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

New Cretaceous snakes from Madagascar + non-dino papers

Ben Creisler

Some new non-dino papers that may be of interest:

Adinophis  and other new snakes

Adam C. Pritchard, Jacob A. McCartney, David W. Krause & Nathan J. Kley (2014)
New snakes from the Upper Cretaceous (Maastrichtian) Maevarano
Formation, Mahajanga Basin, Madagascar.
Journal of Vertebrate Paleontology 34(5):  1080-1093

We describe three new fossil snakes on the basis of recently
discovered vertebrae collected from the Upper Cretaceous
(Maastrichtian) Maevarano Formation of Madagascar. One represents a
new genus and species of madtsoiid, Adinophis fisaka, the third member
of this family recognized from the Maevarano Formation. It exhibits
dorsoventrally compressed centra and dorsally placed synapophyses. The
second taxon is a new species of the nigerophiid genus Indophis, I.
fanambinana, representing the second nigerophiid taxon known from the
Maevarano Formation. It shares numerous features with the Indian
nigerophiid I. sahnii, including small synapophyses positioned
ventrolaterally on distinct synapophyseal processes and a unique
cotylar shape in posterior trunk vertebrae. The discovery of I.
fanambinana demonstrates a strong biogeographic link with
penecontemporaneous snake faunas from India. A third new taxon is
represented by a partial centrum that cannot be assessed thoroughly
due to its incompleteness; this specimen is conservatively assigned to
Serpentes incertae sedis, gen. et sp. indeterminate. It is distinct
from other snakes known from the Late Cretaceous of Madagascar in
possessing a strongly depressed condyle and relatively large lateral
foramina. These new discoveries, together with previous descriptions
of snakes from the Maevarano Formation, make the Maevarano snake fauna
one of the most taxonomically diverse snake assemblages known from the
Mesozoic and the most diverse in terms of body size range.


Hallie P. Street & Michael W. Caldwell (2014)
Reassessment of Turonian mosasaur material from the 'Middle Chalk'
(England, U.K.), and the status of Mosasaurus gracilis Owen, 1849.
Journal of Vertebrate Paleontology 34(5):   1072-1079

The first described genus of mosasaur, Mosasaurus hoffmannii, has been
coarsely diagnosed and defined since its creation, with numerous
specimens and new species being assigned to the genus with little or
no reference to, and thus few real similarities with, the generic type
specimen. One of the earliest examples of a weakly defined and
diagnosed species assigned to the genus is Mosasaurus gracilis.
Location and examination of the various assigned specimens and the
holotype indicate that M. gracilis shares more characters, such as a
short rostrum on the dentary anterior to the first teeth, with
russellosaurine mosasaurs. In addition, M. gracilis is known from
Turonian deposits, whereas other species belonging to Mosasaurus are
upper Campanian–Maastrichtian in age. Based on the evidence of shared
characters and contemporaneity, we suggest that M. gracilis be removed
from Mosasaurus because it shares more affinities with members of the
Russellosaurina. This represents the first step in the very necessary
process of untangling the alpha taxonomy, and subsequently the
complete systematics, of the genus Mosasaurus hoffmannii.

Robert R. Reisz, Mark J. Macdougall & Sean P. Modesto (2014)
A new species of the parareptile genus Delorhynchus, based on
articulated skeletal remains from Richards Spur, Lower Permian of
Journal of Vertebrate Paleontology 34(5):  1033-1043

Description of a new species of the parareptile genus Delorhynchus is
based on a well-preserved partial subadult skeleton, an isolated adult
skull, and disarticulated elements recently collected from the Lower
Permian Richards Spur locality of Oklahoma, U.S.A. Delorhynchus
cifellii, sp. nov., is distinguished from Delorhynchus priscus by the
lack of an accessory articulating anterodorsal flange of the maxilla.
The hypodigm of Delorhynchus cifellii reveals that Delorhynchus is
distinguished from other parareptiles by cranial dermal sculpture
consisting of a system of low, smooth tuberosities and a pattern of
diffuse shallow, circular dimples. In a phylogenetic analysis of
parareptiles, Delorhynchus cifellii is positioned as the sister
species of Lanthanosuchoidea. Recognition of Delorhynchus cifellii,
sp. nov., and its phylogenetic position among parareptiles highlights
the significance of the Richards Spur locality in our understanding of
the early evolutionary history of reptiles.

Eduardo G. Ottone, Mariana Monti, Claudia A. Marsicano, Marcelo S. de
la Fuente, Maximiliano Naipauer, Richard Armstrong & Adriana C.
Mancuso (2014)
Journal of South American Earth Sciences (advance online publication)
DOI: 10.1016/j.jsames.2014.08.008

An absolute age is presented for the continental Triassic Puesto Viejo
Group, Argentina.
The included tetrapods are now 10 Ma younger than by correlations with
South Africa.
The validity of the South African biostratigraphic scheme for Gondwana
is questioned.

The Puesto Viejo Group crops out in the San Rafael Block, southwest
Mendoza, at approximately 35° S and 68°20’ W. It consists of the basal
mainly grayish Quebrada de los Fósiles Formation (QF) overlying by the
reddish Río Seco de la Quebrada Formation (RSQ). The basal unit
includes both plant remains (pleuromeians and sphenopsids) and
vertebrates (scattered fish scales, dicynodont synapsids and an
archosaur). In contrast, the RSQ beds have yielded only vertebrates,
although a more diverse fauna. It includes cynodonts as Cynognathus,
Pascualognathus and Diademodon, and also dicynodonts (Vinceria and
Kannemeyeria). Due to the tetrapod content the bearing levels were
correlated to the Cynognathus AZ of South Africa and thus referred to
the Anisian. A SHRIMP 238U/206Pb age of 235.8 ± 2.0 Ma was obtained
from a rhyolitic ignimbrite interdigitated between the QF and RSQ
formations at the Quebrada de los Fósiles section. This new
radio-isotopic age for the Puesto Viejo Group suggests that the
tetrapod fauna in the RSQ beds was developed, instead, during the Late
Triassic (early Carnian) thus ca 10 Ma later than the age attributed
based only on biostratigraphic correlations. Two scenarios might
explain our results. First, the Cynognathus AZ of South Africa is
wrongly assigned to the lower Middle Triassic (Anisan) and should be
considered younger in age, Late Triassic (Carnian). Second, the
relative age of the Cynognathus AZ of South Africa is correct but the
inferred range of Cynognathus and Diademodon is incorrect as they were
present during the Late Triassic (Carnian) at least in South America.
In any case, this new date pose serious doubts about the validity of
biostratigraphic correlations based solely on tetrapod taxa, a common
practice for Triassic continental successions across Gondwana.


Patrick Zell, , Seija Beckmann & Wolfgang Stinnesbeck (2014)
Age and depositional conditions of the marine vertebrate concentration
Lagerstätte at Gomez Farías, southern Coahuila, Mexico.
Journal of South American Earth Sciences (advance online publication)
DOI: 10.1016/j.jsames.2014.08.009

We provide data about age and depositional conditions of the marine
vertebrate concentration Lagerstätte at Gomez Farías.
We identified ammonites, aptychi, bivalves and radiolarians.
A combination of several processes led to the concentration of fossils
and high phosphorus contents.

A 1.5 m thick coquinite discovered in the Upper Jurassic La Casita
Formation of the Sierra El Jabala near Gomez Farías, Coahuila,
northeastern Mexico qualifies as a concentration Lagerstätte owing to
its richness in marine vertebrates. Ichthyosaurs, pliosaurs and
crocodilians were described to some detail, but other taxa remained
unstudied and the precise biostratigraphical age, as well as
paleoecological conditions that led to the formation of the fossil
deposit, are not known in detail. Here we describe ammonites, aptychi,
bivalves and radiolarians, which allow for a stratigraphic assignation
of the deposit to the uppermost Kimmeridgian Beckeri Zone. The unit
under consideration accumulated in a hemipelagic mud bottom
environment during a period of time characterized by low oxygen
conditions, while a short term benthic colonization phase near the top
of the coquinite corresponds to increased oxygen availability. A
combination of upwelling, bottom currents, winnowing, offshore winds,
storm events, circulatory nutrient traps, low oxygenated bottom
waters, and a transgressional regime with reduced net sedimentation
were crucial factors for the subsequent concentration of fossils, as
well as for marine phosphate generation and phosphorus migration.