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Things To Look Forward To - SVP 2005 (Mesa, Arizona, USA) - Part 2



  For SVP's coming up Friday in Mesa, Arizona, USA (October 21st), the program
is short because of more posters, so this will be a morning-driven day, for
which the posters in the afternoon and the museum trip in the evening (I
assume).

  For Friday morning, three concurrent sessions are running, one on archosaurs
focusing especially on dinosaurs and interspersed with crocs, and another a
symposium on fishies (non-tetrapod gnathostomes, at any rate). I am actually
curious in durophagous chondricthyans, such as rays and some "standard"
selachians, and the story of the goblin shark, *Mistukurina*, is curious as
itself. Robert Carr and Gary Jackson will tackle durophagy in arthrodires in a
critical review of the subject, and note up to 8 separate origins of durophagy
have occured in the Arthrodira. Meanwhile, posters associated with the session
are relatively few (6) of which one (Robert Purdy's) focuses on the oddest
living elasmobranch, *Mitsukurina owstoni* and its possible synonymy with
*Striatolamia macrota* (a tooth-based species): Purday says yes, and the gobbie
is the senior name). BTW, a picture of the teeth of *Mitsukurina* can be found
here (http://www.flmnh.ufl.edu/fish/Gallery/Descript/GoblinShark/dentition.JPG)
and those of *Striatolamia macrota* here
(http://paleontologie.chez.tiscali.fr/lutetien/l1/macrota2.jpg). Pictures of
goblin sharks notwithstanding, they actually do not swim with their upper jaws
extruded, which accounts for the bulk of the illustrations made of this animal,
but like other sharks the upper jaw is usually contained within the snout.

  In the other session, deeenos are probably as popular as ever:

  Mary Schweitzer and Jennifer Wittmeyer will show that the tissue they
collected from an apparently gravid *Tyrannosaurus rex* is not a unique event,
as previously Mary noted they had sampled hadrosaur and other tyrannosaur
specimens to determine if this was isolated or a product of infection. Well,
honey, it ain't. The sample doesn't go further back than the Late Cretaceous,
and includes a moa. At this point, I think I can say that I am sure the novel
tissue preservation is actual, not artifactual, and is correctly interpreted.
Then Jennifer and Mary will do a switchero, and discuss the methods they used
to "revitalize" the tissues for study and isolation from bone.

  Jingmai O'Connor, Luis Chiappe and Gao Keqin (misspelled? Qeqin [I asked him
about this a while back and I think it is Keqin, but I don't think I've seen
"K" in other Chinese names]) will present on a sparrow-sized bird from the
Jiufotang of Chaoyang, Liaoning Province, People's Republic of China, which is
initially said to be similar to *Yanornis* (which includes
"Archaeoraptor"/*Archaeovolans*) and *Yixia[n]ornis* [sic] (curved scapula,
broad mdII-1 phalanx compared to mdII-2, a slender U-shaped furcula lacking a
hypocleidium) and is apparently an ornithuromorph bird, though distinct from
other named birds (on the basis of an elongated tibiotarsus greater than
humeral length, and a forelimb:hindlimb ratio of 0.79). Two talks later, Matt
Lamanna and a host of others will present an enantiornithine from Gansu
Province's Xiagou Formation (from whence *Gansus yumanensis* originates)
including a pelvis and both complete hindlimbs. It is possible it pertains to
the Euenantiornithes, but reference is based on a single feature (extremely
narrower metatarsal IV compared to II and III), though it appears to be
comfortably enantiornithine (posterior iliac alae shallow, distal condyles of
mtI caudally oriented and the condyles joined along their dorsal margin, the
joint between mtII and pdII-1 extremely broad compared to mtIV/pdIV-1, and
distal condyles of mtIV C-shaped in distal aspect)

  Anthony Martin will intervene between the two fossil birds with a review of
extant avian tracks in mud as the originators of mudcracks, and show that
similar features in fossil tracks will constrain interpretations of features as
in Hitchcock's "Dilophosaurus resting trace" as integumental, rather than
artifacts of the animal's deformation of the substrate.

  Julia Clarke and others will assess the timing and radiation of birds, which
largely focuses around *Vegavis*, so expect new and better stuff on this. It
will hope to show that, based on phylogeny, morphology of *Vegavis*, and
molecular timing, at least 5 basal avian divergences were present in the Late
Cretaceous, and that Neoaves itself may have diversified by 100ma.

