[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Hallopus Question



Dan Varner asked this about a year ago:

>       Just in case there are still some croc folks here... Is Hallopus still
> a valid Morrison sphenosuchid taxon? DV

Well, Dan, there ARE some croc folks out here (croc/ hadrosaur folks, in my
case), we are just a little spacey... Hallopus is still "valid" in the
nomenclatural sense (it is the appropriate generic epithet for the type
material of H. victor... no, I'm not trying to be a smart**s :), and the type
material is still probably from the Morrison Formation, at least according to
the summaries of Walker and Ague et al. Walker provided evidence that the
holotype is indeed a "croc" (sensu lato).

Very little work has been done on the Big H since Walker's redescription of the
holotype. Significantly, it has NOT been included in any phylogenetic analysis
of which I am aware (probably due to the lack of a skull). I coded it and it
came out closer to croc-iformes, in the same region of the tree as
Junggarsuchus shows up. I await further work on Junggarsuchus; there may be
problems with the new characters and codings in the supplemental data for the
Junggarsuchus paper, and the included description was abbreviated (as is
typical for the venue).

So, upshot: there is evidence it is a Croc-morph. I'd say there is reasonable
evidence that "Sphenosuchia" as traditionally constituted is paraphyletic.
Hallopus is morphologically of the sphenosuchian grade, making it the
latest-surviving of these animals. It *might* be an "advanced" sphenosuchian,
closer to crociforms. It has not been included in recent studies of
non-crociform crocimorphs, and thus there isn't much more to be said. Except:
damn, it is a gracile little beast!

HP Carpenter may have something to add to this, as he has published on this
taxon.


Hope this helps,

Jon