Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 87. (Budapest 1995)

Farkas, B.: Fossil trionychid turtle types in Hungarian collections - a preliminary review (Reptilia, Testudines)

In total, four "Hungarian" species have been described, the holotypes of two (Trionyx nopcsai, T. pseudovindobonensis) being deposited in the Paleontology Museum of the Hungarian Geological Survey (HGS), Budapest, while the original type material of the third (T. clavatomarginatus) is housed at the University of Cluj, Romania. The cast of one of the paratypes is available at HGS. The holotype of the fourth form (T harmati) has seemingly never been deposited in any public collection, and is assumed lost. For descriptions of the individual localities and the composition of their fauna consult MLYNARSKI (1966; but see below for remarks). SPECIES ACCOUNTS Trionyx nopcsai SZÁLAI, 1934 (Fig. 1) The "holotype" (HGS 3980) consists of a dentary fragment from the Miocene (Pannonian) of Brusturi (formerly Tataros), Transylvania, in present-day Romania. The carapace fragment mentioned by SZÁLAI (1934) is no longer associated with this specimen (probably part of "Trionyx sp." (HGS 3146) fide MLYNARSKI [1966]). Since SZÁLAI (op. cit.) clearly indicated the Hungarian National Museum as the holder of this fragment, this assumption seems unfounded. All material except that burnt in 1956 was transferred to the Hungarian Natural History Museum (HNHM). The validity of this species was questioned by MLYNARSKI (1966), who listed it among the "incerta" in his work. He believed it to represent Chelydra (now Chelydropsis) aff. C. decheni H. v. MEYER, rather than a soft-shelled turtle. Indeed, its dentary strongly resembles those of various Chelydropsis species depicted by DE BROIN (1977), and there is but little doubt that it actually represents one. In most members of the genus Trionyx (sensu lato) seen by me, the lingual ridge exposed nearly all of the underlying part of the dentary in dorsal view; it is exposed only at its tip in this specimen. The width of the triturating surface at its anteriormost portion is slightly greater than posteriorly. A symphyseal ridge is absent. Other fragments possibly referable to a chelydrid turtle have also been recovered at Brusturi (MLYNARSKI 1966, 1976). A similar faunal composition has been described for e.g. the Miocene (Upper Orleanium) of Appertshofen/N-Ingolstadt, Germany by GROESSENS-VAN DYCK & SCHLEICH (1985). Strictly considered, Trionyx nopcsai is a composite of two taxa belonging to two différent families. Trionychid carapace fragments are immediately recognized by their characteristic sculpturing. A somewhat similar pattern occurs also in the family Carettochelyidae, the Pleurosternidae and in an extinct group of pelomedusid pleurodirans (MEYLAN 1990), and is most probably associated with the loss of scutes. I have no doubt that the punctate carapace piece mentioned above actually belonged to a trionychid, even though the specimen is missing by now. The dentary fragment, as has been shown, is of a chelydrid. Since most of the original description is based on the latter, I regard it as the holotype of T. nopcsai, although not designated as such by SZÁLAI (1934). The carapace fragment is no longer available for examination and has no standing in nomenclature, so a tentative assignment of T. nopcsai to Chelydropsis cf. C. decheni (H. v. MEYER) on the authority of MLYNARSKI (1966) seems fully justified.