It was a hot day in the Triassic, the first period of the dinosaur age. An animal called Effigia feeds on the plants of this forest lost in time. He looks like a dinosaur, but he's not.
In the shallow waters of these Triassic oceans, swam Henodus, a reptile with a shell, which looks like a turtle, but is not a turtle, but another lineage of reptiles completely independent of them, a placodont. In any environment during the Triassic period, we could find animals that are very reminiscent of animals from other times, but that are actually part of another lineage, another evolutionary experience, exclusive to the Triassic. The Triassic fauna appears to be the most unusual, unconventional, unfamiliar and, in short, bizarre on planet Earth.
This immense variety of unique new animal designs that occurred during this moment in the history of life can only be compared in intensity to the Cambrian explosion 300 million years earlier. At no time since then have so many new animals evolved in such a short period of time, not even after the asteroid strike that wiped out the non-avian dinosaurs, giving rise to the age of mammals 66 million years ago. Why?
What was special about the Triassic? How did it start and how did it end? Why do the animals of that time seem so strange to us?
To answer these questions, in the first part of this video, we will understand the history of the Triassic and the dawn of the dinosaur era. In the second, I separated a list of 15 obscure, little-known animals from that time, which will tell us something very revealing about the history of life and paleontology itself. Spoiler: NONE of these are dinosaurs.
And lastly, let's finally use all of this to answer our main question: what was Mother Nature smoking at the dawn of the dinosaur age? This is the story of the Triassic explosion. To tell the story of the Triassic, we need to go back in time a little further, to see what the world was like before it.
The period that preceded the Triassic is the Permian. It begins 298 million years ago and ends 252 million years ago, when the Triassic begins, having lasted 46 million years. More than enough time for several biological revolutions.
Especially during the early Permian, the world was colder and more oxygenated than in the Triassic, during the so-called Karoo glaciation. Tetrapods, animals with spines and four legs, were getting the hang of life on continents, forced by a drier climate following the collapse of global rainforests. Their Carboniferous ancestors had just beaten the arthropods in the competition for the dominant life forms on the continents.
A wide variety of amniote lineages, tetrapods adapted for life on dry land, occupied the most different niches in Permian ecosystems. Before them, tetrapods were restricted to an amphibious life, limited by water and unable to live completely on dry land, just like today's frogs. The amniotic egg, protected by a leather or porous shell from the outside world, allowed tetrapods to occupy many new environments, and consequently, to diversify.
The most successful and diverse early amniotes were the synapsids, the lineage to which we mammals belong. But true mammals only appeared much later, at the end of the Triassic. These Permian synapsids are not mammals, they are part of lineages that split before the common ancestor of all current mammals and left no descendants in the overwhelming majority.
Some of these stem mammals* developed immense bodies capable of digesting an equally immense amount of plant matter, with a barrel shape and a small head, such as Cotylorhynchus, one of the largest species of caseids. One of these caseids may even have had a semi-aquatic habit, analogous to modern-day hippos, showing that caseids were one of the most diverse groups during the early Permian. But the Permian was home to many other herbivores besides caseids, such as tapinocephalids, including Moschops, an almost one-ton herbivore adapted for headbutting combat.
Some of the most famous Permian synapsids lived at the beginning of the period, the eupelycosaurs, also ecologically diverse from each other. The most famous of all, Dimetrodon was a carnivore, but Edaphosaurus, despite superficial similarities, was a herbivore. But they were just some of the first, and they didn't even last until the end of the Permian, being replaced by many other increasingly specialized and agile forms on dry land.
In the middle of the Permian, the largest carnivores were dinocephalians, such as Anteosaurus, which reached 5 meters in length and weighed 700 kg. But these predators, comparable to today's largest carnivores, also did not last until the end of the period. The beginning, middle and end of the Permian are three totally different worlds.
In the trees, a synapsid ammodon called Suminia appears to have been an analogue of modern-day apes, with large eyes, long fingers, something like an opposable thumb, and a long, thin, potentially prehensile tail, which may have aided its balance. It was one of the first tetrapods to adapt to an arboreal habit. But perhaps the most emblematic of this lost mammalian era are the late Permian gorgonopsids.
Robust carnivores, the size of the largest carnivores today, with impressive opening mouths, gigantic skulls and long, sharp teeth. The top carnivores of the Permian, prepared to take down even the largest prey in their environments. Gorgonopsids are part of a diverse group of synapsids called therapsids.
They were the last predators of the Permian, having replaced the dinocephalians, also therapsid predators of the middle Permian, which reached gigantic sizes. Despite the dominance of our synapsid relatives, the sauropsids, the other side of the amniote family also thrived, although generally smaller and more inconspicuous. The exception to this rule are the heavily armed and robust-bodied pareiasaurs, such as Scutosaurus, which may have weighed more than a ton, proving that parareptiles also competed for successful herbivory.
