The Dinosaurs of the Triassic Period: A Summary of the First Dinosaurs and their Rise to Dominance

the reign of the dinosaurs was during the Mesozoic Era often called the age of reptiles divided into three periods the Triassic Jurassic and Cretaceous the Mesozoic spanned 186 million years although dinosaurs lived during all three of these periods they did not rule during the Triassic period when it began 252 million years ago dinosaurs hadn't yet evolved by its end dinosaurs were still not the most common megafauna nor were they close to the size of the more famous Titans of the latter two periods this only changed at the beginning of the early Jurassic 201 million years ago because of this Triassic dinosaurs are all too often overshadowed by their later descendants books video games and other media which include dozens of dinosaur species rarely showcase any examples from the Triassic period Beyond coelophysis platiosaurus and more recently herrerasaurus even they are obscure to most of the public compared to the most famous Jurassic and Cretaceous species despite their treatment as a mere footnote in the rise of more iconic Dinosaurs the dinosaurs of the Triassic period were just as amazing and worthy of study this video aims to give an overview of the first chapter of dinosauria's History one which is all too often skimmed over or ignored it will give a summary of The Wider Triassic world the first dinosaurs inhabited then cover each of the major Triassic dinosaur lineages and some individual species of note it will then examine the biogeographical trends of the early dinosaurs and finally cover their rise to dominance the world the first dinosaurs lived in was very different from our own the continents were combined into a single massive land mass called Pangea and global temperatures were higher than today the climate was also much more arid but racked by extremes in addition to having to endure a grueling dry season most animals also faced regular wildfires and mega monsoons created by the effect Pangea had on global wind patterns the plants the first dinosaurs coexisted with would not have seemed alien to most people today but the vast majority of today's plants would have been alien to the Triassic dinosaurs most modern plants even grass are flowering angiosperms which wouldn't evolve until long after the Triassic period the dominant plant in this flourless world were instead conifers cycads and ferns the oceans were already filled with a variety of marine reptiles including the familiar fish like ichthyosaurs in addition to a number of much more obscure reptiles like the thilatosaurs meanwhile freshwater habitats were haunted by a number of large temna spondyl amphibians the Triassic was also home to their more familiar relatives the first true frogs likewise the first true lizards got their start during the Triassic even if similar reptiles had existed long beforehand as strange the Triassic was the first dinosaurs also evolved alongside the earliest members of many modern groups as mentioned before dinosaurs were not the primary terrestrial animals during the Triassic the first period of the age of reptiles was instead filled by a more diverse assortment of animals of which some were not even reptiles some of the most important creatures on land were synapsids the proto-mammals synapses were actually the dominant megafauna during the preceding Permian period and remained so during the early Triassic this was in spite of synapsida losing most of its diversity following the great dying a devastating mass extinction at the boundary of the Permian and Triassic one of the most important groups of Triassic synapsids were the disinodons who were large herbivores with tusks and otherwise toothless beaks the other major groups of Triassic synapsids were the smaller cyanodons who had a wider variety of diets among their number were the direct ancestors of mammals there was a third clade of Triassic synapsides who were similar to the synodonts the therosophilians but they went extinct during the middle Triassic which despite the name began after only the first five million years of the period and ended 10 million years later it was during the middle Triassic that the large synapsids were increasingly upstaged by reptiles most Triassic reptiles remain no larger than most of today's lizards with these new larger reptiles belonging to arkosoromorpha this is a clade consisting of All Reptiles more closely related to dinosaurs and crocodilians than to lizards much like the synapsids many archosauromorphs had a high or warm-blooded metabolism although not as high as that of modern endotherms a high metabolism allowed these archosauromors to be more active than the other ectothermic reptiles at the beginning of the Triassic arcosauromorphs were a collection of small simple lizard-like creatures along with a handful of large carnivores but the arcosauromorphs soon expanded into a wider variety of niches besides dominating the apex predator niches they also came to include herbivores like the allocotosaurs and the rankosaurs other arcosauromorphs invaded freshwater environments including van clevia and the crocodile-like fighter sores the most successful arcosauromorphs were the arkosores those arcosauromorphs descended from the last common ancestor of the dinosaurs and crocodilians however the most abundant Triassic archosaurs were not dinosaurs but pseudosukians the distant relatives of crocodilians despite their modern Representatives reputation for being unchanging pseudosukians were incredibly diverse during the Triassic period among their number were the armored eight of swords the sailback's tenosaurus skids The Fearsome rawasukids and the small terrestrial Runners would one day evolve into the crocodilians many pseudosuchians and other arkosoromorphs greatly resemble dinosaurs this was in part due to their close relationship with each other but also because they filled similar niches this was taken to an extreme by the bipedal shovosaurids who paleontologists initially mistook as ornithomimus or dinosaurs even before true dinosaurs came onto the scene