A Modern Look at Dilophosaurus

long before dinosaurs evolved into giants they started out relatively tiny and lived in a world with a bizarre diversity of strange creatures that ruled the forests and swamps of the triassic period abundant fossils of this strange ancient world have been found in petrified forest national park in arizona where paleontologist dr adam marsh has been diligently working to uncover the mysteries of the early evolution of dinosaurs in north america i'm adam marsh i'm the lead paleontologist at petrified forest national park here we're in the lower part of the chinle formation in a quarry that's about 220 million years old this is one of the dinosaurs found at petrified forest this is the upper leg bone of an animal called chindisaurus and this is about as big as it got now most of the animals that are running around in the late triassic of north america looked like dinosaurs but aren't they belong to a group called sudasuki and archosaurus and they're more closely related to crocodilians this is actually a bony piece of armor of an aida sore which is one of these animals these aeidosaurs were heavily armored for good reason because stalking these lush triassic forests were numerous formidable predators such as the strange bipedal rauzookians and the massive semi-aquatic phytosaurs lurking in the rivers and swamps but none of these large predators were dinosaurs now 35 million years later from where we are here in time we're in a rock unit called the cayenne formation in the early jurassic and there it's post end triassic mass extinction and most of the sudiisuki and archosaurs have gone extinct that end triassic extinction event coincided with a dramatic shift in the climate triggered by hugely elevated atmospheric co2 resulting from volcanic eruptions moving up into the rock layers of the early jurassic the geologic record shows us that the climate was unstable and becoming progressively drier in western north america this drier landscape had fewer flooding river channels and thus buried and preserved fewer bones as fossils but this landscape did preserve an extensive fossil track record which clearly recorded dinosaurs increasing in both body size and abundance as the sudosukians of the triassic went extinct but in a few places on navajo land in northern arizona a few skeletons from some of these early jurassic track makers were preserved and they offer us a rare glimpse into this important period in dinosaur evolution [Music] dilophosaurus was first discovered by a navajo man named jesse williams in 1940 and excavated in 1942 by paleontologists sam wells and wyan langston jr what they found were several skeletons of the oldest large predatory dinosaur yet discovered in north america despite its early discovery and its huge significance to our understanding of the evolution of the first large dinosaurs dilophosaurus has never been thoroughly scientifically described until now for the last six years adam marsh has been painstakingly describing and analyzing every bone of every known skeleton attributed to dilophosaurus including several new specimens to determine where they belong in the family tree of dinosaurs adam's new analysis has revealed that the truth about dilophosaurus is even stranger than its depictions in fiction when dilophosaurus was first discovered it was considered a species of megalosaurus until the discovery of the famous tall crested specimen revealed that it actually had two large crests on its head it was then renamed and reinterpreted as a sort of convenient intermediary between the small coelophysoid theropods of the triassic and the later crested ceratosaurs of the late jurassic but adam's analysis reveals something fascinating the lophosaurus isn't closely related to any of these animals instead it forms a strange grade of theropods along with zupyosaurus from south america and cryolophosaurus from antarctica and none of these dinosaurs were direct ancestors to the ceratosaurs or megalosaurus of the late jurassic while this might seem surprising or confusing it's important to remember that by the time of dilophosaurus theropod dinosaurs had already been a highly successful globally distributed group for millions of years we just don't have any skeletons of what all these animals looked like thus adam's findings demonstrate that the evolution of large body size in dinosaurs wasn't a tidy linear progression from the small dinosaurs of the triassic to the famous giants of the late jurassic but rather the early jurassic was a time of wild evolutionary diversification and experimentation in the wake of the end triassic extinction the prolonged lack of a thorough scientific description has also affected how dilophosaurus has been depicted in paleoart and pop culture the fragmentary nature of the known dilophosaurus skulls led sam wells to speculate that dilophosaurus had a fragile skull and a weak bite this suggestion led to further speculation the dilophosaurus must have been a scavenger or a strict fish eater or that it must have relied on venom to subdue its prey as in jurassic park in order to better understand low thesaurus's skull and biology i collaborated with adam on creating a rigorous skull reconstruction the first skull reconstruction of telophosaurus to take all of the known skull material into account while also considering its three-dimensional structure for a living 3d life reconstruction to be featured in the museum exhibit videos at the st george dinosaur discovery site in st george utah this in-depth analysis of all of the known dilophosaurus skull material quickly made it clear that all of those earlier speculations about dilophosaurus biology are completely unfounded you want to make it move its jaw for the camera that's actually a really impressive muscle attachment area thorough reconstruction and proper scaling reveals that dilophosaurus jaws were actually deep and powerfully muscled its teeth were large and serrated for shearing through flesh and bone and the strange notch between the pre-maxilla and maxilla has been exaggerated in most reconstructions because of breakage and distortion in the most famous tall crested specimen the skull of that famous tall crested specimen is also the largest known specimen and it's larger than any land predator alive today dinosaurs like dilophosaurus are for the first time in north america the macro predators and they're eating things like the long neck dinosaur serosaurus which among other animals of its age are the first long neck dinosaurs in north america dilophosaurus was a dinosaur killer and the apex predator in its environment bite marks on the bones of cerasaurus support this interpretation in the absence of evidence of any other large predator living in the cayenne formation ecosystem several specimens of telophosaurus have numerous injuries and bite marks which show signs of healing all of this suggests the violent lifestyle of an active predator and one which may have engaged in frequent intra-species combat and possibly even cannibalism just as many of its modern relatives do dilophosaurus most bizarre and prominent feature the two bony crests on top of its head have also been the most consistently misunderstood feature of all most paleoart depictions have simply covered the crest in a thin sheet of skin and separate it from the ant orbital fenestra that large window into the nasal sinuses between the nose and eye sockets in the skulls of theropod dinosaurs but when you see the skull from the front it becomes clear that the crest isn't separated from the ant orbital fenestra at all it's an expansion of it in fact most non-bird theropod dinosaurs have small crests formed by the lacrimal and nasal bones in the same area and almost all of these crests have hollow spaces inside of them left by air sacs expanding from the ant orbital fenestra up into the bony crest [Music] this is the holotype of ceratosaurus tyrannosaurus nasal cornice nasal corners not magna cores keep it straight not dentists and really they're all the same thing it turns out it's all antonogenic variation so it's interesting that you have this other fossa within the animal fossil it's fairly deep and almost penetrates through the actual so that that's ascending process yeah that's broken but it you know it was very thin yeah so this ascending process of the maxilla was highly pneumatized if you look at the back side here you can see that this is crushed here but again why was it crushed well probably because there was an air sex yeah so it's all related there's that and then it's got the pneumatic fossa goes all the way up into the crest the crest is hollow the lophosaurus crest is the result of taking this developmental pattern to a bizarre