Episode 464: Dinosaur teeth! Tyrannosaur teeth in Yellowstone, spinosaur teeth in Early Cretaceous England, and more. Plus Brian Engh joins to discuss his documentary series on the Morrison Formation.

News:

• The first tyrannosaur tooth ever described from Yellowstone National Park source
• Machine learning based on Maniraptoran teeth determined they were around about 30 million years earlier than previously thought source
• A tooth shows there were more spinosaurs in the Early Cretaceous in what’s now England source
• There was a diverse theropod community living in what’s now southern Chile up until the K-Pg extinction event source

Interview:

Brian Engh, a paleoartist and creator of the documentary series Jurassic Reimagined. You can find his work at dontmesswithdinosaurs.com on YouTube @DinosaursReanimated on Patreon at HistorianHimself and on twitter and Instagram @BrianEngh_Art

The dinosaur of the day: Eoabelisaurus

• Abelisaur that lived in the Middle Jurassic in what is now Chubut Province, Argentina (Cañadón Asfalto Formation)
• Looked somewhat similar to Majungasaurus
• Walked on two legs, and had a long head, long tail, bulky body, powerful legs, and short arms
• Unlike Majungasaurus, no head ornamentation found
• Had short neck vertebrae
• Had four fingers on each hand
• Had strong, sturdy legs
• Estimated to be up to about 20 to 21 ft (6 to 6.5 m) long
• A later estimate found it to be 19 ft (5.8 m) long
• Had heavy shoulder blades
• Known for its very short arms
• Type and only species is Eoabelisaurus mefi
• Genus name means “dawn Abel’s lizard” and refers to the fact that it’s an early relative of Abelisaurus (talked about Abelisaurus in episode 79)
• Species name is in honor of MEF, the abbreviation for the Edigio Feruglio Museum of Palaeontology, where Diego Pol, who found the fossils, is active
• Diego Pol found the fossils in 2009
• Described in 2012 by Diego Pol and Oliver Rauhut
• Holotype includes a nearly complete skeleton with a skull, of either a subadult or adult (most of the spine, both arms and legs, parts of the skull—missing the front of the skull, lower jaw, end of the tail, though they did find 27 tail vertebrae)
• The back half was articulated
• First grouped as an abelisaurid, but later grouped as an abelisauroid
• Eoabelisaurus helps show how abelisaurs evolved
• Before Eoabelisaurus, the oldest known abelisaurids weren’t well known (only fragments), and only definitively known from the Early Cretaceous
• Eoabelisaurus helps show that abelisaurids were around 40 million years longer/earlier than previously thought
• Abelisaurids were bipedal carnivores, known for their stocky legs and ornamentation on their skulls, like crests or horns
• They had short arms, often without wrist bones, four stubby fingers on their hands, short but tall skulls, and many had bony crests above their eyes
• They lived from the Middle Jurassic to the Late Cretaceous and have been found in Africa, South America, India, Madagascar, Portugal, and France
• Abelisaurs are mostly known from the Southern Hemisphere
• Abelisaurs were the tyrannosaurs of the Southern Hemisphere
• Eoabelisaurus lived before Gondwana split off. Could be there was a big desert that kept abelisaurids from going north
• Eoabelisaurus arms were shorter like later abelisaurids, such as Majungasaurus, which lived at the end of the Cretaceous
• Other abelisaurids from the Early Cretaceous had longer arms
• Eoabelisaurus’s upper arm was longer than the lower arm (upper arm was actually normal in size), which may mean abelisaurs started evolving shorter lower arms first before moving on to the upper arm
• Short arms show that abelisaurids started getting shorter arms early in their evolution
• With its small arms, probably used its teeth more to go after prey. Probably had a powerful bite
• Other dinosaurs that lived around the same time and place include theropods such as Asfaltovenator and Condorraptor, as well as indeterminate spinosaurs, megalosaurs, and more, sauropods such as Bagualia, Patagosaurus, and Volkheimeria, and ornithischians such as the heterodontosaurid Manidens
• Other animals that lived around the same time and place include mollusks, insects, fish, amphibians, turtles, crocodylomorphs, pterosaurs, mammals

Fun Fact:

Moths evolved their proboscis to deal with the harsh arid environment of the early Mesozoic—allowing them to drink water droplets like tears directly from dinosaur eyes.

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