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(Posted for Chris Brochu - mk)
<Yes, *Mekosuchus*, which had relatives in Australia during the
Neogene(*Quinkana* and others), but the mekosuchines (what "family" do they
belong to?) hadn't yet evolved, AFAIK, before the K-T extinction. Neither had
Euramerican Paleogene pristichampsine crocodylids (which apparently died out in
the Eocene-Oligocene event), but at least some of the South American groups
were, and I was talking about crocodiles that probably didn't need wetlands but
survived the K-T event.>
< Is HP Christopher Brochu onlist again? >
No, I'm not, but I check the archives from time to time.
Mekosuchus (the New Caledonian croc alluded to earlier) was initially thought
to represent some sort of basal croc unrelated to modern croc lineages. This
may be why someone linked it with things like Baurusuchus
(though an actual relationship was never suggested). Newer material worked on
primarily by Paul Willis demonstrates that Mekosuchus was a crocodylid (or at
least a crocodyloid - closer to living true crocs than to alligators); Paul's
tree and mine on this subject differ by exactly one node, so there's little
real conflict there. Mekosuchines (you're still using "families?") are present
in Australia from at least the early Eocene.
I had a chance to see Mekosuchus a couple of years ago. Definitely
crocodyloid, but I can see why Balouet and Buffetaut thought it was more
"primitive" - there are some really weird features in the lower jaw that
are sorta kinda primitive-like, though they are almost certainly reversals.
Pristichampsus and its relatives (e.g. Planocrania) are crown-group crocs, and
are closer to alligators and crocodiles than they are to Gavialis, but are
neither alligatoroid nor crocodyloid. Quinkana (the Australian
ziphodont) is a mekosuchine, not a pristichampsine. You are correct in that
pristichampsines have a first fossil appearance in the Tertiary (Upper
Paleocene, to be exact), but on phylogenetic grounds, the lineage must have
been present by at least the Campanian.
The South American ziphodonts are not crown-group crocs.
Christopher A. Brochu
Department of Geoscience
University of Iowa
Iowa City, IA 52242