Merifontichnus, Gand, Garric, Demathieu, and Ellenberger, 2000

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 : 805-806

cf. Merifontichnus isp.

Fig. 4

Material.—MCV 2, left pes-manus couple and right pes of a different step cycle, in convex hyporelief; Ulbe ( Italy), Lopingian.

Description.—Left pes-manus couple and right pedal impression preserved as convex hyporelief. The pes is long about 100 mm, pentadactyl, ectaxonic, with medial functionality, markedly wider than long. Digits are straight, relatively long, radially disposed, and show rounded terminations. Digit IV is the longest and similar in length to digit III, digit V is about as long as digit I. Digit I is parallel to the medial proximal margin of the sole. The sole is very short medially and longer in the external part; the sole proximal margin is straight to laterally convex. The manus is smaller, ectaxonic, markedly wider than long and probably pentadactyl. Digits are straight, relatively long, radially disposed, and show rounded terminations. Digit IV is the longest and similar in length to digit III, the palm is relatively short and oval in shape. The manus is inward-oriented compared to the pes.

Remarks.—The short sole/palm, the footprints wider than long, the long straight digits with enlarged terminations increasing in length from I to IV with subequal digits III–IV and relatively short pedal digit V, the disposition of pedal digit I parallel to the sole, the median lateral decrease in relief of the pes and the manus sensibly inward-oriented compared to the pes are typical of Merifontichnus Gand et al. 2000 , after the preliminary revision of Marchetti (2016).

The only appreciable difference of this material with the Kungurian–Guadalupian material referable to this ichnogenus is its distinct heteropody ( Newell et al. 1976; Gand et al. 2000, Marchetti et al. 2013, Marchetti 2016).

Waiting for a comprehensive ichnotaxonomic revision and because of the incomplete manual track, we tentatively classify these footprints as cf. Merifontichnus isp. A discussion of the differences with morphologically-similar ichnotaxa such as Hyloidichnus and Amphisauropus was recently exposed by Marchetti (2016). The studied material differs significantly from the ichnogenus Limnopus , too, mainly because of disposition/relative proportions of digits and sole length and shape. Moreover, a tetradactyl manus is unlikely, since the digit IV is the longest, whereas in Limnopus digit III is the longest.

A C B D 14.2 7.1 0.0 -9.8 -19.6

Several features are consistent with derived captorhinid producers, such as the long rigid digits terminating in enlarged rounded terminations, the short palm/sole, the median-lateral decrease in relief of the pes, and the ectaxonic tracks with digits III–IV of similar length ( Olson 1962; Sumida 1989; Holmes 2003). Additionally, the stout digits, the tracks wider than long and the convex proximal-lateral margin of the sole are consistent with the pedal structure of Moradisaurus . This last feature is probably due to the fusion of the calcaneum with the distal tarsal V, and the probable contact with the ground of part of the tarsus, due to a stronger vertical push on the appendicular skeleton ( O’Keefe et al. 2005).