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Anhangueria (Pterosauria) osteohistological deposition (free pdf) + more non-dino papers



Ben Creisler
bcreisler@gmail.com

Some recent non-dino papers:

Free pdf:

Lúcia Helena de Souza Eleutério, Renan Alfredo Machado Bantim,
Flaviana Jorge de Lima, Rafael César Lima Pedroso de Andrade, Antônio
Álamo Feitosa Saraiva, Alexander Wilhelm Armin Kellner & Juliana Manso
Sayão (2015)
Biomechanical and physiological influences on the osteohistological
deposition of Anhangueria (Pterosauria, Pterodactyloidea).
Revista Brasileira de Paleontologia 18(3): 403-412
doi: 10.4072/rbp.2015.3.06
http://www.sbpbrasil.org/assets/uploads/files/06_Eleut%C3%A9rio_et_al_pg403a412_web.pdf

The study of bone microstructure preserved in fossils provides
substantial information about physiology, growth gradients and
strategies, and some ecological considerations. Paleohistology is a
useful tool for understanding the biological mechanisms of extinct
animals. Presented here is the microstructure characterization of two
Anhangueria pterosaurs. Thin sections of the first wing phalanx and
metacarpal IV of MN 7060-V have been confectioned, as have sections of
the radius, ulna and first wing phalanx of MPSC R2090. The
histological analysis of bones of MN 7060-V revealed fibrolamellar
tissue, few osteocytes and vascular canals. Bones of MPSC R2090 showed
a mixed plexiform-fibrolamellar tissue and histovariability, showing
that bones from the same individual grew in different patterns. The
vascularization was high in the phalanx, intermediate in the ulna and
absent in the radius. The absence of canals in the radius may be
related to biomechanical issues, due to torsion resistance during
flight. The histology and the absence of fused bones suggests that the
specimens are not adults. Two distinct moments of growth were
established. MN 7060-V is a subadult, with presence of bone porosity
and MPSC R2090 is a young animal as determined by the high number of
canals and plexiform-fibrolamellar tissues, which indicates fast
growth. In this work, we concluded that in the Anhangueria clade, the
growth of bones is not compatible with the ontogenetic stage. Young
animals may present large proportions, whereas there were older
individuals of smaller sizes in the same clade.


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Free pdf:

Rafael G. Souza, Douglas Riff & Alexander W. A. Kellner (2015)
Taxonomic revision of Thoracosaurus bahiensis Marsh, 1869, a supposed
Gavialoidea (Reptilia, Crocodylia) from Cretaceous deposits of the
Recôncavo Basin, Brazil.
Revista Brasileira de Paleontologia  8(3): 565-568
doi: 10.4072/rbp.2015.3.17
http://www.sbpbrasil.org/assets/uploads/files/17_Souza_et_al_pg565a568_web.pdf

In the Recôncavo Basin, Bahia State, Samuel Allport and latter Charles
F. Hartt collected several fossils, being some of them attributed to
reptile teeth. Based on the morphotypes of these teeth Othniel C.
Marsh nominated two species, the first with “delicately wrinkled
surface” as Crocodylus hartti (currently Sarcosuchus hartti), and the
second based on teeth with “strong continuous striae, and coarse
riblets” as Thoracosaurus bahiensis, this latter will be the focus of
this work. Marsh did not designate any holotype and, thus, the five
teeth collected and described by Allport became the type series and
subsequently the syntypes of the species. However, these are currently
lost. Comparing the diagnoses of T. bahiensis with the type species of
the genus and with others crocodyliformes as well as spinosaurids, we
noted that the supposed autapomorphy of the species is highly
variable. Therefore, we propose that T. bahiensis should be considered
as nomen dubium.

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Agustín G. Martinelli, Heitor Francischini, Paula C. Dentzien-Dias,
Marina B. Soares & Cesar L. Schultz (2016)
The oldest archosauromorph from South America: postcranial remains
from the Guadalupian (mid-Permian) Rio do Rasto Formation (Paraná
Basin), southern Brazil.
Historical Biology (advance online publication)
DOI:10.1080/08912963.2015.1125897
http://www.tandfonline.com/doi/full/10.1080/08912963.2015.1125897


In this contribution, we report a distal portion of a left humerus
that likely belongs to an indeterminate basal archosauromorph from the
Guadalupian (mid-Permian) Rio do Rastro Formation (Paraná Basin) of
southern Brazil. A precise taxonomy of the fragmented and isolated
humerus UFRGS-PV-0546-P is not warranted at generic nor familiar level
but, likely, this specimen belongs to an Archosauromorpha due to the
lack of both the entepicondylar and the ectepicondylar foramina. The
narrow distal end of the humerus, the rounded radial and ulnar
condyles, and the moderately developed supinator process with a
shallow ectepicondylar groove (not notched) are features reminiscent
of tanystropheids rather than that of other archosauromorphs. This
material likely represents the first and oldest Permian
archosauromorph from South America and indicates the presence of this
lineage before the P/T boundary.


