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Psittacosaur growth study questioned + new Microphon finds from Russia + more papers



Ben Creisler
bcreisler@gmail.com

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

Psittacosaurus growth study questioned

Nathan P. Myhrvold (2014)
Problems in Erickson et al. 2009 [A life table for Psittacosaurus lujiatunensis]
Anatomical Record (advance online publication)
DOI: 10.1002/ar.23101
free pdf:
http://onlinelibrary.wiley.com/doi/10.1002/ar.23101/pdf

===

V. V. Bulanov (2014)
New finds of Microphon exiguus (Seymouriamorpha, Kotlassiidae) in the
Severodvinian beds of the Sukhona River Basin, Russia.
Paleontological Journal 48(6): 633-644
DOI: 10.1134/S0031030114060045
http://link.springer.com/article/10.1134/S0031030114060045



New data on the morphology and ontogeny of the Permian kotlassiid
Microphon exiguus Ivachnenko, 1983 (Tetrapoda, Seymouriamorpha), based
on the collection from the Ust’e Strelny locality (Russia, Vologda
Region; Severodvinian Regional Stage), are reported. At the definitive
stage, M. exiguus retains the larval skull habitus (short preorbital
region, a few marginal teeth, widely open posttemporal fenestra) and
seismosensory grooves. These features, along with the reduced
nasolacrimal duct, are indicative of an important role of
pedomorphosis in the evolution of Severodvinian kotlassiids and, in
particular, the genus Microphon, which should be regarded as a
neotenic, permanently aquatic Permian amphibian.


====

Permian tetrapod tracks from Spain

Sebastian Voigt & Hartmut Haubold (2015)
Permian tetrapod footprints from the Spanish Pyrenees.
Palaeogeography, Palaeoclimatology, Palaeoecology 417: 112–120
doi:10.1016/j.palaeo.2014.10.038
http://www.sciencedirect.com/science/article/pii/S0031018214005549


Highlights
First description of a diverse Permian tetrapod ichnofauna from Spain
Tracks of temnospondyls, captorhinomorphs, and early diapsids
Predominance of footprints of various non-diapsid eureptiles
Inferred late Early Permian (Artinskian) vertebrate ichnoassemblage


Abstract
Paleozoic tetrapod footprints are a common and well-known phenomenon
in almost all large European countries except for Spain. Here we
report on hitherto unpublished vertebrate tracks from Permian red-beds
of the south-central Pyrenees that with regard to their relative
abundance, diversity and quality of preservation are suitable to fill
this gap of knowledge. The described tracks come from two localities
in muddy to fine-grained, sandy, alluvial plain deposits in the lower
third of the Peranera Formation of the Erill-Castell Basin near Les
Iglésies, northern Catalonia. The tracks can be assigned to five
ichnogenera, i.e., Batrachichnus Woodworth, 1900, Limnopus Marsh,
1894, Varanopus Moodie, 1929, Hyloidichnus Gilmore, 1927, and Dromopus
Marsh, 1894, that we interpret as footprints of temnospondyls,
captorhinomorphs, and araeoscelids or similarly sized sauropsids with
a lacertoid foot pattern. This ichnofossil assemblage is most similar
to ichnofaunas from the Hermit Formation of the Grand Canyon, Arizona,
the upper Abo and Robledo Mountains formations of New Mexico, and the
main trace fossil site of the Tiddas Basin, Morocco, suggesting a late
Early Permian (Artinskian) age for this stratigraphic level of the
Peranera Formation. Considering the relative abundance and diversity
of captorhinomorph footprints, the new Spanish tracefossil localities
may cover the onset of the Early Permian radiation of non-diapsid
eureptiles. The thick Late Paleozoic red-bed successions of the
south-central Pyrenees have the potential to also bear footprints of
otherwise unknown early therapsids, so systematic fossil prospecting
of this area is strongly recommended.


===

Did Ural mountains rise preadapt archosaurs to low oxygen?

