Rhynchosauroides, Maidwell, 1911

Marchetti, Lorenzo, Belvedere, Matteo & Mietto, Paolo, 2017, Lopingian tetrapod footprints from the Venetian Prealps, Italy: New discoveries in a largely incomplete panorama, Acta Palaeontologica Polonica 62 (4), pp. 801-817 : 809-810

Rhynchosauroides isp.

Fig. 7 .

Material.—MCV 4, right track; MCV 65, right manus, right track and possible straight tail impression; MGP-PD 25510; left manus and right track of the same step cycle; left pes and other two tracks of other step cycles, possible tail/ body impression; all tracks preserved in convex hyporelief; Merendaore ( Italy), Lopingian.

Description.—Semiplantigrade, pentadactyl manus with long digits markedly and continuously increasing in length from I to IV, distally bent medially and terminating in sharp, thin, and triangular claws in continuity with the digits. Digit V is thin, about as long as digit II, straight, outward-oriented and its base is separated and more proximal compared to the digit IV base. The palm is short and triangular in shape. Functional prevalence is medial. Incomplete pedal tracks and possible straight tail impressions associated with footprints were observed. All the tracks are preserved in convex hyporelief.

Remarks.—The ectaxonic manus showing long digits with sharp claws, the continuous increase in length between digits

–IV, the short palm, the digit V separated from the digit IV base and outward directed are typical of Rynchosauroides Maidwell, 1911. The lack of associated pedal impressions and the unclear ichnotaxonomic status of several Rynchosauroides species is the reason why we classified these tracks as Rhynchosauroides isp. This typical Lopingian–Mesozoic ichnogenus needs a comprehensive revision, because several ichnospecies were introduced but a few might have a real ichnotaxonomic meaning. The studied material was initially classified as Eumekichnium gampsodactylum ( Mietto, 1975) ; the genus Eumekichnium is presently considered a junior syn-

onym of Dromopus lacertoides ( Voigt, 2005) . However, the manual track of Dromopus differ significantly from that of Rhynchosauroides because it shows a digit IV much longer than digit III, it is semidigitigrade and is identical in morphology with the pes. Rhynchosauroides is the most abundant tracktype of the Val Gardena Sandstone; and in the type locality is usually referred to Rhynchosauroides pallinii Conti, Leonardi, Mariotti, and Nicosia, 1977 . A morphologically-similar ichnogenus is referred to Ganasauripus ladinus Valentini, Conti, and Mariotti, 2007 . The trackmakers were likely lacertoid neodiapsid eureptiles ( Valentini et al. 2007).

Figures

Fig. 7. Lacertoid neodiapsid eureptile trace Rhynchosauroides isp. (MCV 65) from Merendaore (Italy), Lopingian. Complete right manual impression. An incomplete track and a continuous tail are preserved on the same slab. Convex hyporelief (plaster cast), spacing 0.5 mm. Photo (A), interpretive drawing (B), contour lines (C), false-color depth map (D). Scale bar 10 mm.