Brachauchenius

Brachauchenius (meaning 'short neck') is a genus of pliosaurid that lived in North America (United States) during the Late Cretaceous.

The type species, Brachauchenius lucasi, lived in the Western Inland Sea of North America around 93.5-89.3 million years ago, during the Turonian stage of the Cretaceous. An older specimen from the Barremian of Colombia was considered as part of this genus, representing the first re-occurrence of the non-rhomaleosaurid pliosaurs after a Berriasian-Hauterivian hiatus.[2] However, subsequent analysis of this Colombian specimen shows that it was enough distinctive to warrant a new genus and species, named as Stenorhynchosaurus munozi.[3]

The first known (type) specimen (USNM 4989) was collected by Charles Hazelius Sternberg from Ottawa County, Kansas in 1884.[4][5] It had a skull length of about 90 cm. The species was named by Samuel W. Williston.[1][6] Brachaucheniusrepresents the last known occurrence of a pliosaur in North America.

A larger specimen (FHSM VP-321 - skull length 170 cm) was collected by George Fryer Sternberg in 1952 from the Fairport Chalk of Russell County, Kansas, and later described by Carpenter.[7] Schumacher and Everhart (2005) reported on the age and locality of both Kansas specimens.[8] This pliosaur grew to around 10  meters (33 ft) in length. This specimen was reassigned to its own genus and species, Megacephalosaurus eulerti.[9]

In 2013, Benson et al. referred a partial cranium from the Chalk Group of England (previously referred to Polyptychodon) to Brachauchenius indet.[10]