The ancestors of archosaurs, the lineage that would give rise to today's crocodiles and birds, were still quite shy and relatively rare. By the end of the Permian, continental tetrapods had adapted to lead extremely active lives, cosseted by an oxygen-rich atmosphere, much richer than today and much colder, which despite being dry, was comfortable enough. These diverse and dynamic ecosystems thrived even in the dry conditions of most of Pangea, dominating the world for tens of millions of years.
But the Permian world had a tragic end: animal life as a whole was left hanging by a thread, in the worst mass extinction of all time. At the transition from the Permian to the Triassic, our planet was at the limit of what could be considered habitable. The closest life on Earth has ever come to returning to a second era of bacteria.
Analyzes of the temperature at which certain shallow sea rocks were formed, dating from that time, suggest equatorial waters above 50 degrees Celsius. As hot as a hot tub. At the equator, scorching temperatures made animal life practically impossible, which was concentrated in the highest latitudes, to the south and north.
But plant life was also largely unable to deal with extreme heat, as photosynthesis stops at these temperatures. Even with the intense rains of this climate, plants were practically banished from the equator, due to the heat, forming extensive humid deserts. Like animals, plant life also found refuge closer to the Earth's poles.
The ocean, stagnant, acidic and hot, becomes a favorable environment for the growth of purple bacteria, which grow in the absence of oxygen and poison the atmosphere with toxic hydrogen sulfide. The main culprit is probably an immense basalt spill in what is now Siberia, which must have lasted millions of years. Intense volcanic activity causes apocalyptic swings in the global climate.
A scenario of disrupted ocean currents, global desertification and chaotic climate change has toppled food chains and wiped out the large, specialist animals of the Permian. It is estimated that approximately 90% of animals in the oceans and continents were extinguished in this chaotic event on a global scale. Even the hardy trilobites, which were some of the first animals, were lost in this great die-off.
This, which is the greatest mass extinction of all time, ended the Paleozoic and inaugurated the Mesozoic, the era of Dinosaurs, approximately 250 million years ago. The surviving 10% founded the first Triassic animal communities, but during the first 5 million years of the Triassic, the Earth was still wounded and practically empty of life. Evolution was already working at full speed, but environmental conditions were still far from pleasant.
One of the animals that survived the passage was the Lystrosaurus. This synapsid dicynodont, closer to any mammal than to any reptile, although still a distant relative of mammals, dominated the landscapes of the early Triassic. It was a generalist, an animal with a broad niche , capable of feeding on a variety of resources and adapting to different environments and local ways of life, like a raccoon.
The animals that became extinct in this event tended to be the most specialized and largest, adapted to a particular way of life and requiring a good amount of food to maintain themselves, like a panda. In times of mass extinction, when the biosphere is destabilized, it is small generalists like Lystrosaurus that have the best chance of surviving. They are never the most dominant animals in an ecosystem, always living on the margins, exploiting any opportunity, but every now and then they win the lottery of history.
This historical opportunism is often interpreted as biological superiority in a great evolutionary war, when we look at evolution backwards. Survival is not because they were better, but because they were less ecologically demanding, like Lystrosaurus. Never before and never since in the history of life has a single species been so abundant and successful.
Their ability to eat hard plant matter and dig to escape heat may have been the keys to survival when most animals could not. Despite this slow start, ecosystems eventually recovered, and over the next 10 million years, the rate of evolutionary innovation took off even further as forests reestablished. 15 million years into the Triassic, Earth already had one of the most diverse continental faunas in its history.
How did the game change so quickly? Among the survivors of the Permian extinction were the two great amniotic lineages: the synapsids and the sauropsids. On the side of the synapsids, the kings of the Permian, two groups crossed the passage into the Triassic, the small cynodonts, closer to mammals, such as trhinaxodon, and the dicynodonts, such as Lystrosaurus.
The sauropsida, which we popularly call reptiles, were not the largest, most diverse and most dominant, but had several lineages that were small and generalist. Many sauropsid lineages have survived, although most still have a very basal body plan, almost all looking lizard-like. But today's true lizards , which we call lepidosaurs, did not yet exist.
All of these groups are other types of reptiles, the similarities are only superficial. Among the many sauropsid lineages that survived, none diversified as readily and as violently as the archosauromorphs. Today, they are represented by birds and crocodiles, but in the past, their diversity was astonishing.
Archosaurs, archosauriformes and archosauromorphs, their closest relatives , replaced synapsids as the most diverse and dominant group in the ecosystem, although never alone. The small generalists of the Permian, in this open terrain, had the opportunity to explore a world with very little competition, becoming the great specialists themselves. Interestingly, dinosaurs, one of the most successful groups of archosaurs, arrived late to the party.
