Moschops and Simosuchus convergence

Earlier we looked at several instances of convergence within the Reptilia. Here is another illustrated example.

Certain therapsids and crocodylomorphs became plant-eaters.
In doing so some converged on a short, squat body plan. Moschops (Broom 1911, Gregory 1926) is one such therapsid. Much smaller Simosuchus (Kraus and Kley 2010) is one such crocodylomorph (Fig.1).

Figure 1. Moschops (above) was a 2.7m long herbivorous therapsid. Simosuchus was a 75cm long herbivorous crocodylomorph.

Figure 1. Moschops (above) was a 2.7m long herbivorous therapsid. Simosuchus was a 50-75cm long herbivorous crocodylomorph with a similar body shape.

Though different in size,
both taxa evolved from longer, longer-tailed forms with longer jaws filled with sharp teeth. Tiny Simosuchus was armored. Moschops was not. Both taxa had an elevated skull, a deep, wide torso, sprawling limbs and a deep pelvis.

References
Broom R 1911. On some new South African Permian reptiles. Proceedings of the Zoological Society of London 81(4):1073-1082.
Gregory W 1926. The skeleton of Moschops capensis, a dinocephalian reptile from the Permian of South Africa. Bulletin of the American Museum of Natural History 56 (3): 179–251.
Krause DW and Kley NJ eds. 2010. Simosuchus clarki (Crocodyliformes: Notosuchia) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology 30, Supplement to Number 6: 236 pp.

2 thoughts on “Moschops and Simosuchus convergence

  1. I find it interesting that in the Permo-Triassic (pre-Carnian), the most common and successful body plan was short, squat, and ponderous, such as Moschops and therapsids generally, (but also including proterosuchian thecodonts) whereas post-Carnian the most successful body plan was long, lean and mean, including many gracile and bipedal crocs, and of course, the ancestral dinosaurs, culminating in the Late Triassic in rather large dinosaurs, such as Melanosaurus.

    To what do you attribute this morphological transformation, which came about rather quickly during the Mid-to-Late Triassic?

  2. I am impressed by the reduced oxygen content of the atmosphere after the Permo-Triassic event. Perhaps the origin of one-way breathing in archosaurs and the origin of the diaphragm in synapsids are responses to this. Your thoughts?

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