Episode 325 is all about Brontomerus, the “thunder thigh” sauropod from the Early Cretaceous of what is now Utah.

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In this episode, we discuss:

News:

• One of the first known sauropod skulls has been renamed from Morosaurus to Smitanosaurus agilis source
• The Denver Museum of Nature and Science has a new exhibit called Sue: The T. rex Experience source
• The Santa Barbara Museum of Natural History is reopening their Prehistoric Forest (animatronic dinosaur) exhibit source

The dinosaur of the day: Brontomerus

• Camarasauromorph sauropod (possibly dubious) that lived in the Early Cretaceous in what is now Utah, US (Cedar Mountain Formation)
• Looked a lot like other sauropods (long neck and tail), and also had really powerful thighs
• Maybe a strong kicker or a good hiker
• Had unusual hipbones that would have allowed large leg muscle attachments (largest leg muscles of any sauropod). Hip bone projects way forward from the socket
• Ilium has attachments for abductor muscles, which would allow Brontomerus to move its leg away from its body
• Mathew Wedel, co-author, has described Brontomerus as “more athletic than most other sauropods”
• May not have had strong thigh muscles for speed (don’t see strong muscles on the back of the leg)
• May have had a strong kick, and could have kicked in defense against predators like Utahraptor or Deinonychus, or to fight over mates
• Possible that it had thunder thighs to help it walk through rough, hilly terrain (Mathew Wedel has described it as “a sort of dinosaur four-wheel-drive”)
• Also possible that it could have occasionally stood on two legs or even sometimes walked on two legs, or it had really long legs and needed muscles to control them (unclear though, since no leg fossils were found). If it had really long legs, would have looked giraffe-like
• Shoulder blade had unusual bumps, which probably show boundaries of muscle attachments. Means may have had powerful forelimb muscles to go with powerful thighs
• Two fragmentary specimens found, probably an adult and juvenile
• Adult may have been the parent to the juvenile (no way of knowing for sure)
• Paleoart shows a mother Brontomerus protecting a juvenile by kicking a feathery raptor
• Estimated to be 46 ft (14 m) long and weigh 6 tonnes, as an adult
• Juvenile/smaller specimen was about 15 ft (4.5 m) long and weighed about 440 lb (200 kg)
• Herbivorous
• Type species is Brontomerus mcintoshi
• Genus name means “thunder thigh”
• Species name is in honor of John McIntosh, a retired physics professor at Wesleyan University in Connecticut who spent his free time studying fossils in museums around the world. When he retired, he studied sauropods. The paper described him as a “veteran sauropod worker” whose “seminal paleontological work, done mostly unfunded and on his own time, has been an inspiration to all of us who follow”
• Found at the Hotel Mesa Quarry, a site where private collectors had already excavated a number of fossils, so it’s unclear what else has already been found there, and the team that found Brontomerus found a lot of broken fossils
• Pretty basal camarasauromorph, but hard to tell
• Need more fossils
• Possible that there are more Brontomerus fossils in private collections
• In the paper naming Brontomerus: “given the density of bone still present and exposed, and the fact that the existing quarry was already some 5–6 m long and 3 m deep, it appears that a considerable number of elements were removed from the quarry and that the loss of valuable scientific information has unfortunately been considerable. Bones left exposed by these previous collectors were in various states of disrepair”
• Fossils excavated in 1994 and 1995 by a team from the Sam Noble museum in Oklahoma
• Type specimen is OMNH 66430, the left ilium of the smaller specimen (probably juvenile)
• Also found parts of the shoulder, hip, ribs, and vertebrae
• Brontomerus fossils were housed, unidentified, at the Sam Noble Oklahoma Museum of Natural History
• Jim Kirkland and others had considered them to be “comparable to Pleurocoelus” in 1997, which at the time was the only known Early Cretaceous sauropod from North America
• Named in 2011 by Michael Taylor, Matthew Wedel, and Richard Cifelli
• In 2012, Michael D’Emic did a cladistic analysis of titanosauriforms and found Brontomerus to be a nomen dubium, because the holotype was too fragmentary and therefore not diagnostic (distinct enough)
• Mike Taylor is a computer programmer, with a PhD in paleontology. He has named three dinosaurs (Xenoposeidon and Haestasaurus, in addition to Brontomerus), published 18 papers, and co-founded Sauropod Vertebra Picture of the Week
• Apparently Taylor got into hunting for fossils about 20 years ago, when he was inspired after reading a paleontology paper on a long plane ride. So he read a bunch of books and journals. Because he’s published so many papers, he got a formal PhD in 2009 from the University of Portsmouth
• Taylor became pen pals with Mathew Wedel, and he studies fossils in museum collections
• Helped show there was more diversity in sauropods in the Early Cretaceous (8th sauropod named from the Early Cretaceous in North America)
• Other animals that lived around the same time and place include theropods, ornithopods, crocodyliforms, and fish

Fun Fact: The first model of the word’s tectonic plates for the last billion years has been created in a 40 second video. Check it out at https://cosmosmagazine.com/earth/earth-sciences/tectonic-timelapse/