Shell bone histology of the long-necked chelid Yaminuechelys (Testudines: Pleurodira) from the late Cretaceous-early Palaeocene of Patagonia

0 comentarios Publicado por Leonardo Filippi en 6:56

 
 

Juan Marcos Jannello, Ignacio A. Cerda, Marcelo S. de la Fuente

            Yaminuechelys is a long-necked chelid turtle whose remains have been recovered from outcrops of the Santonian- Maastrichtian and Danian of SouthAmerica.With the purpose of providing data about shell sculpturing origin and palaeoecology, the bone histology of several shell elements (including neural, costal, peripheral and plastral plates) of Yaminuechelys is described herein. Histological analysis reveals that Yaminuechelys shares with Chelidae the presence of interwoven structural fibre bundles in the external cortex, and parallel-fibred bone of the internal cortex. The presence of resorption lines in several samples indicates that the particular ornamentation of the external surfaces originated, at least in part, by focalized resorption and new bone deposition. This mechanism for ornamentation origin and maintenance is here described for the first time in a turtle. Compactness of the shell bones is consistent with an aquatic habitat, which supports previous hypothesis based on palaeoenvironmental and morphological data.

Janello, JM, Cerda, IA & de la Fuente, MS. 2016. Shell bone histology of the long-necked chelid Yaminuechelys (Testudines: Pleurodira) from the late Cretaceous—early Palaeocene of Patagonia with comments on the histogenesis of bone ornamentation. Sci Nat. 103:26.DOI 10.1007/s00114-016-1346-3.

 

New Peirosaurid from Cerro Lisandro Formation, Neuquén Group, Patagonia Argentina

0 comentarios Publicado por Leonardo Filippi en 6:36


Francisco Barrios, Ariana Paulina-Carabajal y Paula Bona

Peirosaurids are a group of Cretaceous continental crocodyliforms from Gondwana. Two species are known from the Neuquén Group in Argentina: Lomasuchus palpebrosus (Portezuelo Formation, late Turonian–early Coniacian) and Gasparinisuchus peirosauroides (Bajo de la Carpa and Anacleto formations, Santonian and early Campanian, respectively). Here, we describe the first peirosaurid from the Cerro Lisandro Formation, Bayomesasuchus hernandezi gen. et sp. nov. The material corresponds to a fragmentary skull and mandible. Although fragmentary, this is the most complete crocodyliform specimen recorded for the Cerro Lisandro Formation. In a phylogenetic analysis Bayomesasuchus is depicted in a polytomy together with South American peirosaurids and the African form Hamadasuchus rebouli.

Barrios, F. Paulina-Carabajal, A, y Bona Paula. 2016. A new Peirosaurid (Crocodyliformes, Mesoeucrocodylia) from the Upper Cretaceous of Patagonia, Argentina. Ameghiniana 53 (1):14-25.

 

A new theropod dinosaur from Patagonia

0 comentarios Publicado por Leonardo Filippi en 18:48

 
El Museo Municipal Argentino Urquiza ya tiene su primer dinosaurio terópodo
Ya se encuentra publicado en versión online el trabajo sobre este dinosaurio carnívoro, un nuevo abelisaurio, que proviene de La Invernada (Neuquén, Argentina) de rocas de la Formación Bajo de la Carpa. La excelente preservación y la significativa información que aportó el ejemplar resultaron relevantes para avanzar en el conocimiento de este grupo de terópodos, los abelisaurios. Viavenator ("cazador del camino") exxoni gen. et sp. nov. es el primero dado a conocer de una serie de ejemplares que han sido recuperados en la zona de La Invernada gracias al enorme apoyo de la empresa Exxonmobil.
Filippi, LS, Méndez, AH, Juárez Valieri, R. & Garrido, AC. 2016. A new brachyrostran with hypertrophied axial structures reveals an unexpected radiation of latest Cretaceous abelisaurids. Creataceous Research 61:209-219.

 

Gigantic new dinosaur from Argentina, Mendoza Province

0 comentarios Publicado por Leonardo Filippi en 12:40


Bernardo J. González Riga, Matthew C. Lamanna, Leonardo D. Ortiz David,
Jorge O. Calvo & Juan P. Coria

Titanosauria is an exceptionally diverse, globally-distributed clade of sauropod dinosaurs that includes the largest known land animals. Knowledge of titanosaurian pedal structure is critical to understanding the stance and locomotion of these enormous herbivores and, by extension, gigantic terrestrial vertebrates as a whole. However, completely preserved pedes are extremely rare among Titanosauria, especially as regards the truly giant members of the group. Here we describe Notocolossus gonzalezparejasi gen. et sp. nov. from the Upper Cretaceous of Mendoza Province, Argentina. With a powerfully-constructed humerus 1.76 m in length, Notocolossus is one of the largest known dinosaurs. Furthermore, the complete pes of the new taxon exhibits a strikingly compact, homogeneous metatarsus—seemingly adapted for bearing extraordinary weight—and truncated unguals, morphologies that are otherwise unknown in Sauropoda. The pes underwent a near-progressive reduction in the number of phalanges along the line to derived titanosaurs, eventually resulting in the reduced hind foot of these sauropods.

