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Oviraptor gigante

2006-04-07T10:59:00.000-05:00

A NEW OVIRAPTOROSAUR (THEROPODA, MANIRAPTORA) FROM THE LATE CRETACEOUS (CAMPANIAN) OF UTAH

LINDSAY E. ZANNO and SCOTT D. SAMPSON
Utah Museum of Natural History and Department of Geology and Geophysics, University of Utah, 1390 E. Presidents Circle, Salt Lake City, Utah 84112, U.S.A.

ABSTRACT: Recent field expeditions to Upper Cretaceous deposits within Grand Staircase-Escalante National Monument, southern Utah, have revealed a diverse dinosaurian fauna that includes a previously unknown oviraptorosaur theropod. Represented by a single partial specimen consisting of manal and pedal elements, this new taxon, Hagryphus giganteus, gen. et. sp. nov., is estimated to be 30–40% larger than the coeval oviraptorosaur Chirostenotes. The holotype consists of a nearly complete, articulated left manus, a partial, articulated pedal digit II, and a series of fragmentary pedal phalanges and distal metatarsals. Several autapomorphies are present in the manus, related primarily to proportional differences in metacarpals and phalanges. Previous finds of North American oviraptorosaurs have been restricted to Alberta, Montana, and South Dakota. The discovery of this new specimen from southern Utah greatly expands the known geographic distribution of these theropods, nearly doubling the previously documented range of North American oviraptorosaurs.

DINOSAURIO DE EXTENSO CUELLO

2006-03-23T19:46:00.000-05:00

Un equipo de paleontólogos estadounidenses descubrió en China al dinosaurio con el cuello más extenso en promedio que el de cualquier otro animal que pobló la Tierra hace millones de años.

El nuevo dinosaurio, de la familia de los saurópodos y que fue llamado "Erketu ellisoni", poseía un cuello de 7.3 metros de largo.

El animal fue desenterrado en el desierto de Gobi, en el oeste de China, por un equipo de científicos del Museo Estadounidense de Historia Natural de Nueva York.
El cuello del "Erketu Ellisoni" era más corto que el de su pariente diplodocus, pero medía más de la mitad de la extensión del dinosaurio, convirtiéndolo en el saurópodo que proporcionalmente poseía el cuello más extenso.

Cría de Triceratops horridus

2006-03-07T16:30:00.000-05:00

Ha sido presentado un cráneode 30 cm de longitud de un bebé de Triceratops horridus, de un año de edad y un tamaño de 90 cm. En la imagen un molde de éste que fué hayado en la formación Hell Creeck de Montana.Mas información en UC Bercley News

Ornitópodo Juvenil

2006-03-07T16:26:00.000-05:00

Juvenile ornithopod (Dinosauria: Rhabdodontidae) remains from the Upper Cretaceous (Lower Campanian, Gosau Group) of Muthmannsdorf (Lower Austria)

Geobios, In Press, Available online 6 March 2006 Sven Sachs and Jahn J. Hornung

The fragmentary remains of a juvenile rhabdodontid ornithopod from the Coal-bearing Complex of the Gosau Group (Lower Campanian, Grünbach syncline) at Muthmannsdorf near Wiener Neustadt, Lower Austria are revised. The material, probably belonging to a single
individual, includes a right dentary (lectotype of Iguanodon suessi Bunzel, 1871, designated herein), teeth, a fragmentary parietal, fragments of scapula, ?radius, femur, tibia, two vertebrae (lost) and a manual ungual.

The lectotype dentary does not provide clear autapomorphies or sufficient diagnostic features to determine its position within the Rhabdodontidae at generic level. By this "Iguanodon suessi" Bunzel, 1871 and the genus "Mochlodon" Seeley, 1881, to which it was latter referred as type species, cannot be characterized sufficiently by differential diagnosis and these are best considered nomina dubia.
Based upon combined character comparisons (mainly postcranial features) the Muthmannsdorf ornithopod is referred herein to Zalmoxes Weishampel, Jianu, Csiki and Norman, 2003, a genus so far known from the late Maastrichtian of Romania. It probably but not evidently represents a yet unnamed species, most closely related to Zalmoxes shpiperorum Weishampel, Jianu, Csiki and Norman, 2003. At the present state of knowledge the Austrian material is not further diagnostic at the species level and kept in open nomenclature as Zalmoxes sp.

Origen y radiación de los Terápsidos

2006-03-07T16:23:00.000-05:00

The origin and early radiation of the therapsid mammal-like reptiles: a palaeobiological hypothesis

T. S. KEMP Jour. Evolutionary Biology (In Press)

The replacement of the basal synapsid pelycosaurs by the more `mammal-like' therapsids in the Permian was an important event in the history of tetrapods because it initiated the eventual transition to the mammals. It is also an example of taxon replacement in the fossil
record that is unusually amenable to explanation, based on a combination of analysis of the biological significance of the inferred character changes, with the stratigraphic, palaeogeographic and palaeoecological circumstances of the time. An hypothesis is
presented in which the origin of the therapsids resulted from a correlated progression of character evolution leading to higher levels of metabolic activity and homeostatic regulation of the body.
It was a response to the availability of a seasonally arid, savanna-like biome. The subsequent explosive radiation of therapsids was associated with habitat expansion made possible by the Mid-Permian development of geographical continuity between that biome and the
temperate biomes. The final extinction of the pelycosaurs was a case of incumbent replacement by the new therapsid lineages.

Mesosaurus tenuidens

2006-03-07T16:16:00.000-05:00

The cranial skeleton of the Early Permian aquatic reptile Mesosaurus tenuidens: implications for relationships and palaeobiology

SEAN PATRICK MODESTO Zoological Journal of the Linnean Society Volume 146 Issue 3 Page 345–368 - March 2006

The cranial osteology of the aquatic reptile Mesosaurus tenuidens is redescribed on the basis of new and previously examined materials from the Lower Permian of both southern Africa and South America.
Mesosaurus is distinguished from other mesosaurs in exhibiting an absolutely larger skull and possessing relatively longer marginal teeth. The teeth gradually angle outwards as one progresses anteriorly in the tooth row and become conspicuously procumbent at the tip of the snout. The suggestion that mesosaurs used their conspicuous dental apparatus as a straining device for filter feeding is based upon erroneous reconstruction of a high number of teeth in this mesosaur. Reinterpretation of the morphology and the organization of the marginal teeth of Mesosaurus suggests that they were used to capture individually small, nektonic prey. General morphological aspects of the skull support the idea that Mesosaurus
was an aquatic predator and that the skull was well adapted for feeding in an aqueous environment. The anatomical review permits critical reappraisal of several cranial characters that have appeared in recent phylogenetic analyses of early amniotes. Emendation of problematic characters and reanalysis of amniote phylogeny using a slightly modified data matrix from the literature strengthens the hypothesis that mesosaurs form a clade with millerettids, procolophonoids and pareiasaurs within Reptilia.

Reconstrucción del Hombro de Dromaeosaurus

2006-03-07T16:14:00.000-05:00

An integrative phylogenetic and extrapolatory approach to the
reconstruction of dromaeosaur (Theropoda: Eumaniraptora) shoulder
musculature

SANDRA C. JASINOSKI, ANTHONY P. RUSSELL and PHILIP J. CURRIE

Zoological Journal of the Linnean Society
Volume 146 Issue 3 Page 301–344 - March 2006

Dromaeosauridae is the sister taxon of the Avialae; thus, an investigation of dromaeosaur shoulder girdle musculature and forelimb function provides substantial information regarding changes in the size and performance of the theropod shoulder girdle musculature leading to avian powered flight. Twenty-two shoulder girdle muscles were reconstructed for the dromaeosaurid shoulder apparatus, based on phylogenetic inference, which involves the comparison of lepidosaurian, crocodilian and avian musculature, and extrapolatory inference, which involves a secondary comparison with functional analogues of theropods. In addition to these comparative methodologies, osteological correlates of shoulder musculature preserved in eumaniraptorans are identified, and comparisons with those of extant archosaurs allow these muscles to be definitively inferred in dromaeosaurids. This muscle reconstruction provides a foundation for subsequent investigation of differences in muscular attachment and function, based on scapulocoracoid morphology, across the theropod lineage leading to birds.

Huevos y comportamiento de nidificación

2006-02-10T14:37:00.000-05:00

Dinosaur eggs and nesting behaviors: A paleobiological investigation
Gerald Grellet-Tinner a,b,*, Luis Chiappe b, Mark Norell c, David Bottjer a a Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089-0740, USA b Department of Vertebrate Paleontology, Natural History Museum of, Los Angeles County, CA 90007, USA c Department of Vertebrate Paleontology, American Museum of Natural History, New York, New York 10024-5192, USA Received 8 February 2005; received in revised form 19 October 2005; accepted 28 October 2005

Abstract:
Although dinosaur eggs were first discovered and identified in the late 1800s, limited attention was given to the scientific value of zoological fossils in contrast to observations based on skeletal features. Here, we offer a review of Mesozoic saurischian egg materials,
in comparison with extant crocodilians and avians, and their paleobiological interpretation based either on the presence of embryos in ovo or brooding adults on egg clutches. Our study focuses on the eggs of the oviraptorid Citipati osmolka (Mongolia), the troodontid
Troodon formosus (North America), the theropod oospecies Macroelongatoolithus xixiaensis (China), the ornithothoracine bird (Argentina), an indeterminate theropod (Thailand), and titanosaurs (Argentina). Results show that (1) many oological characters and reproductive behaviors associated with modern birds are rooted among non-avian theropods, (2) there is a reproductive evolutionary cline from crocodilians to modern birds with (3) a noticeable pattern of coeval development between the accretion of eggshell layers,
origination and size increased of larger air cells (inferred from egg polar asymmetry), and brooding/incubating behaviors. Most of these pre-adaptations are grouped in two main clades of the saurischian cladogram: one at the level of Oviraptorosauridae and the
other at Troodontidae. Although undeniably these two theropod taxa seem to represent two important phases for the evolution of avian reproduction, the phylogenetic distance between these clades and Titanosauria cannot be ignored. As such, the reproductive features
that appeared in concert in oviraptorids might have gradually evolved across more basal theropod clades. Although Troodon formosus by its egg shape and nesting behavior seems to be in this study the precursors of modern avian reproduction, the importance of smallbodied
theropods such as those who laid the Phu Phok eggs cannot be dismissed and the eggs of such dinosaurs could suggest a closer phylogenetic ties to Aves than troodontids. At a higher level of inferences, there is a strong possibility that the evolution of these reproductive features is concurrent with profound physiological and metabolic changes that occurred in saurischian dinosaurs throughout their evolution.

