Taxonomic reassessment of Hydralmosaurus as Styxosaurus: new insights on the elasmosaurid neck evolution throughout the Cretaceous.

ABSTRACT: Two extremely-long necked elasmosaurids, AMNH 1495, holotype of Hydralmosaurus serpentinus, and AMNH 5835, previously referred to H. serpentinus, are here reviewed in detail. Unique features of the cervical vertebrae, which are only present on elasmosaurids from the Western Interior Seaway, are recognized based on these specimens and by comparison with penecontemporaneous taxa with biogeographic affinities. Phylogenetic analysis, bivariate graphic analysis of cervical vertebrae proportions, comparisons of different cervical vertebral types, paleobiogeographic distribution and study of the elasmosaurid axial evolution throughout the Cretaceous are here integrated. As a result, at least two separate lineages within the Elasmosauridae are identified by independently acquired extremely-long ne

SUBMITTER: Otero RA 

PROVIDER: S-EPMC4806632 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature