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Liopleurodon from Mexico (free pdf) + Coelurosauravus redescribed + more



Ben Creisler
bcreisler@gmail.com


A number of recent non-dino papers that may be of interest:


Jair Israel Barrientos-Lara, Marta S. Fernández, and Jesús
Alvarado-Ortega (2015)
Kimmeridgian pliosaurids (Sauropterygia, Plesiosauria) from Tlaxiaco,
Oaxaca, southern Mexico.
[Pliosauridos kimmeridgianos (Sauropterygia, Plesiosauria) de
Tlaxiaco, Oaxaca, sur de México]
Revista Mexicana de Ciencias Geológicas 32 (2): 293-304
Free pdf:
http://satori.geociencias.unam.mx/32-2/(09)Barrientos.pdf

Fossil remains of two specimens of the family Pliosauridae are
described in the present manuscript. These fossils are from the
Kimmeridgian shallow marine strata belonging to the informally known
Sabinal formation deposited in the Tlaxiaco Basin, which are exposed
in Yosobé, near Tlaxiaco town, Oaxaca State, southern Mexico. The
first of these specimens consists of a fragment of premaxilla with
teeth, which show diagnostic characters that allow its taxonomical
identification as member of the genus Liopleurodon. The second
specimen is preserved by a significantly higher number of bone
elements; however, this is only identified as a member of the family
Pliosauridae. Despite the shortage of the pliosaurs fossil record so
far recovered in Yosobé, the specimens described here significantly
contribute to the knowledge of this extinct group. On the one hand,
these Kimmeridgian fossils are the southernmost representatives of
these reptiles discovered in North America and the first collected in
deposits of the Hispanic Corridor. On the other hand, the presence of
the genus Liopleurodon in this fossil locality confirms its
biogeographical distribution into the western domain of the Tethys
Sea, beyond Europe.

==

V. V. Bulanov & A. G. Sennikov (2015)
New data on the morphology of the Late Permian gliding reptile
Coelurosauravus elivensis Piveteau.
Paleontological Journal 49(4): 413-423
DOI: 10.1134/S0031030115040048
http://link.springer.com/article/10.1134/S0031030115040048

Based on the material from the type locality (Eliva Mountain,
Madagascar), the cranial morphology of the Late Permian gliding
reptile Coelurosauravus elivensis Piveteau, 1926 (Weigeltisauridae) is
redescribed. The diagnosis of the genus Coelurosauravus is emended
based on comparisons with East European weigeltisaurids of the genus
Rautiania. It is shown that C. elivensis and all weigeltisaurids lack
the postfrontals and supratemporals and have a small preorbital
fenestra between the maxilla and nasal, partially reduced lacrimal,
and large nasolacrimal duct piercing the prefrontal. The poor
development of ornamental outgrowths on the parietal and in the
ventral part of the squamosal as well as the small size of studied
individuals of C. elivensis are caused by their juvenile age.

===



I. G. Danilov, V. B. Sukhanov, E. M. Obraztsova & N. S. Vitek (2015)
The first reliable record of trionychid turtles in the Paleocene of Asia.
Paleontological Journal 49(4): 407-412
DOI: 10.1134/S0031030115040061
http://link.springer.com/article/10.1134/S0031030115040061
A new soft-shelled turtle species (Trionychidae), Gobiapalone
palaeocenica sp. nov. is described based on an incomplete articulated
juvenile skeleton from an unnamed Upper Paleocene locality in the
Bugin Tsav Basin of Mongolia. This is the first reliable trionychid
record in the Paleocene of Asia.

===


Daniel R. Lawver, Armand H. Rasoamiaramanana & Ingmar Werneburg (2015)
An occurrence of fossil eggs from the Mesozoic of Madagascar and a
detailed observation of eggshell microstructure.
Journal of Vertebrate Paleontology (advance online publication)
DOI:10.1080/02724634.2015.973030
http://www.tandfonline.com/doi/full/10.1080/02724634.2015.973030#abstract


Whereas fossil turtle eggs have a near global distribution and range
from Middle Jurassic to Pleistocene, they are rarely documented from
the Mesozoic of Gondwana. Here, we report three fossil turtle eggs
from the Upper Cretaceous (Campanian) of the Morondava Basin,
Madagascar. The spherical eggs range in size from 33.5 to 35.5 mm and
have an average eggshell thickness of 440 µm. They can be confidently
identified as rigid-shelled turtle eggs by the presence of tightly
packed shell units composed of radiating acicular crystals and a shell
unit height to width ratio of 2:1. Lack of associated skeletal remains
precludes taxonomic identification of the eggs. Although a large
vertebrate fauna has been reported from the Upper Cretaceous of
Madagascar, these specimens are the first eggs from the Mesozoic of
the island.