extreme and expanding those air spaces upward so much so that we don't even know the full size and shape of dilophosaurus bony crests because the top edge isn't even preserved because of the lateral crushing of the fossils it's also a bit unclear how many layers of thin-walled air-filled bone actually make up each of the crests and the largest specimen with the best preserved crest has areas with thicker bars of bone reinforcing the inside of the one preserved crest i mean if this is a big pneumatic thing like yeah none of this might even be visible externally but it's interesting to note living bone is much more durable than brittle fossils and so much of the fossil crest is missing or crushed that it's hard to quantify exactly how strong the bone alone would have been but dilophosaurus crests would have been far more durable for another reason believe it or not it's not just extinct dinosaurs that have thin air-filled bony crests there are actually dozens of species of dinosaurs with similar crests that are still alive today many modern birds also have air-filled bony crests connected to their sinuses and all of them sheath their crests in keratin the same hard horny material that makes up birds beaks keratin is a remarkably durable material so much so that large cassowaries can safely run through dense jungles at full speed some large hornbill species actually fight with their hollow crests and some parts of these hornbill crests barely have any bones supporting them at all the keratin keratinous covering also significantly enlarges the size of the crest in life in some birds the keratin expands the size of the crest up to 1.5 times the size of the underlying bony crest keratin can also be grown in any color thus these showy crests play an important role in species recognition and sexual display helping birds to communicate and attract mates but they have other functions as well one recent study demonstrated that cassowary crests are an important structure for thermal regulation by flushing the air-filled crest with blood cassowaries can offload excess heat which helps to keep their brains cool in the hot tropical climate where they live the hollow casks of hornbills may also help to amplify their calls and because the air sacs throughout birds bodies are connected back to their lungs these air sacs help them to be highly efficient at absorbing oxygen while retaining water when they breathe like modern birds hollow spaces in the bones of dilophosaurus didn't stop with the crest on its head in fact dilophosaurus shows the first signs of these air sacs invading its vertebrae this adaptation helped to lighten the bones which helped enable dilophosaurus and later large theropod dinosaurs to become giants while increasingly elaborate air spaces in the bones of these smaller living theropods helped them become light enough to take flight the wild expansion of these air sacs into the crest of dilophosaurus suggests that sexual display and possibly thermal regulation sound resonance or moisture retention were among the main factors driving the evolution of these structures and lightening of the bones for achieving giant size was a secondary adaptation of air sacs in the bones of dinosaurs elaborate display features such as showy keratinous crests often evolve in groups of animals which are widespread and highly successful and dilophosaurus was definitely successful its skeletons being found at multiple levels of the cayenneta formation suggest that these animals persisted in northern arizona for several million years unfortunately the fragmentary nature of the few dilophosaurus skulls preserved make it impossible to see how the head crests may have been evolving during this time studies of modern animals have demonstrated that sexual display features evolve rapidly and exhibit a high degree of variation between closely related species and even among individuals of the same species the presence and variability of elaborate head crests and air sacs in multiple groups of early jurassic theropods contributes to the emerging picture of the early jurassic as a time of radical evolutionary experimentation and diversification in the aftermath of the end triassic extinction event which means we still have a lot to learn about this mysterious time period and how dinosaurs and their ecologies adapting to a shifting climate set the stage for the appearance of the largest land animals that would ever live along with birds direct ancestors and the first true mammals all of which appear in the fossil record in the late jurassic while fossil bones from the early jurassic remain extremely rare in north america a slew of new discoveries outside of arizona are helping paleontologists better understand the world dilophosaurus evolved in in saint george utah paleontologist andrew milner and his intrepid band of museum volunteers and prep lab workers have been hard at work exploring and excavating new fossil sites preserving tracks teeth and plants sometimes all in close association in the early jurassic rocks near st george the reason tracks are so important is because they actually record the behavior and movements of these animals in the environment where they actually lived and the tracks at this site reveal surprising behaviors that nobody would have guessed based on bones alone so what we have here is a collection of dinosaur swim tracks these are made by small meat eaters that are boiled up in the water and as they're kicking their feet their toes strike the muddy bottom leaving these parallel sets of three scrape marks here at the dinosaur discovery site at johnson farm we have the world's largest and best preserved collection of dinosaur swim tracks and these tracks ended all controversy on whether or not dinosaurs actually [Music] swam many of these new finds will be incorporated into upcoming exhibits and the live-action dilophosaurus reconstruction scene in this video is now featured in the st george dinosaur discovery site's new museum intro video which is now playing at the museum just over the utah border in southern nevada paleontologist josh bondi has been discovering exciting new fossil track sites in the early jurassic aztec sandstone a rock formation which records a remarkable transformation of the early jurassic landscape as it developed into a vast sea of desert sand dunes hi i'm dr josh bondi i'm a paleontologist here in southern nevada so today we're out here dinosaur tracking despite how large this geologic unit is spans from southern california to southern montana one of the largest sand seas that we have a record of in the geologic record of our planet there's only been a handful of bones ever found out of this entire pile of sand why sandstone is really porous and so fluids easily go through it so if there was bone there it probably got dissolved away a long time ago another problem is that if you're in a sand dune sands also really abrasive so originally when that animal died on sand dune it's getting abraded it's getting sand blasted through time also decreasing the likelihood of it being preserved [Music] so in settings like this when we have only tracks that's how we have to interpret our ecosystems but here we are in southern nevada finding similar types of tracks as we're finding these other places showing us the same types of dinosaurs that were running around southern utah during this period of time also running around here in southern nevada so we have meat eaters we have bugs we have spiders all making their way through this landscape so it gives us an insight into not just who's here but maybe even to how they're interacting here in nevada we're just beginning to scratch the surface of our dinosaur aged rocks really this is a brand new opportunity for research and brand new stories that we're telling from the age of dinosaurs here in the silver state my most recent project is a diorama exhibit for the las vegas natural history museum based on the paleo environment of the aztec sandstone this diorama will feature casts of newly discovered tracks found in nevada and a life-size sculpture of dilophosaurus i'll be posting progress updates about these new exhibits and the fossil discoveries we're incorporating into them in the coming months i hope you'll follow along on social media and show support for these regional museums and their hard-working paleontologists and volunteers as they attempt to navigate the difficulties of the covet 19 shutdown which has deeply challenged some of these smaller museums and the economies of the communities surrounding them until then we'll be working hard uncovering and studying new fossil sites and attempting to bring them back to life through science and art [Music] [Music] [Music] you