members of their branch of arcosoria Ave meta tarslia were rare until the late Triassic period the earliest examples of these stem dinosaurs are the medium-sized predatory aphanosaurs the rest of the Ave metatarselyans belonged to the clade or nithodera besides dinosaurs ornithidira also includes the flying pterosaurs who were often mistaken for dinosaurs themselves ornithidirans started out as tiny insect eaters a stark contrast to the famous Titans of the future this is even more striking since at the beginning of the Triassic the arcosauromorph ancestors of the archosaurs and therefore dinosaurs were large Predators not the more abundant pseudo lizards the oldest fossils of these diminutive proto-dinosaurs and prototerosaurs are footprints dating to the early Triassic it should be noted the first ornithadirans were already quite bird-like which was also true for the earliest dinosaurs the more reptile-like appearance of many later dinosaurs was a consequence of them growing so massive dinosaurs and those ornithadirans more closely related to them than pterosaurs belong to the clayed dinosaur amorpha many dinosaur morphs such as Lego sukis and saltopus looked very similar to True dinosaurs and already possessed most of the traits which set them apart from other reptiles the reason they are not all simply considered dinosaurs is because of how Dinosauria is defined it is declared formed by three smaller clades and all the descendants of their last common ancestor these are theropoda which includes Birds and most of the carnivorous dinosaurs soropodamorpha which contains the massive long-necked sauropods and smaller prosauropods and ornithischia which includes a number of herbivorous dinosaurs like the not quite duck-billed hadrosaurs the horned ceratopsids and the armored ankylosaurs this makes the question of when the first dinosaur evolved a bit of a technicality since the first true dinosaur was not substantially different from its dinosauramorph predecessors for years the oldest reliably identified and dated dinosaurs were the tiny Eoraptor and the larger herrerasaurus their fossils are from the Argentinian ishigo wall sto formation which is dated to around 231.5 million years ago during the karnian age of the late Triassic similar dinosaurs including nandu Miram and nephovorax have been found in the Brazilian Santa Maria formation and have recently been dated to 233 million years ago these early South American dinosaurs were far less diverse than those dinosaurs from the end of the Triassic let alone the following periods all of them superficially resembled theropods although few if any truly belonged to the group instead the last common ancestor of all dinosaurs from the gigantic sauropods to the armored ankylosaurs is thought to have looked more or less like a small theropod still there are enough differences between these karnian dinosaurs to suggest the oldest dinosaur is likely at least a few million years older one of the ishigoasto dinosaurs eodrameus is often seen as the best representative of what this first dinosaur looked like it was a small Predator only one and a half meters long not much longer than his dinosaur morph ancestors or a tyrannosaurid hatchling like them eodrameus was restricted to small prey including insects and Tiny vertebrates such as the reptile tatalura like most other arkosores eodrameus had five fingers however two of them were very tiny which was true of most other early dinosaurs the exception to this rule were the theropods whose definitive members only had four fingers during the Triassic and often fewer in later periods perhaps the largest controversy relating to early dinosaur evolution is how the three major clades are related to each other it was once accepted that the theropods and sauropodomorphs were more closely related to each other than to the ornithischians being united under the larger clade saurishia this consensus was challenged in 2017 and after much debate it was concluded that there is currently insufficient evidence to determine which of the three dinosaurian clades split off first for the purposes of this video it will be assumed that the traditional sorishia model of dinosaur evolution is basically correct however the silosorids who were once placed outside of Dinosauria will be considered ornithischians while herrerasaurs who were once thought to be theropods will be treated as their own fourth clade the herrerasaurs looked basically like theropods to the degree they were once considered early members of the group after more recent examination of their anatomy and the anatomy of other early dinosaurs it is not even certain if the Herrera swords were true dinosaurs or merely closely related dinosaur morphs today herrerasaurs are commonly classified as early diverging saurusians this means that they may be closely related to theropods and sauropodomorphs but do not belong to either group unlike all definitive Triassic theropods herrerasaurs had five fingers instead of four although both groups only had three non-vistidial fingers so their basic functionality was the same the most iconic herrerasaurs are the Herrera sorids who were among the first karnian dinosaurs they had boxy skulls and looked almost like off-brand Jurassic Park Raptors the possibility that they were primarily scaly only increases the resemblance the Herrera swords stoichosaurus and the previously mentioned nefo vorax lived in the Brazilian Santa Maria formation and are among the oldest known dinosaurs two slightly younger Herrera swords San Juan Soros and herrerasaurus itself are found in the issue guelsto formation all of the named Herrera swords lived in South America but Herrera sword fossils have also been found in Africa and possibly Poland for such early dinosaurs they were remarkably deadly possessing a stocky build and often reaching a length of 3 meters some adult herrerasaurus were about the same size but the largest known individual was between five to six meters long while this may have been a second larger species of herrerasaurus the growth rate of most Triassic dinosaurs was variable which helped them