Aviadactyla Kordos, 1985

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

Ichnogenus Aviadactyla Kordos, 1985

Type ichnospecies.

Aviadactyla media Kordos, 1985 .

Diagnosis.

Bird footprint of small to medium size consisting of three toes. The prints of all three toes are thin, stick-like, shallowly imprinted. Longest is the middle toe, to be followed by the gradually shorter inner and outer toes. The distal end of the inner toe print is, in the normal case, farther away from the basic line (the line normal to the middle toe) than the end of the middle toe print. Consequently, it is slightly asymmetrical ( Kordos 1985).

Emended diagnosis.

Avian footprints of small to moderate size, composed of three digital impressions. Digits of slender to moderate width, tapering distally and sometimes exhibiting distinct, slender claws but typically without, or with only feeble, indication of digital pads or interpad spaces. Length of central digit ( III) less than 25 % greater than that of the lateral digits. Total interdigital span exceeds 95 °. Digits convergent proximally but usually isolated (though digit II may have a minimal contact with digit III). No indication of a metatarsal pad or of webbing between digits (by Sarjeant and Reynolds 2001).

Discussion.

At first, ichnotaxonomically unwebbed small bird footprints were named as Charadriipeda by Panin and Avram (1962) and Avipeda by Vialov (1965). These names were used for both tetra- and tridactyl footprints. The diagnosis of these ichnogenera was not clarified by authors, and later tridactyl bird footprints introduced by Kordos (1983), including Aviadactyla , Ornithotarnocia , and Passeripedia . Footprints of Aviadactyla show thin digit imprints, usually unconnected, and slightly asymmetrical digits II and IV imprints. The type material of Ornithotarnocia shows thick asymmetrical digit imprints with rounded digit tips ( Kordos 1983, text fig. 1, no. 12), although some others have thinner, unconnected digit imprints with sharp digit tips. These thick digit imprints were the ichnotaxonomic base for identifying Ornithotarnocia for Miocene bird footprints California by Sarjeant and Reynolds (2001). Passeripedia includes small tridactyl unconnected bird footprints and differs from Aviadactyla by its smaller size. Sarjeant and Langstone (1994) revised Passeripedia ipolyensis Kordos (1983) and transferred it to Avipeda ipolyensis . Melchor in a strict revision (Melchor in Abbassi et al. in press) consider Aviadactyla as a junior synonym of Ornithotarnocia and Passeripedia as nomen dubium. We, however, would rather regard Aviadactyla as valid and report the studied footprints as Aviadactyla , in the comparison with other found footprints in the studied section.