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Aaron R. H. LeBlanc, Robert R. Reisz, Kirstin S. Brink & Fernando Abdala (2016)
Mineralized periodontia in extinct relatives of mammals shed light on
the evolutionary history of mineral homeostasis in periodontal tissue
maintenance.
Journal of Clinical Periodontology (advance online publication)
DOI: 10.1111/jcpe.12508
http://onlinelibrary.wiley.com/doi/10.1111/jcpe.12508/full

Aim

Dental ankylosis is a rare pathological condition in mammals, however,
it is prevalent in their extinct relatives, the stem mammals. This
study seeks to compare the mineralized state of the periodontal
attachment apparatus between stem and crown mammals and discuss its
implications for the evolution of non-mineralized periodontal
attachment in crown mammals, including humans.

Materials and methods

Thin sections of a fossil mammal and three stem mammals were compared
in order to reconstruct periodontal tissue development across
distantly related lineages.

Results

Comparisons revealed that the extinct relatives of mammals possessed
the same periodontal tissues as those in mammals, albeit in different
arrangements. The ankylotic condition in stem mammals was achieved
through extensive alveolar bone deposition, which eventually contacted
the root cementum, thus forming a calcified periodontal ligament.

Conclusions

Dental ankylosis was part of the normal development of the stem mammal
periodontium for millions of years prior to the evolution of a
permanent gomphosis in mammals. Mammals may have evolved a permanent
gomphosis by delaying the processes that produced dental ankylosis in
stem mammals. Pathological ankylosis may represent a reversion to the
ancestral condition, which now only forms via advanced ageing and
pathology.


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Eric Font, Thierry Adatte, Alcides Nobrega Sial, Luiz Drude de
Lacerda, Gerta Keller, and Jahnavi Punekar (2016)
Mercury anomaly, Deccan volcanism, and the end-Cretaceous mass extinction.
Geology (advance online publication)
doi:10.1130/G37451.1
http://geology.gsapubs.org/content/early/2016/01/06/G37451.1.abstract

The contribution of the Deccan Traps (west-central India) volcanism in
the Cretaceous-Paleogene (KPg) crisis is still a matter of debate.
Recent U-Pb dating of zircons interbedded within the Deccan lava flows
indicate that the main eruptive phase (>1.1 × 106 km3 of basalts)
initiated ∼250 k.y. before and ended ∼500 k.y. after the KPg boundary.
However, the global geochemical effects of Deccan volcanism in the
marine sedimentary record are still poorly resolved. Here we
investigate the mercury (Hg) content of the Bidart (France) section,
where an interval of low magnetic susceptibility (MS) located just
below the KPg boundary was hypothesized to result from
paleoenvironmental perturbations linked to the paroxysmal Deccan phase
2. Results show Hg concentrations >2 orders of magnitude higher from
∼80 cm below to ∼50 cm above the KPg boundary (maximum 46.6 ppb) and
coincident with the low MS interval. Increase in Hg contents shows no
correlation with clay or total organic carbon contents, suggesting
that the Hg anomalies resulted from higher input of atmospheric Hg
species into the marine realm, rather than organic matter scavenging
and/or increased runoff. The Hg anomalies correlate with high shell
fragmentation and dissolution effects in planktic foraminifera,
suggesting correlative changes in marine biodiversity. This discovery
represents an unprecedented piece of evidence of the nature and
importance of the Deccan-related environmental changes at the onset of
the KPg mass extinction.

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J.M. Espinosa-Cardeña, J.O. Campos-Enríquez & M. Unsworth (2016)
Heat flow pattern at the Chicxulub impact crater, northern Yucatan, Mexico.
Journal of Volcanology and Geothermal Research (advance online publication)
doi:10.1016/j.jvolgeores.2015.12.013
http://www.sciencedirect.com/science/article/pii/S0377027315004199

Highlights

A high heat flow is inferred at the Chicxulub impact structure
(northern Yucatan) based on a spectral analysis of aeromagnetic data.

Abstract

Along an east-west profile crossing the Chicxulub impact structure in
northern Yucatán, México, Curie depths were obtained from
statistical-spectral analysis of a grid of aeromagnetic data (256 km
wide and 600 km long). These depths were corrected for flight height
and depth to the sea floor to determine the geothermal gradient,
assuming a temperature of 580 °C for the Curie temperature. Heat flow
was then calculated from the geothermal gradients using a value of
2.67 W/m-K for the mean crustal thermal conductivity. The results show
a conspicuous heat flow high above on the impact basin. In this
location, the heat flow is 80 mW/m2 approximately. Available offshore
estimates of the depth to the crustal magnetic source bases, on the
northern Yucatán platform, and onshore heat flow determination on 8
shallow bore holes, and in a 1,511 m deep one, support the existence
of this major high heat flow anomaly associated with the impact
crater. This high heat flow might be related to the impact through: a)
an uplift of the crystalline basement rocks in the center of the
crater; b) impact induced radioactive element concentration into the
crust below the impact structure. Higher thermal conductivities at the
lower crust might also play a key role. Available seismological and
thermal properties data are compatible with these mechanisms.

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