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Condorodon, first Jurassic amphilestid mammal from South America, and other new non-dino papers



From: Ben Creisler
bcreisler@gmail.com


A few non-dino papers that might interest some members:

Leandro C. Gaetano and Guillermo W. Rougier (2012)
First Amphilestid from South America: A Molariform from the Jurassic
Cañadón Asfalto Formation, Patagonia, Argentina.
Journal of Mammalian Evolution (advance online publication)
DOI: 10.1007/s10914-012-9194-1
http://www.springerlink.com/content/9246520n705v8j62/

We report here the first amphilestid triconodont from the Jurassic of
South America. The specimen, a single isolated molariform, was found
at the Queso Rallado locality from where a growing mammalian fauna is
known (including a triconodontid, two australosphenidans, and an as
yet undescribed allotherian). The specimen, interpreted as a left
lower tooth, presents five mesiodistally aligned, fairly symmetrical
cusps, and is recognized as the type of a new taxon, Condorodon
spanios. The phylogenetic analysis recovers Condorodon as a member of
the clade Amphilestheria, closely related to Tendagurodon janenschi,
an amphilestid triconodont from the Late Jurassic of Tanzania.
Condorodon spanios is only distantly related to Argentoconodon
fariasorum, the other triconodont known from Queso Rallado quarry. The
phylogenetic position of Condorodon spanios points to the origin and
diversification of amphilestherians during the Early Jurassic in a
paleogeographical setting that allowed wide dispersion of these forms
and argues, at least from the mammalian evidence, against a highly
provincialized Pangaea. Some differences are however established
between the filial western/eastern Gondwanan masses and their
respective faunas.
===

S.R. Beardmore, P.J. Orr, T. Manzocchi, H. Furrer & C. Johnson (2012)
Death, decay and disarticulation: Modelling the skeletal taphonomy of
marine reptiles demonstrated using Serpianosaurus (Reptilia;
Sauropterygia).
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
http://dx.doi.org/10.1016/j.palaeo.2012.03.018
http://www.sciencedirect.com/science/article/pii/S0031018212001587?v=s5

Taphonomic models for fossil vertebrates are designed to reconstruct
processes that affected carcasses during the transition from biosphere
to geosphere, in particular in the interval between death and burial.
To circumvent various limitations in existing methodologies, a new
taphonomic method, assessing vertebrate skeletons as nine anatomical
units (the head, neck, dorsal, tail, ribs and four limbs) scored
independently for two characters (articulation and completeness), was
developed.
The potential of the method is demonstrated using the Triassic marine
reptile Serpianosaurus from Monte San Giorgio, Switzerland. Specimens
are preserved in alternations of black shale and dolomite,
representing normal background sediment and event beds respectively,
deposited into a shallow, intra-platform basin. All specimens exhibit
disarticulation of skeletal elements though loss of completeness
varies considerably. Minor loss of fidelity occurred during the
‘floating phase’, but individuals reached the sediment-water interface
relatively soon after death, and largely intact, where they decayed
during the ‘residence phase’. Carcasses allowed to reach extensive
states of decay became prone to the effects of weak bottom currents,
resulting in removal of elements. The episodic deposition of event
beds rapidly buried individuals at various stages of decay, inhibiting
further disarticulation and loss of completeness.

==
Gregory J. Retallac (2012)
Permian and Triassic greenhouse crises.
Gondwana Research (advance online publication)
http://dx.doi.org/10.1016/j.gr.2012.03.003
http://www.sciencedirect.com/science/article/pii/S1342937X12000895?v=s5

Paleoclimatic time series from Permian and Triassic paleosols reveal
transient episodes of unusually warm and wet conditions, interrupting
long periods of cool and dry conditions usual for calcareous red
paleosols. Some of these paleoclimatic events are known from stomatal
index of fossil Lepidopteris leaves to have been episodes of elevated
global atmospheric CO2. The magnitude of 19 known Permian and Triassic
greenhouse crises varied considerably, and they offer new evidence for
the relationship between paleoclimate and atmospheric CO2 levels.
These greenhouse crises also had marked effects on global lowland
vegetation, introducing frost-sensitive tropical lycopsids to high
latitudes and drought-tolerant conifers to low latitude lowlands.
Greenhouse events punctuate phases in plant evolution
(Ottokaria-Callipteris, Plumsteadia-Rufloria, Lidgettonia-Tatarina,
Pleuromeia, and Dicroidium-Scytophyllum floras). Greenhouse events
also punctuate the evolution of reptilian dynasties (successive
pelycosaur, dinocephalian, dicynodont, rhynchosaur and dinosaur
faunas) and respiratory adaptations (such as enlarged bony secondary
palate). Greenhouse crises of the Late and Middle Permian were the
most severe known, and suggest a role for atmospheric pollution with
CH4 and CO2 in those mass extinction events, probably from thermogenic
cracking of coals by intrusive feeder dikes of flood basalts. Because
of formalities in boundary definition these mass extinctions are
neither “end-Permian” nor “end-Guadalupian”, but late Changhsingian
and mid-Capitanian, respectively.


===

Bryan G. Fry, Nicholas R. Casewell, Wolfgang Wüster, Nicolas Vidal,
Bruce Young, Timothy N.W. Jackson (2012)
The structural and functional diversification of the Toxicofera
reptile venom system.
Toxicon  (advance online publication)
http://dx.doi.org/10.1016/j.toxicon.2012.02.013
http://www.sciencedirect.com/science/article/pii/S0041010112000621?v=s5

Abstract
The evolutionary origin and diversification of the reptilian venom
systems is described. The resolution of higher-order molecular
phylogenetics has clearly established that a venom system is ancestral
to snakes. The diversification of the venom system within lizards is
discussed, as is the role of venom delivery in the behavioral ecology
of these taxa (particularly Varanus komodoensis). The more extensive
diversification of the venom system in snakes is summarised, including
its loss in some clades. Finally, we discuss the contentious issue of
a definition for “venom”, supporting an evolutionary definition that
recognises the homology of both the venom delivery systems and the
toxins themselves.