Scolosaurus cutleri (Ornithischia: Ankylosauria) from the Upper Cretaceous Dinosaur Park Formation of Alberta, Canada

Abstract

The synonymy of the ankylosaurid dinosaur Scolosaurus with Euoplocephalus has been widely accepted since the 1970s. However, Scolosaurus cutleri exhibits differences which separate it from Euoplocephalus tutus and Dyoplosaurus acutosquameus. Although the holotype of Euoplocephalus is fragmentary, several other specimens can be reliably referred to this taxon and thus used for comparison. Scolosaurus differs from Euoplocephalus in cervical half-ring, osteoderm, and forelimb morphology. Scolosaurus differs from Dyoplosaurus primarily in pelvic morphology and osteoderm shape. Recognition of Scolosaurus as a valid taxon adds to the growing concept that the Upper Cretaceous ankylosaurid fauna of North America was more diverse than previously thought.

Notice of nodosaur (Dinosauria, Ankylosauria) remains from the mid-Cretaceous of Cambridge, England, with comments on cervical half-ring armour

“…The two cervical half-rings of the North American ankylosaur Scolosaurus cutleri (Fig. 6B, 6C) are very different from Euoplocephalus (Penkalski and Blows, 2013). Scolosaurus half-rings have cranio-caudally broader basal bones with two dorsally mounted osteoderms which appear rounded in shape with low peaks, in particular in half-ring 2 (Fig, 6C) which is similar to Fig.…”

“…Between the half-rings, and particularly between half-ring 1 and the skull, were bands of skin with very small granular armour, often called ossicles, which allowed flexibility of the neck, as seen in the two specimens with in situ armour, i.e. the nodosaurid Edmontonia rugosidens (AMNH P a g e | 7 5665) (Matthew 1922) and the ankylosaurid Scolosaurus cutleri (NHMUK R5161) (Penkalski and Blows, 2013).…”

“…USNM 7943, Fig. 5C) (Penkalski, 2001, Penkalski andBlows 2013). The holotype of Euoplocephalus (CMN 0210, Fig.…”

Systematics, phylogeny and palaeobiogeography of the ankylosaurid dinosaurs

“…M. Arbour and P. J. Currie cervical half rings. Penkalski & Blows (2013) also provided a reassessment of Scolosaurus and argued for its distinctiveness from Euoplocephalus.…”

A new ankylosaurid from the late Cretaceous Two Medicine Formation of Montana, USA

“…then reinstated Dyoplosaurus based on differences between that holotype (ROM 784) and material referred to Euoplocephalus. Dyoplosaurus has since been accepted as a valid taxon (Thompson et al 2012), and Scolosaurus is valid, too (Penkalski and Blows 2013). Moreover, Arbour (2010) concluded that Anodontosaurus is distinct as well, and Arbour and Currie (2013) formally reinstated it.…”