Ahshislepelta (meaning "Ah-shi-sle-pah Wash shield") is a monospecific genus of ankylosaur dinosaur from New Mexico that lived during the Late Cretaceous (late Campanian stage, 74.5 Ma) in what is now the Hunter Wash Member of the Kirtland Formation. The type and only species, Ahshislepelta minor, is known only from an incomplete postcranial skeleton of a small subadult or adult individual. It was named in 2011 by Michael Burns and Robert M. Sullivan. Based on the size of the humerus, Ahshislepelta is larger than Pinacosaurus mephistocephalus but smaller than Talarurus and Pinacosaurus grangeri.
Discovery and naming
In 2005, a partial postcranial skeleton of an ankylosaur was discovered from the Hunter Wash Member in the lower part of the Kirtland Formation, New Mexico at the Ah-shi-sle-pah Wilderness Study Area. The specimen was later collected over consecutive field seasons from 2005 to 2009 and was subsequently described in 2011 by Michael Burns and Robert M. Sullivan. The holotype specimen, SMP VP-1930, consists of a partial girdle, partial scapulocoracoid, a proximal portion of the radius, numerous cervical and/or dorsal vertebrae fragments, complete and fragmentary thoracic osteoderms, and other unidentifiable postcranial fragments. The holotype specimen is currently housed at the State Museum of Pennsylvania, Harrisburg.
The generic name, Ahshislepelta, is derived from Ah-shi-sle-pah Wash, the locality from which the holotype came, and the Ancient Greek word "peltè" (shield). The specific name, minor, is in reference to its small adult size relative to other North American ankylosaurids.
The holotype specimen represents a subadult or adult individual based on the complete fusion of the scapulocoracoids, centra and neural arches of the vertebrae, and the re-modelled osteoderm cores. The holotype falls within the same size range as adult specimens of other ankylosaurid taxa outside of North America and represents an individual that was larger than juvenile specimens of Pinacosaurus grangeri and Pinacosaurus mephistocephalus but smaller than Talarurus and adult specimens of P. grangeri based on humeral size; however, the scapulocoracoid is larger than that of Talarurus.
Description
Distinguishing traits
Burns & Sullivan (2011) diagnosed Ahshislepelta based on the dorsolateral overhang of the scapular acromion process to 25% of the dorsoventral width of the scapula. Ahshislepelta differs from other ankylosaurids, with the exception of Euoplocephalus, by the superficial osteodermal surface texture, characterized by uniformly distributed pitted rugosity, and sparse distribution of reticular neurovascular grooves with neurovascular foramina extending perpendicularly to obliquely into the bone.