New species of Meiolaniform turtle from Patagonia
0 comentarios Publicado por Leonardo Filippi en 14:46
Juliana Sterli, Marcelo S. De la Fuente e Ignacio A.
Cerda
Una nueva
especie de meiolaniforme, Trapalcochelys sulcata gen. nov. sp. nov., de
la Formación Allen (Campaniano tardío–Maastrichtiano temprano), Patagonia,
Argentina, es presentada en este trabajo. Los restos postcraneanos pertenecientes
a esta nueva especie son descriptos macroscópicamente (e.g., morfología
externa) y microscópicamente (e.g., cortes histológicos del caparazón). Trapalcochelys
sulcata gen. nov. sp. nov. comparte con otros meiolaniformes la presencia
de surcos entre los escudos marginales marcadamente curvados anteriormente y la
ornamentación de las placas dérmicas del caparazón constituida por pequeños
forámenes. Esta nueva especie difiere de la otra especie de meiolaniforme del
Cretácico Superior de Patagonia —Patagoniaemys gasparinae— en el tamaño
general y en la forma de la neural 1. La histología ósea está caracterizada por
una estructura diploe, donde una capa externa e interna de tejido compacto
circundan una región de hueso esponjoso. El hueso compacto está compuesto
mayormente por paquetes entrelazados de fibras estructurales. La abundancia de
fibras estructurales en la corteza interna y la presencia de grandes canales
vasculares tubulares son los caracteres histológicos mas distintivos de T.
sulcata. Además, una revisión exhaustiva de los restos de Meiolaniformes
del Cretácico Superior de Sudamérica es presentada. El registro sudamericano
conocido de Meiolaniformes del Cretácico Superior está restringido a Argentina
y en esta revisión hasta seis localidades han sido reconocidas. Se corrobora
que los Meiolaniformes son un componente de la asociación sudamericana Alleniana
de tetrápodos de edad campaniana tardía–maastrichtiana temprana.
Sterli, J., De
la Fuente, M. S. y Cerda, I. A. 2013. New species of Meiolaniform turtle and a
revision of the Late Cretaceous Meiolaniformes of South America. Ameghiniana 50
(2): 240-256.
The dentition of Manidens condorensis (Ornithischia; Heterodontosauridae) from the Jurassic Cañadón Asfalto Formation of Patagonia
0 comentarios Publicado por Leonardo Filippi en 14:26
Marcos G. Becerraa, Diego Pol, Claudia
A. Marsicano and Oliver W.M. Rauhut
The
recently described Manidens condorensis is one of the most completely known
taxa of the family Heterodontosauridae from the southern landmasses. However,
some dental aspects are not well known due to preservational problems in the
type material. This contribution reports new isolated teeth found in the
Canñadón Asfalto Formation (Early-Middle Jurassic). These teeth are referred
to Manidens condorensis based on the presence of autapomorphic characters of
the unusual dentition of this taxon, such as the highly asymmetric tooth crowns
and small crenulations on each denticles. The isolated crowns are well
preserved and reveal the presence of undescribed and new autapomorphical
features, including apical and basal wear facets on the occlusal surface of
isolated crowns and a wear surface also in the caniniform tooth. We carried out
statistical analyses (including morphogeometrical and discriminant analyses),
using the holotype crowns as a morphological starting point, for characterising
shape variation of the crowns along the toothrow and for identifying the
position of isolated crowns. These analyses allow defining morphological
regions within the postcaniniform toothrow and produce a metrically based
discriminant function to predict the hypothetical position of future
discoveries, providing a methodological framework that could be applied to
other extinct heterodont dinosaurs.