The Triassic begins 252 million years ago and ends 201 million years ago, giving way to the Jurassic, lasting a total of 51 million years. The first dinosaurs only appear 30 million years into the Triassic, although their dinosaur ancestors are older. And even until the end of the Triassic, competition with so many different types of reptiles prevented them from diversifying and growing until they reached the status of dominant creatures, after all, wasn't this supposed to be the age of the dinosaurs?
To understand why Triassic animals took the many different forms they did, we need to look at their world, their environment. Planet Earth was very different. On one side, a colossal ocean, called Panthalassa, which means “all sea”.
On the other, a single continent, shaped like a “C”, Pangea, which lasted during the Permian and Triassic periods. Inside this 'C', the sea of Thethys, positioned practically on the equator. During the first 3 million years of the Triassic, Earth apparently reached its highest average temperatures since the beginning of complex animal life.
On our planet, the amount of oxygen and carbon dioxide perform an inversely proportional dance, regulated by the abundance of photosynthetic plant life in the terrestrial ecosphere, the source of gaseous oxygen and the great scavenger of carbon dioxide. Times of high oxygen tend to be cold and with low concentrations of atmospheric CO2, as in the Permian. Already in the Triassic, the world could not be more different.
The heat, regulated by high concentrations of greenhouse gases such as CO2, was accompanied by a drop in oxygen, as suffocating as half of current rates. The drop in oxygen to 1/3 of what it was in a few million years was an evolutionary bomb at the end of the Permian. A hot world with little oxygen is bad news for animals, especially the largest and most active ones, since the hotter the environment, the more oxygen our bodies need to survive.
The Earth of the transition between the Permian and the Triassic was an inhospitable environment for animal life. Even in the best days of the Triassic, this rate still remained consistently well below the current 21% of oxygen in our atmosphere. Towards the end of this video we will understand how dinosaurs took advantage of this to become dominant.
But the channel members already lack knowledge of these things, because they are following my course to understand paleontology, evolution and natural history, which you should check out if we share this interest! Where seasonal rain brought moisture to the supercontinent, the first forests and more densely vegetated environments were established. The equator was probably the most inhospitable environment for animal life, being constantly hit by heat waves that unprotected animals would have difficulty surviving.
Even so, Middle Triassic pangea was already home to a considerable diversity of ecosystems, not just deserts. But the unbearable heat in a large part of the continental portion of the Earth increased the selection of anatomical characteristics and lifestyle habits that would help animals not to die from the heat. And there was always at least one way out: the good old ocean.
Returning from where their ancestors had left, a hundred million years before, as even warm water is easier to deal with than the dry, scorching continental heat. The need to cool off and the low competitiveness of oceanic ecosystems, devastated by the recent Permian extinction, meant that for many reptile lineages, there was more to gain than to lose by diving into the water. And when I say many I mean REALLY MANY.
It is even difficult to understand who is who in the diversity of forms of Triassic aquatic reptiles, since their ancestors are little known and many evolutionary convergences took place, when the same environment sculpted similar characteristics in different lineages. Never before and never again in the history of life have so many tetrapod lineages returned to the sea in such a short period of time. Among the most successful were ichthyosaurs.
They diversified explosively at the beginning of the Triassic, having assumed the most different forms, such as the first colossal animal on planet Earth, Cymbospondylus, the size of a current sperm whale. But also Hupehsuchus, an ichthyosauromorph that has recently been interpreted as a filter-feeding animal, feeding on microorganisms suspended in the water, occupying the niche that many whales occupy today. But these whale ichthyosaurs were just one of many animals that looked eerily like the animals that came after them.
These impostor faunas were actually, in many cases, inventor faunas, as they pioneered many forms and adaptations that would be evolved again in the more successful groups that became known for them. There are many examples of evolutionary convergence, when different lineages end up similar, because they suffered selective pressure from the same environment or lifestyle, such as dolphins, sharks and ichthyosaurs. Their bodies are not similar because they descend from a common ancestor that looks like this, but because they explore the same aquatic environment that forces them to be hydrodynamic.
A good example is the one given in the introduction, between placodonts and turtles. Both developed a flat body and a protective outer shell, but they are independent lineages that evolutionarily converged on a similar shape, as if turtles had evolved twice. Turtles were one of those strange reptiles that the Triassic produced, but because they survive to present times, we rarely see them as strange animals.
However, it was the Triassic that shaped them, and all the evolutionary change this group has undergone since then has been superficial. Placodonts have another evolutionary origin, much debated. They got their name in reference to immense teeth that look like plates, in the roof of the animal's mouth, which were used to break hard shells.
One of the most striking similarities is that between crocodiles, as we know them today, and Triassic phytosaurs. Phytosauria is a group of large archosauromorphs, adapted to semi-aquatic life, with long snouts, short legs and osteoderms covering their bodies like bony armor. Does it remind you of anything?
Not to mention the many lineages that looked like the most different dinosaurs, but dinosaurs themselves were far from being common in their early days. The first dinosaurs were small, bipedal and omnivorous. And as far as we understand, Brazil was one of their birthplaces.
