We computed rates of morphological evolution occurring across sauropodomorph evolutionary history, using phylogenetic ridge regression. Our results could have supported a slowdown correlated to the diversification of eusauropods, but this finding was extremely sensitive to temporal uncertainties.

Astragalus evolution in sauropodomorphs is also linked with pes reorganisation in sauropods, especially eusauropods, with the ankle articulation becoming subhorizontally oriented. It reminds the condition in elephants, with both groups sharing an extensive foot pad and a columnar limb architecture.

Size-related (allometric) morphological variation was consistent with increased body dimensions: a flatter distal articular surface and tighter connections with the tibia and the fibula.

Based on 3DGM shape analyses, our results suggest that the astragalus evolved alongside the emergence of gigantic columnar sauropods in a rather stepwise fashion, similarly to what we saw in the tibia & fibula in our previous study!