to adapt to the all too frequent droughts either way the largest Herrera Source obtained greater size than perhaps any other predatory dinosaur during the Triassic period and was actually larger than the Jurassic Park Raptors still even it was outclassed by the Contemporary carnivorous pseudosukian sorosuchus despite their early success the Herrera swords seemed to have gone extinct only a few million years after they first appeared during the karnian age the possible Herrera sword fossils found in Poland May extend their range by over 15 million years but at best they seem to have been overshadowed by theropods three other Herrera swords have been found that are not Herrera swords these three dinosaurs chintosaurus tawa and daemonasaurus may form a clade with each other but this is currently unclear all three of these herrerasaurs lived in North America after the apparent extinction of the Herrera swords the fragmentary chintosaurus fossils suggest a length of two meters while more complete tawa specimens are two and a half meters long although within the range of Herrera swords tawa had a more elongated skull placing it in a niche closer to that of the contemporary theropods still even if it was smaller than herrerasaurus and lived in fear of pseudosukian predators like postersukas tawa had risen much higher in the food chain than the first dinosaurs like Eoraptor the most unusual Herrera sword was demonosaurus it had a short round skull which held the proportionally largest teeth of any other dinosaur of course in life these impressive teeth may have been obscured behind lips due to the lack of a modern analog it is not clear what sort of animals demonosaurus evolved to Prey Upon it is estimated to have been one and a half meters long although since it is known from little more than a skull from a potentially immature specimen this estimate is unreliable demonasaurus is notable for living during the radian age which was during the last 5 million years of the Triassic period before damonasaurus was found it was assumed more archaic dinosaur lineages like the herrerasaurs had already been out competed by their relatives still the herrerasaurs do not appear to have survived past the Triassic period unless they did not form a true clade but were instead the earliest theropods even though there is a lot of uncertainty regarding which basal dinosaurs are theropods the Triassic period was home to numerous unambiguous theropods all of which belong to the theoretically smaller clayed neotherropoda fragmentary neotheropod fossils have been found in rocks which may have been formed during the late karnian but most are from the following Noreen and radian ages the most famous Triassic theropod is celophysis its fossils are found in the chinlay formation in the southwestern United States notably over a thousand coelophysis skeletons have been found in a single site at Ghost Ranch combined with how many of these skeletons are complete it is one of the most heavily researched of all dinosaurs fortunately unlike the exceptional Tyrannosaurus Rex coelophysis is actually a good representative of the theropods of its time it essentially looked like a more grace Isle version of tawa compared to the Herrera sours silophysis and the other early theropods were built for Speed and Agility over power atop its long neck was a thin slender skull well suited for striking small animals it was able to reach a length of 3 meters and a height of 1 meter many adult sealophysis were much smaller than this which like herrerasaurus was likely a result of the harsh environmental conditions the sealophysis found at Ghost Ranch seemed to have been preserved together during a single event and may have been once part of a massive flock if so celophysis would have needed to have been migratory to avoid rapidly exhausting its food supply models of celophysis thermodynamics found it was much more vulnerable to heat stress during the day than larger contemporary pseudosukian Predators like postosuchus this suggests coelophysis was nocturnal supporting this a similar early Jurassic theropod the unfortunately named migapnosaurus is thought to have been nocturnal due to the size of its eyes which are inferred from its sclerotic rings seeing as the ancestors of the mammals were also already nocturnal the predator-prey relationship between dinosaurs and mammals seen during the rest of the Mesozoic seems to have already been established long before the dinosaur's Reign began at a time when the early theropods still coexisted with much larger synapsids many Triassic theropods such as no tattoosa Raptor were quite similar to coelophysis in both size and lifestyle however other theropods continued to occupy the same niches as eodrameus and Eoraptor examples of smaller Triassic theropods include Pro compsignathus and pendrick both of whom were only one meter long an important distinction between early theropods was where they lived although they eventually expanded to all of Pangea Triassic theropods were less successful in the equatorial low latitudes and like coelophysis seem to have been primarily nocturnal in the cooler high latitudes the local theropods were equally comfortable hunting at day or night and likewise obtained a greater maximum body size one of these larger early theropods was the four meter long zupasaurus who lived in Argentina despite its size zupasaurus was far from the spot of top predator as it coexisted with what may have been the largest terrestrial predator of the entire Triassic period the seven meter long pseudosukian vasolusukas when zubasaurus was first found it was thought to have had a pair of crests on its skull this was exciting since many early Jurassic theropods like Dilophosaurus had similar crests implying they were also common among their Triassic ancestors however later examination found that zupasaurus's supposed crests were actually bone which had been displaced after its death it did have some cranial ornamentation above its eyes but it was much more subtle the largest Triassic theropod is generally held to be the European Lillian sternus who is estimated to