The myth of the Parareptilia

The large reptile tree is not the first attempt at classifying Reptiles. It is only the most recent and the most comprehensive.

Earlier attempts invented the clade “Parareptilia,” a name coined by Olson in
1947 to refer to a group of pre-Triassic reptiles leaving no living descendants, as opposed to the Eureptilia, which included all living reptiles and their last common ancestors. This group included turtles.

Gauthier et al. (1988) attempting to understand Reptile relationships using cladistic analysis, and were among the first to do so. They divided the Amniota into Synapsida  and Sauroposida, then divided the Sauropsida into the Reptilia and Parareptilia.

Unfortunately testing in the large reptile tree (using more taxa) does not support these divisions and several new basal reptiles have been described since 1988.

No longer do synapsids split off first from the rest of the Reptilia. Now the new Archosauromorpha (chiefly insect-eaters) splits from the new Lepidosauromorpha (chiefly plant-eaters). The new Archosauromorpha includes the Synapsida, members of which evolve to become the Diapsida, which includes the Enaliosauria (Mesosauriadae + Sauropterygia + Ichthyopterygia and kin). The new Lepidosaurormorpha includes Captorhinidae, Diadectidae, Millerettidae, Lepidosauriformes and kin.

No longer are mesosaurs nested with procolophonids, but nest far from them with several other marine reptiles.

Laurin and Reisz (1995) revised the concept of the Parareptilia. In their cladogram the Synapaside split off first, followed by the Mesosauridae. The remaining taxa were considered Reptilia. Parareptilia included Millerettidae, Pareiasauria, Procolophonidae and Testudines (turtles). Their Eureptilia included Captorhininidae and Romeriida (Protorothyrididae and Diapsida).

Others (always including O. Rieppel) have moved turtles to the Sauropterygia.

When you stop including suprageneric taxa (and the dangers that follow that practice) and start including hundreds more generic taxa, new nesting patterns emerge, as demonstrated by the large reptile tree and all of its subset clades. All the groupings for Parareptilia proposed by earlier workers get split up and recombined in new patterns and clades. These new clades actually demonstrate the gradual accumulation of character traits for any and all derived taxa without introducing any “strange bedfellows.”

So the Parareptilia and its membership has been falsified in a larger, more comprehensive study. The utility of this term in paleontological work has been invalidated.

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.

Gauthier J, Kluge AG and Rowe T 1988. The early evolution of the Amniota. In M. J. Benton (ed.). The phylogeny and classification of the tetrapods, Volume 1: amphibians, reptiles, birds. 103-155. Oxford: Clarendon Press.
Laurin M, Reisz RR 1995. A reevaluation of early amniote phylogeny. Zoological Journal of the Linnean Society 113 (2): 165–223.
Olson EC 1947. The family Diadectidae and its bearing on the classification of reptiles. Fieldiana Geology 11: 1–53.


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