A new Doswellia snout!~!

Traditional paleontologists are still a little off about Doswellia (Fig. 1). It is a strange one with transverse and square ribs, a horizontal ilium, and a low wide skull that fills in a former lateral temporal fenestra. Unfortunately the rostrum has not been known for the last 30 years. Neither have the feet.

Even so, the large reptile tree firmly nested Doswellia at the base of the Choristodera, derived from Youngoides (RC91) and more distantly related to taxa at the base of the Parasuchia and Proterochampsia, all members of the Pararchosauriformes.

Doswellia in several views

Figure 1. Doswellia in several views from Weems (1980). Missing pieces from 1980 are in black.

News about the rostrum!
Thankfully Heckert et al. (2012) discovered some of the last missing pieces, the premaxilla and maxilla of Doswellia (Fig. 2). Unfortunately they could not bring more focus to relationships, but repeated Dilkes and Sues (2009) assessment that Doswellia was close to proterochampsids, again ignoring the Choristodera and younginoids.

The newfound elements of Doswellia found by Heckert et al. (2012).

Figure 2. The newfound elements of Doswellia found by Heckert et al. (2012). The naris is dorsal. A tiny antorbital fenestra is present. The ventral maxilla is wavy. The premaxilla is deeper anteriorly and tips downward.

So what’s new?
The maxilla has teeth of several sizes and the ventral margin is wavy, not straight as in sister taxa.

There is an antorbital fenestra, small, and without much of a fossa. This follows the pattern seen in some (but certainly not all) Youngina and proterochampsids, and not seen  in the Choristodera.

The naris is dorsal in position, but still at the jaw tips. This is totally in line with the entire clade, which, other than Champsosaurus, all have dorsal nares. The premaxilla is also deeper anteriorly, downturned at the tip, as in several sisters.

The teeth are stout cones ideal for capturing prey.

This is a welcome discovery by Heckert et al. (2012) and fills a minor gap with real data. Glad to see it. Thanks to Dr. Heckert for sending the pdf.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Dilkes D and Sues H-D 2009. Redescription and phylogenetic relationships of Doswellia kaltenbachi (Diapsida: Archosauriformes) from the Upper Triassic of Virginia. Journal of Vertebrate Paleontology 29(1):58-79.
Heckert AB, Lucas SG and Spielmann JA 2012. A new species of the enigmatic archosauromorph Doswellia from the Upper Triassic Bluewater Creek Formation, New Mexico, USA”. Palaeontology (Blackwell Publishing Ltd) 55 (6): 1333––1348. 
Weems RE 1980. An unusual newly discovered archosaur from the Upper Triassic of Virginia, U.S.A. Transactions of the American Philosophical Society, New Series 70(7):1-53

wiki/Doswellia

3 thoughts on “A new Doswellia snout!~!

  1. “Traditional paleontologists are still scratching their heads about Doswellia”

    Except that we’re not, as we have a consensus which you later mention yourself…

    “Unfortunately they could not bring more focus to relationships, but repeated Dilkes and Sues (2009) assessment that Doswellia was close to proterochampsids.”

  2. Then where’s their tree that includes choristoderes and younginoids? Heckert et al could nest Doswellia no closer than the following: Clade ARCHOSAUROMORPHA Huene, 1946
    Family DOSWELLIIDAE Weems, 1980
    Genus DOSWELLIA Weems 1980

    • That authors ignore genera YOU think are closely related to Doswellia doesn’t mean they are “scratching their heads” about its relationships. Similarly, just because Heckert et al. didn’t list Archosauriformes in their Systematic Paleontology section doesn’t mean they don’t think it’s an archosauriform. You said yourself they agree with Dilkes and Sues (2009) that Doswellia is an archosauriform related to proterochampsids.

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