  Luis Chiappe, Jingmai O'Connor and Zhou Zhonghe, not people to leave birds to
Julia and Matt, will come back with a second presentation on the
enantiornithine radiation to note that nearly half of Mesozoic birds were
enantiornithean in origin. This talk is largely, apparently, an advertisement
for a project called the Paleobiology Database (PBDB) which seeks to catalogue
all dinosaur fossil occurences (I think largely for reference and use in
statistics, which this talk is about).

  Lee Hang-Jae and Lee Yuong-Nam will describe a new *Zosuchus*-like
protosuchian from Hadon County, South Korea in the Hasandong Formation (Aptian,
Late Cretaceous) and supplementarily discuss a phylogeny of 13 taxa and 49
characters for a largely protosuchian tree. The new croc is based on features
of the premaxillary teeth (D-shaped, as in some sphenosuchians), pteryogids
parallel with "sharp" ventromedial margins, the anterior jugal not contacting
the lachrymal, and the maxilla comprising the ventral margin of the orbit
(which is just weird, even for crocs).

  Greg Erickson and others will assess bite force parameters and output in
crocodylians, and show that despite jaw variation, tooth variation, fossil and
extant Crocodylia have shown little change in bite force capacity, and this is
apparently consistent between *Alligator* and *Crocodilus* even during
ontogeny. The bone crushing bites are apparently quite ancient.

  Alan Turner, Mark Norell and Diego Pol will describe the first of Ukhaa
Tolgod's crocs, refering it not to a new taxon but recognizing it as yet
another member of the Djadokhtan *Shamosuchus djadochtaensis*, from older sites
in the same formation. The croc accompanies an analysis that shows it appears
to be related to *Rugosuchus*, *Bernisarttia*, and the Glen Rose croc, had
"festooned" jaws (I am told that festooning in the old sense, with an
undulating jaw margin, is not applied much anymore, so this term is noted to
refer to the length of teeth in a series, which in this case show a double
festoon, no antorbital fenestra, no mandibular fenestra, and is linked to
*Rugosuchus* by a ridge on the lower angular, keels on the dorsal osteoderms
that are restriced to the caudal margins, and an internal naris ("choana")
nearly surrounded by the palatines, though the posterolateral extent of the
palatine does not reach the suborbital fenestra.

  Chris Brochu's title makes me think of an Ahnold movie: "Stealth Diversity in
the Cradle of Humanity". The predator aliens in Afar, Ethiopia? Actually, he
will discuss fossil data indicating *Crocidilus* is an African invader,
apparently supplanting *Osteolaemus* and allies as the top crocs. Phylogenetic
data appears to support an osteolaemine ubiquity to African crocs, whereas many
species of *Crocodilus* may actually be osteolaemine instead! Funky crocs
include two apparent diversities of long-snouted crocs, and several horned
crocs, and that some miniature crocs on islands may not have dwarfed based on
island insularity, due to timing of island emergence with fossilization.

  Ursula Goehlich and other croc-lovers will discuss new fossils of
*Macelognathus* from the Fruita Paleontological Area of Colorado, which allow
her to phylogenetically place it as the youngest definitive "sphenosuchian" and
one result also proposed a monophyletic Sphenosuchia, which I think she will
not strictly address. I suspect she may also mention that *Hallopus* is really
crappy despite it's completeness, because the bone is in real bad condition and
too much of it has to be studied from moulds based on bone imprints of the
imperfectly matched slab and counterslab.

  Norman MacLeod and J. David Archibald will discuss the "rise and fall of
dinosaurs" (selectively quoting the title), starting off I am sure with
informing us that there is no settlement to the controversy, despite Gerta
Keller's recent interesting claims on the timing of the Chixulub impact
features with the K/T Event. They review the two main hypotheses, that a bolide
wiped the Earth of these critters which suffered in the weeks and years
thereafter to disappear from the earth, and the gradual declination of the
group with eventual "shot from a window while falling" bolide that finished
them off (a proposal I dislike because it is strictly dino-centric yet tries to
apply to all other extinctions at the K/Pg boundary (yes, I am using the two
terms in the same paragraph, and for a good reason, too). They come down
seriously questioning the gradual model by arguing the long-held condition of
fossil richness and resolution being insufficient to theorize the model, and
make the same point I do above about cross-taxon declination being less than
universal. They also suggest a variety of models may be likely.

