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

The Return of More New Papers

A nod to Donna Braginetz for the header!

Apparently, the _Actas de las III Jornadas Internacionales sobre Paleontología de Dinosaurios y su Entorno_ is out, although I haven't seen the volume yet or know its contents, I have seen a PDF of:

Wilson, J.A. 2006. An overview of titanosaur evolution and phylogeny; pp. 169-190 in Salas, C.A.-P.d. (ed.), Actas de las III Jornadas Internacionales sobre Paleontología de Dinosaurios y su Entorno. Colectivo Arqueológico-Paleontológico de Salas, Burgos.

ABSTRACT: Titanosaurus was named in 1877 for two caudal vertebrae and an isolated femur from Cretaceous rocks of central India. Titanosauridae was coined soon afterwards to encompass numerous taxa, despite their often tenuous associations and limited morphological overlap. Long recognized as wastebasket taxa, "Titanosaurus indicus", "Titanosauridae" and coordinated rank-taxa are now considered invalid, but the unranked taxon Titanosauria remains valid. Titanosauria currentles includes 40+ species and fi rst appeared during the Middle Jurassic in the form of "wide-gauge" trackways. Titanosaur body fossils do not appear until the Late Jurassic, but they are inferred to have occupied nearly all continental landmasses during the Early Cretaceous. Titanosaurs are the predominant or exclusive sauropods during the Late Cretaceous and represent a key clade for investigation of survivorship patterns and the effects of major tectonic rearrangements on dinosaur evolution. Titanosauria includes several large-bodied species (e.g., Antarctosaurus giganteus, Argyrosaurus superbus, Argentinosaurus huinculensis), as well as species that are diminutive by sauropod standards (e.g., Saltasaurus loricatus, Neuquensaurus australis).
Evaluation of previous phylogenetic analyses of Titanosauria provides insight into the structure of the character data thus far generated and a starting point for future studies. Where comparable, analyses agree on several topological points, including (1) the basal position of Andesaurus and Malawisaurus and (2) the derived position of Saltasaurus, Neuquensaurus, Opisthocoelicaudia, and Alamosaurus. This investigation identifi es several stable titanosaur nodes and a core of character data for future analysis. However, many titanosaur species have yet to be included in a phylogenetic analysis. A comprehensive phylogenetic analysis of Titanosauria will require incorporating these taxa as well as new character data. Resolution of titanosaur interrelationships will spur investigation into Mesozoic paleobiogeography, changes in body size distribution through time, wide-gauge limb posture and its biomechanical signifi cance, and patterns in herbivorous apomorphies of Cretaceous dinosaurs. These and other avenues will be explored in future research.

If anyone has this book, and/or knows how to get a copy, please let us know! Next, a couple issues from late last year in _Geological Bulletin of China_:

Ji, S.-A., Ji, Q., You, H.-L., Lü, J.-C., and Yuan, C.-X. 2006. Webbed foot of an Early Cretaceous ornithurine bird Gansus from China. Geological Bulletin of China 25(11):1295-1298.

ABSTRACT: Gansus yumenensis is the first Mesozoic bird found in China. It was collected from the Xiagou Formation in northwestern Gansu, which is considered to be equivalent to the Early Cretaceous strata yielding the Jehol biota in western Liaoning. Based on some characters such as elongated phalanges and short claws with pointed flexor tubercles, Gansus yumenensis is regarded as the bird adapted to life in the aquatic environment. Gansus yumenensis was originally erected only based on a unique specimen of the left pes, and some specimens have been found for a further study recently. In this paper, a newly discovered complete hindlimb of Gansus yumenensis is described, which shows the clear webbed structures among the distal portions of pedal phalanges. It is the first direct evidence to show that Gansus yumenensis with well-developed footwebs is really the oldest known bird specifically well-adapted to life in the aquatic environment in the world.

Lü, J.-C., Xu, L., Jia, S.-H., Zhang, X.-L., and Ji, Q. 2006. Discovery of a gigantic sauropod femur in Ruyang, Henan, China, and its stratigraphic significance. Geological Bulletin of China 25(11):1299-1302.

This one was announced on list before, but I finally managed to scrounge a copy:

Thulborn, T. 2006. On the tracks of the earliest dinosaurs: implications for the hypothesis of dinosaurian monophyly. Alcheringa 30:273-311.

ABSTRACT: From the record of dinosaurian skeletal remains it has been inferred that the. origin and initial diversification of dinosaurs were rapid events, occupying an interval of about 5 million years in the Late Triassic. By contrast numerous reports of dinosauroid tracks imply that the emergence of dinosaurs was a more protracted affair extending through much of the Early and Middle Triassic. This study finds no convincing evidence of dinosaur tracks before the late Ladinian. Each of the three dinosaurian clades - Theropoda, Sauropodomorpha, Ornithischia - produced a unique track morphotype that appears to be an independent modification of the chirotherioid pattern attributed to stern-group archosaurs (thecodontian reptiles). The existence of three divergent track rnorphotypes is consistent with the concept of dinosaurian polyphyly but can be reconciled with the hypothesis of dinosaurian monophyly only by invoking many and rapid reversals in the locomotor anatomy of early dinosaurs. The origin of dinosaurs was not the correlate or consequence of any single event or process, be it global change, competitive replacement, or opportunism in the wake of mass extinction. Instead the origin of dinosaurs is envisaged as a series of three cladogenetic events over an interval of at least 10 million years and possibly as much as 25 million years. This scenario of dinosaurian polyphyly is as well-supported by fossil evidence as is the currently favoured view of dinosaurian monophyly.

It's a more interesting read than the title and abstract suggest -- yes, it's heavy on the ichnology, but also tackles some of the morphological characters used to support dinosaur monophyly. Thulborn also had another paper out late last year:

Thulborn, R.A. 2006. Theropod dinosaurs, progenesis and birds: homology of digits in the manus. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 242(2/3):205-241.

ABSTRACT: The proposition that birds arose from theropod dinosaurs by the evolutionary mechanism of progenesis (accelerated development to sexual maturity) has important consequences for understanding of avian anatomy. One predictable consequence is an avian hand comprising digits 2-3-4 of the pentadactyl format. Ichnological evidence confirms that the theropod hand also comprises digits 2-3-4. By contrast a frame shift hypothesis, which seeks to reconcile theropod digits 1-2-3 with avian digits 2-3-4, is less plausible: it demands substantial reorganization of the standard program oflimb development in arimiotes, and relies on problematical concepts (identity, individualization, horneosis) lacking any clear and consistent relationship to homology.

Jerry D. Harris
Director of Paleontology
Dixie State College
Science Building
225 South 700 East
St. George, UT  84770   USA
Phone: (435) 652-7758
Fax: (435) 656-4022
E-mail: jharris@dixie.edu
and     dinogami@gmail.com

"Trying to estimate the divergence times
of fungal, algal or prokaryotic groups on
the basis of a partial reptilian fossil and
protein sequences from mice and humans
is like trying to decipher Demotic Egyptian with
the help of an odometer and the Oxford
English Dictionary."
              -- D. Graur & W. Martin (_Trends
                  in Genetics_ 20[2], 2004)