Everyone seems to agree that the Tyrannosaurus rex Sue was seriously debilitated with perhaps a lifelong lameness. Peter L. Larson attributes her survival to care and feeding by group members. Is there evidence of group care for the injured among reptiles of any era? Might Sue’s survival be due not to group care but simply to the fact that T. rex was a scavenger and not the terrible lizard we have been told about all these years? Lameness may not have been a serious handicap.

Jack Rankin
Round Hill, Va.

Many paleontologists believe there is strong fossil evidence that some types of dinosaurs moved in herds, bred in colonies, or cared for their young. All of these behaviors have been observed in living reptiles, says Gordon M. Burghardt, an ethologist at the University of Tennessee at Knoxville. For example, young green iguanas often move about in groups and sleep together, and crocodiles exhibit some parental care. However, there is no evidence that any modern reptile takes care of incapacitated adult kin, says Burghardt. —S. Perkins