DINOSAUR NESTING SITES FROM THE ALLEN FORMATION (UPPER CRETACEOUS), RIO NEGRO PROVINCE, NORTHERN PATAGONIA, ARGENTINA

RIBEIRO, CLAUDIA MARIA MAGALHAES; SIMÓN, MARÍA EDITH; FERNÁNDEZ, MARIELA; SALGADO LEONARDO; CORIA, RODOLFO A.

Rio de Janeiro, Brazil.

Congreso; II Congresso Latino-Americano de Paleontología de Vertebrados; 2005

Museu Nacional-Rio de Janeiro

Dinosaur eggs and eggshells collected in several areas of Río Negro Province ( Salitral Ojo de Agua and Salitral de Santa Rosa-Salinas de Trapalcó), from fluvial successions of the Allen Formation (Upper Cretaceous), were studied. Distinct marphothypes were recognized. The thickest eggshells were classified in the oofamily Faveoloolithidae (Morphotype 1). Thinner eggshells, assigned to the oofamily Megaloolithidae (sauropods), were subdivided in two groups (Morphotype 2A and 2B)(Sauropod). Other eggshells belong to the oofamily Elongataloolithidae (Theropoda). The dinosaurs nesting sites of the Allen Formayion are widely distributed in Rio Negro Province, and this diversity of eggshells morphotypes was observed in five egg levels. The taphonomic aspects were also analized. In general, the eggshells are very well preserved, although diagenetic alteration is recorded, as dissolution and later precipitation of the calcite.