What is Aphelosaurus? Something new and something old.
Aphelosaurus lutevensis (Gervais 1859, Falconnet and Steyer 2007, Early Permian 290 mya) has been known for a long, long time and was described as an enigmatic reptile from the Lower Permian. It is represented by a headless, neckless, tail-less but otherwise completely articulated skeleton. Falconnet and Steyer (2007) considered it an araeoscelidian, but not quite one, and the large reptile tree bears this out. Aphelosaurus nests at their base. That makes it a basal diapsid. Those tiny medial fingers and toes are dead giveaways.
Falconnet and Steyer (2007) considered Aphelosaurus a probable biped and a possible arboreal type. Outgroups were likely both, but also this clade strangely led to marine types, as noted earlier. They did not recognize Eudibamus as an early diapsid. I sure would like to see that specimen up close.
Figure 1. Click to enlarge. Aphelosaurus and tracing. sacrals in blue. Image from Steyer 2012.
Here, overlooked by previous workers, the most interesting aspect of Aphelosaurus is a posteriorly elongate ilium, displaced from the sacrals here to align with several caudals. Don’t get your hopes up. No sisters had more than two sacrals. In this case, it’s a toss-up.
As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.
Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.
References
Falconnet J and Steyer J-S 2007. Revision, osteology and locomotion of Aphelosaurus, an enigmatic reptile from the Lower Permian of France. Journal of Morphology (abstract of the 8th International Congress of Vertebrate Morphology, Paris, July 2007): 38.
Gervais P 1859. Zoologie et paléontologie française – 2e édition. Bertrand, Paris, 544 pp.
Steyer S 2012. Earth before the dinosaurs. Indiana University Press, 182 pp.
2013-01-09 12:07:47
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