Platypelta

Platypelta is an extinct genus of herbivorous ankylosaurid dinosaurs within the subfamily Ankylosaurinae. It is known from the Late Cretaceous Dinosaur Park Formation (early Late Campanian stage, about 77.5-76.5 Ma ago) of southern Alberta, Canada. The type species is Platypelta coombsi.

Discovery and naming

In 1914, Barnum Brown and Peter Kaisen, working for the American Museum of Natural History, in Alberta at the Sand Creek near the Red Deer River, eight miles southeast of Steveville, excavated an ankylosaur skeleton, specimen AMNH 5337. In 1971, it was referred to Euoplocephalus tutus by Walter Preston Coombs. In 2001 however, Paul Penkalski concluded that this skeleton was nearly identical to another exemplar, AMNH 5403, and that both likely represented a separate taxon. In 2013, Victoria Megan Arbour and Philip Currie continued to refer AMNH 5337 (and AMNH 5403) to Euoplocephalus, suggesting that differences from other skulls referred to Euoplocephalus could be due to changes occurring with growth and development. They also noted that AMNH 5337 differed from Scolosaurus and Dyoplosaurus in the pelvic region.

In 2018, Penkalski published a study containing a cladistic analyses of such forms. In it, AMNH 5337 and AMNH 5403 were recovered in a joint different position from Euoplocephalus tutus specimens CMN 210, UALVP 31, and AMNH 5406.