González Riga, BJ., Lamanna, MC., Ortiz David, LD., Calvo, JO. & Coria, JP. 2016 A gigantic new dinosaur from Argentina and the evolution of the sauropod hind foot. Nature. Scientific Reports. DOI: 10.1038/srep19165

 

Avanza la preparación del nuevo Titanosaurio

0 comentarios Publicado por Leonardo Filippi en 8:00


 
 
Continúan las tareas de preparación de fósiles en el MAU

Quienes visitan en estas vacaciones de verano el Museo Municipal Argentino Urquiza, Rincón de los Sauces, Neuquén, tienen la posibilidad de observar muy de cerca como se estan preparando los materiales recuperados en la última campaña paleontológica. Se trata de un ejemplar de dinosaurio Titanosaurio, conocido comunmente como "cuello largo", el cual se encontraba completo y articulado desde el cráneo hasta la cadera. Tanto la cola como las extremidades no fueron halladas en el sitio. Se espera que a finales de este año el ejemplar este completamente limpio para dar inicio a su estudio.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 

New fossil tooth assemblage from the Bajo de la Carpa Formation

0 comentarios Publicado por Leonardo Filippi en 7:49



Filippi, L. S, Martinelli, A & Garrido, A. C.

In this contribution, a fossil tooth assemblage from the Bajo de la Carpa Formation (Santonian, Upper Cretaceous) in a different paleoenvironmental context from that recorded at the Neuquén city and Paso Córdova localities (Patagonia, Argentina), is here presented. It includes isolated teeth of Dipnoi, represented by the species Ceratodus kaopen and Atlantoceratodus patagonicus; mesoeucrocodylian isolated teeth referred to Peirosauridae; and isolated teeth of Abelisauridae theropods and Titanosauria sauropods. The Mesoeucrocodylia, Abelisauridae and Titanosauria taxa are consistent with the fossil record of the region, represented by the Coloradoan tetrapod assemblage of Santonian to early Campanian age. However, the lungfish A. patagonicus represents the first occurrence for the Bajo de la Carpa Formation, being this record the oldest one for this taxón.

Filippi, L.S, Martinelli, A.G. y Garrido, A.C. 2015. Una nueva asociación de dientes vertebrados para la Formación Bajo de la Carpa (Santoniense, Cretácico Superior) en Rincón de los Sauces, Neuquén, Argentina. Revista Española de Paleontología 30 (2): 223-238.



 

 
 
 
 
 
 
 
 
 
 
 

 

A new cretaceous crocodyliform from La Rioja Province, Argentina

0 comentarios Publicado por Leonardo Filippi en 8:06


Lucas E. Fiorelli, Juan M. Leardi, E. Martín Hechenleitner, Diego Pol, Giorgio Basilici & Gerald Grellet-Tinner.

The Cretaceous witnessed the greatest diversity of Gondwanan notosuchian crocodyliforms, which displayed high levels of diversity and a notable array of specialized forms that developed in different ecological niches. Among this diversity, the advanced notosuchians are a clade of mid body sized forms which displays a remarkable abundance but is restricted to two lithological units from the Late Cretaceous of South America, the Adamantina Formation in southeastern Brazil and the Bajo de la Carpa Formation in Patagonia (Argentina). The only exceptions known so far were the Late Cretaceous Labidiosuchus from the Marilia Formation in Brazil and Yacarerani from the Cajones Formation in Bolivia. Herein we report a new Cretaceous crocodyliform, Llanosuchus tamaensis gen. nov. et sp. nov., found in the Los Llanos Formation (Campanian?) in northwestern Argentina (La Rioja Province). The small specimen includes well preserved fragments of the cranium and mandible with an estimated skull size of about 9 cm lengths. This crocodyliform shares several derived characters with Notosuchus terrestris from the Bajo de la Carpa Formation (Patagonia) and it was found in a weakly developed sandy paleosol profile formed in wet local conditions but in a region characterized by semi-arid climate and active eolian sedimentation. The presence of a new advanced notosuchian in the Cretaceous of western Gondwana, and its intermediate geographical region between the known South American species (Brazil, Argentina and Bolivia), has interesting implications, and adds another record of an advanced notosuchian in deposits with inferred warm climates and semi-arid paleoenvironments. Finally, Llanosuchus tamaensis supports a Late Cretaceous age for Los Llanos Formation with important geological implications for La Rioja Province.

L. E. Fiorelli, J. M. Leardi, E. M. Hechenleitner, D. Pol, G. Basilici & G. Grellet-Tinner 2016. A new Late Cretaceous crocodyliform from the western margin of Gondwana (La Rioja Province, Argentina). Cretaceous Research 60: 194-209.

 

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