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Ichthyosaur from Lower Cretaceous UK + sexual selection + more papers



Ben Creisler
bcreisler@gmail.com

A number of recent and not so recent papers that may be of interest:

John P. Green & Dean R. Lomax (2014)
An ichthyosaur (Reptilia: Ichthyosauria) specimen from the Lower
Cretaceous (Berriasian) Spilsby Sandstone Formation of Nettleton,
Lincolnshire, UK.
Proceedings of the Geologists' Association (advance online publication)
DOI: 10.1016/j.pgeola.2014.08.007
http://www.sciencedirect.com/science/article/pii/S0016787814000650


A fragmentary ichthyosaur specimen collected in situ at Castle Top
Quarry in Nettleton, Lincolnshire, UK from exposures of the Lower
Cretaceous (Berriasian) Spilsby Sandstone Formation (Subcraspedites
?preplicomphalus Zone) is reported. In general, Early Cretaceous
ichthyosaurs from the Berriasian to Barremian are poorly understood.
Despite the fragmentary nature of the described specimen, it is the
first ichthyosaur reported from this specific zone and adds to the
literature another rare ichthyosaur from the Berriasian.

==

Kevin Padian & John R. Horner (2014)
Darwin's sexual selection: Understanding his ideas in context.
Comptes Rendus Palevol (advance online publication)
DOI: 10.1016/j.crpv.2014.09.001
http://www.sciencedirect.com/science/article/pii/S1631068314001493


Darwin's writings need to be seen in their fullness, as opposed to
quote-mining individual sentences without the context of his passages.
Sometimes Darwin wrote at length, apparently favorably, about ideas
that he subsequently undermined, replacing them with a more
integrative view that reflected his own broad compass. Darwin
understood that nature is not simple, that not all members of a group
may have evolved under the same selective regime, and that variation
of all kinds is fundamental to selection in its several forms. Sexual
selection requires sexual dimorphism; it is not centred on variation
within sexes but on selection for the ability to acquire mates.
“Mutual sexual selection” was rejected by Darwin for every species
except humans. Mating success is not a matter of mere numbers but of
the transmission of the most attractive features to the opposite sex.
The term “sexual selection” should only be used when one sex uses a
feature not present in the other sex to attract mates or repel rivals
for mates.

==

Pavel P. Skutschas (2014)
Kiyatriton leshchinskiyi Averianov et Voronkevich, 2001, a crown-group
salamander from the Lower Cretaceous of Western Siberia, Russia.
Cretaceous Research 51:  88–94
DOI: 10.1016/j.cretres.2014.05.014
http://www.sciencedirect.com/science/article/pii/S0195667114001062

Highlights

Type and newly collected material on Kiyatriton leshchinskiyi is redescribed.
Revised diagnosis for this taxon is provided.
The original assignment of Kiyatriton leshchinskiyi to the crown group
salamanders (Urodela) is confirmed.
New morphological information suggests that Kiyatriton leshchinskiyi
may be a member of the Cryptobranchoidea.

Abstract

Crown-group salamander Kiyatriton leshchinskiyi, from the Lower
Cretaceous (Aptian–Albian) Ilek Formation of the Shestakovo locality
in Western Siberia, Russia, was the first "lissamphibian" discovered
from the Mesozoic of Russia and it is the only Early Cretaceous
salamander from Asia which was found outside China. In this paper a
detailed redescription of type and newly collected material on
Kiyatriton leshchinskiyi, consisting fragmentary cranial and
postcranial bones is presented. The structure of the atlas, trunk
vertebrae and femur suggest that Kiyatriton leshchinskiyi may be a
member of the Cryptobranchoidea.
==

Sharon K. Mcmullen, Steven M. Holland, and F. Robin O'Keefe (2014)
The occurrence of vertebrate and invertebrate fossils in a sequence
stratigraphic context: the Jurassic Sundance Formation, Bighorn Basin,
Wyoming, U.S.A.
PALAIOS 29(6):277-294. 2014
doi: http://dx.doi.org/10.2110/pal.2013.132
http://www.bioone.org/doi/abs/10.2110/pal.2013.132



