Amphicoelias

Whitlock, John A., 2011, A phylogenetic analysis of Diplodocoidea (Saurischia: Sauropoda), Zoological Journal of the Linnean Society 161 (4), pp. 872-915 : 887

AMPHICOELIAS

In addition to the unambiguous synapomorphy listed above (height of mid-dorsal neural spines twice centrum length), Amphicoelias shares an additional ambiguous synapomorphy with more derived diplodocoids: the greatest anteroposterior thickness of the femoral shaft is much greater than 50% of the anteroposterior depth of the distal articular condyles (character 179). The recovery of Amphicoelias as a basal diplodocoid agrees with the findings of Rauhut et al. (2005), although the latter result may hinge on one or two key scorings. As mentioned above, re-scoring Amazonsaurus in Rauhut et al.’s (2005) matrix results in the placement of Amphicoelias in a large polytomy with essentially all other eusauropods. Removing Amazonsaurus from the analysis of Rauhut et al. (2005) entirely returns fewer trees (324) and greater resolution in a strict consensus – the clades Macronaria and Rebbachisauridae + Flagellicaudata are both resolved – although there is still a large polytomy at the node above Shunosaurus that includes Amphicoelias . No other analysis has examined Amphicoelias using modern computational methods ( Table 2).