Channel: BRIAN ENGH PALEOART

Views: 240,372

Rating: 4.9682126 out of 5

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Id: y7jSOp2mr2s

Length: 21min 19sec (1279 seconds)

Published: Thu Sep 17 2020

Reddit Comments

[u/obozo42]

Brian Engh is consistently one of the most engaging persons when it comes to pratical creature effects in science and in his artistic projects (such as his music). I see his work as frankly the closest thing we have to a modern Walking with dinosaurs in terms of accuracy and excellent effects.

[u/phased417]

Anyone else see an Anjanath?

[u/halpscar]

In the Jurassic Park book, the dilophosaurus is large, like 10' iirc. I always wondered why Spielberg made it so small - maybe due to special effects limitations? But the raptors and the t-rex were done so well, idk. Maybe to maximize Nedry's humiliating death?

[u/JonWake]

This is a good dinosaur. No I will not be taking questions. Don't ever speak to me, or my dinosaur again.

[u/amn70]

That doesn't look very scary. More like a 6 foot turkey.

[u/Luke90210]

To be fair, Dennis the System Admin was worth spitting on.

[u/yashoza]

2 things to remember:

Jurassic Park is directly responsible for this surge of new dinosaur research. And if a dinosaur had a fragile bone outside, it was covered in keratin.

[u/Reasonable_Childhood]

Are there ever any artist concepts of dinosaurs with beaks other than one's commonly thought to have them? I find it hard to believe that with increasing evidence of similarities to birds, such as these crests and feathers, that so many dinosaurs would be beakless. Especially after learning of the difficulty for keratin to fossilize. Just read that sauropods probably had turtle like beaks too.

[u/HacksawDecapitation]

I choose to believe what Jurassic Park has programmed me to believe!