New Xinjiangchelys species and other non-dino Mesozoic papers

[Ben Creisler <bcreisler@gmail.com>]

From: Ben Creisler
bcreisler@gmail.com

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

NOTE: This paper is in open access:

Márton Rabi, Chang-Fu Zhou, Oliver Wings, Sun Ge & Walter G Joyce (2013)
A new xinjiangchelyid turtle from the Middle Jurassic of Xinjiang,
China and the evolution of the basipterygoid process in Mesozoic
turtles.
BMC Evolutionary Biology (advance online publication)
DOI: 10.1186/1471-2148-13-203
http://link.springer.com/article/10.1186/1471-2148-13-203


Background

Most turtles from the Middle and Late Jurassic of Asia are referred to
the newly defined clade Xinjiangchelyidae, a group of mostly
shell-based, generalized, small to mid-sized aquatic froms that are
widely considered to represent the stem lineage of Cryptodira.
Xinjiangchelyids provide us with great insights into the plesiomorphic
anatomy of crown-cryptodires, the most diverse group of living
turtles, and they are particularly relevant for understanding the
origin and early divergence of the primary clades of extant turtles.

Results

Exceptionally complete new xinjiangchelyid material from the ?Qigu
Formation of the Turpan Basin (Xinjiang Autonomous Province, China)
provides new insights into the anatomy of this group and is assigned
to Xinjiangchelys wusu n. sp. A phylogenetic analysis places
Xinjiangchelys wusu n. sp. in a monophyletic polytomy with other
xinjiangchelyids, including Xinjiangchelys junggarensis, X.
radiplicatoides, X. levensis and X. latiens. However, the analysis
supports the unorthodox, though tentative placement of
xinjiangchelyids and sinemydids outside of crown-group Testudines. A
particularly interesting new observation is that the skull of this
xinjiangchelyid retains such primitive features as a reduced
interpterygoid vacuity and basipterygoid processes.

Conclusions

The homology of basipterygoid processes is confidently demonstrated
based on a comprehensive review of the basicranial anatomy of Mesozoic
turtles and a new nomenclatural system is introduced for the carotid
canal system of turtles. The loss of the basipterygoid process and the
bony enclosure of the carotid circulation system occurred a number of
times independently during turtle evolution suggesting that the
reinforcement of the basicranial region was essential for developing a
rigid skull, thus paralleling the evolution of other amniote groups
with massive skulls.

==

Marcelo S. de la Fuente, Juliana Sterli & Ignacio Maniel (2013)[2014]
Meiolaniforms: An Extinct Lineage of Turtles of Gondwanan Origin.
Origin, Evolution and Biogeographic History of South American Turtles.
Springer Earth System Sciences : 133-142
DOI: 10.1007/978-3-319-00518-8_6
http://link.springer.com/chapter/10.1007/978-3-319-00518-8_6


Meiolaniformes include the bizarre group of extinct Cenozoic turtles
bearing cranial horns and frills (clade Meiolaniidae) and several
species located in its stem. Most meiolaniforms are from Gondwana
(Australia and South America), with the exception of two Eurasiatic
taxa (Kallokibotion bajazidi and Mongolochelys efremovi).
Meiolaniformes were originated in the present-day South America and
they are known from the Lower Cretaceous until the Holocene. The
oldest fossils within the clade (Chubutemys copelloi and Otwayemys
cunicularius) indicate a minimum age of origin in the Aptian–Albian
(Lower Cretaceous).

