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Non-dino Mesozoic papers: Metoposaurus vertebrae, Saurichthys skeleton, Adocus in Central Asia



From: Ben Creisler
bcreisler@gmail.com


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

D. Konietzko-Meier, A. Bodzioch and P. M. Sander (2013)
Histological characteristics of the vertebral intercentra of
Metoposaurus diagnosticus (Temnospondyli) from the Upper Triassic of
Krasiejów (Upper Silesia, Poland).
Earth and Environmental Science Transactions of the Royal Society of
Edinburgh (advance online publication)
DOI: http://dx.doi.org/10.1017/S1755691013000273
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9015862&fulltextType=RA&fileId=S1755691013000273

Osteohistological characteristics of the large temnospondyl amphibian
Metoposaurus diagnosticus from the Upper Triassic of Poland (Krasiejów
locality) were determined using vertebral intercentra thin-sections
from different regions and growth stages. The intercentra showed a
trabecular structure in both the endochondral and periosteal domains.
Endochondral ossification developed first, and the primary bone occurs
near the periphery with a higher degree of remodelling in the centre.
Periosteal bone deposition begins later; first on the ventral side,
continuing laterally and finally onto the dorsal side. Periosteal
growth rate was initially very rapid, and then subsequently decreased
in rate. In all sections, numerous remains of calcified cartilage are
visible, which may indicate a juvenile, paedomorphic or plesiomorphic
character. The four histologic ontogenetic stages (HOS) of sampled
vertebrae were determined based on growth marks. Most of the sampled
bones belong to juvenile individuals (HOS 1 to 3), apart from one
atlas and the largest anterior dorsal intercentrum, which represent
the oldest described stage (HOS 4). Sharpey's fibres are preserved in
ventro-lateral cortical regions, around parapophyses and on the
posterior side of the neural arch.


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Erin E. Maxwell, Heinz Furrer & Marcelo R. Sánchez-Villagra (2013)
Exceptional fossil preservation demonstrates a new mode of axial
skeleton elongation in early ray-finned fishes.
Nature Communications 4: 2570
doi:10.1038/ncomms3570
http://www.nature.com/ncomms/2013/131007/ncomms3570/full/ncomms3570.html


Elongate body plans have evolved independently multiple times in
vertebrates, and involve either an increase in the number or in the
length of the vertebrae. Here, we describe a new mechanism of body
elongation in saurichthyids, an extinct group of elongate early
ray-finned fishes. The rare preservation of soft tissue in a specimen
of Saurichthys curionii from the Middle Triassic (Ladinian) of
Switzerland provides significant new information on the relationship
between the musculature and the skeleton. This new fossil material
shows that elongation in these fishes results from doubling the number
of neural arch-like elements per myomeric segment. This unique way of
generating an elongate body plan demonstrates the evolutionary
lability of the vertebral column in non-teleostean fishes. The shape
and arrangement of preserved myosepta suggest that S. curionii was not
a highly flexible fish, in spite of the increase in the number of
neural arch-like elements.

===


E.V. Syromyatnikova and I.G. Danilov (2013)
New material and phylogenetic position of Adocus bostobensis, a poorly
known adocid turtle from the Late Cretaceous of Kazakhstan.
Proceedings of the Zoological Institute 317(2): 195-201
free pdf:
http://www.zin.ru/journals/trudyzin/doc/vol_317_2/TZ_317_2_Syromyatnikova.pdf

This paper presents a description of a new material of Adocus
bostobensis, a poorly known adocid turtle from the Late Cretaceous of
Kazakhstan. The new material of A. bostobensis comes from the Bostobe
Formation (Santonian –  early Campanian) of Shakh-Shakh II locality
(northeastern Aral Sea area, Kazakhstan) and includes about 30 shell
fragments and several elements of non-shell postcrania, potentially,
from a single individual. This material allows us to reveal some
previously unknown characters of Adocus bostobensis, improve its
diagnosis and include this species in a phylogenetic analysis of
Adocusia (Adocidae + Nanhsiungchelyidae) for the first time. The
phylogenetic analysis places A. bostobensis in a clade with A. aksary
and A. amtgai (both from the Late Cretaceous of Asia).  Finally, our
study demonstrates presence of at least two different lineages of
Adocus (A. bostobensis and A. foveatus) in the Santonian of Western
Asia.