Turtles snakes centipedes and crocodiles to Plante eating sorop pods like the gigantic janosa and meat eating therapods like the two-legged indos suus and rajasaurus there were even early m like gondwana the an extinct group that looked kind of like big rodents but Cretaceous life on India wasn't all an island paradise as the subcontinent was

just beginning a wild tectonic ride when it first broke away it was traveling at around 5 cm per year that's already pretty fast today the average plate moves at around 1 and A2 cimet per year and India was so fast because it's very thin only 100 kilometers thick compared to other plates like Africa at 300 kilm the gigantic plume of hot material that had emerged from the mantle and caused the initial breakup of gondwana had also melted rock off of India's base and then 80 million years ago the plate accelerated to a Sprint moving at

a rate of over 14 cm per year this is because it was being pulled by two parallel subduction zones where one plate slide beneath another and sinks into the mantle one of these was in the middle of the Tey Sea and the other was along the coastline of laasia because they both pulled in the same direction like two people on the same side of a tug OFW this yanked India northward exceptionally fast India then sped through different climates putting pressure on the plants and animals to adapt to new conditions or perish around 67 million years

ago the plate began to slide over the reunion hotspot fueled From Below by a massive plume of magma and the force of this plume beneath the Indian plates sped up its Pace even more it also triggered a massive volcanic eruption known as the deck and traps this was a flood Basalt erupting lava literally flooded the Earth's surface it poured out enough lava to cover an estimated 1.5 million square kilm an area the size of Mongolia this amount of lava could fill the Great Lakes nearly 50 times over today the remaining Basalt still covers 15% of

Modern India and this volcano came at the worst possible time because one of the main eruptions lasted 700,000 years and began just 300,000 to 400,000 years before the Earth was hit by the asteroid that led to the Cretaceous paleogene Extinction 66 million years ago and while the deck and traps didn't cause this Extinction many scientists think they played a big role in worsening it the eruption spewed out toxic gases like Mercury it also released aerosols that spread out in the atmosphere reflecting sunlight and suddenly cooling the planet but when these cleared the carbon dioxide released

by the same eruption also warmed the planet over the longer term the temperature had come back down by the time the asteroid hit but this roller coaster of climate meant that life was already under incredible stress and in addition to feeling these Global effects life on the island of India also had to contend with lava flows and nearby volcanic gases living basically right on top of the deck and traps meant that the effects of the mass extinction were Amplified nearly all vertebrates were wiped off the subcontinent the few survivors included frogs snakes and Sicilians the

worm-shaped amphibians all of these can burrow into the ground for protection so that might have been the key to surviving both a massive volcano and an asteroid impact after the dust settled there's about a 10 million year Gap in our understanding paleontologists just haven't found many fossils from this time in India so we pick up the story again during the EOS scene around 55 million years ago and the fossils from this time make it clear that the island of India played an important role in the evolution of placental mammal but where did these mammals come

from in the first place one idea is that they could have originated in gondwana and survived the Cretaceous paleogene Extinction in India known as the out of India hypothesis but most scientists disagree see India broke away before mammals with placentas evolved and since the vast majority of modern mammals including all modern Indian mammals have placentas the ancestors of these mammals would need to have somehow made it to the island of India so researchers think that despite being in the middle of the Tey sea at the time it's more likely that India wasn't completely isolated as

the subcontinent neared the Asian mainland but before it had fully docked some animals were able to migrate from the mainland to India they likely did this by hitching a ride on floating objects or jumping between smaller islands like stepping stones and once these manimals made it ancient indan India was home to some big evolutionary milestones in fact both horses and whales can trace their Roots back there for a long time The evolutionary history of ulates mammals with Hooves wasn't well understood see fossils of both groups of ulet those with an even number of toes and

those with an odd number appear suddenly across multiple continents so where they came from in the first place has been a big question for a long time and a study from 2014 describing a 54.5 milliony old fossil of cambium in India provided an interesting clue this was a genus of four-legged herbivores that was an ancestor to the order of pareda the odd toad ulet today this order includes horses and rhinoceroses so this entire order could have originated in India as it was nearing a collision with Asia but what about the even toad ulates called artiodactyls

this group includes UD pigs giraffes and camels as well as whales and dolphins known as sattian who evolve from Land dwelling mammals and Indo highas was one of these mammals Indo highas looked kind of like a deer with a long nose and thin limbs with Hooves but it was around the size of a cat its fossils have been found almost exclusively in India and Pakistan suggesting this is where satti made their transition from land to Sea during the eosine and each stage of this transition can be seen in Indian fossils that is until 49 million

years ago when the protoc seids a group of extinct citations evolved then suddenly their fossils appear all over the world cations had gained the ability to spread out from the island across the world's oceans their ability to swim gave them a head start in terms of spreading out from India but the collision with Asia provided a burst of new landbased species in both directions India fully established a connection to the mainland around 45 million years ago which is when we see plants and animals begin migrating both out of and into the subcontinent one of these

groups was the dipterocarps a family of trees that can grow to over 50 m tall and today dominate Southeast Asian rainforests they originated in gondwana during the mid Cretaceous and were carried across the sea by India and some animals like the ulet originally came from Asia but continued their evolution on the island of India before dispersing out again others like the blind snakes centipedes and Sicilians first originated on gandana survived the mass extinction and diversified in India before spreading out across Asia after a very long fairy ride and the rate at which species migrated back

and forth from India to Asia continued to increase until 15 million years ago because while India's isolation and journey across the sea was a a unique tectonic moment that led to the evolution of equally unique animals it wouldn't be the last time geologic forces isolated India its collision with Asia built the tallest mountains in the world the Himalayas and just like oceans mountains create barriers between groups of species allowing them to evolve in isolation but how the Himalayas changed the world is a story for another episode here on eons we have made a number of

episodes about mammoths over the years and now we want to bring back mammoths we recently partnered with designer David Silva to create a scientifically accurate articulated figure of a woolly mammoth the campaign is going to kick off next month but you can follow our backer kit at the link in the description India wasn't the only island continent that came from gandana in classic Australian fashion Evolution built a family of deadly predators by taking a group of cute harmless herbivores and turning them murderous check out our episode when the combat wombat became an apex predator to

learn more magma Mia we got to thank this month's e onist Addie Annie and Eric Higgins Carl wolle Jake Hart John Davidson in Juan M Melanie Lam Carnivale and Rafael hassa become an eii at patreon.com subscribe at youtube.com/ eons for more Journeys in deep time [Music] time fueled From Below by a massive plume of magma magma oceans made of magma I keep wanting to say magma like Austin Powers magma every time I read the word I have to do it every single time h