Episode 418: A brand new tyrannosaur with Elias and Denver. The new tyrannosaur named Daspletosaurus wilsoni. Plus new details on the megapredator Meraxes, estimates for the largest T. rex that ever lived, and more.

News:

• Presentations from the Theropods session of SVP 2022 source
• A new Daspletosaurus species, wilsoni, was named which appears to be an evolutionary link between two previously known species source

Interview:

Elías Warshaw is a research associate at Badlands Dinosaur Museum & a student at Montana State University. Denver Fowler is the curator at the Badlands Dinosaur Museum.

Sponsors:

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This episode is brought to you by the Sternberg Museum of Natural History. They have amazing summer camps every year including field paleontology, paleoart, and virtual options. Find out more and sign up at https://bit.ly/camps23

The dinosaur of the day: Poekilopleuron

• Tetanuran theropod that lived in the Middle Jurassic in what is now Normandy, France
• Looked like other theropods, with a long tail, long legs, and an elongate skull
• Estimated to be about 30 ft (9 m) long
• Had long forelimbs
• Forelimbs were about 60 cm (about 24 in) long
• Had 14 pairs of belly ribs
• Type and only species is Poekilopleuron bucklandii
• Genus name means “varied ribs”
• Genus name refers to the three types of ribs found
• First named by Jacques-Amand Eudes-Deslongchamps in 1836
• He published more details in a monograph in 1837
• Holotype was destroyed in WWII
• Holotype was at the Musée de la Faculté des Sciences de Caen
• Casts of the holotype exist
• Casts are at the Muséum National d’Histoire Naturelle and Yale Peabody Museum
• Holotype included gastralia, tail vertebrae, ribs, a left forelimb, a hindlimb, phalanges, chevrons
• Gastralia, phalanges, and forelimb were cast, and now they are the plastotype
• Species named after William Buckland
• Eudes-Deslongchamps said there were similarities between Poekilopleuron and Megalosaurus
• Eudes-Deslongchamps chose the name “bucklandii” in case Poekilopleuron got synonymized with Megalosaurus later, so it would keep the species name of “bucklandii”
• In 1923, Friedrich von Huene found Poekilopleuron to be Megalosaurus but a different species, not “bucklandii”
• To avoid confusion, he renamed Poekilopleuron to Megalosaurus poekilopleuron
• Also the way Poekilopleuron has been spelled is different. The name was only partially Latinized (sometimes it’s spelled Poecilopleuron and sometimes Poikilopleuron)
• Had five other species: Poekilopleuron gallicum (Cope renamed Laelaps gallicus in 1869 to Poekilopleuron), Poicilopleuron valens (named in 1870 by Leidy, but probably the fossil was Allosaurus), Poikilopleuron pusillus (named by Owen in 1876, then renamed by Cope in 1879 as Poekilopleuron minor, then named Aristosuchus in 1887 by Harry Seeley), Poekilopleuron schmidti (now a nomen dubium), and Poekilopleuron valesdunensis (renamed Dubreuillosaurus)
• But now there is only the one species
• Some fun quotes:
• In 1870, Leidy wrote the Poekilopleuron had been viewed as a crocodilian “but probably pertains to the dinosaurs,” and said it was estimated to be about 25 ft (7.6 m) long
• Leidy also wrote: “One of the most remarkable characters of the Poicilopleuron is the presence of a large medullary cavity within the bodies of the vertebrae, paralleled among living animals, so far as I know, only in the caudal vertebrae of the ox”
• In 1879, J.W. Hulke wrote: “One difficulty, and not the least, which besets the student beginning to study fossil reptiles is the great embarrassment occasioned by the not unfrequent description of the same reptile under different names, involving the worse than merely useless multiplication of genera and species. Wherever, then, the identification of a newer with an older genus can be established, entailing, as it should, the abandonment of the newer generic name, it is to be looked on as a positive gain. I now submit to the criticism of the Geological Society the evidence which appears to me to identify beyond reasonable doubt Poikilopleuron Bucklandi of Eudes Deslongchamps, père, with an older acquaintance, Megalosaurus Bucklandi.”
• Ronan Allain and Daniel Chure in 2003 found that there was no overlapping material to compare Poekilopleuron and Megalosaurus, so whether or not they were synonymous is unclear

Fun Fact:

We have a really poor understanding of which dinosaurs laid which eggs, but that might be changing thanks to new egg analyses originally used for teeth.

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