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Dinosaur sites in Spain + archosaur digit hyperextension + more new papers

Ben Creisler

A number of recent papers:

Laura Domingo, Fernando Barroso-Barcenilla & Oscar Cambra-Moo (2015)
Seasonality and Paleoecology of the Late Cretaceous Multi-Taxa
Vertebrate Assemblage of “Lo Hueco” (Central Eastern Spain).
PLoS ONE 10(3): e0119968
doi: 10.1371/journal.pone.0119968

Isotopic studies of multi-taxa terrestrial vertebrate assemblages
allow determination of paleoclimatic and paleoecological aspects on
account of the different information supplied by each taxon. The late
Campanian-early Maastrichtian “Lo Hueco” Fossil-Lagerstätte (central
eastern Spain), located at a subtropical paleolatitude of ~31°N,
constitutes an ideal setting to carry out this task due to its
abundant and diverse vertebrate assemblage. Local δ18OPO4 values
estimated from δ18OPO4 values of theropods, sauropods, crocodyliforms,
and turtles are close to δ18OH2O values observed at modern subtropical
latitudes. Theropod δ18OH2O values are lower than those shown by
crocodyliforms and turtles, indicating that terrestrial endothermic
taxa record δ18OH2O values throughout the year, whereas semiaquatic
ectothermic taxa δ18OH2O values represent local meteoric waters over a
shorter time period when conditions are favorable for bioapatite
synthesis (warm season). Temperatures calculated by combining
theropod, crocodyliform, and turtle δ18OH2O values and gar δ18OPO4
have enabled us to estimate seasonal variability as the difference
between mean annual temperature (MAT, yielded by theropods) and
temperature of the warmest months (TWMs, provided by crocodyliforms
and turtles). ΔTWMs-MAT value does not point to a significantly
different seasonal thermal variability when compared to modern coastal
subtropical meteorological stations and Late Cretaceous rudists from
eastern Tethys. Bioapatite and bulk organic matter δ13C values point
to a C3 environment in the “Lo Hueco” area. The estimated
fractionation between sauropod enamel and diet is ~15‰. While waiting
for paleoecological information yielded by the ongoing morphological
study of the “Lo Hueco” crocodyliforms, δ13C and δ18OCO3 results point
to incorporation of food items with brackish influence, but
preferential ingestion of freshwater. “Lo Hueco” turtles showed the
lowest δ13C and δ18OCO3 values of the vertebrate assemblage, likely
indicating a diet based on a mixture of aquatic and terrestrial C3
vegetation and/or invertebrates and ingestion of freshwater.


Xabier Pereda-Suberbiola, Adán Pérez-García, José Carmelo Corral,
Xabier Murelaga, Gorka Martin, Joseba Larrañaga, Nathalie Bardet, Ana
Berreteaga & Julio Company (2015)
First dinosaur and turtle remains from the latest Cretaceous shallow
marine deposits of Albaina (Laño quarry, Iberian Peninsula).
Comptes Rendus Palevol (advance online publication)

We report here on new vertebrate fossils from the latest Cretaceous of
Albaina (Laño quarry, Condado de Treviño), northern Iberian Peninsula.
They consist of an incomplete hadrosauroid femur and two partial
plates of turtles, one belonging to a Pleurodira (Bothremydidae), the
other one to an indeterminate taxon, probably corresponding to a
Pan-Cryptodira. They are the first dinosaur and turtle remains found
in the Late Maastrichtian sublittoral beds of Albaina. Other
components of this shallow marine vertebrate fauna are selachians
(sharks, rays), actinopterygians (pycnodonts, teleosts) and marine
reptiles (mosasaurids, plesiosaurs). The Albaina femur is one of the
few hadrosauroid remains from the Late Maastrichtian of Europe found
in marine environments, and the first one described from this kind of
deposits in the Iberian Peninsula. The histological structure of the
bone indicates that it belongs to an immature individual of small


J. D. Hutson and K. N. Hutson (2015)
Inferring the prevalence and function of finger hyperextension in
Archosauria from finger-joint range of motion in the American
Journal of Zoology (advance online publication)
DOI: 10.1111/jzo.12232

