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Things To Look Forward To - SVP 2005 (Mesa, Arizona, USA) - Part 1
Instead of posting titles and abstracts, I am going to do the impossible and
summarize abstracts. YES! Okay, some of them do it for me by being very concise
and some are rich in detail. Others, such as Peter Galton's paper's title, are
unweildy monstrosities worthy of Bakkerian fame, but that's why we love him!
I am also going to summarize topics that I myself find interesting, as well
as general research that may be of interest in general. This is because these
are the talks I would like to see, since I will not be attending SVP this year.
Wednesday morning begins with a session on general tetrapods, of which one is
a study by Dave Varricchio and crew on observing cattle carcass decomp on the
Yellowstone River (a herd got trapped in icy waters and drowned), and my friend
Pete Buchholz was on the trips to go out there studying this perfect taphonomic
A concordant session is much more specialized in focus, featuring a lot of
pterosaurs, and includes topics on mechanical function to tooth shapes from the
ongoing studies by Rudyard Sadlier and Ralph Chapman, who have been doing this
since 1998 or so, so the sample size is by this time rather huge. They used
samples from theropods, varanids, extinct marine reptiles, and crocodilians
Steve Salisbury and Eberhard Frey will discuss gastropubic recoil aspiration
(lung ventilation aided by gastralial kinesis and the costalsternal apparatus,
aided by active expansion and passive contration of the ventral dermis) in
early archosaurs, and especially crocs. They posit that ventral scutes and
scute-shields would have rigidified the belly in many crocs (one striking
example that _I_ can think of is *Bernissartia*, but this also applies to
ventrally-scaled critters like *Sphenosuchus* and *Scleromochlus* perhaps), and
thus indicate a more active, terrestrial habitus since such features would be
unreasonably restrictive in aquatic environments -- turtles, though make do by
devoting movement to their flippers, as in penguins.
Wang Xiaoling et al. described what they discuss as the first uncontroversial
member of the Ctenochasmatidae, verified by the extremely long, slender,
upcurved skull, long cervicals, and numerous, tiny, needle-like teeth. They
also report tissues within the scleral ring they interpret as eyeball remnants.
Alexander Kellner (also a coauthor on the preceeding abstract) reports with
others on a pterosaur specimen from Araripe, Brazil, which includes a
well-preserved propatagium showing layers of fibers, some criss-crossing, as
well as venation, with fibers connected to muscle or tendon to propose that
actinofibrils are probably muscular tissue, and that the wing membrane of
pterosaurs was a constantly modulated dermal organ much akin to approximating
chiropteran wing digits, only far smaller in size and far greater in number. I
managed to come into a conversation last year with Kellner and several others
on creating models of these tissues for practical wing experiments.
Brian Andres and Jim Clark discuss new Xinjiang pterosaurs of Upper and Lower
Shishugao Formations (as at Dashanpu) including an indeterminate
pterodactyloid, and a rhamphorynchoid apparently closest to both *Dorygnathus*
and *Angustinaripterus*. This is also not the first time someone suggested the
two were allies, and perhaps now we can propose their synonymy? Especially if
the new fossil might be referrable to a single taxon including both, simplicity
may favor lumping rather than a NEW genus and species to mainting the premise
of genera. The study is supported by cladistics, however, though previous
suggestions of similarity in the above taxa are NOT wholly cladistic.
In the afternoon sessions, things get more lizardy:
Gao Keqin, Richard Fox, and Daniel Ksepka present a synthesis of study on
choristoderes from Liaoning, including *Monjurosuchus* (which looks like a
rather cool prickly lizard from afar) and the more derived and long-necked
*Hyphalosaurus* (yet more convergence to a "nothosaur" Bauplan for lizardy
aquatic reptiles), and *Ikechosaurus*-like simoedosaurids. The name Chiufotang
is used in the abstract, yet I suspect this is a spelling variant for
Jiufotang, though I am aware that the two are pronounced differently in
Chinese, this is not a question I can answer.
Hans-Dieter Sues and Jim Clark also discuss a Late Triassic (Carnian of
Nevada, USA) claraziid similar to *Hescheleria* which had undergone a long-term
ambiguity until recently; the skull has an edentulous, upturned rostrum and is
used to support that *Hescheleria* likely also had an upturned rostrum, as
reconstructed by Peyer in 1936.
Thursday morning, another likely chill Arizonan dawn I won't see the sun rise
for, has a single session, will feature a few tasty tidbits of data for me, at
Kenneth Bader will discuss using forensic entomology (which anyone who has
seen at least two episodes of "CSI" will be familiar with by now) in
understanding taphonomy of a Wyoming Morrison Fm. site, including a sinuous
surface etching and a possible dermestid pupal chamber. Using the size and
number of features will help determine duration of exposure, and
paleoenivronment of exposure, as well as "meatyness" of the animals at burial.
Richard Butler discusses a 51 taxon, 228 character ornithischian analysis.