Huellas de dinosaurio en Korea

2006-02-10T14:24:00.000-05:00

Dinosaur-dominated footprint assemblages from the Cretaceous Jindong Formation, Hallyo Haesang National Park area, Goseong County, South Korea: Evidence and implications

Martin G. Lockley a,*, Karen Houck a, Seong-Young Yang b, Masaki Matsukawa c, Seong-Kyu Lim d a Dinosaur Tracks Museum, University of Colorado at Denver, PO Box 173364, Campus Box 172, Denver, CO 80217-3364, USA b 706-010, 5-45 Beomeodong, Suseong-gu, Taegu, South Korea c Department of Science Education, Tokyo Gakugei University, Koganei, Tokyo 184-8501, Japan d Earth Science Department, Kyungpook National University, Taegu, South Korea Received 12 March 2005; accepted in revised form 20 October 2005

Abstract:
The track-rich Cretaceous Jindong Formation comprises part of an intra-arc basin, fluvio-lacustrine succession that represents a late stage in the evolution of the Kyongsang Basin. This formation is replete with track-bearing levels indicating the activity of many generations of dinosaurs and birds. The track-rich beds occur in the upper part of the Hayang Group (Kyongsang Supergroup), which also contains other, underlying dinosaur-track-bearing formations. However the Jindong Formation and underlying formations have produced few age-diagnostic body fossils.

Altered volcaniclastic sediments such as are found the Jindong Formation complicate interpretation of the age of the tracks as discussed in the accompanying companion paper. Nonetheless such settings provided near optimal conditions for the formation and preservation of abundant track assemblages (ichnofaunas), and the Jindong Formation has become an ichnological ‘‘cause celebre’’ producing impressive statistics on
the number of track-bearing sites, number of track-bearing levels and number of measured trackways. These data allow various inferences about certain aspects of the population structure, behavior and distribution of the dinosaurian track makers in these dinosaur-dominated paleocommunities.
The Jindong Formation and underlying Haman Formation have also yielded many bird tracks. The complete lack of avian body fossils in Korea and the rarity of dinosaur skeletal remains means that the footprint record currently provides the vast majority of the Mesozoic vertebrate evidence available for the entire Korean peninsula. Thus, the tracks represent a highly significant addition to the national paleontological heritage of Korea, as well as being a very important component of the East Asian and global footprint records. Detailed studies of a 100e200-m-thick succession at the Sangjok Dinosaur Tracksite National Monument in the Hallyo Haesang National Park area in Kosong County reveal an average
of about two track-bearing levels per meter, making it one of the richest track-bearing sections on record and providing evidence of the activity of hundreds of individuals. Many other track sites are found locally in the Jindong Formation in Kosong County (about 500 km2) including one described herein from near Gohyeon village where the Jindong Formation type section is situated. Other track sites can be traced laterally over larger distances within the Gyeongsang Basin. The composition of ichnofaunas throughout this region appears remarkably consistent.
The Jindong Formation is one of the few localities where sauropod, ornithopod, and bird tracks all occur in abundance, probably due to latitudinal/ climatic controls. The sauropod tracks, which include wide-gauge forms allied to Brontopodus, form the largest brontosaur trackway sample yet reported but are characterized by a high proportion of small individuals. Such unusual size-frequency distributions raise interesting ecological and taphonomic questions about the biasing of the body fossil record towards large individuals by various physical (preservational) or biological/ ecological controls.
The most abundant dinosaur trackways are those of iguanodontids (cf. Caririchnium or Iguanodontipus) that often traveled in herds. By contrast, sauropod tracks show little or no evidence of gregarious behavior and rarely occur on the same bedding planes as ornithopod trackways.

This suggests a pattern of mutual exclusion or geological segregation between these two herbivore groups, which indicates that they probably frequented the area at different times. Sauropod and ornithopod track size-frequency distributions are also fundamentally different, suggesting that the ornithopods were mainly sub-adults and adults, whereas the sauropods were predominantly juveniles. Theropod tracks are uncommon suggesting a low predator:prey ratio of 1:20.

Bird tracks including the large ichnospecies Jindongornipes kimi, an intermediate-sized form, Goseongornipes markjonesi ichnosp. and ichnogen.
nov., and a small ichnospecies Koreanaornis hamanensis occur at several dozen stratigraphic levels in association with nematode trails (Cochlichnus) and other invertebrate traces. These three ichnospecies are assigned to the respective ichnofamilies Koreanornipodidae ichnofam.
nov., Ignotornidae, and Jindongornipodidae ichnofam. nov. All these avian footprints are typical of bird track assemblages in lake shoreline deposits, and indicate the activity of many generations of waders or shorebirds. We also recognize other, much less common, small footprint types tentatively attributed to a perching bird or a diminutive theropod. Collectively the bird tracks indicate the considerable potential of avian ichnites to provide insight into avian paleoecology at an early stage in the evolution of Class Aves.

Tiranosaurio basal de China

2006-02-10T14:18:00.000-05:00

A basal tyrannosauroid dinosaur from the Late Jurassic of China.
2006. Xing Xu, James M. Clark, Catherine A. Forster, Mark A. Norell, Gregory M. Erickson, David A. Eberth, Chengkai Jia and Qi Zhao. Nature 439: 715-718

Abstract: The tyrannosauroid fossil record is mainly restricted to Cretaceous sediments of Laurasia, although some very fragmentary Jurassic specimens have been referred to this group. Here we report a new basal tyrannosauroid, Guanlong wucaii gen. et sp. nov., from the lower Upper Jurassic of the Junggar Basin, northwestern China. G. wucaii is the oldest known tyrannosauroid and shows several unexpectedly primitive pelvic features. Nevertheless, the limbs of G. wucaii share several features with derived coelurosaurs, and it possesses features shared by other coelurosaurian clades. This unusual combination of character states provides an insight into the poorly known early radiation of the Coelurosauria. Notably, the presumed predatory Guanlong has a large, fragile and highly pneumatic cranial crest that is among the most elaborate known in any non-avian dinosaur and could be comparable to some classical exaggerated ornamental traits among vertebrates.

Antiguo Tiranosaurio crestado

2006-02-10T14:08:00.000-05:00

La especie llamada Dragón con Corona, de tres metros de altura es el ancestro del Tiranosaurio Rex.
Paleontólogos chinos descubrieron una nueva especie de dinosaurio denominada Dragón con Corona, que vivió hace 160 millones de años y era el ancestro del Tiranosaurio Rex, uno de los más feroces predadores que habitó la Tierra hace 67 millones de años. De acuerdo a un informe de la revista Nature, fue hallado por científicos del Instituto de Vertebrados y Paleontología de Pekín en el desierto de Gobi, en el oeste de China.

El nuevo ejemplar pertenece a la especie Wucaii que en chino significa cinco colores, en referencia a los colores de las rocas donde fue encontrado el ejemplar. La denominación en chino es Guanlong, que deriva de una palabra empleada para denominar corona y dragón.

Este ejemplar de dinosaurio medía tres metros de altura, se paraba en dos patas y al parecer podría haber estado cubierto enteramente de plumas. Los científicos señalaron que el Dragón con Corona precedió al Tiranosaurio Rex que es físicamente muy parecido, pero medía 13 metros de alto y vivió hace 67 millones de años.

Ambos dinosaurios tenían igual ferocidad, pero a diferencia del Tiranosaurio Rex, el Guanlong poseía una cresta ósea en su nariz. Los expertos consideraron que esa cresta le servía al animal como "ornamento sexual", como lo es el plumaje del pavo real. Xing Xu, uno de los paleontólogos que descubrió al nuevo dinosaurio, calificó el hallazgo de "histórico".

El investigador indicó que "la cresta craneana del Guanlong provee una evidencia crucial para explicar la exagerada ornamentación sexual entre los dinosaurios predadores".

En tanto, el paleontólogo italiano Cristiano Dal Sasso, comprobó que el Spinosaurus fue el dinosaurio predador más grande del mundo, superando al temible Tiranosaurio Rex y al Giganotosaurus Carolini, que habitó la patagonia argentina. Dal Sasso, investigador del Museo de Historia Natural de Milán, en Italia, destacó que el Spinosaurus medía 17 metros de altura, se paraba en dos patas y poseía una cola de gran tamaño.

