First Record of Elongatoolithidae Eggshell Fragments (Dinosauria) from Cuesta Corrales 2 (Lower Barremian, Teruel, Spain)

First International Symposium on Dinosaur eggs and Babies, 24-26 September 1999. Isona i Conda Dellà (Spain), 7-8.

FIRST RECORD OF ELONGATOOLITHIDAE EGGSHELL FRAGMENTS (DINOSAURIA) FROM CUESTA CORRALES 2 (LOWER BARREMIAN, TERUEL, SPAIN)

Amo , O., Canudo , J. I. & Cuenca-Bescós, G. Grupo Aragosaurus. Área y Museo de Paleontología, Universidad de Zaragoza. C/ Pedro Cerbuna s/n, 50.009 Zaragoza. Spain. [email protected] http://www.aragosaurus.com/

The site of Cuesta Corrales 2 is a new site situated at the top of the Castellar Formation in Galve (Teruel). The fossiliferous beds at the top of Castellar Formation are a rich fossil assemblage of mainly isolated bones and teeth, probably accumulated in an ancient lacustrine - palustrine environment of earliest Barremian in age. The rich vertebrate includes Pycnodontiformes, Ammiformes, Hybodontiformes, Amphibia, Crocodylia, Ornithopoda, Sauropoda, Theropoda, Mammalia, Quelonia and Sauria. Previous works about dinosaur eggshell fragments in this area are those of Kohring (1990), who studied the material from Colladico Blanco site, and Amo et al. (1999), who described a association of vertebrate eggshell fragments from Camino Canales site. Both localities are situated at the top of the Castellar Formation, very close to Cuesta Corrales 2. The Cuesta Corrales 2 site contains only dinosaur eggshell fragments. 414 fragments were collected from the surface. The fragments range from 0.25 to 1 cm2 in size. Forty four fragments were thin sectioned and twenty five were analysed under scanning electron microscopy. The thickness of the eggshell fragments varies from 0.40 to 1 mm excluding ornamentation and 0.55 to 1.45 mm including ornamentation. Thirty six fragments show dispersituberculate and coalescituberculate ornamentation with nodes of 0.3-0.7 mm in diameter. The rest of fragments show an outer surface with linearituberculate ornamentation. The pore system is of the angusticanaliculate type and it has pore canals ranging from 0.073 to 0.078 mm in diameter. The continuous layer to mammillary layer ratio (CL:ML) is of 2:1- 3:1 and the boundary of them is not abrupt but there is a change in structure. Horizontal accretion lines following the contour of the outer surface can be seen in the upper part of the shell. Near the pore canals the accretion lines are curved inward . The mammillae have diameters ranging from 0.13 to 0.27 mm. The continuous layer shows a columnar extinction pattern between nodes and wedge-like extinction under nodes and ridges under polarizing light. First International Symposium on Dinosaur eggs and Babies, 24-26 September 1999. Isona i Conda Dellà (Spain), 7-8.

In base of the homogeneity of this sample, the dinosaurian eggshells from Cuesta de los Corrales 2 are included into one type, which has been assigned to the parataxonomic family Elongatoolithidae. It is of the ratite morphotype within the ornithoid basic type. This type is characterized by angusticanaliculate pore system and the ratio CL:ML is 2:1 to 5:1. The Cuesta de los Corrales 2 eggshell fragments have the same pore system, whereas the ratio is in the lower values of the range. The Elongatoolithidae Family is well known in Upper Cretaceous localities and very rare in the Lower Cretaceous. Theare known only in the Lower Cretaceous of Mongolia (Trachoolithus faticanus Mikhailov, 1994) and China (?Elongatoolithus sp. Zhao, 1994). The eggshells from Cuesta de los Corrales 2 is the oldest occurrence of this Family and the first one in the Barremian of Europe.

References

Amo, O., Cuenca-Bescós, G. & Canudo, J. I. 1999. Vertebrate eggshell fragments from the Lower Cretaceous (Lower Barremian) of Camino Canales (Galve Basin, Teruel, Spain). IV European Workshop on Vertebrate Paleontology, Albarracín (Spain), 16.

Kohring, R., 1990. Fossile Reptil-Eirschalen (Chelonia, Crocodilia, Dinosauria) aus dem unterem Barremium von Galve (provinz Teruel, SE-Spanien). Paläontologische Zeitschrift, 64 (3/4), 392-344.

Mikhailov, K. E., 1994. Eggs of theropodian and protoceratopsian dinosaurs from Cretaceous deposits of Mongolia and Kazakhstan. Paleontologgical Journal 28 (3): 141-159.

Zhao, Z. 1994. Dinosaur eggs in China: on the structure and evolution of eggshells. In: Carpenter, K. Horner, J. & Hirsch, K. F (eds.): Dinosaur eggs and babies, Cambridge University Press: 184-203.