have been over 5 meters long despite this exceptional length for an early theropod its skull and skeleton were still more lightly built than those of the stockier herrerasaurus the Contemporary Suzuki and carnivores and equally long specimens of early Jurassic Predators like Dilophosaurus who it should be noted could grow much larger there are a few theropods from this period that may have been larger than Lillian sternus but none of them are without controversy some sources cite the largest Triassic theropod as the 5.5 meter long gojirasaurus who is named after the movie monster Godzilla a contemporary of celophysis gojirasaurus is notably the only large Triassic theropod from the load latitudes since it is only known from immature specimens it likely grew even larger however gojirasaurus may be a chimera meaning it is a collection of Bones from several different species and its validity as a genus is in doubt still at least some of the bones assigned to it do appear to be genuinely from a theropod substantially larger than silophysis another Contender for the largest Triassic theropod is the bone crushing Smock who is the apex predator of Poland at the very end of the Triassic period while this would be quite the achievement for such an early theropod it is unclear whether smok was a dinosaur or something else its skeleton is incomplete and contains a mixture of traits found in theropods pseudosuchians and other more primitive argosauromorphs although the Triassic period may have had a few large theropod Dinosaurs the current evidence suggests that until the dawn of the Jurassic period the iconic image most people have of the meat eating theropause as apex predators seems to have remained a distant dream on the other hand many of the Contemporary sauropodomorph dinosaurs were far from underdogs indeed by the end of the Triassic period they had already outgrown almost all of their local competition of course even the first sauropodomorph started out small like the other early Dinosaurs the oldest sauropodomorph fossils are primarily from South America although a few have also been found in Zimbabwe one of the most basal species was burialestis another dinosaur from the Brazilian Santa Maria formation burialestis was unsurprisingly quite theropod-like its brain case is the best preserved of any early dinosaur the endocast shows that the part of burialesti's brain used for tracking prey with its eyes was enlarged while its sense of smell was lacking compared to the later plant-eating sauropods combined with its sharp recurved and serrated teeth which are called zyphodont teeth it is clear this early sauropodomorph was a carnivore however buriolesties was very different from the local herrerasaurs it was only a meter and a half long about the size of a fox its head was also proportionally smaller than most other early dinosaurs while this prevented it from hunting larger animals burialestis could easily make rapid strikes when trying to catch small prey although once thought to be the first theropod the relatively famous Eoraptor is now considered a basal sauropodomorph some of its teeth were zephedant but others resembled the leaf-shaped teeth of herbivores which led to the idea that Eoraptor was an omnivore however a recent study analyzing the teeth of early dinosaurs found Eoraptor to be a pure carnivore as was thought to be the case when it was first found the shift to a plant-based diet can instead be seen in the more derived sauropodomorph saturnalia whose teeth were intermediate between those of Eoraptor and later sauropodomorphs it also had a much longer torso than Eoraptor which was a deceptively important evolutionary innovation sauropods were hindgut fermenters relying on microbes in their massive intestines to break down the cellulose in their food this method of digestion requires a huge gut and becomes more efficient the larger it is which saturnalia's larger torso helped to accomplish although it had already evolved many traits crucial in the evolution of herbivory saturnalia's neural anatomy and some of its teeth were still adapted for hunting other animals many other sauropodomorphs were omnivores like saturnalia although some like bagulosaurus continued to shift towards a herbivorous diet despite early success in the southern hemisphere most of these basal sauropodomorphs were extinct after the karnian age having been replaced by their larger and more derived pro-sauropod descendants however there was at least one late Survivor named thecodontosaurus who was evolutionarily in between the small karnian sauropodomorphs and the then-dominant prosauropods this two meter long dinosaur lived in Britain at the very end of the Triassic period and like the prosauropods was a herbivore unlike them thickodontosaurus's primary form of defense was the Swift speed it retained from its ancestors although it also possessed large hand claws after the karnian age the pro-sauropods were the dominant sauropodomorphs for the rest of the Triassic period the traits that set them apart were already apparent in the early prosauropod macro column who lived 225 million years ago their necks had become incredibly long which allowed them to access foliage in the trees unavailable to the other contemporary herbivores on the other hand prosauropod heads were proportionately tiny to avoid placing too much weight on their necks longer necks also allowed prosauropods to forage from vast areas without moving most of their bodies in the long term this helps sauropods keep up with the energy demands of their massive bodies but this would not have been possible had the small Triassic Predators like burialestis not become small prey specialists although prosauropod skulls were still notably longer than those of the later sauropods unlike burialestis they could no longer be mistaken for theropods the prosauropods had large hand claws which may have been used to manipulate tree branches or for self-defense this would have been important since they were not as fast as before having become more cumbersome due to possessing even larger guts all of this allowed the sauropodomorph