Parataxonomic review of the Upper Cretaceous dinosaur eggshells

1 comentarios Publicado por Leonardo Filippi en 14:03


Mariela S. Fernández and Ashu Khosla

The eggshell oospecies from India and Argentina are compared and reviewed in detail. These eggshells resemble each other in having a nodular outer surface ornamentation and clearly arched growth lines of the shell units. Microstructurally, the eggshell oospecies belonging to the oofamily Megaloolithidae shows fan-like shell units, which are sharply separated from each other throughout the thickness of the eggshell and can be traced up to the surface of the eggshell. Comparisons between four oospecies from India and Argentina reveal three groupings, which show similarities between megaloolithids of both countries: (1) Megaloolithus jabalpurensis, M. matleyi and M. patagonicus; (2) M. cylindricus, M. rahioliensis and Tipo 1d; and (3) M. megadermus and Tipo 1e. The other two types of eggshell oospecies from India and Argentina show partially fused external nodes and shell units. As a result, growth lines enter into the adjacent shell units with a marked concavity. A new oogenus Fusioolithus have been erected due to fusion between shell units and tubospherulitic morphotype, which include two new oospecies F. baghensis and F. berthei. Till date, morphostructurally, a total of 15 eggshell oospecies belonging to different oofamilies have been recorded from India and seven oospecies from Argentina.

Mariela S. Fernández & Ashu Khosla, Historical Biology (2014): Parataxonomic review of the Upper Cretaceous dinosaur eggshells belonging to the oofamily Megaloolithidae from India and Argentina, Historical Biology: An International Journal of Paleobiology, DOI: 10.1080/08912963.2013.871718.

 

A new titanosaur from Neuquén Basin of Mendoza Province

0 comentarios Publicado por Leonardo Filippi en 12:23

 
 
 
Bernardo González Riga y Leonardo Ortíz David

Quetecsaurus rusconii gen. et sp. nov. is a new titanosaur (Dinosauria, Sauropoda) from the Neuquén Basin of Mendoza Province, Argentina. The specimen comes from red mudstones of the Cerro Lisandro Formation (middle-late Turonian, Upper Cretaceous), and is the first sauropod with well-preserved remains to be discovered in this formation. The holotype includes a postorbital, teeth, the atlas, a posterior cervical vertebra, an incomplete dorsal vertebra, a posterior caudal centrum, dorsal ribs, a coracoid, fragments of a humerus, radius and ulna, and five metacarpals. It is characterized by the following combination of autapomorphies: (1) intercentrum of atlas with a prominent anteroventral border and expanded posteroventral processes; (2) posterior cervical neural spines with incipient lateral expansions; and (3) humerus with strongly sigmoid proximal border, rounded proximomedial border, and angular proximolateral corner. A preliminary cladistic analysis placed Quetecsaurus as a sister taxon of Lognkosauria (Mendozasaurus + Futalognkosaurus). Quetecsaurus shares with the lognkosaurs the presence of cervical neural spines with ‘lateral laminae’, but relatively reduced in comparison with those taxa. This discovery provides new information on the diagnosis of Lognkosauria within South American titanosaurs.

González Riga, B. y Ortíz David, L. 2014.A New titanosaur (Dinosauria, Sauropoda) from the Upper Cretaceous (Cerro Lisandro Formation) of Mendoza Province, Argentina. Ameghiniana 51(1):3-25.

 

;;
Subscribe to: Entradas (Atom)