The macroevolution of the Diplodocimorpha (Dinosauria; Sauropoda): a developmental model

Heterochrony was important in diplodocimorph evolution. The diplodocimorph skull might be the result of local heterochrony and heterotopy. In the postcranium, the high neural spines and short forelimbs can be explained by heterochrony also. One of the most interesting diplodocid heterochronic traits is their forked presacral neural spines, which may be paedomorphic. The small size of dicraeosaurines might be due to paedomorphosis, whereas the diplodocines are mostly peramorphic based on their large sizes.