Falseryx undetermined
Makaleler > Tam Makale · 2021
Yazarlar: Georgalis, Georgios L., Čerňanský, Andrej, Serdar MAYDA
, Uluslararası, 2021
Özet
Falseryx sp. (Fig. 11) MATERIAL. — Turkey. Kargi 2: a posterior caudal vertebra (EUNMH PV 14071). DESCRIPTION The posterior caudal vertebra EUNMH PV 14071 is almost complete, missing only the distalmost edges of the prezygapophyses and pleurapophyses (Fig. 11). The vertebra is tiny with a centrum length of 2.1 mm and a neural arch width of 1.2 mm. In anterior view (Fig. 11A), the neural spine is high and rather thick; there is a slight dorsal thickening. The zygosphene is proportionally thin, narrow, and rather arched. The prezygapophyses are much dorsally inclined. The neural canal is almost subcircular. The cotyle is sub-elliptical and slightly laterally compressed. There are no paracotylar foramina. The pleurapophyses are broad and extend ventrolaterally. In posterior view (Fig. 11B), the neural arch is moderately vaulted. The cotyle is rather small, elliptical in shape, and laterally compressed. In dorsal view (Fig. 11C), the prezygapophyses extend much anteriorly, surpassing the level of the zygosphene. The prezygapophyseal articular facets are narrow and elongated. The base of the neural spine covers almost 2/3 of the mid-line of the neural arch, commencing well posteriorly from the level of the zygosphenal roof. The postzygapophyses are small and do not extend much laterally. A prominent tubercle-like bump is present on the dorsal surface of each of the postzygapophyses. The interzygapophyseal constriction is shallow. The posterior median notch of the neural arch is moderately deep. In ventral view (Fig. 11D), the vertebra is much elongated and narrow, being at least 1.7 times longer than wide. A haemal keel runs throughout much of the centrum. The postzygapophyseal articular facets are narrow. The condyle is developed on a salient condylar neck. In lateral view (Fig. 11E), the neural spine is high at it anterior edge and gradually diminishes in height posteriorly, reaching its lowest level at its posteriormost edge. The interzygapophyseal ridges are almost straight. The haemal keel is prominent and projects ventrally, with this projection being most prominent at around its mid-level. COMMENTS The caudal vertebra EUNMH PV 14071 can be assigned to Falseryx on the basis of its small size, elongated centrum, and presence of a haemal keel instead of haemapophyses (Szyndlar & Rage 2003). Moreover, its small size and its elongation, along with the presence of the haemal keel (and not haemapophyses) and pleurapophyses, denote an origination of the vertebra from the posterior caudal region. Note that the genus Rottophis Szyndlar & Böhme, 1996, from the late Oligocene of Germany, has also caudal vertebrae with haemal keels (instead of paired haemapophyses), with the posteriormost ones having the tips of these keels grooved or slightly bifurcated (Szyndlar & Böhme 1996; Szyndlar et al. 2008). The Anatolian specimen lacks this kind of grooves or bifurcation on its haemal keel, therefore we can exclude its referral to Rottophis. Although a generic attribution of this vertebra to Falseryx seems relatively favorable, a more precise determination is a difficult task on the basis of such limited material. Nevertheless, it seems that the Kargi 2 Falseryx is different from the two named species of the genus, i.e., Falseryx petersbuchi Szyndlar & Rage, 2003, from the early Miocene of Germany and Czech Republic (Szyndlar & Rage 2003; Szyndlar et al. 2008), and Falseryx neervelpensis Szyndlar, Smith & Rage, 2008, from the early Oligocene of Belgium (Szyndlar et al. 2008) in terms of the shape of the neural spine and the convexity and thinness of the zygosphene. Indeed, the height of the neural arch that is an interesting feature. It seems that the Kargi 2 specimen approaches more in morphology the posterior caudal vertebrae of Falseryx described recently from the earliest Miocene (MN 1) of Kılçak, near Ankara (Syromyatnikova et al. 2019a). We tentatively consider the two Anatolian forms as conspecific, although certainly more vertebrae from Kargi 2 are needed in order to confirm such assumption.