Here, we find some of the oldest dinosaurs. We know today that they originated in the southern portion of Pangea, the Gondwana subcontinent, which encompassed South America, Africa, Antarctica, Australia and India. The Santa Maria formation in Rio Grande do Sul provides us with one of the best windows into Brazil's astonishingly rich Middle Triassic.
All the animals you are seeing were found there, which includes Saturnalia tupiniquim, one of the oldest dinosaurs we know of. In addition to dinosaurs, we have lagerpetid reptiles, close relatives of pterosaurs, the strange rhynchosaurs, amphibians, rauisuchians that look like long-legged crocodiles, aetosaurs that look like herbivorous crocodiles, but also a variety of synapsid dicynodonts and cynodonts. All these species are just a fraction of the real diversity of these ecosystems that existed in what is now Brazil, which we will never fully understand.
As we all know, pangea did not last forever, but its fragmentation was traumatic for life on Earth. At the end of the Triassic, geological activity in the equatorial region of Pangea intensified brutally, to the extent that it separated into two parts, one to the south and one to the north: Gondwana and Laurasia. Volcanic gases filled the atmosphere with carbon dioxide, and made the already hot Triassic a place similar to the end of the Permian.
A macabre replay of the trauma that life had just recovered from. Oxygen, which was also already low, reached its lowest point in the last 500 million years at the end of the Triassic. A new mass extinction, the ugly one, shortly after the worst one of all.
A widespread death event so profound that Few of the Triassic novelties have survived. Extreme heat in a suffocating atmosphere selected only those most adapted to these inhospitable conditions. We will understand later how dinosaurs and mammals overcame this challenge.
This means that the Triassic begins and ends with a mass extinction, giving way to the true age of dinosaurs: the Jurassic and Cretaceous periods. If the extinction at the end of the Triassic had not happened, ushering in the Jurassic, dinosaurs most likely would not have dominated the world, and other groups could have taken the lead. But most of them died without leaving descendants, and those who were lucky enough to survive lived for a long time in the shadow of the dinosaurs.
To better understand the astonishing diversity of unfamiliar life forms that inhabited the Triassic, I have selected 15 of the most incredible animals in my opinion. I left out some of the most obvious ones, such as the best-known dinosaurs, pterosaurs and aquatic reptiles of the period, which end up drawing all the attention to them. They tell part of this story, but they were the survivors of the extinction that occurred at the end of the Triassic.
To better understand what was the second largest animal diversification event in the history of life, we need to look at the lineages that went extinct. Those that did not survive, and remained exclusive to this enigmatic and challenging time. Those who were born and died in the Triassic.
These are some of the most incredible and unique animals that evolution has ever produced, but they are not known to the general public, there is not much art representing them, and I would like to give them a space to shine and inspire. I always find myself thinking about what the world would have been like if these bloodlines had prospered longer. And then, we will try to understand why they died and the dinosaurs lived.
1-LYSOWICIA The first animal on this list is Lysowicia, a synapsid dicynodont, descended from the small survivors of the Permian extinction, such as Lystrosaurus. It lived at the end of the Triassic and was described recently, in 2019, having been found in Poland. This giant herbivore was large enough to compete with the first sauropodomorph dinosaurs, which were already quite large at the end of the Triassic.
Before their discovery, it was thought that the sauropods' Triassic ancestors and relatives, the necked dinosaurs, were the only giant herbivores from that era, like Plateosaurus. Having weighed more than 6 tons as an adult, it was the size of the largest land animals today: African elephants. They were the largest non-mammalian synapsids to ever live on Earth.
Its beak and forward-facing “tusks” gave it a unique appearance and may have served several functions, but neither they nor its size were a guarantee of immunity against predators. Unhealed tooth marks on Lisowicia fossils indicate that it was one of the prey of an archosaur predator called Smok. Despite the impressive similarity, it was not a theropod dinosaur, and was one of the largest predators in its ecosystem, even slaughtering the elephants of its time.
Its position in the archosaur tree is still uncertain and hotly debated, but it seems clear that it was closer to crocodiles than dinosaurs, despite the dinos' characteristic bipedal posture. 2-DREPANOSAUR The second animal I separated for you is the Triassic platypus: the drepanosaurus. Drpanosaurus is a genus of drepanosaurids, a group of diapsid reptiles of uncertain evolutionary relationships.
This is because many of their characteristics are so unique that it is difficult to understand who they are closest to. Let's understand this animal: The body looks like that of a chameleon, with a hump, strong legs and a thick tail. On the front paws, a disproportionate claw, like that of a sloth, supposedly used for climbing trees.
At the tip of the tail, which may have been prehensile, a claw-like structure, reminiscent of a scorpion. And to finish this Triassic chimera, a head that resembles a bird, with large eyes and a thin beak, which completes its bizarre appearance. This insectivore may have found itself in trees, a refuge from the many predators of the Triassic.