Marcos G. Becerra , Diego Pol ,
Claudia A. Marsicano & Oliver W.M. Rauhut (2013). The dentition of Manidens condorensis (Ornithischia;
Heterodontosauridae) from the Jurassic Cañadón Asfalto Formation of Patagonia: morphology,
heterodonty and the use of statistical methods for identifying isolated teeth,
Historical Biology: An International Journal of Paleobiology,
DOI:10.1080/08912963.2013.794227
The titanosaur sauropods from the Allen Formation of Salitral Moreno, Río Negro, Argentina
0 comentarios Publicado por Leonardo Filippi en 14:19
Rodolfo García y Leonardo Salgado
The
dinosaur record of the Salitral Moreno locality (Río Negro Province, Argentina)
is characterized by a high diversity of herbivore taxa, among them hadrosaurs, ankylosaurs,
and titanosaur sauropods, but carnivores are rare, consisting of only a few
fragmentary bones of small forms. Titanosaurs are represented by Rocasaurus
muniozi and Aeolosaurus sp., and at least four other taxa,
represented by fragmentary material. The elements preserved include a cervical,
dorsal and caudal vertebrae, chevron, humerii, ulnae, radii, metacarpal,
femora, tibiae, metatarsal, ischia, pubis, and ilium. The Allen Formation is
thought to be correlated with the Marília Formation in Brazil, and their faunas
have certain elements in common such as aeolosaurines, but saltasaurines and
hadrosaurs, are known exclusively from the Allen Formation. These absences, and
particularly that of the saltasaurines, may be because those sauropods
originated late in the Cretaceous, probably in southern South America (Northern
Patagonia?), and they did not have time to disperse to northern South America.
Garcia, R.A. and
Salgado, L. 2013. The titanosaur sauropods from the late Campanian–early Maastrichtian
Allen Formation of Salitral Moreno, Río Negro, Argentina. Acta
Palaeontologica Polonica 58 (2): 269–284.
Palaeopathological Survey of a Population of Mapusaurus
0 comentarios Publicado por Leonardo Filippi en 8:31
Phil R. Bell and Rodolfo A. Coria
Paleoepidemiology
(the study of disease and trauma in prehistoric populations) provides insight
into the distribution of disease and can have implications for interpreting
behavior in extinct organisms. A monospecific bonebed of the giant carcharodontosaurid
Mapusaurus (minimum number of individuals = 9) from the Cañaadón del Gato
site, Neuquén Province, Argentina (Cenomanian) provides a rare opportunity to
investigate disease within a single population of this important apex predator.
Visual inspection of 176 skeletal elements belonging to a minimum of nine
individuals yielded a small number of abnormalities on a cervical vertebra, two
ribs, pedal phalanx, and an ilium. These are attributed to traumatic (two cases),
infectious (two cases) and anomalous (one case) conditions in a minimum of one
individual. The emerging picture for large theropod (abelisaurids, allosaurids,
carcharodontosaurids, tyrannosaurids) populations suggests that 1) osseous abnormalities
were relatively rare (7–19% of individuals) but consistently present, and 2)
trauma was a leading factor in the frequency of pathological occurrences,
evidence of an active, often perilous lifestyle.
Filippi, L. S., Martinelli, A. G. y Garrido, A. C.
The clade
Aeolosaurini is represented by several specimens found, so far, only in
Argentina and Brazil. The material reported here corresponds to a sauropod
titanosaur consisting of four incomplete anterior caudal vertebrae, from the
Narambuena Paleontological Site, Rincón de los Sauces, Neuquén Province,
Argentina. The specimen comes from the Plottier Formation (late Coniacian-lower
Santonian, Upper Cretaceous), Neuquén Group. The specimen has a combination of
features that includes it into the clade Aeolosaurini: anterior caudal centra
with anterodorsal margin bent forward; prezygapophyses elongated in anterior
caudal, in correlation with the extreme displacement of the neural arch
forward; and anteroposteriorly elongated articular facets of prezygapophyses,
at least in the anterior caudals. However, it differs from other Aeolosaurini
by having postzygapophysis with anteroposteriorly short articular facets, not
as elongated in the prezygapophyses. This specimen corresponds not only to the
fi rst discovery of an Aeolosaurini in the north of the Neuquén Basin (because Rinconsaurus
caudamirus Calvo & Gonzalez Riga has been included in another clade,
Rinconsauria), but also the oldest record of the group.
