The Big Dinosaur Podcast

Episode 357 is all about Denversaurus, a nodosaurid ankylosaur found with over one hundred osteoderms.

We also interview Cameron Pahl, software developer, Research Associate, and Lecturer with Portland State University and Oregon Health & Safety University. He authored the controversial Allosaurus as a scavenger paper, which is really more about how sauropod carrion affected the ecosystem.

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In this episode, we discuss:

News:

• Titanosaur osteoderms might have been useful for defense after all, at least while they were young source
• A new ankylosaur, Spicomellus, was named from a spiky osteoderm fused directly to a rib—a first for any animal source
• Four dinosaurs were excavated in Montana including what could be Anzu, Triceratops, a theropod, and a hadrosaur source
• Dinosauria Museum Prague in the Czech Republic is opening October 4 source
• Morrison’s Dinosaur Ridge in Colorado has a new mural of three dinosaurs source
• In Missouri, St. Louis Science Center has a new traveling exhibit, called Tyrannosaurs: Meet the Family source
• Mary Anning’s statue in Dorset will be unveiled on May 21 next year source

The dinosaur of the day: Denversaurus

• Nodosaurid ankylosaur that lived in the Late Cretaceous in what is now South Dakota, US (Hell Creek Formation, Wyoming (Lance Formation), and Texas (Aguja Formation)
• Had a wide snout and a wide skull
• Covered in osteoderms and had shoulder spikes
• Estimated to be about 20 ft (6 m) long and weigh 3 tonnes
• Type species is Denversaurus schlessmani
• Fossils found in 1922 by Philip Reinheimer, a collector and technician at the Colorado Museum of Natural History (now the Denver Museum of Nature and Science)
• Fossils found in Corson County, South Dakota
• Barnum Brown referred those fossils (DMNH 468) to Edmontonia longiceps in 1943
• In 1988, Bob Bakker said that fossil was a new species, Denversaurus, and another species, Edmontonia rugosidens, was Chassternbergia
• Genus name means “Denver lizard”
• Genus name refers to the Denver Museum of Natural History
• Species name is in honor of Lee Schlessman, founder of the Schlessman Family Foundation, a benefactor to the museum
• Holotype is part of the collection of the Denver Museum of Nature and Science
• Holotype includes a skull, no lower jaws, and some osteoderms
• Bakker also referred AMNH 3076 to Denversaurus (a skull found in the Aguja Formation in Texas by Barnum Brown and Roland Bird). Skull has been described as “weathered”
• Bakker said, in a 1988 New York Times article, “Denversaurus was probably a little like a three-ton armadillo with spikes”
• Bakker also said, “There seems to have been an evolutionary trend to get the eyes up off the ground and away from dust, and possibly to allow for a better view of potential predators”
• In 1990 Kenneth Carpenter said Denversaurus was Edmontonia sp.. Said Bakker’s reason for naming Denversaurus (eye sockets were more to the rear of the skull, rather than the middle) was based on Bakker’s reconstruction of the skeleton, which was partially crushed)
• Carpenter said Edmontonia sp. had affinities to Edmontonia rugosidens
• In 2000, Ford found Denversaurus to be valid, after looking at osteoderms in ankylosaur systematics
• In 2015 Michael Burns wrote his thesis on intraspecific variation in ankylosaurs, and found Denversaurus to be likely valid, based on phylogeny
• Mentioned another specimen, BHI 6225, an endocast
• Described the highest point of the skull roof as being between the orbits, and agreed with Bakker that the holotype did have orbits more toward the rear of the skull, but said there was too much variability in individual Denversaurus that this character was “not taxonomically useful”
• Burns said in his thesis that Denversaurus, Edmontonia, and Panoplosaurus were all in the same clade, Panoplosaurinae
• Also said Edmontonia was more basal than Denversaurus
• Team from the Black Hills Institute found a Denversaurus skeleton in Niobrara County, Wyoming, nicknamed “Tank” (BHI 127327)
• Tank includes lower jaws, parts of the torso and over one hundred osteoderms (can order a cast)
• Can see Denversaurus at Woodland Park’s Rocky Mountain Dinosaur Resource Center in Colorado, US
• Other dinosaurs that lived around the same time and place included T. rex, Triceratops, Edmontosaurus, Struthiomimus, Pachycephalosaurus

Fun Fact: We probably have dinosaurs & bats to thank for keeping flying insects small.

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