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Tribosphenic mammals from Lower Cretaceous of Texas and Oklahoma + more non-dino papers



Ben Creisler
bcreisler@gmail.com

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



A.O. Averianov (2015)
Taxonomic revision of tribosphenic mammals from the Lower Cretaceous
Antlers Formation of Texas and Oklahoma, USA.
Proceedings of the Zoological Institute RAS 319(2): 141–181

Free pdf:
http://www.zin.ru/journals/trudyzin/doc/vol_319_2/TZ_315_2_Averianov.pdf

There are five taxa of tribosphenic mammals in the Early Cretaceous
Antlers Formation of Texas and Oklahoma, USA: a basal stem therian
(Kermackia texana), stem therians near the eutherian-metatherian
dichotomy (Holoclemensia texana and Pappotherium pattersoni), and stem
marsupials (Atokatheridium boreni and Oklatheridium szalayi). K.
texana has a primitive therian postcanine formula with three molars,
replacement of p5, M3 with low protocone and no conules, lower molars
with a large trigonid angle, oblique protocristid, paraconid smaller
than metaconid (except m3), strong distal metacristid, narrow talonid,
small talonid basin, and small entoconid (absent on m3). H. texana
also has replacement in the fifth premolar locus and three molars. It
is more derived in having a larger protoconal region with higher
protocone and conules present, lack of distal metacristid, smaller
trigonid angle, transverse protocristid, and wide talonid with larger
talonid basin. It is similar to Eutheria by having M1 with reduced
ectoflexus, semimolariform p5, and low trigonid angle with transverse
protocristid. Holoclemensia cannot be referred to Eutheria because of
the lack of the second rank postvallum/prevallid shear and unwinged
conules. P. pattersoni (=Slaughteria eruptens) has replacement in the
fifth premolar position, premolariform p5, and three molars
(symplesiomorphies for Theria). It is more derived than Holoclemensia
in having a wider and shorter talonid. Pappotherium is similar to
Eutheria in having a low trigonid angle, transverse protocristid, and
the cristid obliqua labial to the protocristid notch. It cannot be
attributed to the Eutheria because of the narrow protoconal region,
low protocone, small conules lacking internal cristae, postprotocrista
not extending labially past the metacone base, and a small talonid
basin. Atokatheridium boreni and Oklatheridium szalayi (=O. minax,
syn. nov.) have four molars and emphasis on the postvallum/prevallid
shear (large metacone on M2, strong postmetacrista, paraconid higher
than metaconid). These taxa cannot be attributed to the Deltatheroida
because of large protoconal region with winged conules. Oklatheridium
is further different from the Deltatheroida in having a wider talonid
and better developed entoconid.

==

Charlotte A. Brassey & James D. Gardiner (2015)
An advanced shape-fitting algorithm applied to quadrupedal mammals:
improving volumetric mass estimates.
Royal Society Open Science 2015 2 150302
DOI: 10.1098/rsos.150302
http://rsos.royalsocietypublishing.org/content/2/8/150302

Free pdf:
http://rsos.royalsocietypublishing.org/content/2/8/150302.full-text.pdf

Body mass is a fundamental physical property of an individual and has
enormous bearing upon ecology and physiology. Generating reliable
estimates for body mass is therefore a necessary step in many
palaeontological studies. Whilst early reconstructions of mass in
extinct species relied upon isolated skeletal elements, volumetric
techniques are increasingly applied to fossils when skeletal
completeness allows. We apply a new ‘alpha shapes’ (α-shapes)
algorithm to volumetric mass estimation in quadrupedal mammals.
α-shapes are defined by: (i) the underlying skeletal structure to
which they are fitted; and (ii) the value α, determining the
refinement of fit. For a given skeleton, a range of α-shapes may be
fitted around the individual, spanning from very coarse to very fine.
We fit α-shapes to three-dimensional models of extant mammals and
calculate volumes, which are regressed against mass to generate
predictive equations. Our optimal model is characterized by a high
correlation coefficient and mean square error (r 2=0.975,
m.s.e.=0.025). When applied to the woolly mammoth (Mammuthus
primigenius) and giant ground sloth (Megatherium americanum), we
reconstruct masses of 3635 and 3706 kg, respectively. We consider
α-shapes an improvement upon previous techniques as resulting volumes
are less sensitive to uncertainties in skeletal reconstructions, and
do not require manual separation of body segments from skeletons.

