Gruipeda dominguensis de Valais & Melchor, 2008

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 Gruipeda dominguensis de Valais & Melchor, 2008

Figs 2 , 4

Materials.

Numerous footprints studied in the field (more than 140 footprints) and one specimen sampled ( IFMI -681 ) .

Revised diagnosis.

Gruipeda preserved as tridactyl or tetradactyl footprints, commonly with a footprint length smaller than 50 mm, and a length / width ratio of 0.7–0.9. Bipedal trackways displaying a zero to inward rotation with relation to the midline, pace angulation ranging from 150 ° to 182 °, and a stride length from 2.5 to 5 times the footprint length. Footprints slightly asymmetrical, typically with the angle between digits II-III larger than those of digits III-IV, and a large divarication of digits II-IV in the range 90 ° – 135 °. Relative digit length is I < II < IV < III. Hallux impression present in almost half of the footprints with a posterior to posteromedial position. Occasional rhomboid to rounded sole.

Description.

Small tetradactyl footprints well to poorly preserved as convex hyporeliefs on the lower bedding plane of medium- to thick-bedded, dark brown to brown, fine-grained sandstone layers. In the well-preserved footprints, all digit imprints are visible, and digit I is smallest, has slightly inward rotation and is not along the longitudinal axis of the footprints. Digit II and IV imprints have the same size but are not symmetrical around the longitudinal axis of footprint. Digit III imprint is the longest, straight, or slightly curved and is more bulged. Usually, all digit imprints are connected with each other proximally by the metatarsal pad imprint. In other imprints, digit I-II-III-IV imprints are preserved as not connected imprints without metatarsal imprints. Footprints have outward orientation on the trackway axis. Some trackways show higher relief digit III imprints with indistinct lateral digit imprints. Three to four digital pad imprints are visible in several footprints, and usually the tip of the digits is sharp.

Discussion.

The studied small bird footprints were preserved with different quality, and in the well-preserved setting they are attributable to Gruipeda dominguensis . These footprints are smaller than Gruipeda becassi and differ from Charadriipeda minima by its smaller digit I imprint and orientation of digit II and III imprints.

Figures

Figure 2. A, B. Ardeipeda egretta, trackway a 1 – a 3 and Gruipeda dominguensis (b), sampled specimen, IFMI - 680; C, D. Aviadactyla vialovi trackway b 1 and Gruipeda dominguensis, trackway a 1 – a 4; mcc – mud crack cast; nvs – non-vertebrate structures; sampled specimen, IFMI - 681.

Figure 4. A, B. Gruipeda dominguensis trackways in the lower bedding plane of a large dislocated block with numerous mud cracks; C – H. Gruipeda dominguensis trackways in the dislocated slabs.