dinosaurs to be incredibly effective browsers of the Treetops the basal macro column was three and a half meters long a fairly respectable size for the time but quaint compared to most of its successors they were the only group of dinosaurs who matched and outright exceeded the size of their contemporaries some of the largest prosauropods were the lesson sorids who were very closely related to the true sauropods the largest Triassic species in gentia had a length of 10 meters and a staggering weight of 10 tons greater than today's elephants after prosoropods came onto the scene the only Triassic animal to match the size of their largest specimens was the Polish dicenidante Lisa Wikia an isolated fossil of the karnian pseudosukian silosuchus suggests it could grow up to 9 to 10 meters long although it was already extinct before the evolution of the prosauropods despite persoropods often being reconstructed walking on four legs like their sauropod Descendants the majority of them were not capable of pronating their forelimbs since this is necessary for efficient quadrupedal Locomotion most prosoropods were obligate bipeds some bipedal prosauropods such as the early Jurassic masospondulus and mosasaurus did walk on all fours as hatchlings while this gives insight into how the sauropods eventually transition to four-legged Locomotion the arms of these hatchlings were still not pronated so they would not have actually been very good at walking combined with their lack of teeth these baby dinosaurs must have been reliant on their parents much like many modern dinosaurs only the less I'm sorids and a few other Triassic prosoropods very closely related to the sauropods such as melanosaurus were able to properly walk on all fours their four limbs were flexed A Relic from when they were arms sauropods instead evolved columnar limbs which were much better at supporting their increasingly extreme weight while the oldest unambiguous body fossils of true sauropods are from the early Jurassic tracks left by Triassic sauropodomorphs with columnar and limbs have been found in Greenland which may have been left by true sauropods the most famous Triassic sauropodomorph is easily platiosaurus who was one of the first dinosaurs discovered at least three species of platiosaurus lived in Europe between 214 to 204 million years ago there is very good evidence that this dinosaur lived in herds over a hundred platiosaurus skeletons some of them complete have been found together in the German trosengan formation additionally three macro column specimens have been found together suggesting it may have been common for prosauropods to live in herds much as it was for their sauropod descendants the largest platysaurus individuals reached a length of 10 meters and a weight of 4 tons but like many other early dinosaurs many adults of the same species were much smaller while far from defenseless these smaller platiosaurus were still potential prey of pseudosukian predators and the fellow dinosaur Lillian sternus platysaurus is an example of just how widespread sauropodomorphs had become while once restricted to the southern hemisphere the prosauropods had managed to spread to the north 215 million years ago where they thrived however they remained absent in the equatorial regions at least in part due to their recently acquired bulk making them far more vulnerable to overheating most evolutionary trees agree that the third major brands of Dinosauria ornithischia must have evolved at the same time as the theropods and probably even earlier until recently the oldest unambiguous ornithischian fossils were from the early Jurassic which created an ornithischian ghost lineage over 30 million years long fortunately the mystery of the missing Triassic ornithiskins seems to have recently been solved an increasing number of paleontologists have concluded that the silosaurids a clade of dinosaur morphs common during the late Triassic were actually the first ornithischian dinosaurs since the later ornithischians are thought to have been directly descended from silosaurids sial soride is not a true clade its former members have instead been given the informal name style sores while all but one of the traditional ornithischians belonged to a derived clade named pranadantia while it will take time to see if this hypothesis becomes widely accepted it will be assumed that the silosaurs are basal ornithischian dinosaurs for the purposes of this video the silosaurus looks similar to aphanosaurs but with longer legs and a more grace I'll build like the earlier Ernest adirins they were primarily quadrupeds but their forelimbs were used for support rather than propelling them forward this has been used as evidence that these primitive ornithischians may have been able to run on only two legs the later prionodons were ancestrally obligate bipeds since the same was true of most Triassic dinosaurs and closely related dinosaur morphs such as marasukas it has generally been held the first dinosaur was also a biped the primarily four-legged stance of the silosaurs May argue against this although this may have been a derived feature that was reversed by their Jurassic descendants since they were early members of the clade silosaurs lack most of the features originally used to define ornithischia ornithischia means birdhipped in reference to how their pubis points backwards like in Birds Beyond this ornithischian hips have little resemblance to bird hips and a backward pointing pubis evolved independently in other dinosaur lineages including the actual ancestors of birds silosaur pubises instead point forwards which is the ancestral condition among reptiles another important feature not present in the first ornithischians is the pre-dentary bone this bone supported the beak on their lower jaws and is unique to the clade however the end of the lower jaw of most silosaurs resembles a predentory bone it likely filled a similar function and was its evolutionary predecessor much like with the sauropodomorph Dinosaurs there was a shift from carnivorie to herbivory among the Triassic or nephesians basalosaurs like Louis