Nycteroleteridae

Nycteroleteridae is a family of procolophonian parareptilians (extinct early reptiles) from the Middle to Late Permian of Russia and North America. They are sometimes classified as a sister group to pareiasaurids (but see Classification). The group includes the genera Macroleter, Bashkyroleter, "Bashkyroleter" mesensis, Nycteroleter, Emeroleter, and probably Rhipaeosaurus. They were carnivorous, and occasionally ate insects.[1] The group was most common in European Russia, with only a few fossils in North America. One fossil has also been found in Africa, but this is the only one from Gondwana.[2]

Nycteroleteridae
Temporal range:
Middle to Late Permian, 264–259.1 Ma
↓
Adult and juvenile skulls of Macroleter (=Tokosaurus)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: †Parareptilia
Order: †Procolophonomorpha
Clade: †Pareiasauromorpha
Family: †Nycteroleteridae
Romer, 1956
Genera[1]

†Bashkyroleter
†"Bashykroleter" mesensis
†Nycteroleter
†Emeroleter
†Macroleter
†Rhipaeosaurus

Classification

Nycteroleteridae is sometimes considered a sister group to the Pareiasauridae, but Bayesian inference suggests that it was in fact paraphyletic, with Rhipaeosaurus a basal member of the Pareiasauridae and other members of the Nycteroleteridae as outgroups. This is supported by the appearance of Rhipaeosaurus' skull and teeth - it had tricuspid teeth and multiple horns on the skull, resembling a pareiasaur but smaller and with a longer tail. For this reason it is often seen as intermediate between more primitive nycteroleterids and more advanced pareiasaurids such as Scutosaurus.[2]

Features

As discussed above, Nycteroleteridae technically includes all pareiasaurs as well as the five given genera. Within the five genera mentioned, there seems to be a smooth gradient of form from Macroleter to Rhipaeosaurus. Where Macroleter has no horns,Emeroleter has a few small horns, and Rhipaeosaurus' horns are quite large.[2]

However, there are some characteristic features of the Nycteroleteridae. They have a deeply incised otic notch, postparietal bones that enter the pineal opening, regular circular pits in the skull, and a row of palatal teeth from the interpterygoid vacuity to the edge of the choana.[2]

Examination of the nycteroleterids' middle ear bones and comparison with living amniotes showed that they probably had efficient impedance-matching hearing. This suggests that they may have been active at night or in dim-light environments. They are thought to have been carnivorous or insectivorous, but Rhipaeosaurus may have been an omnivore.[2]

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References
  1. Tsuji, L.A.; Müller, J.; Reisz, R.R. (2012). "Anatomy of Emeroleter levis and the Phylogeny of the Nycteroleter Parareptiles" (PDF). Journal of Vertebrate Paleontology. 32 (1): 45–67. doi:10.1080/02724634.2012.626004.
  2. "Palaeos Vertebrates Anapsida: Nycteroleteridae". palaeos.com. Retrieved 2018-02-16.


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