3-ATOPODENTATUS Number 3 on our list lived at the beginning of the Triassic, unlike the first two, who lived at the end. Atopodentatus is the oldest known herbivorous marine reptile. At 3 meters long, it is far from small.
It is most likely a basal sauropterygian, a close relative of one of the most successful lineages of aquatic reptiles in history, which includes plesiosaurs and pliosaurs. When the first fossil of this animal was found in China, the skull was deformed, having been crushed on its side during fossilization. As his skull was totally different from anything and there was no reference for comparison, the first interpretations represented him with a zipper mouth, with a vertical opening.
However, new specimens, this time preserved with a less deformed skull, revealed that in fact, its mouth was wide and straight, adapted for scraping algae and low-lying plants from coastal environments. They probably spent part of their lives on land, just like modern pinnipeds, but they certainly fed in the ocean. Having lived just 8 million years after the great death, this animal is a reflection of a time when evolution was working at full speed.
4- HYPERODAPEDON Hyperodapedon was an archosauromorph. This means that it was as close to crocodiles as it was to dinosaurs, as both share a more recent common ancestor with each other than with the Rhynchosaurs, the group of archosauromorphs to which Hyperodapedon belongs. This animal was strange from every angle, none of which saved it.
Looking like a chimera between a naked mole and a reptile, this may be one of the most different Triassic archosaurs. Hyperodapedon was one of the largest rhynchosaurs, measuring about 1. 3 meters in length.
The triangular shape of its head was just the beginning of one of the most bizarre skulls of all time. The premaxillary bone formed a beak in the front of the face, and inside its mouth, several batteries of teeth at the top made it an excellent processor of hard vegetable matter. They lived during the Triassic Carnian epoch, between 231 and 227 million years ago, which is known for a global-scale mass extinction event, interpreted as the consequence of the Carnian pluvial event, a particularly wet period that lasted ca.
2 million years. Not only did they live, but they thrived in the Lystrosaurus style during the Carnian. Fossils of this genus are found all over the world and in some assemblages, they represent more than 80% of the animals found, suggesting that they were ridiculously successful during this extinction event.
This is not one of the Big 5 extinctions, but it is the largest mass extinction event within the Triassic. Before him, dinosaurs rarely represented 5% of animal species in most ecosystems; after him, they rarely represented less than 50%. It was definitely a turning point for dinosaurs, and perhaps the true beginning of their era.
While rhynchosaurs apparently didn't even last until the end of the Triassic, they were perhaps scared out of existence precisely by a variety of new, more derived herbivorous archosaurs. 5- EFFIGIA / SILLOSUCHUS The fifth animal on the list, you already met in our introduction: Effigia. Write it down: it was an archosaur, pseudosuchian, shuvosaurid poposaurid.
Shuvosaurids are a family of 3 species of poposaurids, which are a group of pseudosuchians, which are one of the most diverse groups within archosaurids. I told you to turn on the subtitles. All of this means they are closer to crocodiles than they are to birds, or any dinosaurs.
Like dinosaurs, they assumed a bipedal posture, with reduced forelimbs and small fingers. Its short legs, long back and longer neck still looked reasonable next to its head. With large eyes, no teeth and a beak, it is possible that Effigia was limited to eating by cutting softer plant matter.
It lived in the Late Triassic, just like its Argentine shuvosaurid relative: Sillosuchus. The degree of maturity of the bone tissue of this animal's fossil suggests that as an adult, it could measure more than 10 meters in length, competing with sauropodomorphs for the ecological role of giant bipedal herbivores. Its convergence with plateosaurids, for example, which lived a little later, is frightening.
Sillosuchus may have been the largest pseudosuchian of all time. Their low metabolism allowed them to inhabit the warm regions of the equator, while their dinosaur analogues preferred the higher, cooler latitudes. Think about it: The Triassic dinosaurs' big herbivorous competitors were giant, bipedal relatives of crocodiles, with a huge neck and beak.
6-ARIZONASAURUS The sixth animal on the list is Arizonasaurus, a carnivorous pseudosuchian that lived from the beginning to the middle of the Triassic, in what is now the state of Arizona, in the USA. This animal, closer to crocodiles than dinosaurs, was almost 3 meters long and carried an impressive sail on its back. This sail is very similar to that of Permian pelycosaurs and Spinosaurus, from the Cretaceous, and just like for these animals, its function is still much debated.
But it is likely that it had several, including thermoregulation and exhibition. Not only did it have an upright posture like that of a dinosaur or mammal, it was also probably a facultative biped, able to stand up and walk on its two hind legs. 7- DIADEMODON Diademodon was a synapsid cynodont that lived in the middle of the Triassic, in Gondwana.
