[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Also new in Historical Biology

Yates, A.M. (2006). Solving a dinosaurian puzzle: the identity of _Aliwalia rex_ Galton. Historical Biology, iFirst article, 1-30.

Abstract: "_Eucnemesaurus fortis_ Van Hoepen 1920 from the Late Triassic of South Africa is demonstrated to be the senior synonym of the puzzling dinosaur taxon _Aliwalia rex_ Galton 1985. A new specimen of this poorly-known taxon is described. _Eucnemesaurus_ is clearly a sauropodomorph and increases the diversity of sauropodomorph taxa in the South African Late Triassic to six. It shares a number of femoral synapomorphies with _Riojasaurus_ from the Late Triassic of Argentina and Riojasauridae tax. nov. is erected to accommodate them. These conclusions are supported by a comprehensive cladistic analysis of 46 sauropodomorph and other basal dinosauriformtaxa using 353 osteological characters. This analysis also supports the paraphyletic nature of the traditional ?prosauropod? assemblage.?

Also erects the new taxon Massopoda (defined as _Saltasaurus_ but not _Plateosaurus_), and re-defines Sauropoda (_Saltasaurus_ but not _Melanorosaurus_). Thus Sauropoda is a subset of Massopoda. _Plateosauravus_ and _Eucnemesaurus_ are both valid taxa (mentioned before). The analysis shows _Ruehleia_ as the sister taxon to the Massopoda+Plateosauridae clade. I guess this clade would be Plateosauria - Yates uses it as such, following Sereno (1998). But Plateosauria was defined under the assumption that _Plateosaurus_ and _Massospondylus_ formed a clade to the exclusion of eusauropods, which no longer holds; so Sereno (2005) re-defined Plateosauria such that _Saltasaurus_ is a negative qualifier.

Bonaparte, J.F, Brea, G., Schultz, C.L., and Martinelli, A.G. (2006). A new specimen of _Guaibasaurus candelariensis_ (basal Saurischia) from the Late Triassic Caturrita Formation of southern Brazil. Historical Biology, iFirst article, 1-30.

Abstract: ?The comparison of the anatomy of a second incomplete skeleton of _Guaibasaurus candelariensis_ to that of basal Saurischia suggests that the origin of the ?Prosauropoda? was from unknown basal saurischians, after separating from theropods (except herrerasaurids). _Guaibasaurus_ and _Saturnalia_ are part of this early dichotomy, and they bear mixed characters-states of basal theropods and ?prosauropods? type. The Late Triassic age of both _Guaibasaurus_ and _Saturnalia_(the latter is older) predates the ?dominance? of basal sauropodomorphs as well as the appearance of the basal theropod _Zupaysaurus_, both recorded from the upper Los Colorados Formation of Argentina.?

Ferigolo, J. and Langer, M.C. (2006). A Late Triassic dinosauriform from south Brazil and the origin
of the ornithischian predentary bone. Historical Biology, iFirst article, 1-11.

Abstract: ?The South American Late Triassic offers the most comprehensive window to the early radiation of dinosaurs. This is enhanced by the discovery of _Sacisaurus agudoensis_, a new dinosauriform from the Caturrita Formation of Brazil. Various morphological features suggest its close phylogenetic affinity to _Silesaurus_, and both may be basal ornithischian dinosaurs. __Sacisaurus_ has a pair of elements forming the tip of its lower jaw, hypothesized to be equivalent to the ornithischian predentary. This suggests that during an initial stage of their evolution, those dinosaurs had a paired predentary, which later fused into a single structure. As an originally paired bone, the predentary is comparable to elements that more often form the vertebrate mandible, such as the mentomeckelian bone. Although synapomorphic for ornithischians, the predentary does not seem neomorphic for the group, but primarily homologous to parts of the symphyseal region of the lower jaw of other vertebrates.?

