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Siberian Cretaceous mammals + Triassic fish + early amniote lungs + more papers



Ben Creisler
bcreisler@gmail.com


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

Alexander Averianov & Alexey Lopatin (2015)
Mammal remains from the Lower Cretaceous Bol'shoi Terekhtyul' locality
in West Siberia, Russia.
Cretaceous Research 54: 145–153
doi:10.1016/j.cretres.2014.12.007
http://www.sciencedirect.com/science/article/pii/S0195667114002316


Four mammalian taxa have been identified based on upper molariform
tooth and edentulous dentary fragments from the Bol'shoi Terekhtyul'
locality of the Lower Cretaceous Ilek Formation (Krasnoyarsk
Territory, Russia): Docodonta indet., Amphidontidae indet.,
Zhangheotheria indet. sp. A and sp. B. The docodontan from Bol'shoi
Terekhtyul is smaller than Sibirotherium rossicum from the Ilek
Formation at Shestakovo 1 locality (Kemerovo Province, Russia) and may
belong to a distinct taxon. It is one of the younger docodontans in
the fossil record. The mammal assemblage from the Bol'shoi Terekhtyul'
locality is drastically different from the mammal assemblage of nearby
localities of the Ilek Formation along Bol'shoi Kemchug River, which
consists of Gobiconodontidae and Amphilestidae. The reason for this
faunal discrepancy is unclear for the moment.

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In open access:


Guang-Hui Xu, Li-Jun Zhao & Chen-Chen Shen (2015)
A Middle Triassic thoracopterid from China highlights the evolutionary
origin of overwater gliding in early ray-finned fishes.
Biology Letters (advance online publication)
DOI: 10.1098/rsbl.2014.0960
http://rsbl.royalsocietypublishing.org/content/11/1/20140960
http://rsbl.royalsocietypublishing.org/content/roybiolett/11/1/20140960.full.pdf


Gliding adaptations in thoracopterid flying fishes represent a
remarkable case of convergent evolution of overwater gliding strategy
with modern exocoetid flying fishes, but the evolutionary origin of
this strategy was poorly known in the thoracopterids because of lack
of transitional forms. Until recently, all thoracopterids, from the
Late Triassic of Austria and Italy and the Middle Triassic of South
China, were highly specialized ‘four-winged’ gliders in having
wing-like paired fins and an asymmetrical caudal fin with the lower
caudal lobe notably larger than the upper lobe. Here, we show that the
new genus Wushaichthys and the previously alleged ‘peltopleurid’
Peripeltopleurus, from the Middle Triassic (Ladinian, 235–242 Ma) of
South China and near the Ladinian/Anisian boundary of southern
Switzerland and northern Italy, respectively, represent the most
primitive and oldest known thoracopterids. Wushaichthys, the most
basal thoracopterid, shows certain derived features of this group in
the skull. Peripeltopleurus shows a condition intermediate between
Wushaichthys and Thoracopterus in having a slightly asymmetrical
caudal fin but still lacking wing-like paired fins. Phylogenetic
studies suggest that the evolution of overwater gliding of
thoracopterids was gradual in nature; a four-stage adaption following
the ‘cranial specialization–asymmetrical caudal fin–enlarged paired
fins–scale reduction’ sequence has been recognized in thoracopterid
evolution. Moreover, Wushaichthys and Peripeltopleurus bear hooklets
on the anal fin of supposed males, resembling those of modern
viviparious teleosts. Early thoracopterids probably had evolved a
live-bearing reproductive strategy.


