[D] Ahshislepelta minor [sG] [T]
Burns & Sullivan 2011
Cretaceous Late Campanian
Ornithischia Thyreophora Eurypoda Ankylosauria Ankylosauridae [Ankylosaurinae]
Kirtland Formation (Hunter Wash Member), San Juan Basin, New Mexico, US
Abstract: A new, small ankylosaurid, Ahshislepelta minor, from the upper Campanian Kirtland Formation (Hunter Wash Member), San Juan Basin, New Mexico, consists of shoulder girdle and forelimb elements, vertebral fragments, and numerous osteoderms. Ahshislepelta minor differs from other ankylosaurids on the basis of a prominent dorsolateral overhang of the acromion and its osteoderm texture. It ranks as one of the most complete ankylosaur specimens known from New Mexico and adds to our understanding of ankylosaurid paleobiogeography, stratigraphy, and taxonomy.
Holotype (SMP VP-1930), and only known specimen, was found in the lower part of the Kirtland Formation (Hunter Wash Member) in the Ah-shi-sle-pah Wilderness Study Area along the south side of Ah-shi-sle-pah Wash (Fig. 1). The holotype specimen was discovered in 2005 and collected over consecutive field seasons (2005–2009). This new specimen, while incomplete, provides additional information regarding the diversity and distribution of ankylosaurids during the Late Cretaceous in New Mexico.
Etymology - The generic name is derived from the locality of the holotype, Ah-shi-sle-pah Wash (formerly Meyers Creek), San Juan Basin, New Mexico. The species name “minor” is in reference to its small adult size relative to other North American ankylosaurids of similar age.
Holotype - SMP VP-1930, closely associated incomplete postcranial skeleton including partial left girdle and forelimb (scapulocoracoid, humerus, and proximal portion of the radius), right partial scapulocoracoid, numerous vertebral fragments (likely cervical and/or dorsal), complete and fragmentary thoracic osteoderms, and other unidentifiable postcranial fragments.
Type Locality - SW ¼ of Sec. 8, T22N, R10W (precise UTM coordinates on file at the SMP and are available to professional researchers), Ah-shi-sle-pah Wash, San Juan County, New Mexico.
Horizon/Stratum, Provenance and Age - Kirtland Formation (Hunter Wash Member), San Juan Basin, New Mexico; Late Campanian, Late Cretaceous.
Diagnosis - Apomorphies of taxon: dorsolateral overhang of scapular acromion process to 25% of the dorsoventral width of the scapula. Differs from other ankylosaurids (with the exception of Euoplocephalus sensu stricto) in its 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.