It had a large head, a mouth with a wide opening, and teeth that suggest an opportunistic, omnivorous diet. Its short paws and long body made it an excellent explorer of dens and caves. Diademodon was among the largest relatives of mammals that lived during the Triassic, and may have even preyed on small ancestors of dinosaurs.
From the tip of their snout to the tip of their tail, they could be more than two meters long, a giant compared to the first true mammals that rarely exceeded the size of a mouse. They probably still laid eggs, just like today's monotreme mammals, platypuses and echidinas. They also did not have nipples or ears, characteristics more derived from therian mammals.
But they had a metabolism that allowed them to lead an active life even at night. A testimony to the resistance of synapsids. 8-SHRINGASAURUS The eighth animal on our list is Shringasaurus, which looks like a real-life dragon.
Its name means horned lizard. It was an allokotosaurian archosauromorph, the largest of its group. Weighing more than 500 kg and up to 4 meters in length, with its robust body and long neck, it is considered one of the first tall-leaved herbivores of the Mesozoic.
They lived in the Early Triassic, and may have evolved their long necks to avoid competition with dicynodonts, and were later replaced by sauropodomorphs and shuvosaurids. Its most striking feature was the horns, present in males, presumably used for combat between individuals of the same species. Its rough texture indicates a keratin covering that in life would have made it even larger, but these horns were absent in females.
This is incredible, because it suggests sexually selected active combat behavior in a cold-blooded animal. They are some of the first archosauromorphs to reach these sizes, about 7 million years after the great die-off, playing an important role in the recolonization of the earth. 9-LOTOSAURUS Lotosaurus is a likely enigmatic herbivore from the Chinese Triassic.
Measuring just over two meters long and around 1 meter high, it was a poposauroid, a pseudosuchian close to the shuvosaurids. Its beak and strong bite raised the hypothesis that it was a durophagous, feeding on shells and hard animals in lake environments. But the most accepted hypothesis is that it was adapted to consume materials hard vegetables in arid environments of pangea.
In life, it is likely that he had a turtle-like face, without teeth and with a short face ending in a beak. Perhaps what most attracts attention about this animal are its exaggeratedly elongated neural spines, forming what appears at first glance to be a sail like that of Arizonasaurus, another poposauroid. However, they are thick and wide, more similar to the elongated neural spines of a bison, for example.
This means that they probably did not have a sail-like appearance in life, but rather were large areas of attachment of muscles and fat stores. This would make sense in arid environments, where food resources are scarce and water is rare, a strategy also shared by modern-day camels. 10-ERHYTROSUCHUS The tenth on our list is probably one of the most terrifying animals of all time: Eryhtrosuchus!
This early Triassic archosauriform carnivore had a head disproportionately gigantic in relation to its body, with teeth the size of a Tyrannosaurus rex and an equivalent bite force. Eryhtrosuchus was the largest predator of its time, exceeding 5 meters in length and easily weighing more than 1500 kg. Despite his gangly appearance, his long, strong legs positioned completely below his body suggest that he would be a competent and surprisingly fast runner.
Their active metabolism and warm blood allowed them to be extremely active, but also insatiable. Warm-blooded animals need to eat much more than cold-blooded animals, as we spend energy all the time to keep our bodies at a certain temperature. Close your eyes and imagine one of these animals approaching you running down the hill.
11-TANYSTROPHEUS Thanystropheus is one of the most enigmatic and difficult to interpret animals of the Triassic fauna, although it was very common during its day. Whatever he was doing, he was very successful. This animal resembles the aquatic reptiles plesiosaurs, with small heads, long necks and short bodies.
In fact, more than half of Thanystropheus' 20-foot length was just its neck. It has been suggested that it was a marine animal, feeding in the same way as plesiosaurs, but the anatomy of its legs suggests that it spent at least a good part of its time on dry land. This is where the neck conundrum comes from, as land animals with long necks tend to be herbivores.
Perhaps this animal was a type of heron, which used its long neck like a fishing rod. The piscivorous habit is strongly supported by the anatomy of the teeth, adapted for slippery prey, but also by fossilized fish found in the abdomen of thanystropheus. Although exactly how they fished is still uncertain.
Thanystropheids have been the subject of much taxonomic debate, but recently, the understanding has been that they are archosauromorphs. 12-DESMATOSUCHUS Our twelfth animal is another pseudosuchian, this time an aetosaur: Desmatosuchus. It could reach 5 meters in length and weigh 400 kg, with its robust and heavily armed body with spikes on its shoulders.
These spines are osteoderms that converged with the osteoderms of nodosaur dinosaurs, such as Borealopelta, probably for the same function: protecting the neck from predators. Despite his heavy metal appearance, he was a herbivore. In fact, this group was extremely successful in the late Triassic, having existed throughout almost all of Pangea for a long time and being abundant in its ecosystems.
