Episode 518: Was Saurophaganax an Allosaurid or a Sauropod?

Episode 518: Was Saurophaganax an Allosaurid or a Sauropod?. Plus a brand new sauropod with a tail membership, a probably new Spinosaurus species, and a number of other extra new dinosaurs!

Information:

• A brand new Spinosaurus species was reported final yr from Niger supply
• The vertebrae within the Saurophaganax holotype could have been from sauropod(s) supply
• There’s a brand new sauropod dinosaur, Ardetosaurus viator supply
• There’s one other sauropod with a tail membership! supply
• There’s a brand new ornithopod dinosaur, Emiliasaura alessandri supply
• By the top of the Cretaceous, ornithopod dinosaurs had advanced enamel that made them very profitable plant eaters supply
• Birds from the Late Cretaceous existed alongside dinosaurs like Tyrannosaurus and lived like as we speak’s birds of prey supply
• A uncommon “flat-headed” juvenile pachycephalosaurid lived within the Late Cretaceous in what’s now Texas, U.S. supply

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The dinosaur of the day: Dilophosaurus

• An up to date description got here out in 2020, by Adam Marsh and Timothy Rowe
• Theropod that lived within the Early Jurassic in what’s now Arizona, U.S. (Kayenta Formation)
• Theropod, so walked on two legs, had an extended tail, lengthy arms, sharp enamel, and had two crests on its head
• A lot bigger than the way it was depicted in Jurassic Park, and didn’t have the frill
• However, did look fierce
• Slender and frivolously constructed
• Estimated to be about 23 ft (7 m) lengthy and weigh about 880 lb (400 kg)
• An histology research in 1996 discovered that Dilophosaurus grew 66 to 77 lb (30 to 35 kg) per yr early on (had a woven construction within the bones that confirmed it grew shortly)
• Walked on two legs and was lively
• Had highly effective arms, and 4 fingers on every hand, with a big claw on its first fingers (smaller claws on the center fingers, and a vestigial fourth finger)
• Had a big thigh bones, stout toes, and huge claws on its toes
• Saved the primary toe (hallux) off the bottom
• Third toe was the stoutest
• Had hole, gentle vertebrae
• Had an extended, versatile neck
• Had a big, delicate cranium
• Had a slender snout
• Had a pair of arched crests on its cranium, that had been most likely lined in keratin in life
• Paleoartist Brian Engh reconstructed Dilophosaurus based mostly on Marsh and Rowe’s paper and talked about it had bizarre proportions
• Mentioned the true crest form is unknown (don’t know what the highest regarded like)
• Higher jaw had a spot or kink beneath the nostril
• Can see this hole or kink in different dinosaurs, together with coelophysoids
• Had highly effective jaws
• Had a slender delicate entrance of the higher jaw, that was deep within the again
• Had lengthy, curved, skinny enamel
• Many of the enamel had been serrated
• In 2018, Senter and Sullivan studied the vary of movement for Dilophosaurus’s arms, and located it might grip and maintain objects, in addition to deliver objects to its mouth, and swing its arms, scratch its chest or stomach
• Might have gone after massive animals, in addition to eaten smaller animals and fish
• Debate about how and what it ate. Welles, who named Dilophosaurus, discovered it didn’t have a robust chunk, and was most likely a scavenger. Welles noticed Dilophosaurus as lively, and used its arms as weapons, with palms that might grasp and slash. Bob Bakker later discovered, with its massive neck and cranium and huge enamel, it might kill massive prey. Gregory Paul additionally urged Dilophosaurus hunted massive animals and will additionally go after smaller animals
• A 2005 research discovered the entrance of the jaws had a robust chunk, which might subdue prey, and the stress on the jaws had been according to struggling small prey. So could have slashed prey to wound it, then captured the prey within the entrance of its jaws. Then the prey could have moved to the again of the jaws, the place the most important enamel had been, and killed by slicing bites
• Milner and Kirkland in 2007 urged Dilophosaurus ate fish, based mostly on the ends of the jaws that fashioned a “rosette” of interlocking enamel, much like spinosaurids, that are thought to eat fish
• Each Dilophosaurus and spinosaurids had lengthy arms and well-developed claws, which might assist them catch fish, and nasal openings that had been retracted, which could have helped hold water out whereas fishing
• In 1990, Stephen and Sylvia Czerkas urged Dilophosaurus had an aquatic way of life, with a weak pelvis that wanted the water to assist assist it’s weight, although they didn’t assume it solely lived within the water