====


Marcelo S. de la Fuente, Ignacio J. Maniel, Juan M. Jannello, Leonardo
S. Filippi & Ignacio Cerda (2015)
Long-necked chelid turtles from the Campanian of northwestern
Patagonia with comments on K/P survivorship of the genus
Yaminuechelys.
Comptes Rendus Palevol (advance online publication)
doi:10.1016/j.crpv.2015.04.008
http://www.sciencedirect.com/science/article/pii/S1631068315001098


The long-necked chelid turtle Yaminuechelys aff. maior is described on
the basis of post-cranial material of two specimens from the
Lower–Middle Campanian Anacleto Formation, nortwestern Patagonia
(Argentina). These post-cranial remains are described macroscopically
(external morphology) and microscopically (histological sections of
the shell). Although minor carapace and plastral differences are
reported (e.g., extension of the axillary buttresses on visceral
surfaces of the first costal bone, curled bridge peripheral bones,
absence of a sub-rectangular fenestra retained in adults) the
specimens exibit the shell morphology and surface ornamentation of
specimens referred to Y. maior (Staesche, 1929) from Paleocene levels
of the Salamanca Formation (Central Patagonia). This assignment is
supported by a phylogenetic analysis, in which the new material is the
most closely related to Y. maior. As Yaminuechelys is hypothesized to
be the sister taxon of Hydromedusa, the capability of Hydromedusa
tectifera to adapt to changing environments and the survivorship of
Yaminuechelys genus in K/P boundary is discussed.

======

Free pdf--

Aude Cincotta, Johan Yans, Pascal Godefroit, Géraldine Garcia, Jean
Dejax, Mouloud Benammi, Sauveur Amico & Xavier Valentin (2015)
Integrated Paleoenvironmental Reconstruction and Taphonomy of a Unique
Upper Cretaceous Vertebrate-Bearing Locality (Velaux, Southeastern
France).
PLoS ONE 10(8): e0134231
doi:10.1371/journal.pone.0134231
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0134231

The Velaux-La Bastide Neuve fossil-bearing site (Bouches-du-Rhône,
France) has yielded a diverse vertebrate assemblage dominated by
dinosaurs, including the titanosaur Atsinganosaurus velauciensis. We
here provide a complete inventory of vertebrate fossils collected
during two large-scale field campaigns. Numerous crocodilian teeth
occur together with complete skulls. Pterosaur, hybodont shark and
fish elements are also represented but uncommon. Magnetostratigraphic
analyses associated with biostratigraphic data from dinosaur eggshell
and charophytes suggest a Late Campanian age for the locality.
Lithologic and taphonomic studies, associated with microfacies and
palynofacies analyses, indicate a fluvial setting of moderate energy
with broad floodplain. Palynomorphs are quite rare; only three taxa of
pollen grains occur: a bisaccate taxon, a second form probably
belonging to the Normapolles complex, and another tricolporate taxon.
Despite the good state of preservation, these taxa are generally
difficult to identify, since they are scarce and have a very minute
size. Most of the vertebrate remains are well preserved and suggest
transport of the carcasses over short distances before accumulation in
channel and overbank facies, together with reworked Aptian grains of
glauconite, followed by a rapid burial. The bones accumulated in three
thin layers that differ by their depositional modes and their
taphonomic histories. Numerous calcareous and iron oxides-rich
paleosols developed on the floodplain, suggesting an alternating dry
and humid climate in the region during the Late Campanian.


