Episode 441: Ankylosaurs in Antarctica and sauropods in Australia. Plus Brian Curtice joins us to talk about his work on sauropods and other dinosaurs from all over the world.

News:

• New Antarctic osteoderms helps show how nodosaurids survived in such a hostile environment. source
• A Diamantinasaurus skull helps show the connection between titanosaurs on multiple continents source

Interview:

Brian Curtice, a paleontologist who has studied dinosaurs on 6 continents and lectured all over the world. He’s a sauropod specialist and the founder of Fossil Crates, PaleoPortals, and Express Exhibits.

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The dinosaur of the day: Priconodon

• Nodosaurid that lived in the Early Cretaceous in what is now Maryland, U.S. (Arundel Formation and Potomac Group)
• Only really known from teeth, so hard to say what it looked like or how big it was
• However, as a nodosaurid, would have probably walked on four legs, low to the ground, and been covered in armor and have no tail club
• Type species is Priconodon crassus
• Genus name means “saw cone tooth”
• The species name means “thick”
• Named by Marsh in 1888 (Bone Wars dinosaur)
• Marsh named Priconodon on a large tooth. Compared it to Diracodon (now Stegosaurus)
• Tooth had a large root and was worn (described as a “worn tooth”)
• Marsh wrote there were a number of fragmentary remains, which were not found with the tooth (which he named as the holotype specimen) and said these remains would be “described more fully elsewhere”
• Described the tooth as having a “narrow neck, swollen base, and flattened crown” and that “the serrated edges meet above at a sharp angle”
• Lull recognized five more Priconodon teeth, and found them to be similar to Palaeoscincus (a now dubious ankylosaur also named from teeth, found in what is now Montana)
• Lull also referred a vertebral centrum as Priconodon but Gilmore later tentatively assigned it to Ornithomimus and said it was part of the sacrum (connects to the pelvis)
• In 1921 Gilmore wrote that though how we classified armored dinosaurs at that time “is somewhat in confusion”, recent discoveries that had not yet been described show Priconodon should probably be classified as a nodosaurid rather than a stegosaurid, based on the size of its tooth, features, and wear
• In 1978 Walter Coombs also said the tooth belonged to a nodosaur
• Some scientists think it’s dubious, and others agree that it’s valid
• In 1998 Kenneth Carpenter and Jim Kirkland published a review of Early Cretaceous ankylosaurs found in North America, and found Priconodon to be a valid dinosaur and to be a large nodosaurid
• Carpenter and Kirkland found 12 more (isolated) teeth from the same area where the holotype was found, and also tentatively referred a left tibia (shinbone) to Priconodon
• Left tibia came from a coffee mine in Muirkirk, Maryland
• Tibia is stout, like other nodosaurids, and is about 12 in (31 cm) long
• Carpenter and Kirkland wrote “we find it peculiar that no armor plates have yet been reported from the Arundel Formation”. However, they said that doesn’t mean Priconodon didn’t have armor. “Instead, we advocate that either we are mistaken and Priconodon is not an ankylosaur, or that it is simply fortuitous that armor has not yet been found. This should not be surprising, considering how few fossils have been found in the Arundel.”
• In 2004, Alex West and Neil Tibert found Priconodon to be valid, by comparing its teeth to other nodosaurs and ankylosaurs
• Teeth are different from other nodosaurid teeth because they are so large
• Tooth size ranges from about 0.4 to 0.6 in (1 to 1.5 cm) long and about 0.3 to 0.55 in (0.7 to 1.4) cm tall, according to Carpenter and Kirkland
• For comparison, the largest Edmontonia teeth were about 0.45 in (1.19 cm) long and about 0.4 in (1.5 cm) tall
• Other animals that lived around the same time and place included pterosaurs, sharks, lungfish, turtles, and crocodilians, and dinosaurs including carcharodontosaurids, dromaeosaurs, ornithischians, ceratopsians (most known from fragments and teeth and considered to be indeterminate members of their groups—so not too specific)

Fun Fact:

Ankylosaur heads are one of the most complex armored body parts in the animal kingdom.

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