Abrictosaurus - Sexual Dimorphism

Sexual Dimorphism

The hypothesis of sexual dimorphism in heterodontosaurids has long centered on Abrictosaurus. Tusks are a sexually dimorphic trait in many modern mammals, including musk deer, walrus, Asian elephants and many pigs, with tusks being present primarily in males. The lack of tusks in UCL B54 led to suggestions that it was female; perhaps even a female of another species. The discovery of caniniforms in UCL A100 showed that A. consors also has this 'male' characteristic, suggesting that it is at least a valid species in its own right. However, UCL B54 may actually be a juvenile, based on its short face and unfused sacral (hip) vertebrae. Therefore, the lack of tusks could be a juvenile trait instead of a secondary sexual characteristic, weakening the case for sexual dimorphism.