A new southern Laramidian ankylosaurid, Akainacephalus johnsoni gen. et sp nov., from the upper Campanian Kaiparowits Formation of southern Utah, USA

Wiersma, Jelle P., and Irmis, Randall B. (2018) A new southern Laramidian ankylosaurid, Akainacephalus johnsoni gen. et sp nov., from the upper Campanian Kaiparowits Formation of southern Utah, USA. PeerJ, 6. e5016.

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A partial ankylosaurid skeleton from the upper Campanian Kaiparowits Formation of southern Utah is recognized as a new taxon, Akainacephalus johnsoni, gen. et sp. nov. The new taxon documents the first record of an associated ankylosaurid skull and postcranial skeleton from the Kaiparowits Formation. Preserved material includes a complete skull, much of the vertebral column, including a complete tail club, a nearly complete synsacrum, several fore- and hind limb elements, and a suite of postcranial osteoderms, making Akainacephalus johnsoni the most complete ankylosaurid from the Late Cretaceous of southern Laramidia. Arrangement and morphology of cranial ornamentation in Akainacephalus johnsoni is strikingly similar to Nodocephalosaurus kirtlandensis and some Asian ankylosaurids (e.g., Saichania chulsanensis, Pinacosaurus grangeri, and Minotaurasaurus ramachandrani); the cranium is densely ornamented with symmetrically arranged and distinctly raised ossified caputegulae which are predominantly distributed across the dorsal and dorsolateral regions of the nasals, frontals, and orbitals. Cranial caputegulae display smooth surface textures with minor pitting and possess a distinct conical to pyramidal morphology which terminates in a sharp apex. Character analysis suggests a close phylogenetic relationship with N. kirtlandensis, M. ramachandrani, Tarchia teresae, and S. chulsanensis, rather than with Late Cretaceous northern Laramidian ankylosaurids (e.g., Euoplocephalus tutus, Anodontosaurus lambei, and Ankylosaurus magniventris). These new data are consistent with evidence for distinct northern and southern biogeographic provinces in Laramidia during the late Campanian. The addition of this new ankylosaurid taxon from southern Utah enhances our understanding of ankylosaurid diversity and evolutionary relationships. Potential implications for the geographical distribution of Late Cretaceous ankylosaurid dinosaurs throughout the Western Interior suggest multiple time-transgressive biogeographic dispersal events from Asia into Laramidia.

Item ID: 54939
Item Type: Article (Research - C1)
ISSN: 2167-8359
Keywords: Paleontology, Taxonomy, Biodiversity
Copyright Information: Copyright © 2018 Wiersma and Irmis. Distributed under Creative Commons CC-BY 4.0.
Funders: Geological Society of America (GSA), Bureau of Land Management (BML), University of Utah (UU)
Projects and Grants: GSA Graduate Student Research Grant 10631-14, BML National Landscape Conservation System Grant JSA071004, BML National Landscape Conservation System Grant L12AC20378, UU Department of Geology & Geophysics Graduate Student Travel Grant
Date Deposited: 08 Aug 2018 07:40
FoR Codes: 37 EARTH SCIENCES > 3705 Geology > 370506 Palaeontology (incl. palynology) @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 50%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960803 Documentation of Undescribed Flora and Fauna @ 50%
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