Definitivo, los saurópodos no tenían trompa

2006-01-26T15:38:00.000-05:00

Paleoneurological evidence against a proboscis in the sauropod dinosaur Diplodocus

Abstract:
The dinosaur Diplodocus has a single, relatively large external bony narial orifice that is positioned far back between the orbits. In some mammals, such as elephants and tapirs, the caudal position of the narial opening is associated with a proboscis, so it has been suggested that Diplodocus possibly also had a trunk. In elephants, the facial nerve is large as it emerges from the brain. A branch of this nerve and a branch of the trigeminal nerve unite to form the proboscidial nerve that supplies the muscles of the powerful and complex motor system of the trunk. In contrast to the situation in modern elephants, the absolute as well as the relatively small size of the facial nerve in Diplodocus (deduced from an endocranial cast) indicates that there is no paleoneuroanatomical evidence for the presence of an elephant-like proboscis in this genus.

Hallan en Neuquén un "titanosaurio" de 71 millones de años

2005-12-29T09:09:00.000-05:00

Se trata de un hallazgo de importancia mundial para la paleontología, porque el ejemplar de 10 metros de largo y 12 toneladas, permitirá conocer más detalles de la especie y de su hábitat

El hallazgo cobra doble importancia; por un lado permite conocer más detalles de los titanosaurios y, por otra parte, se podrá estudiar el hábitat en que vivió este dinosaurio y la causa de su muerte.

“Lo extraordinario de esto es que los restos estaban articulados, como si el animal se hubiera caído o acostado y se hubiera quedado así, es decir, no había signos de depredación" detalló Bernardo González Riga, geólogo, paleontólogo con orientación en dinosaurios y profesor de la U.N. de Cuyo.

"Encontramos restos de un pie con todos sus dedos y garras en un estado excepcional de preservación. además, hallamos la extremidad posterior completa, la cola, las costillas y parte de la cintura pélvica”, agregó, el investigador al diario "Los Andes".

El ejemplar pertenece a un dinosaurio herbívoro, de la familia de los titanosaurios o “saurios titanes”, que fueron los animales terrestres más grandes de todos los tiempos.

Los titanosaurios dominaron los ecosistemas de América del Sur durante gran parte del período Cretácico y, en general, habitaron en ambientes fluviales.

En este grupo se incluyen Mendozasaurus, que vivió en el extremo sur de Mendoza, Saltasaurus, que ocupó el norte argentino, y Argentinosaurus, de la Patagonia.

Los restos hallados remiten a un ejemplar joven, que habría alcanzado 10 metros de largo y 12 toneladas de peso.

El hallazgo se concretó en la zona norte de Neuquén, a unos 40 Km. de Rincón de los Sauces y fue efectuado por un equipo de la Universidad Nacional del Comahue.

La extracción y traslado de los restos estuvieron a cargo de dos equipos de trabajo, uno mendocino y otro neuquino

No se observaron restos ni de la cabeza ni del cuello del ejemplar, probablemente porque el agua los degradó a través del paso del tiempo.

Hay sólo uno o dos titanosaurios en el mundo con pie completo y ahora se suma éste y aporta nueva información de relevancia regional, nacional e incluso internacional.

Ahora resta que se analicen los bloques que se extrajeron y que se guardaron en el Centro Paleontológico Lago Barreales, en Neuquén. La tarea no es menor; sólo los restos de la cola pesan 200 Kg. y miden 4 metros

Fuente: infobae.com

Libro Dinosaurios en Chile

2005-12-27T07:11:00.000-05:00

Dinosaurios en Chile y los vertebrados del Mesozoico, es un libro que reúne la mayoría de la información disponible sobre la vida prehistórica del Mesozoico en nuestro país, abarca los periodo Triásico, Jurásico y Cretácico, analizando los diferentes hallazgos e investigaciones, nos muestra una síntesis del desarrollo de la paleontología nacional y nos entrega las bases para entender en parte esta ciencia. Sin duda que este libro servirá a todo aquel que quiera introducirse en el conocimiento de nuestro pasado y sentara las bases para el que quiera iniciar sus propias investigaciones.

ASÍ MISMO incentivará y abrirá las mentes de aquellos que realmente aman la paleontología.

Contacto pasra ventas:

Juan Castillo C.

Paleomundo.cl

Huevos de Dinosaurios en Chile

2005-12-23T13:13:00.000-05:00

Dieciocho huevos fosilizados, que corresponderían a dinosaurios extintos hace 75 millones de años, fueron encontrados en un sector cordillerano de la localidad de Lonquimay, en la sureña provincia chilena de Temuco, según publica la prensa local.

Según publica el diario El Mercurio, algunos de los huevos son del tamaño de un balón de rugby y dos kilos de peso. Fueron encontrados en una grieta surgida de la erosión del terreno en un sector de Lonquimay, a unos 668 kilómetros al sur de Santiago, por el profesor de una escuela rural de la zona, Mario Cid.

El docente afirmó que envió fotografías de los huevos a un paleontólogo de la Universidad de Chile, quien le habría confirmado su origen prehistórico.

Los huevos se encuentran en poder del alcalde de Lonquimay, Guillermo Vásquez, quien dijo que el hallazgo tuvo lugar hace tres meses, informándose de ello a la Gobernación a fin de adoptar las medidas de resguardo del lugar.

Los huevos se encontraban sepultados a medio metro de profundidad y dispersos en unos diez metros cuadrados. La erosión provocada por las lluvias invernales hizo que varios de ellos asomaran a la superficie.

Vásquez y Cid solicitaron la ayuda de especialistas del Museo de Historia Natural de Chile y de expertos argentinos, a fin de examinar este material y continuar investigando el sitio en que se encontró.

La zona argentina de Neuquén, a la altura de Temuco, es un importante depósito mundial de fósiles de dinosaurios. Equipos multidisciplinarios suelen trabajar en yacimientos considerados como laboratorios abiertos de paleontología.

Fuente y forografía: elmundo.es

Archaeopteryx con características de raptoriforme

2005-12-09T17:03:00.000-05:00

A Well-Preserved Archaeopteryx Specimen with Theropod Features
Gerald Mayr, Burkhard Pohl, D. Stefan Peters

A nearly complete skeleton of Archaeopteryx with excellent bone preservation
shows that the osteology of the urvogel is similar to that of nonavian
theropod dinosaurs. The new specimen confirms the presence of a hyperextendible
second toe as in dromaeosaurs and troodontids. Archaeopteryx had
a plesiomorphic tetraradiate palatine bone and no fully reversed first toe.
These observations provide further evidence for the theropod ancestry of
birds. In addition, the presence of a hyperextendible second toe blurs the
distinction of archaeopterygids from basal deinonychosaurs (troodontids and
dromaeosaurs) and challenges the monophyly of Aves.

Artículo de prensa en inglés

Dakosaurus andiniensis

2005-11-11T13:27:00.000-05:00

Nuevo cocodriliforme descubierto en Argentina y apodado "Godzilla" por su gan cabeza.

"A new, virtually complete fossil skull has revealed that an ancient marine relative of the crocodile was a very strange sea monster indeed.

The 80-centimetre-long fossil, discovered in Argentina, shows that Dakosaurus andiniensis had the massive and terrifying skull of a predatory dinosaur. Previously known only from bone fragments, the animal was nearly 4 metres (12 feet) long, with four flippers and the tail of a fish."

Mas información en New Scientist, en National Geographic, y en NewsWise

Basal Neoceratopsiano de China

2005-10-26T07:44:00.000-05:00

On a New Genus of Basal Neoceratopsian Dinosaur from the Early Cretaceous of Gansu Province, China.

YOU Hailu, LI Daqing, JI Qiang, Matthew C. LAMANNA and Peter DODSON

Abstract: A new genus and species of basal neoceratopsian dinosaur, Auroraceratops rugosus, is reported based on material from the Early Cretaceous Xinminpu Group in the Gongpoquan Basin of Gansu Province, China. Auroraceratops is represented by a nearly complete skull and low jaws, and different greatly from all other neoceratopsians by its considerable breadth of the nasals, fungiform expansion of the dorsal end of the lacrimal, highly developed rugosity of the jugal, dentary and surangular, and inflated, striated premaxillary teeth. The finding of Auroraceratops adds diversity and helps elucidate the evolution of basal neoceratopsian dinosaurs.

Lanzhousaurus magnidens

2005-10-26T07:42:00.000-05:00

Lanzhousaurus magnidens gen. et sp. nov. from Gansu Province, China: the largest-toothed herbivorous dinosaur in the world

Hai-lu You, Qiang Ji, Da-qing Li

Abstract: A new ornithopod dinosaur, Lanzhousaurus magnidens gen. et sp. nov., from the Early Cretaceous of the Lanzhou Basin, Gansu Province, China, possesses the largest teeth of any herbivorous dinosaur yet discovered. The dental morphology of Lanzhousaurus, in which only 14, ~4 cm-wide tooth families are preserved in the tooth row of the 1 m long lower jaw, augments the known morphological diversity of dinosaurs. Cladistic analysis recovers a close relationship between L. magnidens and Lurdusaurus arenatus from the Early Cretaceous of Africa. Together, these species represent a previously unrecognized, massively-constructed quadrupedal lineage in the evolution of ornithopod dinosaurs. This discovery also implies a close connection between Eurasia and Africa during the Early Cretaceous.

