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RE: Parringtonia (Archosauria) from Triassic of Tanzania redescribed



Very cool paper, as I love redescriptions of old and largely ignored taxa.  It 
also suggests why Erpetosuchus was left out of Nesbitt's (2011) original study, 
which seemed odd at the time since it's a fairly complete archosaur not clearly 
belonging to a major group.  Notice that Erpetosuchus is mentioned in the 
character list several times as if it was included, but not mentioned 
otherwise.  Perhaps it and possibly Parringtonia (also mentioned once) were 
originally included, but left out because they decreased resolution.  Or 
perhaps at least Erpetosuchus was originally included, but left out because 
Nesbitt planned to redescribe Parringtonia and/or hoped Parringtonia would help 
resolve Erpetosuchus' position. Hmm...

Mickey Mortimer

----------------------------------------
> Date: Thu, 30 Aug 2012 11:06:46 -0700
> From: bcreisler@gmail.com
> To: dinosaur@usc.edu
> Subject: 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.