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Dinosaur papers: a new hope
I don't have any of these. Sadly. If somebody wants to throw them my way,
I'd be forever grateful. :-)
Irmis, R.B., Parker, W.G. Nesbitt, S.J. and Liu, J. (2007). Early
ornithischian dinosaurs: the Triassic record. Historical Biology 19(1):
3-22.
ABSTRACT: "Ornithischian dinosaurs are one of the most taxonomically diverse
dinosaur clades during the Mesozoic, yet their origin and early
diversification remain virtually unknown. In recent years, several new
Triassic ornithischian taxa have been proposed, mostly based upon isolated
teeth. New discoveries of skeletal material of some of these tooth taxa
indicate that these teeth can no longer be assigned to the Ornithischia
using unambiguous synapomorphies. The Triassic record of ornithischian
dinosaurs now comprises only three probable occurrences: _Pisanosaurus_ and
an unnamed heterodontosaurid from Argentina, and an unnamed specimen from
the uppermost Triassic of South Africa. This revised Triassic record
suggests that ornithischians were not very diverse or abundant through the
Triassic, and there are large gaps in the Triassic ornithischian fossil
record. Moreover, traditional living analogues for interpreting the feeding
ecology of early ornithischians from their tooth morphology are generally
inappropriate, and "herbivorous" archosaur teeth such as those found in
early ornithischians are not necessarily diagnostic of herbivorous feeding."
Marsicano, C.A., Domnanovich, N.S., and Mancuso, A.C. (2007). Dinosaur
origins: evidence from the footprint record. Historical Biology 19(1):
83-91.
ABSTRACT: "Triassic tracks and trackways assigned to dinosaur trackmakers or
closest relatives have been mentioned from several Middle to the latest
Triassic successions from both northern and southern Pangea. At present, the
earliest gondwanan records are those from the Middle Triassic Los Rastros
Formation in west-central Argentina. A reanalysis of Los Rastros ichnites at
the Ischichuca area, including new material, has revealed the presence of a
more diverse ichnofauna than previously suspected. The ichnocoenosis
includes several tracks and trackways of bipeds with functionally tridactyl
digitigrade pes, well developed claws, and a parasagittal posture of the
hindlimbs. Previously, some large tridactyl footprints from the Ischichuca
area were allied to theropod dinosaurs, although no synapomophies are
preserved in the three-toed footprints that might discriminate among
theropods, basal saurischians and basal ornithischian groups as their
possible trackmakers. If the Ischichuca trackmakers are referred to a
dinosaur taxon and/or to a close dinosaur sister-taxon, their presence in
the Los Rastros levels suggests that derived dinosauriforms (including
dinosaurs) had diverged and acquired their characteristic functionally
tridactyl pes by at least the Middle Triassic, something that the
body-fossil record has failed to document to date."
Pol, D. and Powell, J.W. (2007). Skull anatomy of _Mussaurus patagonicus_
(Dinosauria: Sauropodomorpha) from the Late Triassic of Patagonia.
Historical Biology 19(1): 125-144.
ABSTRACT: "The skull anatomy of _Mussaurus patagonicus_ from the Upper
Triassic Laguna Colorada Formation is described based on a revision of the
type material and several recently found specimens. The studied material
include two distinct size classes of individuals. The type material consists
of extremely young individuals whereas the new specimens are interpreted as
juvenile or subadult individuals. The latter are significantly larger,
having a skull approximately three times longer than the type material. The
skull anatomy of this taxon shows derived characters shared with some basal
sauropodomorphs and eusauropods, which are absent in other basal
sauropodomorphs (e.g. _Thecodontosaurus_, _Plateosaurus_). These include the
presence of an extension of the infratemporal fenestra ventral to the orbit,
dorsal and anterior rami of quadratojugal subperpendicular to each other,
dorsoventral expansion of dentary at mandibular symphysis, slightly
procumbent teeth with broad serrations restricted to the apical region
(absent in some teeth). Differences among the studied specimens helps to
understand the early ontogenetic changes occurring in this basal
sauropodomorph, revealing major changes in the rostral and temporal
regions."
Sereno, P.C. (2007). The phylogenetic relationships of early dinosaurs: a
comparative report. Historical Biology 19(1): 145-155.
ABSTRACT: "Surprising new anatomical information has come to light for the
early dinosaurs _Eoraptor lunensis_ and _Herrerasaurus ischigualastensis_.
_Eoraptor_ has a mid mandibular jaw joint, and _Herrerasaurus_ has a
promaxillary fenestra at the anterior end of the antorbital fossa. Initial
cladistic interpretation placed _Herrerasaurus_ outside Dinosauria. Since
then, _Eoraptor_ and _Herrerasaurus_ have been placed at the base of
Saurischia or within Theropoda in two large-scale quantitative analyses. A
comparative approach is taken here to show, first, that character choice is
a major factor behind differing results; only half of the character data
critical for each interpretation is incorporated into the opposing analysis.
In that shared portion of data, furthermore, nearly 40 percent of character
state scores vary for identical, or comparable, ingroup taxa. Resolving
these conflictive interpretations is clearly where future progress will be
made in understanding early dinosaur phylogenesis."
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