Paleoilustración

2005-10-26T07:29:00.000-05:00

Amargasaurus cazaui
Bruno Hernández ®2005

Centrosaurus brinkmani

2005-10-19T10:01:00.000-05:00

A new centrosaurine ceratopsid from the Oldman Formation of Alberta and its implications for centrosaurine taxonomy and systematics.
Ryan, M.R. and Russell, A.P. (2005). Can. J. Earth Sci. 42: 1369–1387.

Abstract: "Centrosaurus brinkmani" (sp. nov) is distinguished from "Centrosaurus apertus" by key features of its cranial ornamentation, including the shape and orientation of the postorbital horn and parietal ornamentation at parietal locus 3, the shape of the parietal ornamentation at locus 2, and the possession of accessory parietal ossifications developed as short spines on the caudal parietal ramus. This species is restricted to the Oldman Formation of southern Alberta and is the oldest ceratopsid represented by diagnostic material in Canada. Phylogenetic analysis of the Centrosaurinae suggests that the development of spike-like ornamentation at the parietal locus 3 parietal locus is inversely related to the development of the P1 parietal ornamentation."

Registro de impresiones de las patas delanteras en Titanosaurus

2005-10-14T08:32:00.000-05:00

Manus-only titanosaurid trackway from Fumanya (Maastrichtian, Pyrenees): further evidence for an underprint origin

BERNAT VILA, ORIOL OMS AND A ANGEL GALOBART Vila, B., Oms, O. & Galobart, A . 2005 09 12: Manus-only titanosaurid trackway from Fumanya (Maastrichtian, Pyrenees): further evidence for an underprint origin. Lethaia, Vol. 38, pp. 211–218. Oslo. ISSN 0024-1164.

The origin of manus-only and manus dominated sauropod trackways has been a matter of intense debate since two hyphothesis exist: (a) manus-only and manus-dominated trackways result from a ‘swimming’ sauropod, and (b) they result from a selective underprint phenomenon that only leaves the manus recorded. Several new sauropod trackways are reported in the Fumanya tracksite area (Maastrichtian), in SE Pyrenees, where both tracks and undertracks are found on the same stratigraphic bedding surface. In one of the trackways, footprint morphology together with the trackway pattern displays a clear succession of manus-only impressions attributed to a sauropod dinosaur in a walking gait. The ichnological comparison between the manus-only trackway with the other complete trackway (manus-pes) display an identical distribution of the manus pattern. This fact clearly points towards an underprint phenomenon as the origin for manus-only trackways, since it is rather unlikely that the same pattern would completely match different locomotion behaviours such as walking and swimming. Therefore, we suggest an interpretation based on the differential loading between the hindfoot and the forefoot on an upper stratigraphic track-level, for the studied manus-only trackway. & Fumanya tracksite, manus-only trackways, titanosaurs, trackway pattern, underprint, Upper Cretaceous.

Funcion del pteroides en el vuelo de los Pterosaurus

2005-10-14T08:28:00.000-05:00

High lift function of the pteroid bone and forewing of pterosaurs

Matthew T. Wilkinson1,*, David M. Unwin2 and Charles P. Ellington1 1Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK 2Institut fu¨ r Pala¨ontologie, Museum fu¨ r Naturkunde, Humboldt-Universita¨ t zu Berlin, Invalidenstrasse 43, Berlin 10115, Germany

The pteroid bone is a rod-like element found only in pterosaurs, the flying reptiles of the Mesozoic. It articulated at the wrist, and supported a membranous forewing in front of the inner part of the wing spar.
The function of this bone, particularly its orientation, has been much debated. It is widely believed that it pointed towards the body, and that the forewing was relatively narrow. An alternative hypothesis states that it was directed forwards during flight, resulting in a much broader forewing that acted as a leading edge flap. We tested scale models in a wind tunnel to determine the aerodynamic consequences of these conflicting hypotheses, and found that performance is greatly improved if the pteroid is directed forwards: the lift : drag ratios are superior and the maximum lift is exceptionally high in comparison with conventional aerofoils.

Antiguo dromaeosaurido de Sud América

2005-10-14T08:18:00.000-05:00

The earliest dromaeosaurid theropod from South America

Peter J. Makovicky1, Sebastia´n Apesteguı´a2,4 & Federico L. Agnolı´n3

The evolutionary history of Maniraptora, the clade of carnivorous
dinosaurs that includes birds and the sickle-clawed Dromaeosauridae,
has hitherto been largely restricted to Late Jurassic and
Cretaceous deposits on northern continents. The stunning Early
Cretaceous diversity of maniraptorans from Liaoning, China1–3,
coupled with a longevity implied by derived Late Jurassic forms
such as Archaeopteryx, pushes the origins of maniraptoran
lineages back to Pangaean times and engenders the possibility
that such lineages existed in Gondwana. A few intriguing, but
incomplete, maniraptoran specimens have been reported from
South America4–8, Africa9 and Madagascar10. Their affinities
remain contested11–13, however, and they have been interpreted
as biogeographic anomalies relative to other faunal components of
these land-masses. Here we describe a near-complete, small
dromaeosaurid that is both the most complete and the earliest
member of the Maniraptora from South America, and which
provides new evidence for a unique Gondwanan lineage of Dromaeosauridae
with an origin predating the separation between
northern and southern landmasses.

Buitreraptor gonzalezorum

2005-10-12T13:27:00.000-05:00

El reciente descubrimiento de un pequeño dinosaurio dromaeosaurido de 90 millones de años de antiguedad en la patagonia, demuestra que éstos animales, cercanamente emparentados con los raptores y las aves de empezaron a desarrollar mas tempranamente de lo que se creía.

Noticia completa en inglés

La garra terrible, para matar o escalar ?

2005-10-12T08:17:00.000-05:00

Dinosaur killer claws or climbing crampons?

Phillip L. Manning1,*, David Payne2, John Pennicott2, Paul M. Barrett3 and Roland A. Ennos4

Dromaeosaurid theropod dinosaurs possess a strongly recurved, hypertrophied and hyperextensible ungual claw on pedal digit II. This feature is usually suggested to have functioned as a device for disembowelling herbivorous dinosaurs during predation. However, modelling of dromaeosaurid hindlimb function using a robotic model and comparison of pedal ungual morphology with extant analogue taxa both indicate that this distinctive claw did not function as a slashing weapon, but may have acted as an aid to prey capture.

Primer registro de Mosasaurios en Suecia

2005-10-12T08:14:00.000-05:00

THE FIRST RECORD OF HAINOSAURUS (REPTILIA: MOSASAURIDAE) FROM SWEDEN

JOHAN LINDGREN
Department of Geology, GeoBiosphere Science Centre, Lund University, So¨lvegatan 12,
SE-223 62 Lund, Sweden, ,johan.lindgren@geol.lu.se.

ABSTRACT: Isolated marginal tooth crowns of the early Campanian mosasaur Hainosaurus Dollo, 1885, from the Kristianstad Basin and the Vomb Trough, southern Sweden, are described and illustrated. The teeth have been collected from a narrow stratigraphic interval corresponding to the highest belemnite zone in the lower part of the European two-fold division of the Campanian stage. A reexamination of dental and skeletal characters in two alleged species of Hainosaurus, ‘H.’ pembinensis Nicholls, 1988 and ‘H.’ gaudryi (The´venin, 1896), and detailed comparisons with the corresponding elements in H. bernardi Dollo, 1885 and Tylosaurus proriger (Cope, 1869a), strongly indicate that ‘H.’ pembinensis and ‘H.’ gaudryi are both Tylosaurus Marsh, 1872. Diagnostic features of Hainosaurus include a very small infrastapedial process on the quadrate (conspicuous protuberance in Tylosaurus), flattened, symmetrically bicarinate marginal teeth (asymmetric and conical in Tylosaurus), short and wide pygal centra, and anteriorly situated intermediate

Evolución en el sistema locomotor de los Plesiosaurios

2005-10-12T08:10:00.000-05:00

Correlated trends in the evolution of the plesiosaur
locomotor system

F. Robin O’Keefe and Matthew T. Carrano

Abstract: This paper investigates trends in the evolution of body size and shape in the Plesiosauria, a diverse clade of Mesozoic marine reptiles. Using measures from well-preserved plesiosaur specimens, we document and interpret evolutionary patterns in relative head size, body size, and locomotor variables. Size increase is a significant trend in the clade as a whole, and in constituent clades. The trend in relative head size is of variance increase; observed head sizes are both smaller and larger than ancestral values. In the locomotor system, changes in propodial and girdle proportions appear concomitant with body size increase and are interpreted as allometric responses to the physical constraints of large body size. Other trends in the locomotor systemare significantly
correlated with both body size and relative head size. These locomotor trends evolved convergently in several clades of plesiosaurs, and may have had an ecomorphological basis, although data are lacking to constrain speculation on this point. The evolution of the locomotor systemin plesiosaurs sheds new light on the response of aquatic tetrapods to the physical constraints of foraging at large body size.

Analisis de la musculatura de extremidades posteriores del T-rex

2005-10-07T07:58:00.000-05:00

Analysis of hindlimb muscle moment arms in Tyrannosaurus rex using a three-dimensional musculoskeletal computer model: implications for stance, gait, and speed.

John R. Hutchinson, Frank C. Anderson, Silvia S. Blemker, Scott L. Delp,
Paleobiology 31(4): 676-701.

