Author:
Xu Guang-Hui,Shang Qing-Hua,Wang Wei,Ren Yi,Lei Hong,Liao Jun‑Ling,Zhao Li‑Jun,Li Chun
Abstract
AbstractSauropterygia is the largest, most successful group of Mesozoic marine diapsids, spanning from the late Early Triassic to the Late Cretaceous. Plesiomorphic for sauropterygians, pachypleurosauroids are important for our understanding on the early evolution of this group. Here, we present a new pachypleurosaurid,Luopingosaurus imparilisgen. et sp. nov., based on an exceptionally preserved skeleton from the early Middle Triassic Luoping Lagerstätte in Yunnan, China. The discovery documents the first long-snouted pachypleurosaurid with an unexpected hyperphalangy in the manus, providing new insights into the morphological diversification, ecological adaption and biogeographic evolution of this clade. The discovery further indicates that there is a morphological divergence between short-snouted (brevirostrine) keichousaurids and relatively long-snouted (longirostrine) pachypleurosaurids, which was probably driven by ecological specializations related to feeding and foraging. Additionally, an evolutionary trend towards the reduction of the ratio of the hyoid length to mandibular length (HM ratio) is recognized in pachypleurosauroids. This reduction of HM ratio, associated with the increase of the snout length, might implicate a gradual recession of suction feeding in pachypleurosauroid evolution. Phylogenetic studies incorporatingLuopingosaurusrecover European pachypleurosaurids as successive sister groups to Chinese derived pachypleurosaurids, supporting a western Tethyan origin for this family.
Funder
Strategic Priority Research Program (B) of the Chinese Academy of Sciences
National Natural Science Foundation of China
Publisher
Springer Science and Business Media LLC
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