In open access:

Sven Kurbel (2014)
Animal evolution and atmospheric pO2: is there a link between gradual
animal adaptation to terrain elevation due to Ural orogeny and
survival of subsequent hypoxic periods?
Theoretical Biology and Medical Modelling (advance online publication)
DOI: 10.1186/1742-4682-11-47
http://link.springer.com/article/10.1186/1742-4682-11-47


Abstract
Considering evolution of terrestrial animals as something happening
only on flat continental plains seems wrong. Many mountains have
arisen and disappeared over the geologic time scale, so in all periods
some areas of high altitude existed, with reduced oxygen pressure
(pO2) and increased aridity. During orogeny, animal species of the
raising terrain can slowly adapt to reduced oxygen levels.

This review proposes that animal evolution was often driven by
atmospheric oxygen availability. Transitions of insect ancestors and
amphibians out of water are here interpreted as events forced by the
lack of oxygen in shallow and warm water during Devonian. Hyperoxia
during early Carboniferous allowed giant insects to be predators of
lowlands, forcing small amphibians to move to higher terrains,
unsuitable to large insects due to reduced pO2. In arid mountainous
habitats, ascended animals evolved in early reptiles with more
efficient lungs and improved circulation. Animals with alveolar lungs
became the mammalian ancestors, while those with respiratory duct
lungs developed in archosaurs. In this interpretation, limb precursors
of wings and pneumatised bones might have been adaptations for moving
on steep slopes.

Ural mountains have risen to an estimated height of 3000 m between 318
and 251 Mya. The earliest archosaurs have been found on the European
Ural side, estimated 275 Myr old. It is proposed that Ural orogeny
slowly elevated several highland habitats within the modern Ural
region to heights above 2500 m. Since this process took near 60 Myr,
animals in these habitats fully to adapted to hypoxia.

The protracted P-Tr hypoxic extinction event killed many aquatic and
terrestrial animals. Devastated lowland areas were repopulated by
mammaliaformes that came down from mountainous areas. Archosaurs were
better adapted to very low pO2, so they were forced to descend to the
sea level later when the lack of oxygen became severe. During the
Triassic period, when the relative content of O2 reduced to near 12%,
archosaurs prevailed as only animals that could cope with profound
hypoxia at the sea level. Their diverse descendants has become
dominant terrestrial animals, until the K-Pg extinction due to meteor
impact.

===
Triassic cynodont coprolites with parasite eggs

In open access:


Jean-Pierre Hugot, Scott L Gardner, Victor Borba, Priscilla Araujo,
Daniela Leles, Átila Augusto Stock Da-Rosa, Juliana Dutra, Luiz
Fernando Ferreira, Adauto Araújo (2014)
Discovery of a 240 million year old nematode parasite egg in a
cynodont coprolite sheds light on the early origin of pinworms in
vertebrates.
Parasites & Vectors (advance online publication)
DOI: 10.1186/s13071-014-0486-6
http://link.springer.com/article/10.1186/s13071-014-0486-6



Abstract

Background

We report the discovery of a nematode parasite egg (Nemata: Oxyurida)
from a coprolite closely associated with the remains of several
species of Cynodontia, dated to 240 million years old. This finding is
particularly significant because this is the oldest record of an
oxyurid nematode yet discovered, and because the cynodonts are
considered a stem-group of the mammals.
Methods

We extracted material from a fully mineralized coprolite by both
scraping the surface, and removing fragments from its interior with
clean dental instruments used a single time. A single drop of glycerol
from a new vial was added as a clearing reagent. Each slide was sealed
with wax and examined with an optical microscope at 100× to 400×
magnification.

Results

>From one coprolite, 550 slides were examined; from 275 of these
slides, sediment was examined that was scraped from the surface of the
coprolite, and from the other 275 slides, material was examined that
was extracted from the interior of the coprolite. All microscopic
structures encountered were photographed, measured, and identified
when possible.

