Limnogyrinus elegans (Fritsch, 1881)

Milner, Andrew R. & Sequeira, Sandra E. K., 2003, On a small Cochleosaurus described as a large Limnogyrinus (Amphibia, Temnospondyli) from the Upper Carboniferous of the Czech Republic, Acta Palaeontologica Polonica 48 (1), pp. 143-147 : 146-147

L. elegans

Emended diagnosis.—A species of Limnogyrinus with the following characters: Skull length from 7–21 mm. Orbits situated in the anterior half of the skull. Snout short and blunt. Frontals short. Postfrontal expanded posterolaterally. Postorbital as long as wide. Maxilla with 35–40 teeth, the fifth from the frontal is enlarged. Occipital shelf is a narrow strip or forms paired lappets.

The remainder of each diagnosis is unaffected, Werneburg’s palatal, mandibular and postcranial characteristics being taken from genuine Limnogyrinus specimens.

The third consequence concerns our understanding of dissorophoid ontogeny. There has been a recent resurgence ofinterestinthegrowthseriesofearlyamphibiansandtheinformation that they may convey about the origins of metamorphosis ( Carroll et al. 1999; Boy and Sues 2000; Steyer 2000; Schoch 2001 and in press). Plausible growth series of single taxa are still very infrequent in the fossil record, so it is most important that those which appear to be present are genuine, and not composed of more than one genus, otherwise there is no prospect of making sense of the ontogeny of early tetrapods. Steyer (2000: 459) discussed this as a problem of associating larvae with named adults. In this instance, the problem is actually the misassociation of a large specimen with named smaller specimens. This problem is particularly acute in the study of the temnospondyls of the Nýřany assemblage because there are at least six genera present ( Cochleosaurus , Capetus , Branchiosaurus , Limnogyrinus , Platyrhinops , and Mordex ). Thus, although the Nýřany tetrapod assemblage is rich in temnospondyl larvae and juveniles and a potentially important source of ontogenetic series, its richness in taxa means that the specimens have to be described and studied with greater rigour.

Finally, the reidentification of this specimen has implications for phylogenetic analyses of dissorophoid relationships. These are in a state of flux ( Boy 1981; Milner 1990; Daly 1994). Micromelerpetontids have been argued to be the sister−group to the Branchiosauridae ( Boy 1981: fig. 5), a distinct primitive offshoot of the Dissorophoidea ( Milner 1990) and have been associated with the Amphibamidae as a part of that family ( Daly 1994). If the most primitive micromelerpetontid genus were to be represented in analyses by character−states found in a cochleosaurid skull, it is likely that micromelerpetontids would appear to be extremely primitive dissorophoids for entirely spurious reasons. They might also ultimately “attract” the Micromelerpetontidae and possibly the Dissorophoidea towards long−snouted temnospondyls in phylogenetic analyses, on the same incorrect basis. This is a good reason for not conducting phylogenetic analyses from information taken from the literature.