Revisiting the earliest terrestrial fossil record from the paleo Kura bay (Eldari and Udabno faunas, Late Miocene, South Caucasus) – diversity of bovids

The late Miocene fossil land mammalian sites Udabno (Georgia) and Eldari (Azerbaijan) are found in the Middle Kura Basin, in the fluvial sediments along the Kura bay deposited during regression of the Eastern Paratethys and represent the earliest terrestrial faunal evidence from the area. The Udabno and Eldari fossil vertebrate sites are roughly contemporaneous and supposedly embrace time span from ca. 9.5 to 7.5 Ma. Yet, there remain correlation issues and questions regarding the detailed chronological framework of the deposits. These questions are under study.

The Udabno and Eldari bovid remains were revised, research involved the Georgian National Museum collections only. This study aims to clarify taxonomy and to draw biostratigraphic and paleogeographic conclusions. Following taxa were identified:

Tragoportacini: Miotragoceros valenciennesi eldaricus (Eldari), Miotragoceros valenciennesi maius (Udabno),Tragoportax sp. (Udabno);

Antilopini:      Gazella cf. capricornis (Eldari), G. cf. pilgrim (Udabno), Prostrepsiceros rotundicornis (Udabno), Prostrepsiceros vallesiensis (Eldari), Aff. Hispanodorcas orientalis (Udabno);

Caprini:         Tethytragus sp. (Udabno), Skoufotragus sp.(Udabno), Caprini gen et sp nov. (Udabno);

Alcelaphini:    Udabnocerus georgicus (Udabno-Hadjia, Azerbaijan);

Bovidae indet.: Bovidae indet. 1 (Udabno) – dwarf antelope, strongly posteriorly inclined horn cores without basal swelling, with posterior keel, without torsion. Eotraginae?; Bovidae indet. 2 (Udabno, Eldari) - dwarf antelope, long upright horn cores without torsion, without keels - Hypsodontinae?; Bovidae indet. 3 (Udabno) - dwarf antelope, horn cores transversally compressed, with anterior keel and very weak homonymous torsion- Hypsodontinae?

Lack of exact stratigraphic information for most of these fossils does not allow to judge about their stratigraphic distribution. Yet, a strong Vallesian component in this bovid composition is evident (Miotragoceros, Prostrepsiceros vallesiensis) suggesting MN10. Presence of Middle Miocene relict bovids (Tethytragus sp., possible Hypsodontinae and Eotraginae) is indeed striking and enhances the evidence of the Vallesian age. Tragoportax, Gazella capricornis, G. pilgrimi, Prostrepsiceros rotundicornis, Skoufotragus are among the typical Turolian taxa. Yet, absence of Oioceros- a very frequent antelope, that appears in the Early Turoloan might be a significant biostratigraphic indicator, pointing to the earliest Turolian (earliest MN11) as a minimum age.

The core of the bovid fauna is composed of “local”, Greko-Iranian taxa. Yet, out of Africa dispersal can be the immediate explanation for the presence of a primitive, early alcelaphin bovid -Udabnocerus georgicus. However, the story might be more complicated. This fossil comes from the locality Hadjia (Azerbaijan) of the Udabno site. We did not have a possibility to survey this place. Yet geoglogical maps indicate that youngest deposits in the area is Eldari Formation with supposed minimum age ca. 7.5 Ma. what makes Udabnocerus as old or even older than the African alcelaphine record. It is paradoxical evidence, once again reminding us how limited is our vision of the past world.

The study was conducted in the framework of Shota Rustaveli National Science Foundation of Georgia grant #FR-21-1979.