sukis were very small Predators with zyphodon's teeth later xylosaurs like silosaurus itself were a bit larger and ate both plants and insects the derived cylosaur kuanasaurus was the most dedicated plant eater among the silosaurs its teeth were diamond shaped with coarse denticules the typical shape of the prionidant ornithischians of the early Jurassic one of the most derived Triassic ornithiskins was basanasaurus before the hypothesis that cylosaurs are basal ornithischians gained much acceptance it was repeatedly reassigned between each group a testament to them being one in the same although personasaurus is not well enough preserved to determine whether it more closely resembled silosaurs or the early Jurassic ornithischians it was evolutionarily between the two since pisanosaurus lived around the middle of the Triassic and the first prionidant fossils are from the very beginning of the early Jurassic it is probable the more derived ornithischians evolved before the end of the Triassic period indeed the prionidant EO cursor may have actually lived during the end of the Triassic period although the exact age of the rocks it was found in is currently debated therefore it and the early Jurassic ornithiskins will be covered here as proxies for their slightly older Triassic ancestors they were primarily herbivores although a recent study of the pranadant lesothosaurus found it and perhaps some other early ornithisians may have been omnivores eating insects and other fauna when the opportunity presented itself in this regard they had not changed that much from their silosaur ancestors unlike silosaurs pariana.phemers were shorter than their tibias which is typical of animals Built For Speed there is evidence that at least some of these dinosaurs lived in herds since numerous skeletons of lesothesaurus have been found together in a single Bone Bed a notable clade of early Jurassic ornithischians or their heterodontosaurids these dinosaurs had distinctive fang-like tusks at the front of their mouths which are thought to have been used in fights against each other over mates and territory these large sharp teeth were once believed to have been holdovers from their carnivorous ancestors but due to their absence in silosaurs and other basal ornithischians this is no longer considered likely the most primitive early Jurassic ornithiskian was La Quinta Sora who is just outside of priodontia but also not a silosaur since a complete laquintasaurus skeleton hasn't yet been found it is currently unknown whether or not it had a predentory bone although its longer legs suggest a bipedal gait like its contemporaries to summarize the various types of Triassic Dinosaurs the first species were small carnivores most theropods and Herrera swords remained small to medium-sized predators a few grew larger but even they seem to have remained consistently overshadowed by larger archosaurs the sauropodomorph dinosaurs shifted from a carnivorous diet to a herbivorous one and afterwards Grouch become the only truly massive Triassic dinosaurs the smaller ornithischian dinosaurs also became plant eaters most Triassic ornithiskins were four-legged silosaurs although the bipedal prionodons had likely already evolved before the Jurassic dinosaurs were geographically limited to the southern hemisphere 233 million years ago since early dinosaur fossils are most common in South America it is suspected that they first evolved there by 215 million years ago dinosaurs had not only become more abundant but had also spread throughout the entire world they were smaller and less common at low latitudes but Triassic dinosaur fossils and Footprints become more common the closer the region once was to the North and South Poles notably the environment preserved in the ishigwalsto formation the home of many of the first dinosaurs was very cold the upper estimates for the temperature only come to 11 degrees Celsius or about 55 degrees Fahrenheit while few Triassic body fossils have been found in the poles themselves their Footprints indicate they were most abundant there one of these Triassic polar sites is the jungar Basin in Northwestern China which was within the Arctic Circle 200 million years ago notably debris that had been characteristically moved by Ice was found among the sediment there indicating the prehistoric Lake there periodically froze since global temperatures were higher during the Triassic even the poles were not Tundra but cool humid temperate forests even so this is remarkably different from the common image of dinosaurs who are often envisioned living in tropical environments although it has been known for some time that they also inhabited the colder Arctic and Antarctic polar dinosaurs were treated as exceptional now it appears dinosaurs started out as cold climate Specialists and then moved to the tropics the dinosaurs were able to survive in such places in part due to their high metabolism producing their own body heat allowed them to keep warm in spite of the external environment some other Orca soromorphs including the pseudosuchians also had high metabolisms and could be found in high latitudes however they were reliant on the ability to hibernate during the winter dinosaurs were able to be active throughout the year due to their secret weapon feathers while it has been known that many theropods had feathers since 1996 primitive feathers have also been found in ornithiscions such as chanyulong and even the closest relatives of the dinosaurs to survive to the Jurassic period the pterosaurs all of this suggests the very first dinosaurs had simple feathers it is thought these primitive feathers originally evolved to provide thermal insulation the heat produced by the body of an endothermic or mesothermic animal like a dinosaur is eventually lost to the environment this process becomes quicker the smaller the animal and the colder the external environment a covering of proto-feathers would have meant the Triassic dinosaurs could maintain a high body temperature even when it was freezing although no Triassic dinosaur fossil is in good enough condition to determine what