Conclusions

>From the coprolite examined, we discovered an egg representing a new
species of pinworm that, based on the egg structure, clearly places it
in the family Heteroxynematidae. Nematodes of the order Oxyurida have
very constrained life-histories, occurring only in animals that are
not strictly carnivorous and also ingest large amounts of plant
material. This fact enabled us to determine which species of cynodont,
from several collected at the site in Brazil, are most likely the
depositors of the coprolite, and therefore were the putative host of
the parasite.

===

Turtle bone histology

T. M. Scheyer, A. Pérez-García & X. Murelaga (2014)
Shell bone histology of solemydid turtles (stem Testudines):
palaeoecological implications.
Organisms Diversity & Evolution (advance online publication)
DOI: 10.1007/s13127-014-0188-0
http://link.springer.com/article/10.1007/s13127-014-0188-0

Lately, solemydid turtles have been repeatedly recovered as stem
Testudines, indicating that they belong to neither one of the two
major branches of crown turtles, the Pancryptodira and Panpleurodira.
Despite their wide temporal (Late Jurassic to Late Cretaceous) and
spatial (North America and Europe) distributions, solemydid turtles
are not particularly well known, as exemplified by the fact that only
a single skull has been described for the whole group so far.
Furthermore, the palaeoecology of solemydid turtles is still contested
with hypotheses ranging from semi-aquatic to terrestrial lifestyles.
However, the habitat preference of stem Testudines, such as
solemydids, is important to understand the evolution and early
radiation of the turtle crown, which is primitively aquatic. Here we
describe the shell bone microanatomy and histological microstructures
of solemydid turtles using a broad sample of taxa of different ages
and localities, as well as review previous histological accounts, to
elucidate the palaeoecology of the group independent of the geological
setting and gross anatomy of the fossil finds. Our results indicate
that Solemydidae share unique histological features pertaining to
their strongly ornamented shell bones, which a) in cases allow
taxonomic identification of even small shell fragments and b)
unambiguously corroborate a terrestrial lifestyle of its members. The
latter further supports a terrestrial lifestyle preference of most
representatives of the turtle stem.
==

Antarctica Cretaceous wildfires

Joseline Manfroi, Tânia Lindner Dutra, Silvia Gnaedinger, Dieter Uhl &
André Jasper (2014)
The first report of a Campanian palaeo-wildfire in the West Antarctic Peninsula.
Palaeogeography, Palaeoclimatology, Palaeoecology (advance online publication)
doi:10.1016/j.palaeo.2014.11.012
http://www.sciencedirect.com/science/article/pii/S0031018214005707


Highlights
First evidence for Campanian palaeo-wildfire in West Antarctica is presented;
Macroscopic charcoal remains were preserved by volcanic ashes;
Taxonomic affinity to conifers is established for charred woods.



Abstract
The analysis of palaeofloras and the related palaeoecological
conditions is of great importance for the understanding of past
environmental and palaeoclimatic events in Antarctica. At the end of
the Cretaceous, subtropical forests developed there because of wet and
temperate climate conditions. On the Antarctic Peninsula, which is
geologically characterized by a forearc context, volcanic activity
caused by tectonics favours the ignition of vegetation fires. In the
present study, the occurrence of palaeo-wildfires during the Upper
Cretaceous is demonstrated for the Rip Point outcrop on Nelson Island,
South Shetland Islands. During Brazilian expeditions to the area,
macroscopic charcoal was collected and subsequently analysed under a
stereomicroscope and scanning electron microscope (SEM). The charred
wood remains were identified as belonging to conifers, which were
important components of the Antarctic palaeoflora during the
Cretaceous. A review of the data published thus far regarding
palaeo-wildfires in the Southern Hemisphere confirms that the charcoal
remains analysed here are the first to verify the occurrence of
palaeo-wildfires in the upper Campanian levels of the West Antarctic
Peninsula.