Crichtonpelta

''Crichtonpelta'' is a genus of extinct herbivorous ankylosaurid dinosaur from the Late Cretaceous (Cenomanian) of China.

Discovery and naming

In 2007, Lü Junchang, Ji Qiang, Gao Yubo and Li Zhixin named and described a second species of '' Crichtonsaurus'': ''Crichtonsaurus benxiensis''. The specific name refers to the Benxi Geological Museum.

The holotype, BXGMV0012, is a skull found near Beipiao in a layer of the Sunjiawan Formation probably dating from the early Cenomanian (~99–95 Ma). Specimen BXGMV0012-1, a skeleton lacking the skull, discovered in the same quarry as the holotype, was referred to the species. Furthermore, a skeleton with skull, displayed by the Sihetun Fossil Museum as a ''Crichtonsaurus bohlini'' specimen, was in 2014 referred to ''Crichtonpelta''. In 2017, a fourth specimen was described, from the same quarry as the holotype, G20090034, consisting of a skull lacking the front snout.YANG Jingtao, YOU Hailu, XIE Li & ZHOU Hongrui, 2017, "A New Specimen of ''Crichtonpelta benxiensis'' (Dinosauria: Ankylosaurinae) from the Mid-Cretaceous of Liaoning Province, China", ''Acta Geologica Sinica'' 91(3): 781-790

In 2014, Victoria Arbour concluded that ''Crichtonsaurus'' were a ''nomen dubium''. Therefore, she named a separate genus for its second species: ''Crichtonpelta''. The generic name combines a reference to Michael Crichton, the author of ''Jurassic Park'', with a Greek πέλτη, ''peltè'', "small shield". At the time this was an invalid ''nomen ex dissertatione''. However, in 2015, ''Crichtonpelta'' was validly named by Arbour and Philip John Currie. The type species is ''Crichtonsaurus benxiensis''; the ''combinatio nova'' is ''Crichtonpelta benxiensis''. There was a possibility that, though ''Crichtonsaurus bohlini'' was a ''nomen dubium'', its fossil material in fact belonged to ''Crichtonpelta''. Arbour however, noted clear differences in the scapula and humerus between BXGMV0012-1 and LPM 101, a specimen previously referred to ''Crichtonsaurus bohlini'': the scapula of the former has a tab-like acromion and its humerus a much longer deltopectoral crest.

Description

Arbour established several distinguishing traits. One of these was an autapomorphy, unique derived trait: the apex of the (quadrato)jugal, or cheek, horn, is pointing upwards. Also a unique combination of in themselves not unique traits is present. The upper snout armour forms an amorphous mass, not clearly separated into distinctive tiles. The jugal bone is deeper than that of ''Pinacosaurus''. The skull roof is not notched at the lacrimal bone as in ''Pinacosaurus grangeri''. The squamosal horns are shorter than those of ''Pinacosaurus mephistocephalus''. However, these horns are longer and more pointed than those of ''Gobisaurus'' or ''Shamosaurus''. The point of the cheek horn is located on the rear edge. The transverse crest on the top of the rear skull has two points.

The holotype of ''Crichtonpelta'' is somewhat larger than ''Crichtonsaurus'', itself about three to four metres long. It is uncertain whether ''Crichtonpelta'' already possessed a tail club.

Classification

''Crichtonpelta'' was, within the Ankylosauridae, placed in the Ankylosaurinae, in a basal position. If correct, this makes it the oldest known ankylosaurine.

References

{{Taxonbar, from=Q20737863

Ankylosaurinae
Dinosaur genera
Cenomanian dinosaurs
Taxa named by Philip J. Currie
Fossil taxa described in 2015
Dinosaurs of China