its outer covering was like a recent study which modeled the thermodynamics of early dinosaurs found that most of them would have not been able to even survive without the thermal insulation feathers provided this even extends to celophysis despite its native environment being much warmer than its higher latitude cousins even though the first dinosaurs likely had feathers large fluffy Coats were not retained in all of their descendants this is best demonstrated by the extensive scale Impressions found on many late Cretaceous hadrosaurs the massive Triassic prosauropods were already so large that they likely lost their feathery coats to avoid overheating much like how many of today's similarly sized mammals have lost most of their fur although thermal insulation can remain useful or even outright necessary for large animals in sufficiently cold environments the polar Triassic forests were still a far cry from The Frigid Landscapes that later produced the likes of the woolly mammoth even without insulation larger prosauropods would have struggled in the tropics likely explaining their absence there whether or not the Herrera swords or the largest Triassic theropods had feathers remains unexplored however the largest known feathered dinosaur the tyrannosauroid utiranus was larger than even the most massive theropods from not just the Triassic period but from the early Jurassic as well its native environment in early Cretaceous China experienced cold Winters not unlike those endured by many of its Triassic predecessors at high latitudes suggesting they needed feathery coats as well the role of the dinosaurs during the Triassic was very different from those of the Jurassic and Cretaceous but understanding them also requires understanding what changed to allow the age of dinosaurs to happen it was once thought the dinosaurs gradually replaced most of their competition who were perceived as comparatively primitive it is true many of the more basal arcosauromorphs particularly those with lower metabolisms did become extinct as the Triassic period progressed and were replaced by arcosaurs however most of the replacements were pseudosukians not dinosaurs instead the rise of the dinosaurs was much more opportunistic rather than driving the incumbent of a niche to Extinction they merely took over when the previous holder was wiped out by something else this was actually something of an argosauromorph tradition they only became so successful in the first place due to the synapses being devastated by the Permian mass extinction and the resulting fragility of the unpredictable early Triassic ecosystems the dinosaur's first Big Break was during the karnian age when volcanic activity increased for a period of about 2 million years among the effects on the global environment was a spike in global humidity called the karnian pluvial event the changing climate led to the extinction of numerous species this may have been responsible for the downfall of the Herrera swords and basosauropodomorphs but many of the other vacant niches were filled by dinosaurs they then slowly became more common for the rest of the Triassic period but remained underdogs to their pseudosukian cousins this changed 201.3 million years ago when another period of volcanic activity began in the equator only this time far more extreme various toxic gases were released into the atmosphere and the concentration of atmospheric CO2 soon doubled or even tripled leading to Rapid global warming the release of another gas sulfur dioxide acidified the oceans decreasing their pH well below what most marine organisms could endure when this volcanic activity finally ended 600 000 years later 76 percent of all species have been driven to Extinction almost all of the pseudosukians perished during the n-triassic mass extinction with the only survivors being small crocodilomorphs like svenosuchus likewise besides the flying pterosaurs almost all of the other non-dinosaurian arcosauromorphs were wiped out along with the disinodons and most of the large amphibians in contrast an unusual number of dinosaurs survived the mass extinction including some of their largest Representatives that is not to say they came out completely unscathed herrerasaurs and silosaur ornithischians were rendered entirely extinct still the early Jurassic dinosaurs were not simply the descendants of a handful of species that got lucky multiple branches of therapeuta and sauropatomorpha managed to survive a mass extinction that wiped out all other terrestrial animals of remotely comparable sides part of the reason for this seemingly miraculous survival of so many large dinosaurs was their location the eruptions that caused the mass extinction were at the equator While most dinosaurs were concentrated closer to the poles of course dinosaurs were not the only large animals there but they did have another Advantage one which made them largely immune to another and until recently underappreciated killer behind the entrancic mass extinction the Ash and debris from the largest volcanic eruptions remain in the atmosphere for some time blocking so much sunlight that even with more CO2 reflecting it back to Earth temperatures fell drastically these volcanic Winters could have easily lasted 10 years at the tropical equator temperatures may have dropped to below freezing levels something most of the local fauna would have been completely unprepared for in contrast the dinosaur's feathers meant they were uniquely predisposed towards surviving these suddenly colder conditions Furthermore with their malleable growth rates younger dinosaurs would have been able to stop growing during the resulting famine the largest species of Triassic dinosaurs may have survived due to their ability to stay small to summarize the Dinosaurs Ruled the Jurassic and Cretaceous periods not because they were Superior to other reptiles but because their ancestors happened to be better suited to survive a random and geologically brief disaster at the end of the Triassic period this mirrors how one group of synapsids would later replace the dinosaurs indeed the early mammals and the