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

Mojoceratops and venomous Sinornithosaurus



Nicholas R. Longrich. 2010 Mojoceratops perifania, A New Chasmosaurine
Ceratopsid from the Late Campanian of Western Canada. Journal of
Paleontology 84(4):681-694.


Abstract

A new genus of long-horned chasmosaurine ceratopsid is described from
the Dinosaur Park Formation (upper Campanian) of Western Canada.
Mojoceratops perifania is represented by a skull and a parietal from
the Dinosaur Park Formation of Alberta and an isolated parietal from
the Dinosaur Park Formation of Saskatchewan. Several other specimens
are provisionally referred to this taxon. While Mojoceratops shares
many plesiomorphies with Chasmosaurus, the animal lacks the
forward-curving parietal epoccipitals and reduced postorbital horns
that diagnose the genus Chasmosaurus, and it differs from all other
chasmosaurines in exhibiting a prominent sulcus on the anterior margin
of the parietal, swellings on the anterodorsal surface of the parietal
rami, and a small accessory process on the first parietal epoccipital.
Other unusual features include anteriorly extended parietal fenestrae,
a broad, heart-shaped frill, and transverse expansion of the
postfrontal fontanelle. The type material of “Eoceratops canadensis”
and “Chasmosaurus kaiseni” are nondiagnostic and these names are
therefore considered nomina dubia, but their morphology is consistent
with Mojoceratops and they probably belong to this genus. The frill of
Mojoceratops shows marked variation. Some of this variation probably
results from intraspecific variation or ontogenetic changes, but
because the Dinosaur Park Formation encompasses more than a million
years of time, evolution may explain some of these differences.
Phylogenetic analysis shows that Mojoceratops forms a clade with
Agujaceratops mariscalensis; Chasmosaurus is the most basal member of
Chasmosaurinae.


(I thought we heard last of this venomous Sinornithosaurus , but I
guess not....)

Federico A. Gianechini, Federico L. Agnolín and Martín D. Ezcurra 2010
A reassessment of the purported venom delivery system of the bird-like
raptor Sinornithosaurus
Paläontologische Zeitschrift, online first

Abstract
Gong and colleagues recently described unusual traits in the
dromaeosaurid Sinornithosaurus that were interpreted as the first
evidence of a venomous dinosaur. This interpretation was based on
extremely elongated maxillary teeth, morphologically similar to those
present in poisonous snakes; labial grooves on maxillary and dentary
tooth crowns; and an additional ornamented depression in the lateral
surface of the maxillary bone (subfenestral fossa). A reappraisal of
each of these morphological traits is provided here in light of
comparisons with other theropod dinosaurs and previous discussions for
inferring poisonous capabilities in fossil taxa. We fail to recognize
unambiguous evidence supporting the presence of a venom delivery
system in Sinornithosaurus. For example, the extremely elongated teeth
seem to be a taphonomic artifact due to the displacement of teeth
outside the alveoli; the labial grooves are present in a wide variety
of theropods; and no strong evidence for the lodging of a venomous
gland is recognized. In contrast, the cranial and dental anatomy of
Sinornithosaurus is congruent with that of other dromaeosaurids. The
weak support for a venomous Sinornithosaurus renders unlikely the
ecological model proposed by Gong and colleagues for this predatory
dinosaur.

and a response

Enpu Gong,Larry D. Martin, David A. Burnham  and Amanda R. Falk 2010
Evidence for a venomous Sinornithosaurus
Paläontologische Zeitschrift, online first

Also a new species of atoposaurid crocodylian

Komsorn Lauprasert, Chalida Laojumpon, Wanitchaphat Saenphala, Gilles
Cuny,Kumthorn Thirakhupt and Varavudh Suteethorn 2010
Atoposaurid crocodyliforms from the Khorat Group of Thailand: first
record of Theriosuchus  from Southeast Asia
Paläontologische Zeitschrift, online first

Abstract
We describe a partial crocodilian skull from the Mesozoic non-marine
sediments of the Khorat Plateau Sao Khua Formation
(Berriasian-Barremian) in northeastern Thailand and assign it to
Theriosuchus grandinaris sp. nov. An isolated dentary from the Phu
Kradung Formation (latest Jurassic–Early Cretaceous) is also
tentatively assigned to the genus Theriosuchus, and an isolated tooth
from the Khok Kruat Formation (Aptian-Albian) may belong to this
genus. The Thai fossils represent the first unambiguous evidence of
presence of Theriosuchus outside Europe. Its occurrence in Thailand
increases the known diversity of neosuchian crocodyliforms from
Southeast Asia and suggests that Atoposauridae had a wide geographical
distribution from the Late Jurassic to the Early Cretaceous.

btw if someone has access to those last three papers I would gladly
recieve a copy.


Cheers

-Ville