===


Robert V. Hill, Eric M. Roberts, Leif Tapanila, M.L. Bouaré, Famory
Sissoko, and Maureen A. O’Leary (2015)
Multispecies shark feeding in the trans-saharan seaway: evidence from
Late Cretaceous dyrosaurid (Crocodyliformes) fossils from northeastern
Mali.
PALAIOS 30(7): 589-596
doi: http://dx.doi.org/10.2110/palo.2014.109
http://www.bioone.org/doi/abs/10.2110/palo.2014.109


Feeding traces help to characterize trophic interactions of ancient
ecosystems. In rare cases, they may also provide information that is
not otherwise represented by body fossils in a particular
paleoenvironment. Here, we describe a diverse suite of surficial bone
modifications preserved on dyrosaurid crocodyliform bones. These new
fossils come from extensive Upper Cretaceous (Maastrichtian) bone and
coprolite-dominated phosphate conglomerates from deposits of the
Trans-Saharan Seaway in northern Mali. Five specimens have bite traces
indicative of feeding by at least two species of neoselachian sharks.
Features of some traces suggest they were not made in a fatal attack,
but after the dyrosaurids had died, and therefore represent instances
of scavenging. Other traces may be attributed to predation or early
scavenging. In addition to the shark bite traces, one specimen bears
minute, crescent-shaped traces that we tentatively attribute to
invertebrate activity. Importantly, the traces described here document
the presence of species for which body fossils have not yet been
discovered.

===


Nicolas Thibault & Dorothée Husson (2015)
Climatic fluctuations and sea surface water circulation patterns at
the end of the Cretaceous era: calcareous nannofossil evidence.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
doi:10.1016/j.palaeo.2015.07.049
http://www.sciencedirect.com/science/article/pii/S0031018215004253

Highlights

Late Maastrichtian paleobiogeography of M. murus indicates major
sea-surface currents
Global correlation of the calcareous nannofossil expression of Deccan warming
Cyclostratigraphy shows Maastrichtian C29r encompasses 15 to 19
precession cycles
Drop in nannofossil species richness during the Deccan warming
Return to high species richness in the last 100/140 kyr before K-PgB

Abstract

New paleoecological data are presented for late Maastrichtian
calcareous nannofossil assemblages of the Indian Ocean and the Boreal
epicontinental Chalk Sea. These data are compiled with recent results
in the tropical Atlantic, Pacific and Tethys oceans in order to
characterize environmental changes by the end of the Cretaceous era.
The paleobiogeographic distribution of the warm-water species Micula
murus is updated and indicates the existence of major sea-surface
currents in the late Maastrichtian Atlantic Ocean similar to the
present day. The end-Maastrichtian greenhouse warming is characterized
at tropical and sub-tropical latitudes by an increase in abundance of
Micula murus and the temporary disappearance of the high-fertility
marker Biscutum constans. In the Boreal realm, the greenhouse episode
is marked by a contemporaneous acme of Watznaueria barnesiae
coincident with very rare occurrences of M. murus and other tropical
nannofossil species which have never been reported before at boreal
latitudes. A review of cyclostratigraphic and calcareous nannofossil
data in the Atlantic, Pacific, Indian and Tethys oceans points to the
following evolution of sea surface paleotemperatures for the last ca.
350 to 380 kyr of the Cretaceous: the end-Maastrichtian greenhouse
warming lasted on average a little more than 200 kyr and was followed
by a ca. 100 to 120 kyr cooling. In the Tethys, a 30–40 kyr additional
pulse of warming is highlighted immediately below the
Cretaceous-Paleogene boundary. These findings indicate an important
instability of the climate system at the end of the Maastrichtian,
most likely caused by Deccan volcanism. The calcareous nannofossil
species richness dropped during the end-Maastrichtian greenhouse
warming, which may indicate environmental stress and/or ocean
acidification. However, nannoplankton diversity returned rapidly to
higher values after this climatic episode and remained high up to the
Cretaceous-Paleogene boundary. No significant extinction is recorded
in this biotic group prior to the boundary clay.

