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Parringtonia (Archosauria) from Triassic of Tanzania redescribed



From: Ben Creisler
bcreisler@gmail.com


A new online paper:


Sterling J. Nesbitt and Richard J. Butler (2012)
Redescription of the archosaur Parringtonia gracilis from the Middle
Triassic Manda beds of Tanzania, and the antiquity of Erpetosuchidae.
Geological Magazine (advance online publication): 1-14
DOI: http://dx.doi.org/10.1017/S0016756812000362
http://128.232.233.5/action/displayAbstract?fromPage=online&aid=8682391&fulltextType=RA&fileId=S0016756812000362


Parringtonia gracilis Huene, 1939 is represented by both cranial and
postcranial material collected from the lower Middle Triassic
(Anisian) Lifua Member of the Manda beds in southwestern Tanzania.
This aberrant taxon was previously proposed to have affinities with
pseudosuchian archosaurs, and specifically with the enigmatic
Erpetosuchus granti from the Upper Triassic of Scotland. Here, we
confirm the close affinities of Parringtonia gracilis and Erpetosuchus
granti based on the following unambiguous synapomorphies:
mediolaterally expanded posterior portion of the maxilla, alveoli
present only in the anterior half of the maxilla, and absence of tooth
serrations. Furthermore, the two taxa share osteoderms with deep
sculpturing, a deep fossa on the dorsal margin of the neural spines
and a heavily waisted shaft of the scapula. We added both Parringtonia
gracilis and Erpetosuchus granti into a comprehensive phylogenetic
analysis of early archosaurs and found that these taxa are clearly
referable to Archosauria but that relationships are poorly resolved at
the base of this clade. However, our analysis demonstrates that
Erpetosuchus granti is not closely related to Crocodylomorpha, as has
been hypothesized previously. The Erpetosuchidae are a clade of
small-bodied archosaurs that have a poor fossil record but have
members from both northern and southern Pangaea, ranging temporally
from the Middle to Late Triassic. Thus, Erpetosuchidae is part of the
early archosaurian radiation.