Perhaps most peculiar of this analysis is his finding of Heterodontosauridae as
the sister-taxon to Genasauria, meaning its more basal even than thyreophorans;
if as suggested by others we accept *Heterodontosaurus* as a specifier for
Ornithopoda, this means that name is now used for the Genasauria +
Heterodontosauridae clade, and the sister-taxon to Marginocephalia is unnamed.
Now, however, few other analysis have suggested such a radical interpretation,
and *Agilisaurus* and *"Yandusaurus" multidens* are placed outside of the
Cerapoda. Others have suggested such a basal position, so this may be more
acceptable. It may remain to be seen how many marginocephalian features were
used to suggest heterodontosaurs were THEIR closest allies.
Leon Claessens helps to trash the previous ideas of theropod cold-breathing
as proposed by Ruben and his allies, by noting movement ranges and ossification
between crocs and birds differ distinctly in costosternal and in rib
orientation/belly size between the two taxa: birds have large ossified sternal
ribs and are broadest at the back and on the bottom of the belly, whereas crocs
lack ossified sternal ribs, have intermediate ribs between the sternal and
lateral pairs, and are broadest in the trunk anteriorly. In no less than two
"non-birds" such as *Velociraptor* and *Oviraptor* (I'm sure he used a better
known taxon, likely GIN 100/42 here and not AMNH 6517, since the holotype of
*O. philoceratops* is poorly known in this region and GIN 100/42 is not
*Oviraptor*), we have a broad rear trunk, ossified sternal ribs indicating a
more rigid costosternal "pump", and no intermediate ribs to increase the
flexibility of the ribcage.
Thursday afternoon we have a choice between early mammal phylogeny studies,
stratigraphics, and a whole session on theropods. Aside from a tricky choice in
a few mammal talks (Luo Zhexi and John Wible on *Fruitafossor* as a
"scratch-digger" using osteological correllates with armadillo-like teeth, yet
still a primitive mammal), I go with the dinner-saurs. You know, the ones like
make dinner of other saurs.
Larry Witmer and Ryan Ridgely look at tyrannosaur braincase anatomy and the
middle ear region, a topic that was recently upon this list, and they managed
to scan not just one, but several skulls. They show that while the brain of
*Nanotyrannus* is slightly different from those of adults, they do regard it as
a juvenile without a dural pineal peak in the endocranium. Additionally, the
orientation and structure of the middle ear indicates a delicate
vestibulo-coular reflex which suggests to these authors a reliance on the
visual system. Hmm, contra Jack Horner? On that subject, Francois Therrein,
Farheen Ali and Dave Weishampel tackle the topic of olfactory bulb size versus
olfaction capability, regarding no less important a device than LOCATING the
bulbs using only osteological correlates. Perhaps they could have used birds,
since the authors chose to compare to known conditions in *Crocodilus acutus*.
*Tyrannosaurus*, carcharodontosaurids, and *Allosaurus* have better olfactory
acuity than the croc, *Saurornitholestes* has about the same, whereas olfaction
in ornithomimids and troodontids were less. This also seems to correlate to
relative eye to snout size. The acuity increase is about attention to and
differentiation of odors, not neccessarily using it's "sharky-senses".
Andrew Lee, Paul Bybee and Ellen-Therese Lamm reconstruct the growth-curve
for *Allosaurus* using the histological methods of Greg Erickson and others,
proposing that while all adults they sampled were between 13-19 years of age,
maximum adult growth was acheived at 14 (ave?) and that maximum age accessible
may be in the mid to upper 20's (wow, I'm older than allosaurs!).
Thom Carr and Thomas Williamson investigated the Iren Dabasu tyrant
*Alectrosaurus*, known from the lectotype, as well as an undescribed crushed
skull that is apparently a juvenile tyrannosaurid (secondary antorbital fossa)
with the juvenile features in the lachrymal of a laterally deflected cornual
ridge, rather than a "horn". The skull also shows teeth with fine serrations
similar to teeth from Uzbekistan.
Alberto Prieto-Marquez and others try to sex a dinosaur through bones while
Kevin Padian, Jack Horner and Andrew Lee review all the other data on the
subject. On Prieto-Marquez' front, they reiterate Chris Brochu's rebuttal to
Pete Larson that alligators do not show any significant bivariance in
phenotypes using a sample of alligators and iguanas, showing no significant
differences between male and female pelvises, chevron lengths, or first chevron
position. Padian et al. however note that a review of the evidence shows that
if there were differences, most of them would be "obvious" (yet mammalian)
features such as antlers (says the caribou: "HA!") or frill morphology (even
Dodson was highly cautious on his own study), or would be [unpreserved]
Well, thus end days 1 and 2. The poster sessions begin on Thursday, so the
afternoon session will be short. I will next relate what I'd like to see on
Friday, then follow that with Saturday, then finish with discussion of the
posters, though this will needfully be short as I don't have the posters
Jaime A. Headden
"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
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