A systematic analysis of late Campanian–early Maastrichtian ankylosaurids from Northern Laramidia reveals greater diversity than recognized to date. Legacy taxa include Euoplocephalus tutus, Dyoplosaurus acutosquameus, Scolosaurus cutleri, and Anodontosauruslambei, plus the recently erected Oohkotokia horneri and Zuul crurivastator. Platypelta coombsi, gen. et sp. nov., has numerous large, rugose, low-keeled osteoderms and can be distinguished by its skull, pelvis, pes, and armour. Anodontosaurus inceptus, sp.nov., is a transitional form from higher in section also possessing large plates and distinguished by autapomorphies including a fan-shaped nasal plate, round, unkeeled me- dial osteoderms on the first cervical half-ring, and unusual pyramidal lateral osteoderms; this taxon links Dyoplosaurusand Anodontosaurus. Scolosaurus thronus, sp. nov., is a descendant of S. cutleriand the stratigraphically highest ankylosaurid known from Dinosaur Provincial Park. An even more diverse taxonomy could be supported. The systematics are complicated by fragmentary holotypespecimens and conservative skull evolution, making armour critical in discriminating species. Cladistics, morphometrics, and stratigraphy show unanimous support for the proposed taxonomy which is also consistent with hypothesized biozones. The high diversity represents a radiation that tookplace at or before the start of Dinosaur Park time. Some of the observed variation may be attributable to ecotypes or other phenomena.

Keywords

taxonomy •dinosauria •osteology •cretaceous •ridae •campanian

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Original paper

Revised systematics of the armoured dinosaur Euoplocephalus and its allies

Penkalski, Paul

Abstract

Keywords