Abstract. — Muscle moment arms are important determinants of muscle function; however, it is challenging to determine moment arms by inspecting bone specimens alone, as muscles have curvilinear paths that change as joints rotate. The goals of this study were to (1) develop a three-dimensional graphics-based model of the musculoskeletal system of the Cretaceous theropod dinosaur Tyrannosaurus rex that predicts muscle-tendon unit paths, lengths, and moment arms for a range of limb positions; (2) use the model to determine how the T. rex hindlimb muscle moment arms varied between crouched and upright poses; (3) compare the predicted moment arms with previous assessments of muscle function in dinosaurs; (4) evaluate how the magnitudes of these moment arms compare with those in other animals; and (5) integrate these findings with previous biomechanical studies to produce a revised appraisal of stance, gait, and speed in T. rex. The musculoskeletal model includes ten degrees of joint freedom (flexion/extension, ab/adduction, or medial/ lateral rotation) and 33 main muscle groups crossing the hip, knee, ankle, and toe joints of each hindlimb. The model was developed by acquiring and processing bone geometric data, defining joint rotation axes, justifying muscle attachment sites, and specifying muscle-tendon geometry and paths. Flexor and extensor muscle moment arms about all of the main limb joints were estimated, and limb orientation was statically varied to characterize how the muscle moment arms changed. We used sensitivity analysis of uncertain parameters, such as muscle origin and insertion centroids, to deterimine how much our conclusions depend on the muscle reconstruction we adopted. This shows that a specific amount of error in the reconstruction (e.g., position of muscle origins) can have a greater, lesser, similar, or no effect on the moment arms, depending on complex interactions between components of the musculoskeletal geometry. We found that more upright poses would have improved mechanical advantage of the muscles considerably. Our analysis shows that previously assumed moment arm values were generally conservatively high. Our results for muscle moment arms are generally lower than the values predicted by scaling data from extant taxa, suggesting that T. rex did not have the allometrically large muscle moment arms that might be expected in a proficient runner. The information provided by the model is important for determining how T. rex stood and walked, and how the muscles of a 4000–7000 kg biped might have worked in comparison with extant bipeds such as birds and humans. Our model thus strengthens the conclusion that T. rex was not an exceptionally fast runner, and supports the inference that more upright (although not completely columnar) poses are more plausible for T. rex. These results confirm general principles about the relationship between size, limb orientation, and locomotor mechanics: exceptionally big animals have a more limited range of locomotor abilities and tend to adopt more upright poses that improve extensor muscle effective mechanical advantage. This model builds on previous phylogenetically based muscle reconstructions and so moves closer to a fully dynamic, three-dimensional model of stance, gait, and speed in T. rex.

Icnitas del triasico medio en francia: reevaluación de la nomenclatura

2005-10-07T07:48:00.000-05:00

The French Middle Triassic Dinosauroid trackways: palaeontological result and nomenclatural re-evaluation

Georges Gand, and Georges Demathieu

Numerous dinosauroid footprints which showing sometimes manus imprint mark were gathered, since 1960, from the lower sandstones Triassic formations of the eastern border of the Massif Central (France).
Tracks bearing levels are dated from palynological, micropalaeontological and palichnological data. They belong to the period upper Anisian-lower Ladinian. The paleontological results show bipedal digitigrade reptiles with erected, long hind limbs, having also pentadactyl mani and (II-IV) tridactyl feet. The osteological feet inferred structure is like that of Ceratosauria of Late Triassic age. The skeletons of first Dinosauria, diversified already well, are known in summit Ladinian and lower Carnien and those of their ancestors, Dinosauriformes, in Ladinian. And, for this reason, the aniso-ladinian dinosauroid footprints are ascribed to these last animals which thus appeared earlier, to Anisan even to late Olenekian. The chirotheroid hands show a "pseudosuchian" origin which possibly took place during the late Olenekian; feet modifications of these Crurotarsi being characterized by I and V digits reduction and a meso-tarsal joint. The Anisian-Ladinian dinosauroid footprints are ascribed to the ichnospecies Coelurosaurichnus perriauxi and Anchisauripus bibractensis. The discriminant analysis computed from these latter ichnospecies, and others from the German Triassic, French and USA Hettangian indicate that C. perriauxi and A. bibractensis can not be included into Grallator sensu Lull, 1953 or Coelurosaurichnus of Franconie. By this way, these taxa are well original and till now, there was no reason to change their nomenclature. Nevertheless because the numerous changes of Grallator which gathers now, most of dinosauroid footprints, it could be possible to include them into Grallator for the feet and into Atreipus when the manus trace is connected with the foot.

Theriosuchus (Atoposauridae, Crocodylomorpha)

2005-10-07T07:41:00.000-05:00

A new species of Theriosuchus (Atoposauridae, Crocodylomorpha) from the Late Jurassic (Kimmeridgian) of Guimarota, Portugal

Daniela Schwarz and Steven W. Salisbury

A new species of an atoposaurid crocodilian, Theriosuchus guimarotae, is described from the Late Jurassic (Kimmeridgian) of Portugal. Theriosuchus guimarotae can be distinguished from other species of Theriosuchus by a lateral surface of squamosal bevelled ventrally; a rounded, caudally projecting and dorsally sculptured caudolateral corner of the squamosal; a premaxillomaxillary suture aligned caudomedially in dorsal aspect; a minimum space between the supratemporal foramina that comprises one third of the total width of the cranial table; a minimum width of the frontal between the orbits that comprises one third of the maximum width of the skull at the orbits; a dentition that comprises only pseudocaniniform and lanceolate-shaped teeth; the presence of an external mandibular fenestra and all vertebral bodies amphicoelous. Its osteology also sheds light on the diagnosis of Theriosuchus within Atoposauridae.
The material additionally includes specimens representative of several ontogenetic stages, each of which is discussed here. With its Late Jurassic age, T. guimarotae represents the oldest well-preserved material of Theriosuchus and reveals further knowledge about the palaeobiogeography of the genus in western Europe.

Ornitisquio "fabrosaurido" de Sud Africa

2005-10-07T07:37:00.000-05:00

The ‘fabrosaurid’ ornithischian dinosaurs of the Upper Elliot Formation (Lower Jurassic) of South Africa and Lesotho

RICHARD J. BUTLER

Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK, and Department of Palaeontology, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK

The Upper Elliot Formation of South Africa and Lesotho contains the world’s most diverse fauna of early Jurassic ornithischian dinosaurs. Nevertheless, despite four decades of work on this fauna there remains significant taxonomic confusion and many important specimens remain undescribed. A review of the non-heterodontosaurid (‘fabrosaurid’) ornithischians of the Upper Elliot Formation is presented, following re-examination of all known ornithischian material from the Elliot Formation. ‘ Fabrosaurus australis’ is based upon a single undiagnostic dentary, and is here considered a nomen dubium

Lesothosaurus diagnosticus is considered to be valid and is rediagnosed based upon a unique combination of plesiomorphic and derived characteristics. Stormbergia dangershoeki gen. et. sp. nov. is described from three partial skeletons including numerous postcranial material. Stormbergia dangershoeki is significantly larger than previously described Elliot Formation ornithischians, and can be recognized on the basis of a unique combination of characters, the most important of which is the possession of a distinctive tabshaped obturator process on the ischium. A preliminary systematic analysis is presented, the results of which differ significantly from other recent ornithischian phylogenies.
© 2005 The Linnean Society of London, Zoological Journal of the Linnean Society , 2005,

Hallan los fósiles de dos nuevas especies de reptiles voladores

2005-10-07T07:27:00.000-05:00

Un equipo de científicos brasileños ha identificado en China dos especies de reptiles voladores que vivieron hace 120 millones de años y que, aparentemente, peleaban por el territorio con aves primitivas.

El descubrimiento de fósiles de estas dos especies hasta ahora no conocidas, del que también informa en su última edición la revista Nature, fue hecho en el marco de un acuerdo entre instituciones académicas de Brasil y China.

Las dos especies identificadas por los brasileños, el "Feilongus youngi" y el "Nurhachius ignaciobritoi", medían cerca de 2,5 metros de envergadura y se alimentaban básicamente de peces e insectos, dijeron los paleontólogos en una rueda de prensa en Río de Janeiro.

Ambos reptiles tenían una mandíbula de unos 33 centímetros de ancho, dientes afilados y alas de unos 2,4 metros, mientras que de la cabeza del "Feilongus" salían dos crestas.

Los fósiles fueron hallados en la región china de Liaoning, un rico yacimiento en donde han sido identificadas hasta ahora 2.000 ejemplares de 26 especies de aves primitivas y 140 ejemplares de 16 especies de "pterosauros" o reptiles voladores.

A partir de esa constatación los investigadores han elaborado una nueva teoría sobre la competencia y ocupación de esa zona por parte de aves primigenias y reptiles voladores durante el período cretácico.

Según el estudio, las regiones continentales eran dominadas por las aves y las zonas costeras por los reptiles voladores.

Ahora los investigadores tratan de descubrir si había enfrentamiento directo entre ambos grupos de animales, cuáles eras sus hábitos alimentarios y cuáles alimentos se disputaban.

El proyecto fue realizado en conjunto por investigadores del Instituto de Paleontología de Vertebrados y Paleonantropología de China, y por los brasileños Departamento Nacional de Producción Mineral y Museo Nacional de Brasil.

La investigación es resultado de un acuerdo de cooperación entre las academias de Ciencia de Brasil y China para investigar en conjunto las especies de reptiles voladores localizados por científicos chinos.

El equipo fue dirigido por el brasileño Alexander Kellner, del Museo Nacional de Río de Janeiro.