Ezcurra, M. (2006). The cranial anatomy of the coelophysoid theropod _Zupaysaurus rougieri_ from the Upper Triassic of Argentina. Historical Biology, iFirst article, 1-18.

Abstract: ?_Zupaysaurus rougieri_ is a theropod dinosaur that is known from an almost complete skull and limited postcranial material (e.g., axial elements, scapulocoracoid, tibia, astragalocalcaneum), from the Los Colorados Formation (La Esquina Fauna, Norian), NW Argentina. This taxon was originally interpreted as a basal tetanuran, but is actually a member of the Coelophysoidea. _Zupaysaurus_ differs from other basal dinosaurs in the presence of the following cranial apomorphies: a maxillary-jugal ventral margin describing an obtuse angle in lateral view, a horizontal ramus of the maxilla with parallel dorsal and ventral margins, a notch at the base of the ascending process of the maxilla, and a sigmoid ventral process of the squamosal. Furthermore, the skull of this theropod reveals anatomical novelties (e.g., pneumatic lacrimal, maxillary fenestra, oval orbit, wide contact between squamosal and quadratojugal) absent in any other Triassic dinosaur hitherto described, including remaining coelophysoids. Interestingly, these features resemble morphological aspects of more derived theropods, approaching some traits of tetanuran and ceratosaurian neotheropods. In this regard, a redescription of the skull of _Zupaysaurus_ and comparisons with basal neotheropods, mainly coelophysoids, is presented here in order to provide a better cranial anatomical record for this Triassic theropod and insights to their early cranial evolution.?

Ezcurra, M.D. and Novas, F.E. (2006). Phylogenetic relationships of the Triassic theropod _Zupaysaurus rougieri_ from NW Argentina. Historical Biology, iFirst article, 1-18.

Abstract: ?The anatomy and phylogenetic relationships of the Upper Triassic theropod _Zupaysaurus rougieri_ are reviewed. This taxon is represented by a nearly complete skull and fragmentary postcranial remains recovered from the Los Colorados Formation (Norian), NW Argentina. Originally, _Zupaysaurus rougieri_ was considered a basal member of the Tetanurae, but its anatomy closely resembles that of the Coelophysoidea, supporting its nesting within this theropodan subclade. Thus reinterpreted, _Zupaysaurus_ represents the first record of coelophysoids in South America. Phylogenetic analyses perfomed in this study depict _Zupaysaurus_ as a non-coelophysis [sic]coelophysoid. Autopomorphic traits of _Zupaysaurus_ include: maxillary-jugal ventral margin forming an obtuse angle in lateral view, tibia with a very deep and caudally open caudal fossa for the reception of an astragalar caudal process. Within the phylogenetic context outlined here, the derived features shared with Tetanurae (e.g. maxillary fenestra, caudally forked ascending ramus of the maxilla) are better interpreted as homoplasies rather than tetanuran derived features.?

And the one already mentioned?

Irmis, R.B., Parker, W.G, Nesbitt, S.J., Liu, J. (2006). Early ornithischian dinosaurs: the Triassic record.

The holotype of _Technosaurus_ is restricted to the premaxilla and dentary. The premaxilla (at least) very closely resembles that of _Silesaurus_. The posterior mandibular fragment is referred to _Shuvosaurus_

_Azendohsaurus_ - probably non-dinosaurian, and related to a Madagasan taxon originally (and erroneously, based on more material) described as a prosauropod (Flynn et al., 1999).

_Galtonia_ and _Pekinosaurus_ - referred to _Revueltosaurus_ as _Revueltosaurus_ sp.

_Tecovasaurus_, _Lucianosaurus_, _Crosbysaurus_ and _Protecovasaurus_ - all valid taxa, but cannot be classified as anything other than Archosauriformes incertae sedis.



All-in-one security and maintenance for your PC. Get a free 90-day trial! http://clk.atdmt.com/MSN/go/msnnkwlo0050000002msn/direct/01/?href=http://www.windowsonecare.com/?sc_cid=msn_hotmail