Figure 1. Click to enlarge. Atopodentatus and Claudiosaurus (ghosted) and the small one above Atopo’s shoulder to scale. Sometimes it just helps to compare sister taxa to see how far, and in what direction, they have come.
Earlier we looked at the latest Triassic marvel, Atopodentatus unicus. Today there’s a reconstruction (Fig. 1) alongside a more familiar and pleisomorphic Claudiosaurus for comparison.
Atopodentatus was bigger overall with a relatively larger and more robust torso and tail and a weaker shoulder girdle and pelvis, making it a slower swimmer, but more of a tail swimmer. The humerus was larger, but the antebrachium was smaller, so the forelimbs were likely acting as props rather than propulsive organs. The necks was longer and more flexible. Looks like the hands and feet had become paddles.
Those who suggested this was a filter-feeding bottom feeder were probably right on the money.
Look for more transitional taxa between these two in the future.
Cheng L, Chen XH,Shang QH and Wu XC 2014. A new marine reptile from the Triassic of China, with a highly specialized feeding adaptation. Naturwissenschaften. doi:10.1007/s00114-014-1148-4.