remaining crocodilomorphs would have otherwise been in a great position to take over the new Jurassic world if not for the fact that the dinosaurs were already significantly larger and therefore able to fill most of the empty niches before the rest of the survivors had a chance to make much progress mammals and a few other cyanodons would remain in the shadows until the cenozoic era although they were highly diverse the largest Mesozoic mammals were only as large as a badger and most were far smaller the remaining pseudosuchians had far better luck reclaiming the niches of their ancestors some of them took advantage of the extinction of the semi-aquatic phytosaurs giving rise to the crocodilians including a number of massive dinosaur killers many crocodilomorphs remained on land and some of these eventually also managed to compete with the now dominant dinosaurs the largest of these land cracks razan Andrew gobe was already a sizeable dinosaur killer as early as the middle Jurassic echoing its extinct Triassic kin others like the herbivorous simosuchus followed new evolutionary paths likewise the fellow arcosaurian pterosaurs grew in diversity while they largely remained small during the Jurassic period Cretaceous pterosaurs became some of the only other large terrestrial animals besides dinosaurs some became the largest creatures to ever fly and in some cases where Terrors on land as well still although there were some exceptions nearly all large terrestrial animals were dinosaurs for the next 135 million years the age of dinosaurs had truly begun sauropodomorph dinosaurs quickly expanded into the tropics sauropods were the most successful there and were the largest dinosaurs of the early Jurassic although they were not yet substantially larger than the largest Triassic sauropodomorphs however the cooler regions remained dominated by prosauropods very similar to those from the Triassic it didn't take long for theropods like Cryolophosaurus to grow large enough to hunt the largest of their distant kin replacing the pseudosukians who had terrorized their own ancestors other early Jurassic theropods such as tacharaptor held essentially the same niches as before some of them were once even classified as species of celophysis the only thing that really changed for the smaller dinosaurs is that their predators now happen to be fellow dinosaurs rather than pseudosuchians all of the surviving ornithischian dinosaurs were the prionodons with the exception of the closely related lacking to Sora while the iconic Hadrosaurus and horned ceratopsids wouldn't evolve until the Cretaceous Period the ornithiski enclaved thyria4a had already developed bony armor soon the thyriophoren skeletosaurus became quadrupedal to better support its greater size replacing the now extinct pseudosukian aidasaurs still the smaller bipedal ornithisians stuck around to the very end of the Mesozoic Era living much as their primeval ancestors had however this was an exception although the early Jurassic dinosaurs were similar to those of the Triassic except for those who had replaced their extinct competition by the middle Jurassic they had come to exceed them the sauropods grew more massive than anything before or since while the prosauropods declined and finally became extinct likewise a single plate of theropods a varostra had replaced all others by the late Jurassic they seem to have been descended from large dilophosaurus-like Predators but soon went on to include small carnivores as well as omnivores herbivores and of course Birds from the late Jurassic onwards few dinosaurs could be mistaken for their Triassic ancestors of course even though giant dinosaurs are the most iconic the majority of the Jurassic and Cretaceous dinosaurs remain small with almost no competition these small dinosaurs were actually more abundant and diverse than the dinosaurs of the Triassic but if it were not for those early dinosaurs the great radiation of Dinosauria would have never happened and the current multitude of birds would not exist the Triassic dinosaurs placed the evolution of Dinosauria into context for all their Fame they started out as just one of many Clays of reptiles at a time when not all of their competition even were reptiles but within 30 million years they went from a geographically isolated group of tiny carnivores to a diverse array of species which served as the foundation of nearly all the later megafauna for well over 100 million years before then they thrived in climates most other reptiles shunned and almost single-handedly invented an entirely new class of large herbivore although they were fewer in number than later dinosaurs those dinosaurs which did exist during the Triassic period were equally remarkable animals thank you for watching and a thank you to the matalorian for narrating this video also a thank you to Bethany luster for creating this illustration depicting Triassic dinosaurs in a snowy environment in the high latitudes without her there would not have been any visual depictions of Triassic dinosaurs and such surroundings this is particularly important since such temperate seasonally chilly environments were where they thrived during the Triassic period I hope this video has achieved its aim to give an effective overview of the Triassic dinosaurs and sparked interest in learning even more if you enjoyed it please remember to hit the like button and subscribe if you'd like to see more finally be sure to have a great day

Channel: CHimerasuchus

Views: 799,170

Keywords: Fossil, Dinosaur, Paleontology, Prehistoric, Prehistory, Reptile, Archosaur, Dinosaurs, Archosaurs, Reptiles, Crocodiles, Crocodile, Mesozoic, Science, Triassic, Triassic Period, Triassic Dinosaurs, Triassic Dinosaur, Theropod, Sauropodomorpha, Herrerasaurus, Eoraptor, archosauromorph, pseudosuchians, Daemonosaurus, Coelophysis, Zupaysaurus, Dilophosaurus, Buriolestes, Macrocollum, Plateosaurus, Silesaurs, Silesaurids, Silesaurus, dinosauromorphs, Feathered Dinosaurs, Polar Dinosaurs, Pisanosaurus, Eocursor, extinction

Id: POK2oI7PwtI

Length: 51min 2sec (3062 seconds)

Published: Sat Apr 01 2023