Ichthyosaura sp.

Ichthyosaura sp.

Figure 3 View Fig

Material. Spilia 4: two trunk vertebrae ( UU SP4 661 and UU SP4 663).

Description.

Te trunk vertebrae are moderately large ( Fig. 3 View Fig ). Te centrum is opisthocoelous and 3 mm long in the largest specimen (UU SP4 663; Fig. 3f View Fig ). Te anterior condyle has a flat and very poorly ventrally inclined anterior surface and a well-developed neck. In ventral view, a pair of subcentral foramina are visible on each side of the centrum. Te anterior ventral crests are moderately developed. Te posterior ones are not well preserved in any of the specimens, but in the best cases they appear only slightly less developed than the anterior ones. Te transverse processes are slender and posterolaterally directed. A small foramen is present anterior to them. Te zygapophyseal crests are well developed and straight. In anterior view, the neural canal is rather high and vaulted, being roughly as large as the anterior condyle. Te neural arch is high and rather flat dorsally. In lateral view, the portion dorsal to the level of the zygapophyses makes up about one third of total height of the vertebrae. In dorsal view, the anterior margin of the arch is concave and has its posteriormost point in correspondence with the end of the anterior fourth of the prezygapophyses. Te latter are rather wide, subelliptical and very slightly dorsally inclined. In dorsal view, they display diverging medial margins. Te neurapophysis is present, starting very far from the anterior margin of the neural arch (posterior to the end of the prezygapophyses). It appears rather low, but this is most probably due to its incomplete status. Te posterior margin of the neural arch is damaged, but it is preserved enough in at least some specimens to show that the neurapophysis was in contact with it. No expanded area is visible by the posterior end of the latter.

Remarks. A second, slightly larger, salamandrid taxon is represented in the Spilia 4 assemblage, by these vertebrae. Te combination of well-developed neck, anteriorlyinclined condyle, high neural arch, neurapophysis in contact with posterior margin of the neural arch, moderately to well-developed ventral and zygapophyseal crests, anterior zygapophyseal crests not bending ventrally to contact parapophyses, small foramen at the base of parapophyses, and elliptical prezygapophyses with diverging medial margins supports an identification as an indeterminate member of the genus Ichthyosaura (Macaluso et al., 2023b; Ratnikov & Litvinchuk, 2007). Ratnikov and Litvinchuk (2007) reported a straight anterior margin of the neural arch in Ichthyosaura alpestris (Laurenti, 1768) (their Mesotriton alpestris ), but Macaluso et. al. (2023b) mentioned variation in this feature, with precaudal vertebrae of this species displaying either a concave or a straight margin. Te concave anterior margin of the neural arch in these vertebrae from Spilia is thus not in conflict with an attribution to the genus.

Urodela indet.

Figures 4 View Fig , 5 View Fig

Material. Spilia 1: three fragmentary vertebrae ( UU SP1 1066– UU SP1 1068) and one humerus ( UU SP1 1065); Spilia 4: one dentary ( UU SP4 687), five trunk vertebrae ( UU SP4 662, UU SP4 686, UU SP4 688, UU SP4 717, and UU SP4 718), one caudal vertebra ( UU SP4 719), three humeri ( UU SP4 665, UU SP4 722, and UU SP4 723), three femora ( UU SP4 664, UU SP4 666, and UU SP4 721), and one tibia ( UU SP4 667).

Description.

Te dentary (UU SP4 687) from Spilia 4 is small ( Fig. 5a, b View Fig ). Only the anterior portion is preserved. Te crista dentalis shows a large number of small and closely-spaced tooth positions. Teeth were pleurodont, but they are not preserved. Medially, the canalis primordialis is almost completely closed in the preserved portion of the dentary; the incisura dentalis is represented only by a very narrow groove, which ends very far from the anterior end of the bone. A deep sulcus dentalis is present dorsally. It strongly deepens posteriorly due to a well-developed dorsal expansion of the bone present medial to the sulcus. Anteriorly, the mandibular symphysis is wide and subcircular, with a somehow flattened medial border. Te lateral surface seems to display a very light roughness, but this could be due to taphonomical processes rather than to the presence of a real sculpturing. A line of mental foramina is present at midheight. A very low ridge is present on the ventral surface of the dentary, starting from the symphysis and lowering posteriorly.

Te vertebrae from Spilia 1 ( Fig. 4 View Fig ) and Spilia 4

( Fig. 5d–f View Fig ) are too poorly preserved to provide a satisfactory description.

Te humeri from Spilia 1 and Spilia 4 are small to medium sized and rather slender. Only the proximal epiphysis is preserved in UU SP1 1065 and UU SP4 665, whereas the other two specimens are complete. Te processus dorsalis is preserved only in UU SP1 1065 and UU SP4 723 ( Fig. 5g View Fig ): it is rather short and either pointed ( UU SP4 723) or rounded ( UU SP1 1065). In anterior view, the crista ventralis is elongated and poorly inclined. Te distal epiphysis has a rather deep fossa cubitalis ventralis, whereas the fossa olecrani is very shallow .

Te femora from Spilia 4 are also medium sized and slender. UU SP4 666 and UU SP4 721 ( Fig. 5h View Fig ) preserve the proximal half, with a very deep fovea trochlearis, a shallow fovea dorsocaudalis, and a well-developed trochanter. Te caput femuris is well ossified. UU SP4 664 preserves the distal epiphysis alone, with a deep fossa intercondylaris.

Te small tibia (UU SP4 667) from Spilia 4 is moderately slender ( Fig. 5i, j View Fig ). It carries a very well-developed tibial crest, which reaches the distal epiphysis. Te free portion of the crest is missing. Te opposite surface of the tibia is smooth, devoid of any ridge.

Remarks. All these remains pertain to urodeles (Francis, 1934; Holman & Stuart, 1991; Macaluso et al., 2020, 2023b; Ratnikov & Litvinchuk, 2007). A more precise identification is hindered either by poor preservation or by the still poorly understood comparative osteology of these amphibians. Nevertheless, they likely belong to one of the two salamandrid urodeles identified from Spilia based on better preserved vertebral material.