It lived in North America at the same time as the famous dinosaur Coelophisis, although Coelophisis had no chance of preying on a Desmatosuchus. This was the role of Postosuchus, a famously huge carnivorous pseudosuchian that also lived with Desmatosuchus. 13-FASOLASUCHUS While we're talking about Postosuchus, number 13 was its South American relative, Fasolasuchus.
He was one of the last of this lineage of quadrupedal carnivores: the rauisuchians, having lived closer to the end of the Triassic. It, like many fascinating Triassic animals, is found in the Ischigualasto formation of Argentina. Fasolasuchus was simply the largest non-theropod land carnivore that ever existed, and it inhabited our continent.
It is possible that their gigantism was an adaptation that allowed them to prey on the increasingly larger herbivorous sauropodomorph dinosaurs of the late Triassic. Its body covered in bone armor could reach 10 meters in length, making it as large as some of the largest predatory dinosaurs of the Jurassic. Their knife-shaped teeth, combined with a strong bite and robust neck made them one of the first super predators specialized in killing giant herbivorous dinosaurs.
14-SHAROVIPTERYX Our penultimate animal on this list of Triassic circus freaks is the little Sharovipteryx. It stood out among other gliding animals of the time, having been the only known glider with a membrane on its hind legs. Its long hind legs would be clumsy on the ground, which leads us to think that it had an arboreal and climbing habit, throwing itself between trees and gliding to move faster.
This group, composed of just one species, is interpreted as a light-bodied archosauromorph about 25 cm long. He was probably an opportunist, feeding on insects and vertebrates smaller than himself. It may seem like the wings on Sharovipteryx's legs were crazy, but it was during the Triassic that the first group of flying vertebrates evolved: the pterosaurs.
They lasted until the end of the Mesozoic, having been the largest flying animals of all time. Today, birds and bats are the only flying vertebrates, but the longest-lived were the pterosaurs. They performed a slow flight, unlike Sharovipteryx, which did not have the musculature for this, therefore not being a truly flying animal.
15-VENETORAPTOR To close our list, our fifteenth animal is Venetoraptor. Venetoraptor was a bipedal animal with a long and slender body, with light, hollow bones. Although it was almost a meter long, in life it would have weighed less than a domestic cat.
Its long hind legs ended in 4 fingers in an unconventional arrangement, while its front legs were strong and also had 4 long fingers, with the fourth finger being the longest. Just what supports the wings of pterosaurs. Its small head with large eyes was armed with small needle-like teeth and ended in a beak, something that evolved convergently many times in archosaurs.
Their diet was probably very varied. Venetoraptor was found in Rio Grande do Sul, it is part of the Santa Maria formation, one of the richest windows into the Triassic on planet Earth. It was part of the large group of Lagerpetids, pterosauromorphs that are interpreted as the sister group to true pterosaurs.
The recent discovery of Venetoraptor and the slightly less recent discovery of another Lagerpetid found in the Santa Maria formation, confirmed the hypotheses that the ancestors of pterosaurs were small, bipedal, agile and with powerful arms and long fingers. The known lagerpetids are not the ancestors of pterosaurs, but they may have preserved a body shape more similar to their common ancestor. Now that we know these 15 unique animals and we have a better idea of the disparity of forms that inhabited the Triassic on planet Earth, it's time to answer the question that this video poses: after all, why were they so strange?
And to help us with this, let's first understand why dinosaurs survived and thrived, while most forms went extinct at the end of the Triassic. The historic low in atmospheric concentrations of oxygen gas made active life on the continents very costly. With less than half the current oxygen, many lineages, in a way, suffocated to death.
It was more difficult to grow, move, eat, regulate one's temperature, all in one wave of heat within an already very hot period. Breathing may seem trivial, but it's not. Reptiles, for example, move in a sinuous movement that compresses the lungs and makes breathing difficult during locomotion.
Therefore, they have peaks of activity and long periods of downtime. It is practically impossible for them to breathe while running. Mammals eliminated this problem by galloping: positioning their legs at the bottom of the body, like columns, and changing the movement from lateral to vertical.
The galloping movement that the mammalian posture allows literally couples movement and breathing, through the powerful diaphragm muscle, which compresses and expands the lungs very efficiently in different phases of the running cycle. Adaptations that are a legacy of the suffocating end of the Triassic, without which, our ancestors could have remained among the bizarre things of the period, and we would never have existed. Likewise, dinosaurs have a highly efficient respiratory system, a hint at the secret of their survival.
Although there were many quadrupedal dinosaurs, they all descended from a small, bipedal ancestor. Surprisingly, bipedalism may have been a respiratory efficiency strategy, as it eliminates the problem of lung compression by the forelimbs during locomotion. But it didn't end there.
Saurischians, the most common dinosaurs at the end of the Triassic, like theropods and sauropodomorphs, were equipped with air sacs, which are still present in today's birds. They allowed airflow to be more constant and efficient than in the lungs of mammals and other sauropsids. Septated air chambers increased the exchange surfaces between the animal and the environment, also fulfilling the role of regulating temperature.
