SITIOS DE NIDIFICACIÓN DE DINOSAURIOS DE LA FORMACIÓN ALLEN (CRETÁCICO TARDÍO) PROVINCIA DE RÍO NEGRO, PATAGONIA, ARGENTINA

MARÍA EDITH SIMÓN, CLAUDIA MAGALHAES RIBEIRO, ALBERTO C. GARRIDO, RODOLFO A,. CORIA, LEONARDO SALGADO, RAÚL ORTIZ Y DANIEL CABAZA

Plaza Huincul, Neuquén

Jornada; XXI JORNADAS ARGENTINAS DE PALEONTOLOGÍA DE VERTEBRADOS; 2005

Comisión ad hoc

Twenty two different sites in two major areas of Río Negro Province (Salitral Ojo de Agua and Salitral de Santa Rosa-Salinas de Trapalcó), preserving eggs and eggshells from the Allen Formation (Upper Cretaceous) were studied, and five egg levels were identified. Three different types of eggshell were recognized. Eggs possessing thick eggshells of Type 1 are abundant in both areas, sometimes associated with eggs of thinner eggshells. Eggs of eggshell Type 1 are included in the oofamily Faveoloolithidae of the parataxonomic classification. Eggshell Type 2 is subdivided into two groups (Type 2A and 2B), mostly based on the mean thickness of the eggshells and other parameters. Eggs of eggshell Type 2 are assigned to the oofamily Megaloolithidae of the parataxonomic classification, and ascribed to titanosaurs.  A third type of eggshell (Type 3) is only recorded at one of the localities (Salitral Ojo de Agua, egg level 2). This eggshell type is intimately associated with theropod bones, and its microstructure agrees with an assignation to the Theropoda. It is assigned to the oofamily Elangotaloolithidae.