Quadrupedal dinosaurs and other archosaurs are hypothesized to
alleviate differences in height between shorter forelimbs and longer
hindlimbs via digitigrady (standing on fingers). An alternative
hypothesis suggests that they trend toward metacarpogrady (vertical,
columnar palms with finger reduction and loss) to abandon
semi-pronated (mechanically misaligned) wrist and finger joints. Range
of motion (ROM) studies provide support for the latter hypothesis by
showing that some dinosaurian fingers were held hyperextended away
from the palm at metacarpophalangeal (MCP) joints. However, recent
studies dispute traditional MCP hyperextension characters. Moreover,
in vivo ROM is assumed to be less than fossil ROM because of the
constraining influence of lost soft tissues, further implying that
reports of MCP hyperextension in fossil archosaurs may be overstated.
Because crocodilian fingers reportedly hyperextend during the high
walk, a ROM study of their MCP joints could clarify these issues. Here
a repeated-measures analysis was used to gather ex vivo finger joint
ROM data in degrees from fully fleshed to skeletonized conditions in
digit III of the American alligator Alligator mississippiensis.
Results verify that MCP joints hyperextend, and show that soft tissues
significantly affect ex vivo ROM. Skeletal ROMs were greater than
fleshed ROMs in the three interphalangeal joints; however the MCP
joint had the opposite result after losing curved articular
cartilages. These results suggest that studies of flattened metacarpo-
and metatarsophalangeal joints in fossil archosaurs may underestimate
in vivo hyperextension. A comparison of characters in Alligator
mississippiensis and the rauisuchid Postosuchus suggests that
Postosuchus metacarpal adaptations represent a transitional stage
toward vertical quadrupedal support with hyperextended MCP joints.
This information provides support for the preexisting hypothesis that
quadrupedal archosaurs tend to transform their wrist + palm into a
rigid stilt-like extension of the forearm, which implies that
locomotor abandonment of semi-pronated wrist/finger joints and
alleviation of limb disparity evolve synchronously.


Non-dino papers that may be of interest:

Michel Laurin & Vivian de Buffrénil (2015)
Microstructural features of the femur in early ophiacodontids: A
reappraisal of ancestral habitat use and lifestyle of amniotes.
Comptes Rendus Palevol (advance online publication)

Ophiacodontids have long been considered the basalmost synapsids, and
to have retained a fairly aquatic, piscivorous lifestyle typical of
stem-amniotes. A restudy of their bone histology and microanatomy
shows that Clepsydrops collettii, a Late Carboniferous ophiacodontid,
has a thin, compact cortex and lacks a medullary spongiosa, two
features that suggest a truly terrestrial lifestyle. The Early Permian
Ophiacodon uniformis has a thicker cortex with a few resorption
cavities and bone trabeculae surrounding the free medullary cavity. An
inference model yields a terrestrial lifestyle for both taxa, though
O. uniformis may have been slightly more aquatic (possibly amphibious)
than C. collettii. However, an optimization of inferred lifestyle of
other early stegocephalians (based on bone microanatomy) suggests that
the first amniotes were terrestrial. The potentially amphibious
lifestyle of O. uniformis, though not supported by our inference
model, would thus be secondary. Histological features of femoral
cortices in these two taxa closely resemble those previously described
in extant species of large varanids and teids. This similarity, along
with other comparative elements, is discussed in reference to the
possible growth patterns and life history traits of Clepsydrops and O.


Federico J. Degrange, Claudia P. Tambussi, Matías L. Taglioretti,
Alejandro Dondas & Fernando Scaglia (2015)
A new Mesembriornithinae (Aves, Phorusrhacidae) provides new insights
into the phylogeny and sensory capabilities of terror birds.
Journal of Vertebrate Paleontology (advance online publication)

Terror birds constitute the most outstanding group of the South
American Cenozoic avifauna. Considered as apex predators, their
hunting skills have recently been examined, but their diversity is
still unresolved. Here we report a new terror bird from the late
Pliocene of Argentina, represented by the most complete articulated
skeleton of one yet found. Our phylogenetic analysis places this taxon
among derived phorusrhacids (Mesembriornithinae). One of the most
striking cranial features of the new species is the suppression of
intracranial kinesis due to the presence of an independent ossified
bone that increases the structural link between the lacrimal and jugal
bars, and the absence of both palatal hinges. The new species
possesses ossified tracheal rings and a tracheobronchial syrinx, as
well as sclerotic ossicles to adjust the shape of the cornea during
its diurnal vision, and reveals a mean hearing sensitivity (~2300 Hz)
below the average for living species. The discovery of this new
species provides new insights for studying the anatomy and phylogeny
of phorusrhacids and a better understanding of this group's