Finally, my copy of the new issue of the Journal of Vertebrate Paleontology arrived. I am eagerly awaiting this and the next few issues because there are quite a few "in press" Triassic articles. The recent issue was a surprise because three of these articles were in there including the long awaited redescription of the enigmatic Late Triassic archosauriform Doswellia kaltenbachi by David Dilkes and Hans Sues; a response by Emily Rayfield and colleagues to what I consider to be one of the most blatent ad hominem attacks I've ever seen in a publication; and the long awaited description of the postcrania of the rauisuchian Batrachotomus (one of the greatest names ever) kupferzellensis by David Gower and Rainer Schoch. As an added bonus there is a description by Ricardo Martínez of a new basal sauropodomorph, Adeopapposaurus mognai, from the Lower Jurassic of Argentina that reintroduces the hypothesis of the presence of a horny beak in basal sauropodomorphs. Once I have had the opportunity to read through each of these papers 3-4 times I may comment some more on them. For now here are the citations and abstracts.
Dilkes, D. and H.-D. Sues. 2009. Redescription and phylogenetic relationships of Doswellia kaltenbachi (Diapsida: Archosauriformes) from the Upper Triassic of Virginia. Journal of Vertebrate Paleontology 29:58-79.
ABSTRACT-A detailed redescription of the Late Triassic archosauromorph reptile Doswellia kaltenbachi Weems, 1980 from the Poor Farm Member of the Falling Creek Formation in the Taylorsville basin (Newark Supergroup) in Virginia is presented based upon additional preparation of the holotype. The euryapsid skull has a distinctive occiput with a prominent supraoccipital process that is flanked by posterior "horn-like" projections of the squamosals. Postfrontals, tabulars, and postparietals are absent. Plesiomorphic features of the palate and braincase include a plate-like horizontal parabasisphenoid, a pair of foramina for the internal carotid arteries on the ventral surface of the basisphenoid and two fields of teeth on the palatal surface of the pterygoid. A sharp angle along the cervical and anterior dorsal ribs clearly separates the dorsal and lateral sides of the neck and anterior thoracic region. The posterior thoracic region has shorter ribs that project laterally with only a slight curvature. The ilium has a laterally deflected blade with numerous deep grooves along its distal edge. The laterally extensive set of osteoderms includes a nuchal element that is composed of several interlocking osteoderms that lack the arrangement in distinct transverse rows that characterize the remainder of the osteoderms. A phylogenetic analysis of basal archosauriforms incorporates new data of Doswellia and the taxa Turfanosuchus, Yonghesuchus, and Qianosuchus that have not previously been combined in a single study. Results include a sister-group relationship between Doswellia and proterochampsids, placement of Qianosuchus as a crurotarsan archosaur, and Yonghesuchus and Turfanosuchus as successive sister taxa to Archosauria.
Rayfield, E.J., Barrett, P.M., and A. R. Milner. 2009. Utility and validity of Middle and Late Triassic 'land vertebrate faunachrons'. Journal of Vertebrate Paleontology 29:80-87.
ABSTRACT-A tetrapod-based biochronologic framework for the terrestrial Triassic, which subdivides the Triassic into eight 'Land Vertebrate Faunachrons' (LVFs), has been proposed and developed by Lucas and coworkers. In a recent article, these authors reiterated their support for this scheme and used this opportunity to respond to criticisms dealing with the validity and utility of Triassic LVFs. This article is a reply to Lucas and colleagues and demonstrates that many aspects of this Triassic biochronology are dependent on: (1) subjective opinions regarding the taxonomic assignments of key specimens; and (2) unjustified extrapolation of correlations on the basis of geographically restricted endemics. Furthermore, it is suggested that the methodological basis for recognizing the onset of a particular LVF, the identification of the 'first appearance datum' for those taxa deemed to be biochronologically significant, leads to imprecision in correlation and potential ambiguity in dating. Finally, it is argued that geographic information systems are ideal tools for testing biostratigraphic hypotheses.
Gower, D.J., and R.R. Schoch. 2009. Postcranial anatomy of the rauisuchian archosaur Batrachotomus kupferzellensis. Journal of Vertebrate Paleontology 29:103-122.
ABSTRACT-Batracholomus kupferzellensis is an upper Middle Triassic (Late Ladinian) rauisuchian archosaur. The postcranial skeleton of this species is well-represented by fossil material, including the holotype, from the localities of Kupferzell, Crailsheim and Vellberg-Eschenau in southern Germany, and is described here in detail for the first time. All postcranial elements are known except the interclavicle and parts of the carpus, manus, tarsus, pes and some osteoderms and axial elements. B. kupferzellensis is now one of the best-known rauisuchians and will be important in advancing understanding of the group's biology. A period of new anatomical and taxonomic work since 2000 has improved understanding of rauisuchians. Renewed effort in rauisuchian phylogenetics will benefit from these new data, but will also require a careful and detailed approach to character formulation.
Martínez, R.N. 2009. Adeopapposaurus mognai, gen. et sp. nov. (Dinosauria: Sauropodomorpha with comments on adaptations of basal Sauropodomorpha. Journal of Vertebrate Paleontology 29:142-164.
ABSTRACT-Prosauropods are basal sauropodomorphs that were the major terrestrial faunal components from the Norian until their extinction during the Toarcian. Their status as a natural group is debatable. In the present work I describe Adeopapposaurus mognai, a new sauropodomorph from the Cañon del Colorado Formation, in northwestern Argentina. Diagnostic autapomorphies and combination of characters of Adeopapposaurus include a series of large foramina in a sub-vertical row on the lateral surface of the premaxilla; strongly rugose depression bordered by a protuberance with a series of foramina in a sub-vertical row, on the lateral surface of the anterior end of the dentary; eleven anteroposteriorly elongated cervical vertebrae and thirteen dorsal vertebrae with neural arches taller than the respective centra. Phylogenetically Adeopapposaurus is resolved as the sister group to Massospondylus; differing from the latter based on differences in mandible and premaxilla and addition of one dorsal vertebra to the neck. The specimens described here reveal numerous herbivorous adaptations, including the presence of a highly vascularized bony plate in the premaxilla and dentary, which indicates that it had a horny beak.
Kurt Gödel's Open World
2 hours ago in The Curious Wavefunction