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Marcelo S. de la Fuente, Juliana Sterli & Ignacio Maniel (2013)[2014]
Early Differentiation of Mesozoic Turtles.
Origin, Evolution and Biogeographic History of South American Turtles
Springer Earth System Sciences : 143-160
DOI: 10.1007/978-3-319-00518-8_7
http://link.springer.com/chapter/10.1007/978-3-319-00518-8_7



Panpleurodiran clade Platychelyidae extends from the Oxfordian to the
Valanginian of Cuba, South America, and Europe. The oldest member of
Platychelyidae was recovered from the Oxfordian of Cuba. The Upper
Jurassic record is represented in Europe by only one
Kimmeridgian–Tithonian species and in South America by two species. A
shallow marine connection between the Western Tethys and Eastern
Pacific through central Pangaea was present since the beginning of the
Jurassic and acted as a corridor for numerous pelagic reptile groups
as the panpleurodiran turtles. Stem turtles (i.e., stem Testudines)
from the Late Triassic until the Middle Jurassic have had a Pangaean
distribution, and they are known from all continents except Australia
and Antarctica. Two species are recognized in South America: the Late
Triassic Palaeochersis talampayensis and the Middle Jurassic
Condorchelys antiqua.

==


Marcelo S. de la Fuente, Juliana Sterli & Ignacio Maniel (2013)[2014]
South Gondwana Pleurodiran Turtles.
Origin, Evolution and Biogeographic History of South American Turtles.
Springer Earth System Sciences: 53-93
DOI: 10.1007/978-3-319-00518-8_4
 http://link.springer.com/chapter/10.1007/978-3-319-00518-8_4

Extant and extinct species of chelid turtles are limited in
distribution to South America and Australasia with an extensive fossil
record in South America (Early Cretaceous–Recent) and more scarce in
Australasia (Early Cretaceous, Eocene, Oligocene, and Miocene to
Recent). Taking into account their specific richness, chelids are one
of the most diverse South American turtle clades. This fact and the
above-mentioned disjointed distribution, the early fossil record, and
the phylogenetic data suggest an early differentiation from
Pelomedusoides at least in the Early Cretaceous in South Gondwanan
landmasses.


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Open access:

Nathalie Bardet, José Francisco Baeza Carratalá, Verónica Díez Díaz,
Ángel Carbonell, Manuel García Ávila & Vicente Giner (2013)
First occurrence of Mosasauridae (Squamata) in the Maastrichtian
(latest Cretaceous) of Alicante (Valencia Community, Eastern Spain).
Estudios Geológicos 69(1): 97-104
doi:10.3989/egeol.40792.169
http://estudiosgeol.revistas.csic.es/index.php/estudiosgeol/article/view/875

Although the mosasaurid genus Prognathodon is known worldwide during
the latest Cretaceous (Campanian-Maastrichtian), we report here its
first occurrence in the Eastern area of the Iberian Peninsula. It was
previously known from coeval levels of the Basque Country. The
specimen from Castalla (Alicante) corresponds to a pterygoid tooth.
Though it cannot be precisely determined at the specific level, the
tooth belongs to a Prognathodon species with 'slender' teeth such as
P. compressidens, P. sectorius and P. mosasauroides, all known in the
Campanian-Maastrichtian of Europe, or P. kianda from the Maastrichtian
of Angola.


==

Vanessa C. Bowman, Jane E. Francis and James B. Riding (2013)
Late Cretaceous winter sea ice in Antarctica?
Geology (advance online publication)
doi: 10.1130/G34891.1
http://geology.gsapubs.org/content/early/2013/10/16/G34891.1.abstract

The Late Cretaceous is considered to have been a time of greenhouse
climates, although evidence from Maastrichtian sediments for rapid and
significant sea-level changes suggests that ice sheets were growing
and decaying on Antarctica at that time. There is no direct geological
evidence for glaciation, but we present palynomorph records from
Seymour Island, Antarctica, that may suggest Maastrichtian sea ice.
The dinoflagellate cyst Impletosphaeridium clavus is dominant. We
propose that its profusion may signify the accumulation of resting
cysts from dinoflagellate blooms related to winter sea ice decay.
Prior to the Cretaceous-Paleogene transition, I. clavus decreased
dramatically in abundance; we link this with climate warming.
Terrestrial conditions inferred from pollen and spore data are
consistent with our climate interpretations based on I. clavus
together with delta18O values from macrofossils. These data and our
interpretation support the presence of ephemeral ice sheets on
Antarctica during the latest Cretaceous, highlighting the extreme
sensitivity of this region to global climate change.