Dehnaripus incognitus, Abbassi & Salehi Tinooni & Ghorbani Dehnavi & Shakeri & Eshaghi, 2024

Abbassi, Nasrollah, Salehi Tinooni, Mohammad, Ghorbani Dehnavi, Mahdi, Shakeri, Safoora & Eshaghi, Ali, 2024, Oligocene vertebrate footprints from the Lower Red Formation, Central Iran, Fossil Record 27 (2), pp. 265-287 : 265-287

Ichnospecies Dehnaripus incognitus isp. nov.

Figs 5 , 6

Materials.

Seven pes and manus footprints of five trackways, in three slabs, sampled ( IFMI -683 / 1-3) .

Holotype.

Specimen No. IFMI -683 / 2 includes pes and manus imprints.

Etymology.

From Latin incognitus, meaning unknown.

Type-locality.

Iran, Esfahan (= Isfahan) province, Kashan township, west Ab Shirin, northwest Deh Nar, 34 ° 19 ' N – 38 ° 46 ' N, 51 ° 12 ' E.

Type horizon.

lower Oligocene (Rupelian).

Diagnosis.

As for ichnogenus.

Description.

Footprints preserved as mound-shaped convex hyporeliefs in the lower bedding plane of dark brown, thin to thick, fine-grained sandstone. Usually, the surface of footprints is marked by radial wrinkles, and identifying digit imprints is difficult; hence, measuring digital geometry is impossible. In special imaging, however, five-digit imprints in the manus and three-digit imprints in the pes are distinguishable. Dehnaripus incognitus was found in three slabs. Slab 1 was studied in the field, comprising two large footprints (Fig. 5 A ). The pes imprint in this slab is smaller, with three large and thick digit imprints, a small metatarsal imprint, and numerous radial wrinkles preserved in the proximal part of the pes imprint (Fig. 5 B ). The manus imprint is larger, showing five short digit imprints, completely connected to a large, circular metacarpal imprint. No claw imprints are visible in the digits, and the tips of digits are round (Fig. 5 C ). Slab 2 ( IFMI - 683 / 1) includes one manus imprint as a large mound-shape with large, radial five-digit imprints. The metacarpal imprint is not developed in the footprint (Fig. 5 D, E ). It is preserved as radial wrinkles and a rough imprint. Slab 3 includes two pairs of pes and manus imprints, belonging to separate trackways (Fig. 6 A ). One of them is slightly smaller (Holotype, IFMI - 683 / 2, Fig. 6 B, C ), and has large manus imprints, with short digit imprints and unclear outlines of digit imprints. It shows a large, circular metacarpal imprint. The pes imprint includes three-digit circular imprints without a clear metatarsal imprint. Another pes-manus set is larger and comprises pes and manus imprints ( IFMI - 683 / 3). Pes imprints show three-digit imprints without metatarsal imprints, and the manus is larger and has unclear outlines of digit imprints, but five-digit imprints are distinguishable (Fig. 6 D, E ).

Discussion.

Quality of preservation contributes to the unusual morphology of Dehnaripus incognitus , as circular imprints and unclear digit imprints. Definitely, the footprints are traces of the outer morphology of the feet, and the final morphology of a footprint is affected by trackmaker behavior, autopodia anatomy and substrate features ( Melchor 2015; Marchetti et al. 2019). The anatomical characteristics of the “ heel, ” control the sole morphology, thus controlling the morphology of footprints. Dehnaripus incognitus shows distinctive morphology, and we would rather consider it as a new ichnotaxon. Dehnaripus incognitus differs from Proboscipeda enigmatica by its smaller size and radial wrinkles and number of digit imprints. Dehnaripus incognitus differs from Glyptodontichnus pehuencoensis Aramayo et al. (2015) and Platykopus maxima ( Kordos 1985) by its number of unclear digit imprints.

Figures

Figure 5. Dehnaripus incognitus nov. A – C. Mound shaped footprints preserved as convex hyporeliefs in lower bedding plane of large slab, front footprints considered as pes and footprints behind as manus imprints; D, E. Preserved as convex hyporelief and including photogrammetric false-color depth map, sampled specimen, IFMI - 683 / 1.

Figure 6. Dehnaripus incognitus nov. in the studied block (A) and sampled parts of slab; B, C. Holotypes of pes and manus imprints with their photogrammetry photo (IFMI - 683 / 2); D, E. Other pes and manus imprints and including photogrammetric false-color depth map their photogrammetry photo (IFMI - 683 / 3).