===
Ashu Khosla (2015)
Palaeoenvironmental, palaeoecological and palaeobiogeographical
implications of mixed fresh water and brackish marine assemblages from
the Cretaceous-Palaeogene Deccan intertrappean beds at Jhilmili,
Chhindwara District, central India.
Revista Mexicana de Ciencias Geológicas 32 (2): 344-357
Free pdf:
http://satori.geociencias.unam.mx/32-2/(12-SE2)Khosla.pdf

The Deccan infra- and intertrappeans volcano-sedimentary sequences
have been considered as terrestrial to fluvio-lacustrine deposits.
Presence of planktonic foraminifera and brackish water ostracods in
the Jhilmili basal Danian intertrappean beds, recorded earlier,
indicates complex palaeoenvironment, palaeoecology and
palaeobiogeography. The intertrappean sediments span 14 m between two
Deccan basaltic flows deposited under terrestrial, palustrine and
flood plain environments. In the middle of this section is a 60
cmthick layer (unit 3) that contains fresh water ostracods,
charophytes and Early Danian planktonic foraminifera.
Palaeoecologically, the ostracod assemblage includes active swimmers
(Cypridopsis, Cypria, Mongolianella, Paracypretta and Zonocypris) and
poor swimmers (Limnocythere, Gomphocythere, Frambocythere and
Darwinula). The bulk of the ostracod fauna points to a freshwater,
lacustrine depositional environment. Presence of planktonic
foraminifera and two brackish water ostracod species (Buntonia sp. and
Neocyprideis raoi) invigorates discussion of a marine seaway into
central India, with this fauna carried through the Narmada and Tapti
rift zones by seasonal offshore currents (short lived transgressive
phase), which created temporary estuarine conditions and deposited
marine micro-biota. Above this interval, sediments in unit 4 and 5
consist of reddish and greenish grey clayey siltstone with rare fine
sand layers deposited in palustrine and terrestrial conditions. The
ostracod fauna shows extensive endemism which come across among the
Indian Maastrichtian non-marine ostracods sustained into the Early
Danian, which further proposed geographically isolated Indian plate
and intercontinental dispersal of Maastrichtian to early Danian
freshwater ostracods that support the Out-of-India hypothesis. Age of
the Jhilmili intertrappean beds is Early Danian-Maastrichtian based on
planktonic foraminifera and few brackish water ostracods.


===


Martin Schobben, Alan Stebbins, Abbas Ghaderi, Harald Strauss, Dieter
Korn, and Christoph Korte (2015)
Flourishing ocean drives the end-Permian marine mass extinction.
Proceedings of the National Academy of Sciences (advance online publication)
doi:10.1073/pnas.1503755112
http://www.pnas.org/content/early/2015/07/28/1503755112.abstract?sid=eecfc380-f65a-4e78-bc95-344fb846243e

Significance

This study provides geochemical evidence that links some of the most
important finds associated with the end-Permian mass extinction,
including climate warming, enhanced weathering, increased primary
productivity, and widespread marine anoxia under a common denominator:
the linked biogeochemical sulfur and carbon cycles. Lethal marine
conditions are likely the result of climate feedback mechanisms acting
to increase nutrient input to the ocean, thereby stimulating global
organic carbon production. With future projected climate change in
mind, such climate feedback mechanisms could induce widespread
eutrophication and expansion of anoxic and sulfidic zones, thereby
fundamentally altering marine ecosystems.

Abstract

The end-Permian mass extinction, the most severe biotic crisis in the
Phanerozoic, was accompanied by climate change and expansion of
oceanic anoxic zones. The partitioning of sulfur among different
exogenic reservoirs by biological and physical processes was of
importance for this biodiversity crisis, but the exact role of
bioessential sulfur in the mass extinction is still unclear. Here we
show that globally increased production of organic matter affected the
seawater sulfate sulfur and oxygen isotope signature that has been
recorded in carbonate rock spanning the Permian−Triassic boundary. A
bifurcating temporal trend is observed for the strata spanning the
marine mass extinction with carbonate-associated sulfate sulfur and
oxygen isotope excursions toward decreased and increased values,
respectively. By coupling these results to a box model, we show that
increased marine productivity and successive enhanced microbial
sulfate reduction is the most likely scenario to explain these
temporal trends. The new data demonstrate that worldwide expansion of
euxinic and anoxic zones are symptoms of increased biological carbon
recycling in the marine realm initiated by global warming. The spatial
distribution of sulfidic water column conditions in shallow seafloor
environments is dictated by the severity and geographic patterns of
nutrient fluxes and serves as an adequate model to explain the scale
of the marine biodiversity crisis. Our results provide evidence that
the major biodiversity crises in Earth’s history do not necessarily
implicate an ocean stripped of (most) life but rather the demise of
certain eukaryotic organisms, leading to a decline in species
richness.

News:

http://phys.org/news/2015-08-end-permian-mass-extinction-driven-ocean.html
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