  Yesterday, I posted on some forensic entomological applications to
fossilization processes and taphonomy in general, but Friday Brooks Britt, Anne
Dangerfield, and Brent Greenhalgh will approach osteophagous beetle traces at
the Dalton Wells Quarry, 20% of the bones of which have such entomological
ichnites on them, as fine as to show that V-shaped grooves are mandible traces,
and likely culprits are silphid, scarabaeid and histerid coleopterans, though
they suggest a non-coleopteran etiology is possible.

  William Straight and collaborators will propose that dinosaurs had fever,
often associated with fighting infections and wounds, but never conclusively or
evidentially substantiated. They show that delta-oxygen-18 isotope analysis
shows cortical growth of animals with a warmer core-body temperature than other
cortical layers implies mean body increase (as in fevers). This is applied
through diagenetic models derived from mammals, and while hadrosaurs are not
human, the hadrosaur specimens sampled  show they were ectothermic enough to
acheive fever states when injured or sick.

  The third session of the morning will be on mammals, but of these, aside from
mild interest on Rybczynski, Pabst and McLellan's work on soft-tissue anatomy
and inferrence of such to the tail anatomy of beavers or the sloth talks, the
only one I seem curious about is Peter Kondrashov and Alexandre Agadjanian on a
new specimen of *Ernanodon* which is proposed to show that while it forms
polytomies with xenarthrans, pholidotes and palaeanodonts, or tends to be
associated with pholidotes when *Manis* and related fossils are included, they
argue that *Ernanodonta* and the monotypic Enanodonta is the sister-taxon to
Palaeoanodonta. This kinda weirds me out a little, because I am not fond of
super-generic taxa being used to support relationships, rather than the
included taxa. Why, for example, can't *Ernanodon* simply be a basal
palaeanodont? This also shows that the prior odd structure of the limbs that
had been previously shown to be polytypic (Inés Horovitz's work) can be
accurately sorted out.

  Shifting after lunch into the three afternoon sessions prior to the second
and last poster session, we have non-avian archosaurs, birds, and mammals. I'll
hit the mammals last because the last talk is curious, but will try to pass
between archosaur and bird sessions (as the two sessions are going to be held
across the quad, as it were, folks may need to consider one or the other as a
priority, but since both sessions are chock full of archosaur goodness, I will
bet a lot of people will try to get friends to attend with notes).

  So starting with the "boids": 

  David Krauss, Jillian Petrucelli and Taylor Lincoln will present details on
perhaps the most fascinating and needed taphonomic experiment in attempting to
figure out how avian corpses get preserved the way they do, including typical
"bloat and float" processes, and weighted burial. They find that the best way
to get to a bird preserved with integument and intect skeleton is actually a
terrestrial sediment subsequently buried in water, implying that even at
Liaoning and Solnhofen, the fossils were not formed IN the lagoon or lake, but
on the shores nearby, since scavening and "bloat and float" would tend to
disarticulate skeletons, rather than keep them intact, due to pneumatic
invasion of bones lightening them and requirement of penetration of the
diverticular membrane to force water into the cavities (which they also tried).
All told, I will definately think this would force me to chose this session
above the archosaur one.

  Daniel Ksepka and others  review a phylogeny of Palaeognathae, creating a
matrix of primarily genus-based OTU's including skeleton, integument and eggs,
with a host of before-now unused characters. They will find that the
(Tinamiformes (Lithornithidae + Ratitae)) grouping is likely (which in some
definitions means lithornithids ARE ratites), and within Ratitae, a more
unconventional association of struthionids with rheids, and the classic
association of New Zealand ratites in a monophyly, and they also support
elephant birds with kiwis and moa.

  Erin Maxwell will assess the old addage "ontogeny recapitulates
phylogeny,"this time applied to birds, by assessing phylogenentics with
juveniles for species along with adults, and finding virtually little
similarity among the results, indicating massive amounts of adult features
develop through ontogeny and that juveniles are more and more similar to one
another than adults (this has been covered before).

  Gareth Dyke and others will discuss fossil birds from Dånmark's Fur Formation
(lower Eocene) of Limfjord, Jutland. Among the fossils are included many
apparently new more species for Dyke to name from Palaeognathae, Galliformes,
Charadriiformes, Psittaciformes, Coraciiformes, and Apodiformes. These new
fossils will accompany more Eocene birds, as from the Green River of Wyoming
and Utah and the English London Clay, in elaborating Lauriasian avian
radiation.