=====

Margret Steinthorsdottir, Anne-Marie P. Tosolini, and Jennifer C.
McElwain (2015)
Evidence for insect and annelid activity across the Triassic-Jurassic
transition of east Greenland.
PALAIOS 30(8):  597-607
doi:10.2110/palo.2014.093
http://palaios.geoscienceworld.org/content/30/8/597.abstract

During a study of macroflora from the Astartekløft locality in Jameson
Land, East Greenland, endophytic insect ovipositions (egg traces)
belonging to ichnogenus Paleoovoidus were recorded for the first time
in ginkgoalean (Ginkgoites, Sphenobaiera, and Baiera) fossil leaves
across the Triassic–Jurassic (Tr–J) transition (ca. 200 Ma). The
ovipositions may have been produced by insects in the order Odonata
(dragonflies and damselflies) and are relatively more abundant before
than after the Tr–J transition, possibly reflecting changes in
plant-insect association. Fossil clitellate annelid (leech) cocoons
were also discovered in a macerated sample from a single bed within
the Tr–J transition. The cocoons belong to two species: Dictyothylakos
pesslerae and Pilothylakos pilosus, extending the range of the latter
genus from the Early Cretaceous to the Early Jurassic. This new
evidence suggests that the ecosystem and food webs were profoundly
affected by the environmental degradation surrounding the end-Triassic
event (ETE), which was marked by faunal mass extinctions and floral
turnover. Invertebrate ichno- and body fossils may add significantly
to paleoenvironmental information provided by plant fossil
assemblages, and therefore a protocol for recording evidence of
invertebrate activity in paleobotanical research is suggested,
including analyzing a standardized number of specimens for fossil
traces and bulk maceration for discovery of invertebrate body fossils.
More well-designed studies on Mesozoic plant-invertebrate associations
are needed and will provide deeper knowledge about the structure and
evolution of complex ecosystems.


=====

Bernard Gomez, Véronique Daviero-Gomez, Clément Coiffard, Carles
Martín-Closas, and David L. Dilcher (2015)
Montsechia, an ancient aquatic angiosperm.
Proceedings of the National Academy of Sciences (advance online publication)
doi: 10.1073/pnas.150924111
http://www.pnas.org/content/early/2015/08/12/1509241112.abstract

Significance

The importance of very early aquatic flowering plants is not well
understood currently and is poorly documented. Here we present details
of the morphology and reproductive biology of Montsechia, an extremely
early fossil angiosperm that, because it is so ancient and is totally
aquatic, raises questions centered on the very early evolutionary
history of flowering plants. This paper challenges the paradigm of how
we view the early evolution of basal angiosperms and particularly the
role of aquatic habitats in the very early evolution and
diversification of flowering plants.

Abstract

The early diversification of angiosperms in diverse ecological niches
is poorly understood. Some have proposed an origin in a darkened
forest habitat and others an open aquatic or near aquatic habitat. The
research presented here centers on Montsechia vidalii, first recovered
from lithographic limestone deposits in the Pyrenees of Spain more
than 100 y ago. This fossil material has been poorly understood and
misinterpreted in the past. Now, based upon the study of more than
1,000 carefully prepared specimens, a detailed analysis of Montsechia
is presented. The morphology and anatomy of the plant, including
aspects of its reproduction, suggest that Montsechia is sister to
Ceratophyllum (whenever cladistic analyses are made with or without a
backbone). Montsechia was an aquatic angiosperm living and reproducing
below the surface of the water, similar to Ceratophyllum. Montsechia
is Barremian in age, raising questions about the very early divergence
of the Ceratophyllum clade compared with its position as sister to
eudicots in many cladistic analyses. Lower Cretaceous aquatic
angiosperms, such as Archaefructus and Montsechia, open the
possibility that aquatic plants were locally common at a very early
stage of angiosperm evolution and that aquatic habitats may have
played a major role in the diversification of some early angiosperm
lineages.