===

In open access:

Markus Lambertz, Kristina Grommes, Tiana Kohlsdorf & Steven F. Perry (2015)
Lungs of the first amniotes: why simple if they can be complex?
Biology Letters (advance online publication)
DOI: 10.1098/rsbl.2014.0848
http://rsbl.royalsocietypublishing.org/content/11/1/20140848
http://rsbl.royalsocietypublishing.org/content/roybiolett/11/1/20140848.full.pdf


We show—in contrast to the traditional textbook contention—that the
first amniote lungs were complex, multichambered organs and that the
single-chambered lungs of lizards and snakes represent a secondarily
simplified rather than the plesiomorphic condition. We combine
comparative anatomical and embryological data and show that shared
structural principles of multichamberedness are recognizable in
amniotes including all lepidosaurian taxa. Sequential intrapulmonary
branching observed during early organogenesis becomes obscured during
subsequent growth, resulting in a secondarily simplified, functionally
single-chambered lung in lepidosaurian adults. Simplification of
pulmonary structure maximized the size of the smallest air spaces and
eliminated biophysically compelling surface tension problems that were
associated with miniaturization evident among stem lepidosaurmorphs.
The remaining amniotes, however, retained the multichambered lungs,
which allowed both large surface area and high pulmonary compliance,
thus initially providing a strong selective advantage for efficient
respiration in terrestrial environments. Branched, multichambered
lungs instead of simple, sac-like organs were part and parcel of the
respiratory apparatus of the first amniotes and pivotal for their
success on dry land, with the sky literally as the limit.

====

Shawn A. Hamm (2015)
Paraptychodus washitaensis n. gen. et n. sp., of Ptychodontid shark
from the Albian of Texas, USA.
Cretaceous Research 54: 60-67
doi:10.1016/j.cretres.2014.10.015
http://www.sciencedirect.com/science/article/pii/S0195667114001906

A new genus and species of Ptychodontiform elasmobranch, Paraptychodus
washitaensis n. gen. et n. sp. is described on the basis of 13 teeth
from the Middle Albian Duck Creek Formation of the Washita Group in
north central Texas, USA. This material is significant as it
demonstrates an intermediate tooth form between the Lonchidiidae and
Ptychodus with regard to occlusal ornamentation of the crown and tooth
root morphology; the new taxon represents the earliest member of the
family Ptychodontidae in North America. Analysis of dental characters
and stratigraphic occurrences within the family suggests that P.
washitaensis is a basal taxon and is the most recent ancestor of
Ptychodus. Morphological trends of derived species of Ptychodus
demonstrate continuous specialization in tooth crown morphologies. The
diagnosis of P. washitaensis from the upper Albian of Texas adjusts
the stratigraphic distribution of the genus Ptychodus to lower
Cenomanian through lower Campanian.

===

Chris Manias (2014)
Building Baluchitherium and Indricotherium: Imperial and International
Networks in Early-Twentieth Century Paleontology.
Journal of the History of Biology (advance online publication)
DOI: 10.1007/s10739-014-9395-y
http://link.springer.com/article/10.1007/s10739-014-9395-y


Over the first decades of the twentieth century, the fragmentary
remains of a huge prehistoric ungulate were unearthed in scientific
expeditions in India, Turkestan and Mongolia. Following channels of
formal and informal empire, these were transported to collections in
Britain, Russia and the United States. While striking and of immense
size, the bones proved extremely difficult to interpret. Alternately
naming the creature Paraceratherium, Baluchitherium and
Indricotherium, paleontologists Clive Forster-Cooper, Alexei Borissiak
and Henry Fairfield Osborn struggled over the reconstruction of this
gigantic fossil mammal. However, despite these problems, shared work
on the creature served as a focus for collaboration and exchange
rather than rivalry between these three scientific communities. Not
only did the initial interpretation and analysis depend on
pre-existing connections between British and American paleontological
institutions, but the need for comparative material, recognition and
contacts brought British and American scholars into communication and
exchange with their counterparts in the Soviet Union. This article
examines these processes. It first uses these excavations as a
comparative case-study of different manifestations of colonial science
in this period, examining how scholars in the Britain, the Russian
Empire and the United States used formal and informal colonial links
to Asia to pursue new research. It then moves to examine how the
common problem of reconstructing this giant animal drew metropolitan
scientific communities together, at least for a time. The construction
of the Baluchitherium and Indricotherium illustrates the drives to
expand research both imperially and internationally in the
early-twentieth century, but also the continual problems in resources,
institutionalization, transport and communication that could run up
against scientific work.