Here's the second part of the SVP dinosaur presentations.
Clarke and Norell report a new ornithurine very close to Neornithes from Ukhaa Tolgod in Mongolia. It's a nearly complete skeleton and presumedly different than the "Protoavis-skulled" coelurosaur at the Fighting Dinosaurs exhibit (which has troodontid synapomorphies).
Coria, Chiappe and Dingus report their new carnotaurine abelisaurid from the Anacleto Member of the Rio Colorado Formation of Argentina. It's 30% smaller than Carnotaurus and is almost complete. It differs from Carnotaurus in that it has a- longer and lower snout, maxillary fenestra, "swells" instead of horns, reduced coracoid process, slender and craniocaudally compressed humerus with well-defined condyles, open haemal canals. It's the sister group of Carnotaurus based on- cranially projected cervical epipophyses, proximal and mid-caudals with hyposphene-hyantra, frontal protuberances, broad coracoid, large hemispherical humeral head, very short radius and ulna. Traces of soft tissue are preserved around the pelvis.
Darrough, Armstrong-Hall and Fix discussed hadrosaur vertebrae, phalanx and tooth remains from the Cretaceous Chronister site in Missouri.
A new Bathonian tracksite from England has 42 well preserved continuous trackways. Two-thirds are Brontopodus, while the others are Megalosauripus. The latter are 60 cm in length and at least one was running. The many parallel tracks suggests herding behavior. This was presented by Day, Burton and Norman.
The Early Maastrichtian Williams Fork Formation in Colorado preserves seven saurischians and five ornithischians, including Pentaceratops. Diem and Archibald presented this mostly mammalian talk.
Eberth, Currie, Coria, Garrido and Zonneveld gave more details regarding the unnamed large carcharodontosaur bonebed in the Rio Limay Formation (Huincul Member) of Argentina. Although the cause of death is unknown, the fact that six individuals died here at the same ime suggests a pre-mortem community and/or social structure.
Erickson and Curry Rogers used Developmental Mass Extrapolation to reconstruct growth curves for dinosaurs and concluded they were comparable to extant marsupials.
Evans, Prasad and Manhas announced small theropod and ornithopod remains from the Early-Middle Jurassic Kota Formation of India. These are the first ornithopod remains from that subcontinent.
Theropod teeth from the Prince Creek Formation of Alaska (Middle Maastrichtian) were examined by Fiorillo and Gangloff. They concluded that species diversity is less than that in Judith River, Aguja and Hell Creek Formations. Troodon dominates the fauna, unlike in Judith River.
Forster and O'Connor describe new avian remains from the Maeverano Formation of Madagascar. Two distal humeri are assigned to Rahonavis, while two partial humeri and an ulna are assigned to Vorona. This is based on morphological and morphometric evidence. Additional remains include a dentary, furcula, tibia, coracoid, two types of synsacra and three types of humeri. These are from enantiornithines with derived features (ten sacral vertebrae, well-developed bicipital crests, enlarged ventral tubercles, large coracobrachialis scars) and most are small, although one moderately large synscarum is present.
Galton and Upchurch present a paper on the confusing state of sacral transformation in prosauropods. The plesiomorphic condition is to add a third sacral from the caudal series. This is present in Marasuchus, Sauropoda, Saturnalia, Thecodontosaurus, Ammosaurus, Melanorosaurus, Euskelosaurus, Plateosaurus and Sellosaurus. The apomorphic condition of adding a sacral from the dorsal series is present in Riojasaurus, Jingshanosaurus, Massospondylus, Yunnanosaurus, Lufengosaurus, ?Sellosaurus and "Gyposaurus" sinensis. Why Sellosaurus is mentioned twice I'm not sure. A 135 character, 16 genera cladistic analysis indicates the apomorphic condition developed more than once and reversed as well.
Gauthier and Gishlick report on the manus of Compsognathus. "Metacarpal I" is really phalanx I-1. The mystery element above the skull is a very short metacarpal I. There is a collateral ligament pit on metacarpal III, but no preserved phalanges. Thus, there may have been a third digit or not.
Gimenez describes the skin impressions of Tehuelchesaurus, which originate from the thorax and scapular regions. The skin is covered with tubercular scales with two diferent patterns- semi-smooth and hexagonal scales (3x2.5 cm) alternating with smaller ones (2x1.5 cm) in small roseate patterns; rhomboidal scales (2-4 mm).
Gishlick studied the forelimb of Deinonychus and concludes that it was poorly designed for quadrupedal climbing. This is because the wrist flexes in the lateral plane, unlike scansorial animals, which have wrists that flex in the dorsoventral plane. The arm would pull a dromaeosaurid into the surface it was climbing instead of up it, and the laterally folding wrist would twist the claws out of the surface they were clinging to.
Grellet-Tinner reports on the titanosaurid eggshells from Auca Mahuevo. The membrana testacea (organic eggshell membrane) is preserved. The eggs contain radiating acicular calcite crystals in the mammillary layer, like those of Deinonychus and Oviraptor. Troodon shows blocky calcite crystals in the same area. Thus, the former condition is considered symplesiomorphic for Saurischia.
Happ and Morrow describe soft tissue of Triceratops from a specimen (SUP9713) found in the Hell Creek Formation of Montana. A mineralized layer on the supraorbital horn core contains a mass of vessel traces. These traces are mineralized with ferruginous hollow tubular structures. Arteries and veins are 2.3-5.8 mm in diameter, while arterioles and venules are .16-1.3 mm. In the braincase, solid tubular structures passing through the exoccipital exit through the jugular foramen. These are probably cranial nerves IX, X, XI and the jugular vein. In addition, a solid ovate structure is preserved in the typanic cavity.
Hartman concludes that lengthening of primary and caudal feathers in maniraptorans provided pitch control and stability to short duration leaps on to prey (as has been hypothesized for dromaeosaurids). He thinks this shows that wing and caudal feathers may have evolved in a terrestrial context.
Henderson reports on the hindlimb changes associated with size increase in ornithopods. These include- increase in angle between digits II and IV; increased robustnes of digit IV; equalization of lengths of digits II-IV. Theropods do not show these changes, which is said to be due to their saurischian pelvis. Although birds show convergent changes, ornithopods were "hip walkers" and changed for balance reasons. Birds are "knee walkers" that modified their foot structure for propulsion reasons.
Hernandez-Rivera and Delgado-De Jesus describe skin impressions from two hadrosaurs from the Cerro del Pueblo Formation (Late Campanian) of Mexico. One hadrosaur is preserved as a nearly complete skeleton that has impressions from the tail, limbs and hip. Another is preserved as skin impressions without an associated skeleton.
Holtz presented a phylogenetic analysis of neotheropods. He advocates the inclusion of poorly preserved taxa that show novel character combinations, as (although there are often more most parsimonious trees) they can produce trees with combinations of taxa not seen in more inclusive analyses. He also warns that using more derived members of the outgroup can alter the results of an analysis. Finally, he warns against excluding characters a priori. Unfortunately, details of the analysis are not presented :-(
There are still more talks to be covered, so look for updates later this week.