  And ending the day for talks with archosaurs (and since I'm not too concerned
with statistical studies, will leave out Matt Carrano's abstract):

  Julia Heathcote, Paul Barrett and Matthew Wills will compare the fossil
record of dinosaurs with stratigraphic congruence, relating
phylogeny/stratigraphy congruence, showing that while the completeness is weak,
the congruence is relatively good.

  Bill Parker, Sterling Nesbitt and Randy Irmis will present a three part
discussion of the Late Triassic dinosaur record of North America. 

  Part one will be presented by Bill Parker, most likely, and addresses the
recently published topic of *Revueltosaurus* cranial and postcranial anatomy,
this time rather than the poster from 2004 discussing the postcrania (which
includes a broad, proximally restricted deltopec crest, a short, robust
anterior iliac ala, and two sacral rib articulations [by which I assume means
there is no known sacrum, though given that *Silesaurus* also has only two rib
articulations but a 4-sacral sacrum, does NOT mean it has a 2-vert sacrum]; a
large fourth trochanter accompanies the poorly-rounded femoral caput [by which
I think means it was angular]; a crocodile-normal ankle; and extensive
osteoderms). They also present on more *Revueltosaurus*-like skeletons from the
Chinle Formation (Blue Mesa Member) of Arizona, USA, and Pekin Formation (North
Carolina, USA) imply a greater distribution of such fossils.

  Randy Irmis will present the second part, assessing the fossil record of
Triassic "ornithischians", almost exclusively relegated to tooth-based taxa
(which I hate anyway), but while the authors were not capable of assessing the
only really apparent Triassic ornithischian, *Pisanosaurus*, they were capable
of determining that the dental record of Triassic dinosaurs may not be
ornithischians based almost entirely on the absence of a cingulum. I am not
happy with this assessment, since it may seems likely that *Silesaurus* has a
cingulum, via the broadening of the definition into a basal swelling around the
crown above a root, with or without a constriction between crown and root, and
the condition in *Lesothosaurus* is virtually absent. Thus I do not agree so
far as the abstract proposes the situation to be.

  And finally, part three will likely be presented by Sterling Nesbitt, who
will focus on saurischians, beginning with using *Coelophysoid* as the
representative saurischian, and further making me wonder why it's not called
"Theropods". *Camposaurus* is suggested as potentially synonymous with
*Coelophysis*, *Gojirasaurus* is considered a chimaera, *Protoavis* appears to
have the femur, astragalus and calcaneum of a coelophysoid, a new skeleton of
*Shuvosaurus* shows the skull belongs to the postcrania named as *Chatterjeea*
(which would be a junior synonym), *Caseosaurus* and *Chindesaurus* are
probably synonyms (sigh, first its a referred specimen of *Chindesaurus*, then
a new taxon, and now a subsumation of the new taxon). And finally,
*Eucoelophysis* may not even be a dinosaur but has "ornithodiran" apomorphies
(other suggestions noted previously have been to call this a *Silesaurus*-like
animal. Thus the implication is that all Late Triassic saurischians from North
America are coelophysoids.

  Jorge Ferigolo and Max Langer will discuss the origin of the ornithischian
predentary, discussing also other "predentaries" found in nature, including the
mentomeckelian of some lizards, and birds, and an _ossicula mentalia_ which is
a bilateral bone that fused to the dentary later in ontogeny, and the
suggestion appears weak, yet they found a new ornithischian from the Caturrita
Formation of southern Brasíl [Brazil] with a pair of rostral bones at the
rostral end of the dentaries with the shape of a hook that apparently reveals
the origins of the medial predentary as an ossification of these paired
_ossicula mentalia_. (In my opinion, this may also lend credence to claims that
the mandible of *Silesaurus* is even more ornithischian-like, but I would argue
the mutual appearance of the hook (?fused) to each dentary but not to one
another is reminiscent of the condition they describe for other taxa, but not
in ornithischians; it also does not overturn the host of data which imply
*Silesaurus* is non-dinosaurian. That all said, perhaps this is another of
those "silly saurids"....)

  Anyways, this is it for Friday, since the posters took up the rest of the
afternoon. Next, Saturday, which will be a full day and has lots (as
traditional) funky stuff.

  Cheers,

Jaime A. Headden

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

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