Paleoblog

2005-10-02T11:27:00.000-05:00

Excelentes fotos y artículos en este blog de Michael Ryan.

Un par de fotos como muestra de una expe en Mongolia.

Impresión de piel de Hadrosaurus que muestra arrugas

Huella de Hadrosaurus en la formación Nemegt

Pequeños huevos de dinosaurio

2005-10-01T20:11:00.000-05:00

Minute theropod eggs and embryo from the Lower Cretaceous of Thailand and the dinosaur-bird transition

Abstract: We report on very small fossil eggs from the Lower Cretaceous of Thailand, one of them containing a theropod embryo, which display a remarkable mosaic of characters. While the surficial ornamentation is typical of non-avian saurischian dinosaurs, the three-layered prismatic structure of the eggshell is currently known only in extant and fossil eggs associated with birds. These eggs, about the size of a goldfinch's, mirror at the reproductive level the retention of small body size that was paramount in the transition from non-avian theropods to birds. The egg-layer may have been a small feathered theropod similar to those recently found in China.

Patrones filogenéticos en Microestructuras del esmalte en dientes de dinosaurios

2005-10-01T20:04:00.000-05:00

Phylogenetic Patterns of Enamel Microstructure in Dinosaur Teeth
Sunny H. Hwang Division of Paleontology, American Museum of Natural History, New York, New York 10024

ABSTRACT: The tooth enamel microstructure of all the dinosaur taxa that are adequately represented in the American Museum of Natural History collections were analyzed using scanning electron microscopy. This study aims to determine whether or not better sampling within a major nonmammalian amniote (hereafter referred to descriptively as “reptile”) clade will unearth phylogenetic patterns in enamel microstructure in addition to those
dictated by tooth function. While interest in reptile enamel microstructure has increased in the past few years, intensive sampling focused on just one monophyletic reptile clade was not previously implemented. This study reveals that phylogenetic constraints play a larger
role in shaping enamel microstructure in reptiles than previously thought. Within many monophyletic dinosaur clades the combination of enamel types and enamel features
within a tooth "the schmelzmuster" is the same in all the taxa due to their common ancestry, and their schmelzmusters are diagnostic of their respective clades.
While distantly related taxa with similar teeth and diets have similar schmelzmusters due to functional constraints, phylogenetic constraints keep those schmelzmusters distinct from one another. An interesting finding of this analysis is that the enamel complexity of a taxon does
not necessarily coincide with the position of the taxon on a phylogenetic tree; more derived taxa do not necessarily have more derived enamel and more primitive taxa do not necessarily have more primitive enamel.

Oviraptor del sur de China

2005-10-01T19:59:00.000-05:00

A new oviraptorid (Theropoda: Oviraptorosauria) from the Upper Cretaceous of the Nanxiong Basin, Guangdong Province of southern China.
Lü, J. and Zhang, B.-K. 2005.
Acta Palaeontologica Sinica 44(3): 412-422.

ABSTRACT: "Shixinggia oblita" gen. et sp. nov. herein described was collected from Shixing County, Nanxiong Basin of Guangdong Province, southern China, by the Beijing Natural History Museum in 1995. It is characterized by a relatively short preacetabular process of the ilium compared with its postacetabular process, and relatively high ratio of the ilium height (above the center of the acetabulum) to its length, the ventral margins of the preacetabular and postacetabular processes are much higher than the dorsal margin of the acetabulum, however. "Shixinggia" shows a special character of large openings present on the anterior mesial surface of the trochanteric ridge in the femur, and the proximal end of the tibia, those openings are not reported in any known oviraptorosaurs. This is the second new genus of oviraptorosaurs from southern China in addition to "Heyuannia huangi", which was reported in 2003.

Cavidad endocranial en dinosaurios ornitisquios. Nueva evidencia

2005-09-20T17:50:00.000-05:00

New evidence on brain−endocranial cavity relationships in ornithischian dinosaurs

DAVID C. EVANS Evans, D.C. 2005. New evidence on brain−endocranial cavity relationships in ornithischian dinosaurs. Acta Palaeontologica Polonica 50 (3): 617–622.

Discussions of brain morphology and relative brain size in nonavian dinosaurs have been complicated by uncertainty in the extent to which the brain filled the endocranial cavity.Recently reported vascular imprints (valleculae) on the endocranial surfaces of the braincase suggest that nonavian maniraptoriform theropods had brains that tightly fit the endocranium. Similar impressions of the intracranial vascular system are reported here in two ornithischian clades, Hadrosauridae and Pachycephalosauridae. These structures are more widespread in dinosaurs than previously thought, and suggest that the brain closely fit the endocranium in some regions of the forebrain through hindbrain in several distantly related dinosaur groups.

Primer Saurópodo en Shan-Thai, Asia

2005-09-20T14:40:00.000-05:00

First dinosaur from the Shan-Thai Block of SE Asia: a Jurassic sauropod from the southern peninsula of Thailand

Eric Buffetaut, Varavudh Suteethorn, Haiyan Tong, Adrijan Kosir. Journal of the Geological Society. May 2005.Vol.162 Part 3.pg. 481, 4 pgs

A vertebra collected from the Jurassic non-marine Khlong Min Formation of southern Thailand is referred to the family Euhelopodidae, a group of sauropod dinosaurs that apparently was endemic to eastern Asia during the Jurassic and Early Cretaceous, at a time when that part of the world was isolated from other land masses. The occurrence of a euhelopodid in the Jurassic of the Shan-Thai Block supports the idea of a collision of the Shan-Thai Block with the Indochina Block, thus establishing connections with 'mainland Asia', early in the Mesozoic, probably before the Jurassic.

Nuevo Pterosaurio de la Isla de Wight

2005-09-20T12:19:00.000-05:00

A new pterodactyloid pterosaur from the Wessex Formation (Lower Cretaceous) of the Isle of Wight, England

Lorna Steel, David M. Martill, David M. Unwin and John D. Winch

Abstract: A new pterosaur specimen comprising a partial skull and associated postcranial elements from the Lower Cretaceous Wessex Formation of Yaverland, Isle of Wight, southern England, is assigned to a new genus and species of ornithocheirid pterosaur, Caulkicephalus trimicrodon gen. et sp. nov., based on several unique features including a heterodont dentition in which the fifth, sixth and seventh teeth are reduced in size compared with those at positions 1e4 and 8e9; the presence of a frontoparietal crest and maxillopremaxillary crest that do not unite over the antorbital fenestra or cranium; a palatal ridge that extends no further forward
than the eighth to ninth tooth pairs. The new taxon is the second species of pterosaur from the Wealden Group of the Wessex Basin.

Tomografía computarizada del endocráneo de Ceratosaurus

2005-09-19T13:22:00.000-05:00

The endocranium of the theropod dinosaur Ceratosaurus studied with computer tomography

Sanders, R. Kent, & David K. Smith, 2005.
Acta Palaeontologica Polonica 50 (3): 601-616

Abstract: A well preserved specimen of the theropod Ceratosaurus has
from the Upper JurassicMorrison Formation of western Colorado was
recently described and given the name C. magnicornis. The systematics
of the genus is outside the scope of the present study but, as a
generally accepted basal tetanuran, the braincase was CT scanned to
provide a description of the endocranium, inner ear, pneumatic, and
venous sinus systems in a primitivemember of this clade. Fivemajor
subregions of the theropod endocranium are distinguished for the
purpose of simplifying cranial computed tomographic interpretation and
to provide a systematic means of comparison to other endocrania. The
skull morphology of Ceratosaurus influences the overall braincase
morphology and the number and distribution of the major foramina. The
low pontine angle and relatively unflexed braincase is considered a
more primitive character. The orientation of the horizontal
semicircular canal confirms a rather horizontal and unerect posture of
the head and neck.As in birds, the narrower skullmorphology of
Ceratosaurus is associated with fewer cranial nerve foramina.
Additionally, the maxillary dominated dentigerous upper jaw of
Ceratosaurus is felt to share with the alligator a large rostrally
directed maxillary division of the trigeminal nerve and a small
ophthalmic branch. The upper bill of birds, being dominated by the
premaxillary and lacking teeth, is innervated predominantly by the
ophthalmic division of the trigeminal nerve. For this reason,
avian−based cranial nerve reconstructions are felt to be inappro−
priate for basal theropods. Ceratosaurus skull pneumatization and
possible evidence of olfactory conchal structures is on the other hand
very avian in character. Based on computed tomography, Ceratosaurus is
determined to have possessed a typical basal theropod endocranium and
bipedal vestibular system similar to Allosaurus.

18 Metros de Pterosaurio !!

2005-09-09T10:13:00.000-05:00

Fragmentos de huesos encontrados en Israel, Rumanía y Brasil permiten dimensionar la envergadura de este Pterosaurio en mas o menos 18 metros.
Los hallazgos fueron presentados en Dublín para la reunión anual de la Asociación Británica para el Avance de la Ciencia.

