Plesioliopleurodon
Encyclopedia
Plesiopleurodon is an extinct genus
of plesiosauroid from the Late Cretaceous
of North America. It was named by Carpenter based upon a complete skull and lower jaws, neck vertebrae, and a right coracoid. It was collected from the Belle Fourche Shale (lower Cenomanian
), in the Rattlesnake Hills of Wyoming. In naming the specimen, Carpenter (1996, p. 264) noted "Of all known pliosaurs, Plesiopleurodon wellesi most closely resembles Liopleurodon ferox from the Oxfordian of Europe, hence the generic reference."
The species is characterized by a moderately long symphysis bearing 8 pairs of teeth, teeth that are nearly circular in cross-section and which are smooth on the outer surface (except near the base), ribs of the neck vertebrae being singled-headed (double-headed in Jurassic pliosaurs), and a long slender interpectoral bar on the coracoid.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of plesiosauroid from the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
of North America. It was named by Carpenter based upon a complete skull and lower jaws, neck vertebrae, and a right coracoid. It was collected from the Belle Fourche Shale (lower Cenomanian
Cenomanian
The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...
), in the Rattlesnake Hills of Wyoming. In naming the specimen, Carpenter (1996, p. 264) noted "Of all known pliosaurs, Plesiopleurodon wellesi most closely resembles Liopleurodon ferox from the Oxfordian of Europe, hence the generic reference."
The species is characterized by a moderately long symphysis bearing 8 pairs of teeth, teeth that are nearly circular in cross-section and which are smooth on the outer surface (except near the base), ribs of the neck vertebrae being singled-headed (double-headed in Jurassic pliosaurs), and a long slender interpectoral bar on the coracoid.