Eureptilia

The subfamily Moradisaurinae comprises the most derived captorhinids and forms a monophyletic group. They are opposed to the "Captorhininae", the more basal, mainly single-tooth-rowed forms which closely resemble other generalized amniotes, such as Protorothyris or Hylonomus. The "captorhinines" are a paraphyletic group and therefore this term is only used for comparative purposes.

All moradisaurines are characterized by having multiple rows of teeth in their jaws which virtually form whole tooth batteries. The teeth are positioned on medially extended tooth plates formed by the maxillary and dentary bones. From this follows that these teeth are homologous to the teeth of the single tooth row seen in more basal captorhinids. However dentition on palatal bones, a common trait of basal amniotes, is greatly reduced or even entirely absent in moradisaurines. It has been speculated whether the medial margins of the upper tooth plates were connected to each other by a layer of soft tissue and formed a secondary palate in the living animal.

Because multiple tooth rows, however not in that great extent, also occur in captorhinids that fell outside the moradisaurine clade (e.g. in Captorhinus aguti) it seems that multiple tooth rows have evolved several times within captorhinids.

The teeth itself often show a distinct wear pattern. Wear facets occur just below the tip on both sides of the crown and sometimes reach down to the half of te crown's height. This quite regular wear pattern differs from the more irregular pattern observed in Captorhinus aguti and most likely was generated by the occlusion of opposing teeth of the upper and lower jaw in a way that one tooth row of the upper jaw fitted between two tooth rows of the lower jaw, and vice versa. This, in turn, is suggestive of changes in feeding behavior in the moradisaurines compared to their more generalized "captorhinine" ancestors (however, it is important to note that C. aguti is quite specialized already).

Most conclusive is to assume a herbivorous diet for the moradisaurines. However in most genera no postcranial elements are preserved which could provide evidence for that assumption, such as an expanded, barrel-shaped rib cage, appropriate for carrying an enlarged intestinal tract which would be required for digestion of plant material. Solely in Moradisaurus, the type genus of the subfamily, there are signs for modifications of the postcranial skeleton due to adaptation to herbivory. Its hindlimb is much more massive built than those of the "captorhinines". It resembles strongly that of an edaphosaur or a pareiasaur, both of which are Late Paleozoic, unequivocally herbivorous amniotes, hence this massiveness may not result from allometric scaling anlone. Alternative models of moradisaurine feeding behavior include omnivory or durophagy, the latter meaning that they used their tooth batteries to crush hard shelled invertebrates, such as clams or crabs, to achieve their meat.

Labidosaurikos meachami is a large, multiple-tooth-rowed captorhinid. It is the basalmost member of the subfamily Moradisaurinae. It is known from one single, however almost complete and virtually perfectly preserved skull coming from Lower Permian terrestrial deposits of central Oklahoma.

Scientific History: L. meachami has been discovered as early as in 1939 but has not been named and introduced to paleontology until 1950. Finally a detailed description of the skull has been published in 1995.

Skull: The heavily ornamented skull of L. meachami measures about 28 cm in length. Given that the trunk length in Captorhinus is approximately 3.6-fold the skull length, the overall body length in L. meachami was as much as 1.3 m. L. meachami shows almost the whole range of features which define the moradisaurines. Its snout is, compared to the posterior part of the skull, very narrow. Its dentigerous bones form wide tooth plates equipped with batteries of relatively small subconical teeth. The supratemporal is comparativley large and sculptured. The postparietal is not entirely overlapped dorsally by the parietal and its exposed portion is sculptured as well. Both supratemporal and postparietal contribute to the skull table in a way that the parietal is excluded from the posterior rim of that table. L. meachami, however, differs from the other well known moradisaurine Moradisaurus in retaining a band of small denticles on the posterior egde of the transverse flange ("wing") of the pterygoid. Another difference to Moradisaurus is the lateral wall of the mandible being only modestly bulged, however this bulge is still much more pronounced than in smaller moradisaurines such as Kahneria or Gecatogomphius.

Teeth: The only premaxillary tooth preserved is the largest tooth of the upper jaw and slightly recurved. The anteriormost dentary tooth is the largest of the lower jaw, however, only its base is preserved. The teeth of the maxillary and dentary tooth plates are arranged in six and five, respectively, longitudinal rows in which the teeth of two adjacent rows each alternate resulting in a chessboard-like pattern. Most of these teeth show distinctive wear facets. The teeth of the most labial row are exclusively worn on the lingual side whereas wear in the most lingual row is restricted to the labial side. Almost all teeth of the median rows are worn on both labial and lingual sides. This wear pattern is apparently the result of interdigitation of the tooth rows of upper and lower jaw. Thus it is very likely that the teeth were used for grinding fibrous plants.

A second species(?): A second species of Labidosaurikos, L. barkeri, has been described from the deepest part of the "Choza Formation" (upper part of Clear Fork Group) of North Texas in 1954 but has been questioned as early as 1959. It differs from L. meachami in having one less row of teeth in both maxillary and dentary. The material, however, is fragmentary. Given that the Texas specimens seem to be immature the number of tooth rows could be related to age. Because no further unequivocal difference between L. meachami and L. barkeri is as yet reported a revisional examination of the Texas fossils is needed to verify the validity of L. barkeri.