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RE: Ankylosuchus, new doswelliid archosauromorph from Upper Triassic of Texas (free pdf)



Note: "chinlegroupensis," not "chinlensis" as has been popular previously. 
Pushing the limits here.

Cheers,

  Jaime A. Headden
  The Bite Stuff (site v2)
  http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
Backs)


----------------------------------------
> Date: Mon, 23 Dec 2013 00:03:36 -0800
> From: bcreisler@gmail.com
> To: dinosaur@usc.edu
> Subject: Ankylosuchus, new doswelliid archosauromorph from Upper Triassic of 
> Texas (free pdf)
>
> From: Ben Creisler
> bcreisler@gmail.com
>
> A new recent paper not yet mentioned. The pdf is free at the link:
>
> Spencer G. Lucas, Justin A. Spielmann and Adrian P. Hunt (2013)
> A new doswelliid archosauromorph from the Upper Triassic of West Texas.
> in Tanner, L.H., Spielmann, J.A. and Lucas, S.G., eds., 2013, The
> Triassic System.
> New Mexico Museum of Natural History and Science, Bulletin 61 : 382-388
> Free pdf:
> http://paleo.cortland.edu/globaltriassic2/Bulletin%2061%20Final/31-Lucas%20et%20al%20(Ankylosuchus).pdf
>
> Ankylosuchus chinlegroupensis is a new genus and species of
> heavily-armored archosauromorph from the Otischalkian Colorado City
> Formation of the Chinle Group in Howard County, West Texas. The
> incomplete holotype skeleton consists of cranial and pelvic (?)
> elements, vertebral centra, a partial limb shaft and numerous
> osteoderms. The skull elements reveal a thick, heavily armored
> braincase and skull roof with parasagittal crests. The relatively
> short sacral vertebrae suggest an animal less than 1 meter in total
> body length, not including the tail. The morphology of the osteoderms
> does not match any currently known armored archosauromorph, but it is
> most similar to doswelliids. Most of the osteoderms posse
> closely packed pits that form no obvious pattern. Some osteoderms have
> raised, linear ridges running across them and others have anterior
> laminae with faint patterning on the articular surface. Some of the
> osteoderms are tightly sutured to each other via digitate sutures; all
> are relatively thick. The patterning of the ostoderms matches well
> with that of doswellids in being coarse, deeply incised and mostly
> composed of equal-sized pits and in the possession of anterior
> laminae. Even so, these osteoderms are readily distinguished from
> those of Doswellia, the only doswelliid previously reported from the
> Chinle Group, by their coarser pitting, greater thickness and (at
> least in some osteoderms) fusion with laterally adjacent osteoderms
> along their mutual sutural boundaries. A. chinlegroupensis is derived
> from the oldest strata of the Texas Chinle Group, the Otischalkian,
> whereas the genus Doswellia is known from the Chinle Group in Texas,
> New Mexico and Utah, in strata of Otischalkian-Adamanian (late
> Carnian) age. Doswelliids are very rare, but visible components of
> global Triassic faunas. They include Tarjadia (= Archeopelta) from the
> Berdyankian (Ladinian) of Argentina and Brazil, Doswellia from the
> Otischalkian-Adamanian of the American Southwest and the Otischalkian
> of the Newark Supergroup in the eastern USA, and now Ankylosuchus from
> the Otischalkian of West Texas.