Triturus undetermined
Creators: name: Villa, Andrea
name: Macaluso, Loredana
name: Mörs, Thomas
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Amphibia
Caudata
Salamandridae
Triturus
Triturus undetermined

description: Triturus sp.
Figure 12
Material. Hambach 6C: one atlas (IPB-HaH 2196); 10 trunk vertebrae (IPB-HaH 2101/2103, IPB-HaH 2155, IPB-HaH 2163, IPB-HaH 2166/2167, IPB-HaH 2172/2173, IPB-HaH 2224); one caudal vertebra (IPB-HaH 2168).
Description. IPB-HaH 2196 (Figure 12 A-E) is a moderately small atlas (centrum length is 3 mm). The odontoid process is wide, gutter-shaped and bears two ventrolaterally directed articulation surfaces; it is roughly as large as the posterior cotyle and slightly narrower than the neural canal. The occipital joints, the posterior cotyle, and the neural canal are subcircular. The ventral surface shows only very rare and small foramina, and evident inferior crests (sensu Macaluso et al., 2020). The lateral surface of each lateral process shows a well-developed and sharp lateral crest. A low and wide neurapophysis is visible on the dorsal surface of the neural arch; it widens posteriorly and it is flanked by a secondary dorsal crest by each side. The latter touch the former by its posterior third and anteriorly they split into two low ridges. The dorsal portion of the neural arch is strongly sloping anteriorly in lateral view and thick and subtrapezoidal in posterior view. The postzygapophyses are subelliptical and very slightly tilted dorsally; their posterior margin develops beyond the posterior margin of the neural arch, which is slightly wavy in dorsal view.
Trunk vertebrae (Figure 12 F-O) are large in size (centrum length up to 7 mm). They are opisthocoelous and have a weakly developed neck and small subcentral foramina. Ventral and zygapophyseal crests are well developed. The transverse processes are moderately slender and posterolaterally directed (more laterally in IPB-HaH 2172 and IPB-HaH 2173). The neural arch is moderately low in its anterior portion, but tends to rise abruptly posteriorly. The anterior margin is straight or concave and reaches the anterior half of the prezygapophyses. The posterior margin is well preserved only in IPB-HaH 2103 and IPB-HaH 2224: it does not show a medial notch, but instead it has either a convex outline (IPB-HaH 2103; Figure 12H) or a small posteriorly directed point (IPB-HaH 2224; Figure 12K). The margin does not reach the posterior end of the postzygapophyses in IPB-HaH 2224, but it is roughly aligned with the latter in IPB-HaH 2103 (and in IPB-HaH 2101 and IPB-HaH 2102 as well). Absence of the posterior notch can be supposed for other vertebrae as well based on less preserved posterior margins. Zygapophyses are suboval and subhorizontal. The neurapophysis is low and is present along the entire preserved portion of the neural arch, but starting at some distance from the anterior margin in at least some vertebrae (e.g., IPB-HaH 2101 and IPB-HaH 2102). The morphology of the caudal vertebra is similar to that of the trunk vertebrae.
