Skeletal remains of a small theropod dinosaur with associated soft structures from the Lower Cretaceous Santana Formation of northeastern Brazil

Abstract

Associated well-preserved, uncrushed skeletal remains, comprising the pelvic girdle, partial sacrum, both femora, and parts of the right tibia and fibula, from the Romualdo Member of the Lower Cretaceous Santana Formation of northeastern Brazil record the presence of a previously unknown coelurosaurian theropod dinosaur in that formation. The pelvic girdle is noteworthy for the bilaterally asymmetrical development of various bony features. The specimen also preserves a segment of lithified intestinal tract. While still in the matrix, the fossil preserved a vacuity behind the pubic apron that may indicate the existence of a postpubic air sac.