Previous studies of the sequence stratigraphic distribution of fossils
have focused on the record of relatively abundant marine
invertebrates. Only a handful of studies have examined how sequence
stratigraphic architecture influences the occurrence of vertebrates,
particularly large and rare tetrapods. The Jurassic Sundance Formation
of the Bighorn Basin, Wyoming, USA, contains a rich suite of
invertebrate and vertebrate fossils, including large and rare marine
reptiles, and this allows the sequence stratigraphic controls on the
distribution of these groups to be compared. The Sundance Formation
consists of four depositional sequences, with the lower two being
carbonate dominated and the upper two siliciclastic dominated. Two
incised valley fills are also present. The presence of multiple
depositional sequences and strongly erosional sequence boundaries is
the likely cause of the complicated lithostratigraphic nomenclature of
the Sundance. Invertebrates (mollusks and echinoderms) in the Sundance
conform to well-established patterns of occurrences, including strong
facies control and fossil concentrations at maximum flooding surfaces,
in the upper portion of parasequences, and within lags overlying
sequence boundaries. As expected from their rarity, marine reptiles
(ichthyosaurs, plesiosaurs, and pliosaurs) show a weaker connection to
sequence stratigraphic architecture. Nonetheless, they do display
facies control and are found primarily in offshore mudstone, rather
than shoreface and estuarine sandstone. They are also more common at
hiatal surfaces, including a zone of concretions at the maximum
flooding surface and in lag deposits overlying sequence boundaries.
These associations suggest that sequence stratigraphic architecture
may be a useful approach for discovery of marine vertebrates and that
sequence stratigraphic context should be considered when making
paleobiological interpretations of marine vertebrates as well as
invertebrates.

===

Thecodontosaurus

Pedro A. Viegas & Michael J. Benton (2014)
The Bristol Dinosaur Project - A Conservation and Preparation Overview.
Journal of Paleontological Techniques 13: 50-64
http://palaeo.gly.bris.ac.uk/Benton/reprints/2014Viegas.pdf

The Bristol Dinosaur Project involved extensive preparation and
conservation of a large collection of macro- and microvertebrate
fossils. The starting point was some four tonnes of fossiliferous
cave-fill breccia, and the laboratory procedures involved a broad
range of physical and chemical approaches to reduce this matrix and
extract, conserve, and curate the dinosaur bones and microvertebrate
remains. The initial state of the remains, and the laboratory
procedures followed provide a good case study of historical
collections found in many institutions that are in urgent need of care
and dedicated work. The program also provided examples of good and bad
practice, while training students in laboratory skills.

===

Open Access

Yuguo Yu, Jan Karbowski, Robert NS Sachdev & Jianfeng Feng (2014)
Effect of temperature and glia in brain size enlargement and origin of
allometric body-brain size scaling in vertebrates.
BMC Evolutionary Biology 14:178
DOI: 10.1186/s12862-014-0178-z
http://link.springer.com/article/10.1186/s12862-014-0178-z


Abstract

Background
Brain signaling requires energy. The cost of maintaining and
supporting energetically demanding neurons is the key constraint on
brain size. The dramatic increase in brain size among mammals and
birds cannot be understood without solving this conundrum: larger
brains, with more neurons, consume more energy.

Results
Here we examined the intrinsic relationships between metabolism,
body-brain size ratios and neuronal densities of both endothermic and
ectothermic animals. We formulated a general model to elucidate the
key factors that correlate with brain enlargement, and the origin of
allometric body-brain size scaling. This framework identified
temperature as a critical factor in brain enlargement via
temperature-regulated changes in metabolism. Our framework predicts
that ectothermic animals living in tropical climates should have brain
sizes that are several times larger than those of ectothermic animals
living in cold climates. This prediction was confirmed by data from
experiments in fish brains. Our framework also suggests that a rapid
increase in the number of less energy-demanding glial cells may be
another important factor contributing to the ten-fold increase in the
brain sizes of endotherms compared with ectotherms.

Conclusions
This study thus provides a quantitative theory that predicts the brain
sizes of all the major types of animals and quantifies the
contributions of temperature-dependent metabolism, body size and
neuronal density.