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Parahupesuchus, new marine reptile from Early Triassic of China



From: Ben Creisler
bcreisler@gmail.com


New in open access PLoS ONE:

Xiao-hong Chen, Ryosuke Motani, Long Cheng, Da-yong Jiang & Olivier
Rieppel (2014)
A Carapace-Like Bony 'Body Tube' in an Early Triassic Marine Reptile
and the Onset of Marine Tetrapod Predation.
PLoS ONE 9(4): e94396.
doi:10.1371/journal.pone.0094396
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0094396


Parahupehsuchus longus is a new species of marine reptile from the
Lower Triassic of Yuan'an County, Hubei Province, China. It is unique
among vertebrates for having a body wall that is completely surrounded
by a bony tube, about 50 cm long and 6.5 cm deep, comprising
overlapping ribs and gastralia. This tube and bony ossicles on the
back are best interpreted as anti-predatory features, suggesting that
there was predation pressure upon marine tetrapods in the Early
Triassic. There is at least one sauropterygian that is sufficiently
large to feed on Parahupehsuchus in the Nanzhang-Yuan'an fauna,
together with six more species of potential prey marine reptiles with
various degrees of body protection. Modern predators of marine
tetrapods belong to the highest trophic levels in the marine ecosystem
but such predators did not always exist through geologic time. The
indication of marine-tetrapod feeding in the Nanzhang-Yuan'an fauna
suggests that such a trophic level emerged for the first time in the
Early Triassic. The recovery from the end-Permian extinction probably
proceeded faster than traditionally thought for marine predators.
Parahupehsuchus has superficially turtle-like features, namely
expanded ribs without intercostal space, very short transverse
processes, and a dorsal outgrowth from the neural spine. However,
these features are structurally different from their turtle
counterparts. Phylogeny suggests that they are convergent with the
condition in turtles, which has a fundamentally different body plan
that involves the folding of the body wall. Expanded ribs without
intercostal space evolved at least twice and probably even more among
reptiles.