thought, that as soon as they were hatched, they would have to fend for themselves. Two "morphs" of Coelophysis have been identified: a more gracile form, as in specimen AMNH 7223, and a slightly more robust form, as in specimens AMNH 7224 and NMMNH P-42200. Skeletal proportions were different between these two forms; the gracile form has a longer skull, a longer neck, shorter forelimbs, and has sacral neural spines that are fused; and the robust form has a shorter skull, a shorter neck, longer forelimbs, and unfused sacral neural spines. Historically, many arguments have been made that this represents some sort of dimorphism in the population of Coelophysis, probably sexual dimorphism. Raath agreed that dimorphism in Coelophysis is evidenced by the size and structure of the forelimb. Rinehart et al. studied 15 individuals, and agreed that two morphs were present, even in juvenile specimens, and suggested that sexual dimorphism was present early in life, prior to sexual maturity. Rinehart concluded that the gracile form was female and the robust form was male based on differences in the sacral vertebrae of the gracile form, which allowed for greater flexibility for egg laying. Further support for this position was provided by an analysis showing that each morph comprised 50% of the population, as would be expected in a 50/50 sex ratio. However, more recent research has found that C. bauri and C. rhodesiensis had highly variable growth between individuals, with some specimens being larger in their immature phase than smaller adults were when completely mature; this indicates that the supposed presence of distinct morphs is simply the result of individual variation. This highly variable growth was likely ancestral to dinosaurs but later lost, and may have given such early dinosaurs an evolutionary advantage in surviving harsh environmental challenges. Reproduction Through the compilation and analysis of a database of nearly three dozen birds and reptiles, and comparison with existing data about the anatomy of Coelophysis Rinehart et al. (2009) drew the following conclusions. It was estimated that average egg of Coelophysis was 31–33.5 millimeters across its minor diameter, and that each female would lay between 24 and 26 eggs in each clutch. The evidence suggested that some parental care was necessary to nurture the relatively small hatchlings during the first year of life, where they would reach 1.5 meters in length by the end of their first growth stage. Coelophysis bauri invested