Varanus sp.

Delfino, Massimo, Rage, Jean-Claude, Bolet, Arnau & Alba, David M., 2013, Synonymization of the Miocene varanid lizard Iberovaranus Hoffstetter, 1969 with Varanus Merrem, 1820, Acta Palaeontologica Polonica 58 (4), pp. 731-735 : 731-733

Varanus sp.

Figs. 1 , 2 .

1955 Ophisaurus sp. ; Crusafont et al. 1955: 237–238.

1969 Iberovaranus catalaunicus sp. nov.; Hoffstetter 1969: 1052, fig. 1.

1983 Iberovaranus catalaunicus Hoffstetter, 1969 ; Estes 1983: 182.

1974 Iberovaranus catalaunicus Hoffstetter, 1969 ; Antunes and Rage 1974: 52.

2004 Iberovaranus catalaunicus Hoffstetter, 1969 ; Molnar 2004: 36–37, fig. 2.11.

Material.— IPS 31701, cervical vertebra; IPS 58437, trunk vertebra, holotype of Iberovaranus catalaunicus Hoffstetter, 1969 from Can Mas, El Papiol, Barcelona, Spain, early Miocene .

Description.—IPS 58437, the type specimen of Iberovaranus catalaunicus , is an eroded, partial trunk vertebra ( Fig. 1 ). Only the base of the neural spine is preserved, and the surface of the centrum is broken at its right anterolateral sector. Conversely the synapophyses, prezygapophyses, left postzygapophysis, and the condyle are significantly eroded. The centrum is procoelous and slightly convex ventrally in transverse section. No foramina are evident. In ventral view, the centrum is approximately triangular in shape, with a clear precondylar constriction (width at the constriction 4.9 mm; maximum width of the cotyle 5.8 mm; ratio 0.84), reduced by the erosion of the condyle. The cotyle and condyle are depressed. The cotyle faces anteroventrally so that the inner surface of the cotyle is largely visible in ventral view, whereas the condyle shows a symmetric orientation with the surface only minimally exposed. Therefore, there is a significant difference between the minimum, 8.4 mm, and the maximum, 10.6 mm, centrum lengths (measures taken according to Bailon and Rage 1994, biased by the erosion of the vertebra). Prezygapophyseal facets are clearly tilted dorsally but their shape cannot be evaluated because of abrasion. The space between the prezygapophyseal facets and the neural spine is not markedly recessed. The anterior edge of the neural arch is slightly eroded (and asymmetric in dorsal view), but it seems likely that it was markedly tectiform in anterior view and approximately straight or slightly concave in dorsal view. There is no hint of a “pseudozygosphene” or of a structure similar to it (see Holmes et al. 2010). The posterior edge of the neural arch is rather high, with posterodorsal edges quite steep in posterior view. A “pseudozygantrum” is absent. The lateral erosion of the postzygapophyses (mostly of the left one) contributes to the narrowness of the posterior section of the neural arch. The best preserved postzygapophyseal facet is tilted at about 45 ° and ovalshaped. On the lateral and dorsal surfaces of the neural arch there are distinct “fibrous” striae, which are particularly evident possibly following moderate surface erosion (note that the apparent striae on the ventral surface of the centrum are not “fibrous” structures). Because the neural spine is broken at the base and the dorsal surface of the neural arch is eroded in the anterior sector, it cannot be confirmed that the neural spine was developed along the entire length of the neural arch as reported by Clos (1995). The thickness of the remnants of the neural spine suggests that it was likely developed only in the posterior half of the neural arch. The remnants of the synapophyses indicate that they were rather massive. The size of the neural canal, filled with matrix, cannot be evaluated.

IPS 31701 is a partially preserved posterior cervical vertebra from CMA previously catalogued as “cf. Testudo sp. ?” ( Fig. 2 ). The neural spine, the left parapophysis, and the pre− and postzygapophyses are broken off, but the ventral surface of the centrum is well preserved. The centrum, 9.5 mm long, is slightly convex transversely and not as triangular in shape as that of IPS 58437. A hint of a median keel is present in its anterior sector. The centrum has a distinct, obtuse precondylar constriction (width at the constriction 4.9 mm; maximum width of the cotyle 6.2 mm; ratio 0.78), which involves a significant portion of the lateral side of the centrum. The cotyle and condyle are markedly dorsoventrally depressed; although the dorsal rim of the cotyle, as preserved, did not overhang the preceding condyle, this is likely an artefact of erosion. The ventral edge of the condyle is close to the posterior edge of the centrum (so that only a little portion of the condyle is visible in ventral view). The synapophyses are massive, nearly vertical and strikingly laterally projected, so that the vertebra is 12.3 mm wide at their level. They are ventrally linked to the edge of the cotyle by a sub−horizontal ridge (“ventral parapophyseal lamina” in Houssaye et al. 2011). The diapophysis and parapophysis are well defined and slightly separated by a posterior concavity; the former is larger than the latter. Between the parapophyses and the rim of the cotyle there is shallow concavity posteromedially marked by a step.

Figures

Fig. 1. Varanid lizard Varanus sp. from Can Mas, early Miocene, IPS 58437; holotype of Iberovaranus catalaunicus Hoffstetter, 1969, a taxon here considered as taxonomically non valid. Trunk vertebra in dorsal (A), ventral (B), anterior (C), posterior (D), and left lateral (E) views.

Fig. 2. Varanid lizard Varanus sp. from Can Mas, early Miocene, IPS 31701. Cervical vertebra dorsal (A), ventral (B), anterior (C), posterior (D), and left lateral (E) views.