When oxygen rose again during the Jurassic, this adaptation allowed theropods to be very active large predators and sauropods to become the largest land animals of all time. The prize that dinosaurs won for having gone through the biggest oxygen crisis in the history of animals was the world. It is estimated that the extinction at the end of the Triassic eradicated 75% of all life on the planet.
An echo of the great Permian die-off 50 million years earlier. This is what explains the Triassic and its impressive explosion of animal diversity and disparity. The Permian survivors had a world to call their own, without the pressure and competition of the big animals of the past.
They founded the Triassic, but things weren't destined to be any particular way. Life had to reinvent itself and experiment with what worked. This new world was not the best, this was not a healthy land, but it was theirs.
This relatively empty environment gave freedom for evolutionary innovation, and almost everything worked, for a while. Without fierce competition from well- established and diverse ecosystems, evolutionary innovation and mutations are not punished as severely and can accumulate more easily. When generalist animals encounter a seemingly inexhaustible source of untapped food, adaptations to that way of life are heavily rewarded and the numbers of these populations explode.
This is how some relatives of crocodiles became herbivores, more than once, for example. This explosion of evolutionary innovation and convergent ecological specialization experiences from diverse lineages is what we call an adaptive radiation event. They follow mass extinctions, times when the biosphere becomes impoverished enough to eliminate much specialized ecological competition.
These are opportunities for small, adaptable generalists to found a new era. It was like that with dinosaurs, it was like that with mammals. But this phase of explosive experimentation doesn't last long, and soon, entire ecosystems with herbivores and large predators are established and change relatively little until the next mass extinction.
This is the view of macroevolution defended by Stephen Jay Gould in his punctuated equilibrium thesis. He opposes evolutionary gradualism, which sees evolution as a slow and gradual, but relatively constant, process. According to punctuated equilibrium, one of the greatest forces of nature is the so-called “evolutionary stasis”, staying where you are.
In nature, we all play a role. Being born different, trying something new is generally very dangerous and does not pay off evolutionarily. There are few beneficial mutations.
This means that in competitive and sophisticated ecosystems radical evolutionary change is rare. These are the so-called moments of balance, although true balance is impossible in nature and evolution never stops working. But sometimes she does much more than work, she revolutionizes everything.
Punctuated equilibrium sees biological crises as major cogs in the machine of evolution, and proposes that adaptive radiation is proportional to the void left by mass extinction. For a few million years, a brief moment in geological time, survivors experiment with new forms, until competition sets in and begins to curb evolutionary innovation once again. This is consistent with the story the fossil record tells.
And if the punctuated equilibrium is right, it makes sense that the greatest of all diversifications of continental life happened precisely after the greatest mass extinction of all time. This may explain the explosion of Triassic diversity, but it doesn't completely explain why they seem so much stranger than animals from other times. It is actually the extinction at the end of the Triassic that completes this reasoning.
Our idea of “strange” has to do with something we are unfamiliar with. If we think about it in depth, are today's animals really more “normal” than the Triassic fauna? Or are we just more used to them?
What does it mean, after all, to say that an animal is normal or strange? Even the animals we see in fossils and represented in the media end up becoming familiar to us. But the Triassic was a sandwich of catastrophic extinctions, which confined many of these forms to just this period and prevented them from leaving descendants that would make those bodies “normal” for us today.
As it began and ended with great losses of diversity, many of these lineages end up being obfuscated to the general public, due to the difficulty of explaining what they were about. This chaotic, challenging and psychedelic beginning of the dinosaur era is the least explored by the media and least known by the public, making its animals unpopular. If the extinction at the end of the Triassic had not occurred, many of these forms could have survived longer and would not be considered bizarre.
But it is special, because it converged in a frightening way with some of the most successful groups of all time, giving the impression that the Triassic had a fauna of impostors. This is actually evidence that they were not primitive or inferior. After all, weren't they the ones who suppressed the powerful dinosaurs and delayed their era by 20 million years?
The advantage of dinosaurs was circumstantial, there was nothing biologically superior or more advanced about them. They, like mammals, had efficient respiration, and perhaps, if the challenge had been different, they would have become extinct and other Triassic groups would have prospered. This is because evolution does not predict the future and does not prepare for the catastrophes that are to come, it is a game of survival and death.
And that's how many of the most impressive creatures in Earth's history were born and died in the Triassic. Paleontology is a rich, multidisciplinary and complex science, but I am producing a course that can help you become familiar with the basic concepts to understand natural history and evolution. In the course “Evolution, earth and time” We will understand the basics about geological time, evolution, animal and plant diversity, mass extinctions, among other essential areas.
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” And like everything I write, influenced by the immortal spirit of Stephen Jay Gould. Thank you very much for following me here, share with your friends, subscribe and have a great life!