Remarks. The above-described large and opisthocoelous trunk vertebrae provided with subcentral foramina (Ratnikov and Litvinchuk, 2007) are evidence for the presence of another rather large-sized salamandrid in the fossil material from Hambach 6C. The small atlas can be assigned to the same urodele family due to the following combination of features (Ratnikov and Litvinchuk, 2009): processus odontoideus gutter-shaped, with two ventrolateral articular surfaces; dorsal part of neural arch thick in posterior view; dorsal margin of neural arch anteriorly sloping in lateral view; presence of neurapophysis and well-developed secondary and lateral crests; posterior margin of the postzygapophyses extending beyond the posterior margin of the neural arch in dorsal view. Furthermore, all these vertebrae share Triturus features. These are, for the atlas (Ratnikov and Litvinchuk, 2009): dorsal margin of neural arch inclined; posterior margin of neural arch slightly wavy; lateral crests well developed; neurapophysis large and low; and subcircular neural canal. As far as the trunk vertebrae are concerned, on the other hand, they are (Ratnikov and Litvinchuk, 2007): condyle neck weakly developed; low neural arch, which rises posteriorly; and anterior margin of the neural arch either straight or concave in dorsal view, located at midlength of the prezygapophyses. A specific identification of the fossils is hindered by the scant knowledge of the comparative osteology of the genus Triturus, as well as by a set of differences observed with the few species for which axial bone morphology is known (data mainly from Ratnikov and Litvinchuk, 2007, 2009). The atlas from Hambach differs from Triturus cristatus (Laurenti, 1768) in the strongly evident inferior crests, from Triturus dobrogicus (Kiritzescu, 1903) in the larger size and the neurapophysis not disappearing posteriorly, and from Triturus karelinii (Strauch, 1870) in the secondary dorsal crests not reaching the posterior margin, the neural arch not arched in posterior view, and the absence of accessory crests on the lateral processes. It shares with T. karelinii the neurapophysis expanded in a sort of subtriangular area posteriorly and with T. dobrogicus the secondary dorsal crest not reaching the posterior margin, the inclination and orientation of the articular facets of the processus odontoideus, and the already mentioned strongly evident inferior crests. It also shares with both species, as well as with T. cristatus, the processus odontoideus that is as wide as the cotyle but narrower than neural canal and the inclined neural arch that is thick and subtrapezoid in posterior view. The trunk vertebrae differ from all T. cristatus, T. dobrogicus, and T. karelinii in the larger size and the well development of all crests, and from T. cristatus and T. dobrogicus only in the neurapophysis devoid of an increased development in its middle part. Triturus marmoratus (Latreille, 1800) has a posterior margin of the neural arch ending well anterior to the postzygapophyses (Holman, 1998), which is not always the case in the Hambach fossils. Moreover, the trunk vertebrae show some minor differences with all the known species of Triturus, as the shape of the postzygapophyses is narrow and drop-shaped in the Hambach fossils (L.M., pers. obs.). The caudal vertebra is here assigned to the same taxon as the rest of the material due to the morphological similarity shared with the trunk elements. Considering all of this, the Hambach Triturus may either be a new species or a member of a lineage the osteology of which is not deeply investigated (such as T. marmoratus, which currently reaches up to northwestern France in Western Europe; Sillero et al., 2014). Pending a more detailed comparison with other Triturus, both fossils and extant, the material is here only identified as Triturus sp.
Urodela indet.
Material. Hambach 6C: one dentary (IPB-HaH 2003); 27 trunk vertebrae (IPB-HaH 2075/2076, IPB-HaH 2107/2109, IPB-HaH 2122/2131, IPB-HaH 2143, IPB-HaH 2152/2154, IPB-HaH 2159/ 2160, IPB-HaH 2169, IPB-HaH 2176, IPB-HaH 2187/2188, IPB-HaH 2223); 28 caudal vertebrae (IPB-HaH 2077/2079, IPB-HaH 2104/2106, IPB-HaH 2132/2141, IPB-HaH 2146/2149, IPB-HaH 2161, IPB-HaH 2170/2171, IPB-HaH 2184/2186, IPB-HaH 2376/2377); two femurs (IPB-HaH 2047, IPB-HaH 2394); one tibia (IPB-HaH 2049); one indeterminate limb element (IPB-HaH 2040).
Remarks. The fossil material from Hambach 6C includes numerous urodele specimens that cannot be identified more precisely due to either poor preservational status or poor taxonomic significance.
description: Published as part of Villa, Andrea, Macaluso, Loredana & Mörs, Thomas, 2024, Miocene and Pliocene amphibians from Hambach (Germany): New evidence for a late Neogene refuge in northwestern Europe, pp. 1-56 in Palaeontologia Electronica (a 3) (a 3) 27 (1) on pages 17-19, DOI: 10.26879/1323, http://zenodo.org/record/10962296