Distribución espaciotemporal de saurópodos primitivos (resúmen)

2005-09-06T19:56:00.000-05:00

Integrating ichnofossil and body fossil records to estimate locomotor posture and spatiotemporal distribution of early sauropod dinosaurs: a stratocladistic approach
Jeffrey A. Wilson

Abstract: Fossil vertebrate distributions are typically based on body fossils, which are often poorly sampled at the margins of their true temporal and spatial ranges. Because vertebrate ichnofossils can be preserved in great abundance and in different environments than vertebrate body fossils, inclusion of ichnofossil data may improve sampled ranges. However, if ichnofossils are to serve as an independent source of distributional data, then their attribution to a body fossil group (i.e., trackmaker identification) cannot rely on temporal and spatial coincidence. Ichnofossils identified by synapomorphies can act as an independent source of distributional data that can modify spatial, temporal, and character distributions, which in turn may influence hypotheses of locomotor evolution.
In this paper I evaluate the spatial, temporal, and character distributions of early sauropod dinosaurs by using a combined ichnofossil and body fossil data set. Sauropod ichnofossils supplement the spatiotemporal distributions of early sauropods and provide important information on early sauropod foot posture that is rarely preserved or can only be inferred from body fossils. The presence of derived features in early-appearing ichnofossils challenges previous hypotheses of character transformation, implying either parallelism, reversal, or ghost lineages. Stratocladistics can be used to resolve conflicting character and temporal distributions frombody fossils and ichnofossils. Stratocladistic analysis of a combined ichnofossil and body fossil data set suggests a richer, more widely distributed diversity of early sauropods than currently recognized in body fossils and suggests that several locomotor characters originatedmuch earlier than implied by body fossils.

Jeffrey A. Wilson. Museum of Paleontology & Department of Geological Sciences, University of Michigan, 1109 Geddes Road, Ann Arbor, Michigan 48109-1079.

Función en las extremidades anteriores de Monoykus olecranus (resúmen)

2005-08-29T09:04:00.000-05:00

Function in the stunted forelimbs of Mononykus olecranus (Theropoda), a dinosaurian anteater. Senter, P. (2005). Paleobiology 31(3): 373-381.

Abstract: "Mononykus olecranus, a theropod dinosaur from the Upper Cretaceous of Mongolia, exhibits reduced forelimbs with a single functional digit. These bizarre forelimbs have aroused great curiosity as to the behavior of the animal, but until now no functional study on the forelimbs of Mononykus has been undertaken. Here I show that the orientation and range of motion in the forelimb elements of Mononykus are such that the humeri sprawl laterally, the antebrachia are held subvertically, the palms face ventrally, and intramanual movement is restricted to subparasagittal motion. This is a radical departure from the typical theropod condition, in which the palms face medially and intramanual movement is transverse. The results of this study confirm that the forelimbs of Mononykus could not have been used to grasp prey or dig burrows, but were well suited for scratch-digging or hook-and-pull movements such as are used by extant anteaters and pangolins to open tough insect nests. Mononykus likely occupied a niche equivalent to that of an anteater or pangolin, an unusual niche for a dinosaur."

Nuevos restos de Ornitisquio en el sur de Africa (Abstarcto)

2005-08-28T18:48:00.000-05:00

NEW ORNITHISCHIAN REMAINS FROM THE UPPER ELLIOT FORMATION (LOWER JURASSIC) OF LESOTHO AND STRATIGRAPHICAI, DISTRIBUTION OF SOUTHERN AFRICAN FABROSAURIDS

FABIEN KNOLL, BERNARD BATTAIL
Knoll, F., Battail, B., 2001. New ornithischian remains from the Upper Elliot Formation (Lower Jurassic) of Lesotho and stratigraphical distribution of southern African fabrosaurids.

Abstract: Unpublished postcranial dinosaur material from the Upper Elliot Formation (Hettangian) of Likhoele Mountain (Mafeteng district, Lesotho) is described. The bone assemblage includes elements from both the axial (centra) and appendicular (ilium, femora, tibiae, fibula) skeleton, from, at least, three individuals. Although being clearly ornithischian, the specimens do not belong to heterodontosaurids. They rather appear close to Lesothosaurus diagnosticus. The stratigraphical distribution of southern African fabrosaurids is also discussed on the basis of both the skeletal and ichnological record. © 2001 Éditions scientifiques et m6dicales Elsevier SAS

Nuevo Hadrosaurio Primitivo (abstracto)

2005-08-27T12:52:00.000-05:00

A new primitive hadrosauroid dinosaur from the Early Cretaceous of Inner Mongolia (P.R. China)

Pascal Godefroit, Hong Li, Chang-Yong Shang
a Department of Palaeontology, Institut royal des sciences naturelles de Belgique, rue Vautier 29, 1000 Bruxelles, Belgium Inner Mongolia Museum, Xinhua street 2, Hohhot 010020, People’s Republic of China Received March 2005; accepted 5 July 2005

Abstract: The right dentary of a new hadrosauroid dinosaur, Penelopognathus weishampeli, has been discovered in the Bayan Gobi Formation (Albian, Lower Cretaceous) of Inner Mongolia (P.R. China). This new taxon is characterised by its elongated, straight dental ramus, whose lateral side is pierced by about 20 irregularly distributed foramina. Its dentary teeth appear more primitive than those of Probactrosaurus, but more advanced than those of Altirhinus, both also from the Lower Cretaceous of the Gobi area. Non-hadrosaurid Hadrosauroidea were already well diversified in eastern Asia by Early Cretaceous time, suggesting an Asian origin for the hadrosauroid clade.

To cite this article: P. Godefroit et al., C. R. Palevol 4 (2005).
© 2005 Published by Elsevier SAS on behalf of Académie des sciences.

Redescripción de Nemegtosaurus (Abtracto)

2005-08-26T14:01:00.000-05:00

Wilson, J.A. (2005). Redescription of the Mongolian sauropod "Nemegtosaurus mongoliensis" Nowinski (Dinosauria: Saurischia) and comments on Late Cretaceous sauropod diversity. Journal of Systematic Palaeontology 3: 283-318.

Abstract: "The isolated skulls of "Nemegtosaurus mongoliensis" and "Quaesitosaurus orientalis" from the Nemegt Basin of Mongolia are among the most complete sauropod cranial remains known from the Late Cretaceous, yet their evolutionary relationships to other neosauropods have remained uncertain. Redescription of the skull of "Nemegtosaurus" identifies key features that link it and its closely related counterpart "Quaesitosaurus" to titanosaur sauropods. These include a posterolaterally orientated quadrate fossa, `rocker'-like palatobasal contact, pterygoid with reduced quadrate flange and a novel basisphenoidquadrate contact. Other features are exclusive to "Nemegtosaurus" and "Quaesitosaurus", such as the presence of a symphyseal eminence on the external aspect of the premaxillae, a highly vascularised tooth bearing portion of the maxilla, an enclosed `maxillary canal', orbital ornamentation on the postorbital, prefrontal and frontal, exclusion of the squamosal from the supratemporal fenestra and dentary teeth smaller in diameter than premaxillary and maxillary teeth.

"Re-examination of Late Cretaceous sauropod distributions in the light of this well-supported phylogenetic hypothesis has important implications for their diversity at the end of the Mesozoic in Asia and elsewhere. Cretaceous Asian sauropod faunas consist solely of titanosauriforms, which probably migrated there from other landmasses during the Late Jurassic, during which time neosauropods were absent from Asia. Globally, narrow-crowned titanosaurs and rebbachisaurids radiated during the Cretaceous, but only titanosaurs survived into the latest Cretaceous. These late-surviving sauropods flourished on most continental landmasses until the end of the Maastrichtian."

Amurosaurus riabinini

2005-08-05T07:54:00.000-05:00

Un equipo belga de paleontólogos descubrió, cerca del río Amour, en la frontera entre Rusia y China, un nuevo ejemplar de dinosaurio del grupo de los hadrosauros.

El equipo, compuesto por once aficionados y cuatro profesionales, que estaba dirigido por el paleontólogo Pascal Godefroit, del Instituto Real de Ciencias Naturales de Bélgica, realizó durante dos semanas excavaciones en la localidad rusa de Blagoveschensk, informó ayer un portavoz del organismo científico.

El mayor descubrimiento ha sido un gran número de huesos que pertenece a una especie hasta ahora desconocida de hadrosauro, que los investigadores han bautizado como Amurosaurus riabinini, por el nombre del río en el que fue encontrado y el del paleontólogo Andrey Riabinin.

En sus excavaciones, el equipo encontró varias costillas y vértebras, un radio, tres tendones, un pequeño hueso de una pata o una mano; una parte de mandíbula y de pómulo, así como otros huesos todavía no identificados.

Los huesos descubiertos serán analizados en Bélgica y luego devueltos a Rusia, aunque en el Museo de Ciencias Naturales de Bruselas se expondrán copias en escayola, se indica.

El equipo de paleontólogos también encontró en Blagosveschensk vértebras de algunos saurópodos y, según Godefroit, es la primera vez que se hallan vestigios de este animal en esa zona.

La desaparición de los dinosaurios, hace unos 65 millones de años, es todavía un enigma científico, pero el descubrimiento de ese nuevo ejemplar apunta a que poco antes de aquella remota época la especie no se estaba extinguiendo, lo que reafirmaría la teoría de un fin súbito debido a una catástrofe, como el impacto de un meteorito, según indica la versión científica acerca del que formó el cráter de Chicxulub.

Fuente: Diario de Yucatán

Identificados fósiles embrión dinosaurio de 190 millones de años

2005-07-29T09:16:00.000-05:00

Un equipo de científicos ha descubierto varios huevos con embriones fosilizados de dinosaurios en Sudáfrica, que datarían de hace 190 millones de años, es decir del período Jurásico, y, por ello, serían mucho más antiguos que otros conocidos, que se refieren a la época del Cretáceo.