• Marsh and Rowe in 2020 urged that Dilophosaurus might prey on massive animals, although it could have additionally eaten fish and small prey. Advised the premaxilla and maxilla of the higher jaw was not cell and extra sturdy than beforehand thought, and Dilophosaurus might have grasped animals with its arms whereas searching and scavenging
• Giant tooth marks on the sauropodomorph Sarahsaurus regarded as from Dilophosaurus (proper dimension)
• Brown and Rowe in 2021 mentioned Dilophosaurus might puncture bone with its jaws. Additionally discovered it had unidirectional respiration, like birds, the place air flows out and in of lungs, and means it had a excessive metabolism and was most likely quick and agile
• Thought Dilophosaurus was an apex predator, and never a scavenger
• Crests began as low ridges on the entrance of the cranium and received larger and plate-shaped on the roof of the cranium
• Unclear what it used the crests for (too weak to combat with, however perhaps used for show, to acknowledge one another and entice mates)
• Had air sacs within the bones across the mind, they usually had been linked with sinus cavities within the entrance of the cranium. The opening in entrance of the attention sockets had been additionally linked to the aspect of the crests, so crests most likely additionally had air sacs
• Doable the crests helped regulate its physique temperature
• Or the crests could possibly be for species recognition or for attracting mates
• Kind species is Dilophosaurus wetherilli
• Three skeletons present in 1940 in Arizona (two collected in 1942)
• Took 10 days to gather the 2 skeletons (Welles mentioned it was a rush job) and produce them again to Berkeley (UC Museum of Paleontology)
• Jesse Williams, a Navajo man, first discovered the fossils in 1940
• Based on Navajo fantasy, footprints and dinosaur bones had been usually defined as belonging to monsters, killed off by the Hero Twins, who slayed monsters
• When the Hero Twins slayed a monster, they buried the monster and turned it into stone. Over time, they removed all of the monsters on Earth and other people had been capable of take over
• The three skeletons had been discovered organized in a triangle. First one was practically full, second one was eroded, however had the entrance of the cranium, decrease jaws, vertebrae, limb bones, and an articulated hand. Third one was so eroded it was nearly gone, and there have been solely fragments of vertebrae
• Holotype is almost full, and solely lacking the entrance of the cranium, elements of the pelvis, and a few vertebrae
• Holotype cranium was crushed
• Took three individuals two years to scrub and mount the holotype
• Holotype was initially named as a brand new species of Megalosaurus, Megalosaurus wetherilli, in 1954 by Samuel Welles
• Thought of to be Megalosaurus at first as a result of that they had related limb proportions
• Additionally didn’t understand it had crests. The crests had been skinny, and crushed collectively, and regarded as a misplaced cheek bone
• In 1964 Welles discovered one other skeleton close to the place the primary ones had been discovered, that was practically full and bigger than the holotype
• Realized there have been crests on the cranium, so he named Dilophosaurus wetherilli in 1970
• Welles mentioned the crests had been as sudden as discovering “wings on a worm”
• Genus identify Dilophosaurus means “two-crested lizard”
• Species identify is in honor of John Wetherill, a Navajo councilor that Welles mentioned was an “explorer, buddy of scientists, and trusted dealer”
• Curiously, Welles didn’t assume the 1964 specimen was Dilophosaurus, although they each had crests, however he died earlier than he might identify the dinosaur. Different paleontologists both discovered no important variations between the 1964 specimen and the holotype or they discovered the variations had been attributable to particular person variation or how they had been preserved or their completely different ages
• The 1964 specimen was thought-about to be an grownup (due to its dimension) and the primary two skeletons discovered had been thought-about to be juveniles
• Doable the smaller specimens are juveniles, however may be sexual dimorphism, the place some are extra gracile and a few extra sturdy (later discovered no proof of dimorphism, although it’s doable there have been variations within the crests)
• Robert Homosexual in 2001 recognized not less than three extra Dilophosaurus specimens, based mostly on hip bone fragments and completely different sized femora or thigh bones
• Specimens present in 1978, additionally close to the unique specimens, and had been labeled as a “massive theropod”
• Helps fill in some gaps in regards to the skeleton
• Among the bones belonged to an toddler