Filippi, L. S., Martinelli, A. G. y Garrido, A.
C. 2013. Registro de un dinosaurio
Aeolosaurini (Sauropoda, Titanosauria) en el Cretácico Superior (Formación
Plottier) del Norte de la Provincia de Neuquén, Argentina, y comentarios sobre los Aeolosaurini
sudamericanos. Revista Brasilera de Paleontología 16 (1): 147-156.
First Occurrence of stomach stones in Pterosaurs
0 comentarios Publicado por Leonardo Filippi en 15:09
Laura Codorniú, Luis M. Chiappe, and Fabricio D. Cid.
Two nearly complete
skeletons of the filter-feeding pterodactyloid Pterodaustro guinazui from the Lowe Cretaceous of Argentina exhibit
clusters of poorly sorted coarse sand to fine gravel inside the abdominal
cavity. These stones are interpreted as ingested gastroliths (geogastroliths),
which are commonly found in a variety of archosaurs (including birds) but have
never before been reported in a pterosaur. The geogastroliths found in these Pterodaustro specimens are interprete as
having assisted in the digestion of hard food items such as ‘shelled’
crustaceans that are abundant in the fossil beds of this pterosaur. One of
these specimens with geogastroliths has anteriormandibular teeth that are
notably thicker than the posterior teeth and are somewhat procumbent. We
suggest that these teeth might have facilitated the apprehension of fine
gravel.
Codorniú, L., Chiappe,
L.M. and Cid, F.D. 2013. First Occurrence of stomach stones in Pterosaurs.
Journal
of Vertebrate Paleontology 33(3): 647–654.
Huevos de saurópodos de la Fm. Cerro Barcino Chubut, Argentina
0 comentarios Publicado por Leonardo Filippi en 15:19
Eloísa Argañaraz,
Gerald Grellet-Tinner, Lucas E. Fiorelli, J. Marcelo Krause y Oliver W. M.
Rauhut
Para efectuar
una interpretación paleobiológica del primer material oológico hallado en la
provincia de Chubut, inferir su escenario paleoambiental y compararlo con
huevos de dinosaurios de otras áreas, se describen detalladamente varios
fragmentos y dos huevos fósiles incompletos provenientes de la localidad de
Huanimán, en el centro-norte de la provincia. El material fue extraído en una
arenisca tobácea fina, depositada en facies de planicie de inundación proximal
asociada a canales multiepisódicos sinuosos. Esta roca es asignable al Miembro
Cerro Castaño de la Formación Cerro Barcino (Aptiano–Albiano). La morfología de
las cáscaras es similar a la de otros huevos megalolítidos (un grupo
parafilético en la parataxonomía de huevos) de Patagonia tales como los de Auca
Mahuevo (Neuquén), identificados como huevos de saurópodos titanosaurios a
partir de embriones in ovo, y los de Salitral Moreno (Río Negro). Sin
embargo, este nuevo material de Chubut, presenta un nuevo carácter estructural.
La red de poros horizontal se ubica debajo de la superficie nodular, a
diferencia de los huevos neuquinos donde se encuentra sobre la membrana
testácea. Este carácter morfológico y el grosor de cáscara (1.5 mm), sugieren una
novedosa adaptación a un ambiente específico de nidificación. Aunque sólo se
han encontrado dos huevos aislados en Huanimán, este descubrimiento puede
implicar la existencia de un nuevo sitio de nidificación en el área.
Argañaraz, E., Grellet-Tinner, G.,
Fiorelli, L.E., Krause, J. M. y Rauhut, O.W.M. 2013. Huevos
de Saurópodos del Aptiano–Albiano, Formación Cerro Barcino (Patagonia,
Argentina): Un enigma Paleoambiental y Paleobiológico. Ameghiniana 50 (1):
33-50.
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