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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
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
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
225 South 700 East
St. George, UT 84770 USA
Phone: (435) 652-7758
Fax: (435) 656-4022
"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
-- D. Graur & W. Martin (_Trends
in Genetics_ 20, 2004)