Esta época del Cretáceo habría concluido hace 65 millones de años con la caída de un enorme meteorito, que pudo acabar con la existencia de los dinosaurios y hacer surgir los mamíferos y las aves primitivas, al final de la Era Mesozoica.

Las características de estos embriones fosilizados descubiertos en Sudáfrica delatan que los mismos corresponderían a dinosaurios 'Massospondylus', según desvela el equipo de investigadores responsable de este trabajo, dirigido por el científico Robert Reisz, miembro de la canadiense Universidad de Toronto, en Mississauga.

Según los resultados de este estudio que se publica mañana en la revista 'Science', los restos identificados de embriones de 'pro-saurópodos' tempranos desvelan evidencias de que esos animales salían del cascarón a cuatro patas al nacer, lo que contrastaría con su forma de moverse posteriormente en la edad adulta, que era sólo con dos extremidades.

En un artículo en esa revista, los autores de este trabajo indican además que en la edad adulta esos animales llegaban a medir aproximadamente cinco metros, y su cabeza, de pequeño tamaño, se apoyaba sobre un largo cuello.

Por el contrario, los nuevos datos de embriones de dinosaurio desvelan que estos nacían con extremidades delanteras y cabeza relativamente grandes, mientras que su cuello se mantenía en posición horizontal, al igual que su cola, de corta dimensión.

Ello implica que estos animales serían cuadrúpedos en sus movimientos al escapar del cascarón, lo que hace pensar a los expertos que los saurópodos tardíos, también con moción a cuatro patas, evolucionaron a partir de la preservación de este estado embrionario y de desarrollo inicial.

Según la investigación, las proporciones de los cuerpos de los embriones hallados, dotados de gran cabeza, hacen difícil pensar en la idea de que las crías podrían moverse sólo con dos extremidades una vez fuera del cascarón, ya que necesitarían al menos cuatro.

Con este trabajo, titulado 'Embriones de un dinosaurio prosaurópodo del Jurásico Temprano y su significado evolutivo', los científicos comprobaron además que apenas existen evidencias de la posible existencia de dientes en los restos de esos embriones identificados.

Ello les hace suponer a los expertos que las crías de esos dinosaurios habrían requerido un mínimo de atención y cuidados parentales durante un período de tiempo una vez fuera del huevo.

Fuente El Universal online

Huellas de un juvenil de saurópodo en Asturias, España

2005-07-24T13:13:00.000-05:00

Se trata de un saurópodo, una variedad cuadrúpeda y vegetariana del tamaño de un perro actual cuando se trata de un ejemplar adulto, pero en este caso se trata de un individuo recién salido del nido, indica José Carlos Martínez García-Ramos, director científico del Muja. El asegura que el hallazgo tiene "mucho interés" porque las huellas de saurópodo más pequeñas del mundo estaban documentadas con un tamaño de 18 centímetros, y las asturianas tienen 6 centímetros menos: cuentan con 12. Se trata de la longitud de la huella del pie.

Los científicos calculan que este bebé medía unos 60 centímetros de altura y contaba con pocos meses de vida. Hay muy pocos registros de saurópodos de poco tamaño, debido a que estos dinosaurios crecían de manera muy rápida en sus primeros años de vida.

Aún más. Estos bebés pesaban muy poco; eran ligerísimos y por tanto era difícil que su paso quedara marcado en el barro. Tuvo que darse la circunstancia de que este pequeño saurópodo atravesara por una gruesa capa de lodo. García-Ramos calcula que tenía un espesor de 12 centímetros, y que el autor de la pisada "no quedó enterrado de milagro".

Este experto, que es profesor de Estratigrafía de la facultad de Geología de la Universidad de Oviedo, indica que Martin Lockley, el más conocido especialista en huellas de dinosario del mundo, fue el que documentó las que hasta ahora se consideraban los rastros más pequeños. Aparecieron en Corea del Sur y miden 18 centímetros. A pesar de ser bastante mayores que las huellas ahora descubiertas en Asturias, Lockley, profesor de la Universidad de Denver (Colorado) las encontraba excepcionalmente pequeñas.

Este hallazgo será objeto de un trabajo que se presentará del 3 al 9 de octubre próximos en el Congreso Internacional sobre Dinosaurios y otros Vertebrados (Paleoicnología) que tendrá como sede Barcelona y una localidad francesa. Posteriormente se publicará en una revista científica.

Las huellas de este bebé dinosaurio se encontraron en acantilados próximos a Tazones y han sido rescatadas porque estaban situadas en una zona de difícil acceso y corrían peligro de desaparecer, ya que se trata de un área de frecuentes desprendimientos.

Una vez que estos rastros se preparen, se expondrán en el Muja. Son aproximadamente una decena de impresiones en barro fosilizado. Se trata de manos y pies del mismo ejemplar. La huella de la mano tiene forma de media luna, y la del pie es ovalada.

Actualmente trabaja con el equipo científico del Muja un experto en huellas de dinosaurios y otros reptiles, Marco Avanzini, que es director del departamento de Geología del Museo de Historia Natural de Trento. Prepara una publicación sobre algunos aspectos de comportamiento de los dinosaurios, a partir de huellas.

El trabajo se publicará en la revista americana Journal of Vertebrate Paleontology y está basado en trabajos realizados en el museo asturiano. Allí explicará cómo caminaban y colocaban los pies los dinosaurios, algo que no se puede estudiar a partir de huesos, sino de los rastros que dejan.

Los científicos del Muja tienen además en imprenta dos publicaciones más, una sobre huellas de tortuga del jurásico, y otra sobre rastros de cocodrilo del mismo periodo geológico. Aparecerán en la revista americana Ichnos y en Paleontología Polónica .

Noticia sacada del diario electrónico "La Voz de Asturias"

Fallece John Ostrom

2005-07-19T20:22:00.000-05:00

El sábado 16 de Julio en la mañana muere a la edad de 77 años el destacado palentólogo John Ostrom después de las complicaciones que tuvo con la enfermedad de Alzheimer.

El profesor Ostrom jugó un papel destacado en la década de 1970 al reinterpretar, gracias a sus estudios en la dinosauriología, la visión colectiva que se tenía aquel entonces de los dinosaurios. Los estudios de Ostrom y sus colegas nos dejaron un legado lleno de animales activos, inquietos, dinosaurios reales que desembocó en la dinosauriología moderna y sus protagonistas actuales. El padre del muy conocido depredador Deinonychus antirrhopus siempre mantuvo la idea de que las aves evolucionaron de los dinosaurios, idea propuesta anteriormente por Henry Huxley en 1860.

John Ostrom nació en 1928 y fué profesor de la Universidad de Yale para luego ser curador del Museo Peabody.

Nos unimos al sentir de todos los que directa o indirectamente conocimos la obra de este destacado personaje.

Buen viaje Doc... ahora conoce la verdad absoluta.

Sacos aéreos en Majungatholus atopus

2005-07-14T19:51:00.000-05:00

Los dinosaurios como el Tiranosaurio Rex tenían un sofisticado sistema respiratorio semejante al de las aves actuales. Así, al menos, lo sostiene un estudio aparecido ayer en la revista científica británica Nature. La investigación revela que los dinosaurios tenían bolsas de aire y huesos huecos que conectaban con los pulmones, lo que permitía una entrada constante de oxígeno y dinamizaba el metabolismo de esos animales prehistóricos.

Esta es una de las características que hacen que las aves tengan sangre caliente, por lo que el nuevo descubrimiento demuestra que entre los dinosaurios —ancestros de las aves— debía de haber al menos un mecanismo de sangre caliente. Aunque anteriormente ya se sabía de la existencia de huesos huecos en ciertos dinosaurios, no se tenía clara cuál era su función.

Leon Claessens, investigador de la Universidad de Harvard, explica que "el sistema pulmonar de los dinosaurios carnívoros como el Tiranosaurio Rex presenta muchas similitudes estructurales con el de las aves modernas". Y según Claessens, estas últimas parecen contar con "el sistema respiratorio más eficaz de todos los vertebrados vivos, terrestres o voladores".

Este hallazgo es el último de una serie de descubrimientos que han ayudado a crear una imagen del Tiranosaurio Rex —uno de los grandes "villanos" de películas como Jurassic Park— y otros dinosaurios terópodos mucho más cercana a la de las actuales aves.

Así, los científicos creen que ya en aquella época prehistórica pudieron existir muchas criaturas con alas, que incubaran huevos y que crecieran con un rápido "estirón", atributos característicos de las aves.

Sin embargo, también advirtieron que esto no significa que funcionaran con un sistema completamente de sangre caliente, sino que lo más probable es que el sistema fuera mixto, aunque su mecanismo respiratorio parece situarlos más cerca de los animales de sangre caliente.

Para su estudio, los investigadores examinaron fósiles que se encuentran en los museos de Nueva York, Berkeley (California), Chicago, Pittsburgh, Washington DC, Berlín y Londres, y los compararon con las estructuras óseas de las aves modernas.

También estudiaron un dinosaurio depredador que vivió en Madagascar hace 67 millones de años. Se trata de un "pariente lejano" del Tiranosaurio Rex, que vivió en la isla del sudeste de Africa. Era un cazador terrible, del tamaño de un pequeño autobús y dueño de una poderosa dentadura, que se alimentaba de carroña. Al parecer, atacaba y devoraba a otros dinosaurios como los titanosaurios, gigantescos herbívoros de cuello largo.

Fuente:

Clarín.com

Abstracto del artículo en Nature.com