• A 2005 research of the bones discovered most specimens had been juveniles, and solely the most important one was an grownup (bones had been co-ossified)
• Adam Marsh and Timothy Rowe redescribed Dilophosaurus in 2020. Marsh spent seven years finding out the specimens
• Adam Marsh and Timothy Rowe studied 5 specimens, and located Dilophosaurus to be a neotheropod
• A number of extra specimens have been referred to Dilophosaurus, however not sufficient options to verify, in order that they referred them to cf. Dilophosaurus wetherilli
• Know the jawbones, elements of the cranium, together with the braincase, backbone, neck, again, and tail bones, elements of the shoulders, arms, palms, hips, legs, and toes
• There was a second species, Dilophosaurus sinensis, named in 1993 and located in China, however now thought-about to be Sinosaurus
• Holotype had plenty of pathologies, however onerous to inform the way it received them. One risk is it’s from one encounter (colliding with a tree or rock whereas preventing)
• Holotype had a groove on a tail bone that will have been from an harm or being crushed, and two pits on the correct arm that will have been from collections of pus, or could have been artifacts of the way it was preserved. Additionally had a smaller, extra delicate left humerus (higher arm bone) than the correct, and a smaller, extra delicate decrease proper arm bone than the left, which could possibly be a developmental anomaly generally known as fluctuating asymmetry, which could possibly be attributable to stress or pressures within the surroundings, or from traumatic occasions
• All of the accidents had healed, so the Dilophosaurus appears to have survived for some time after (months and even years)
• Whereas therapeutic, most likely couldn’t use its arms nicely to seize prey, so could have accomplished plenty of fasting or solely ate small prey
• Additionally had bony tumors and different pathologies, and a finger that couldn’t flex, and should have had osteodysplasia (bone progress abnormalities, often genetic)
• Footprints discovered close to the place the primary Dilophosaurus specimens had been discovered, they usually had three-toes, and should have been Dilophosaurus tracks
• Tracks had been present in 1966 by a bulldozer operator, they usually had been assigned to Eubrontes, which grew to become the state fossil of Connecticut in 1991
• Space was being excavated for a brand new state constructing, after which in 1968 it grew to become Dinosaur State Park as an alternative
• Welles named the ichnogenus Dilophosaurus williamsi, based mostly on Williams, who discovered the skeletons
• Different tracks discovered world wide that at instances had been thought-about to be made by a dinosaur like Dilophosaurus, however in some circumstances could possibly be different theropods and even sauropodomorphs
• One resting monitor thought-about to be made by a theropod much like Dilophosaurus and Liliensternus, and for some time thought-about to have feather impressions, however a 2004 research discovered the impressions had been pressure-release constructions that had been attributable to the dinosaur transferring after it rested. Discovered the theropod sat again on its toes, shifted its weight to the correct when it stood up and moved ahead. Doesn’t imply it didn’t have feathers, simply that feather marks would look completely different
• Resting tracks confirmed the dinosaur was crouching, and utilizing its palms to take action, and it left skinny drag marks from the top of its tail
• Tracksite attributed to Dilophosaurus in Arizona is called Naasho’illbahitsho Biikee by the Navajo, or “huge lizard tracks”
• Dilophosaurus is the state dinosaur of Connecticut as of 2017, based mostly on tracks discovered there thought-about to belong to dinosaurs much like Dilophosaurus
• Can see Dilophosaurus within the film Jurassic Park (additionally talked about within the novel), although not like in actual life, it couldn’t spit venom and it most likely didn’t have a neck frill. Additionally, it was a lot greater in actual life
• Sam Welles mentioned it was fairly a thrill to see Dilophosaurus in Jurassic Park although, and was “very comfortable to seek out Dilophosaurus an internationally identified actor”
• Lived in a dry space, that had a waterway lined with conifers
• Different dinosaurs that lived across the similar time and place embrace the armored herbivore Scutellosaurus and the sauropodomorph Sarahsaurus, in addition to Megapnosaurus and Kayentavenator
• Different animals that lived across the similar time and place embrace sharks, fish, salamanders, frogs, turtles, lizards, crocodylomorphs, mammals, and pterosaurs

Enjoyable Truth:

Ants farmed fungus within the Late Cretaceous

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