Equus gmelini ANTONIUS, 1912

Demeshkant, Vitalii & Rekovets, Leonid, 2021, The Ultrastructure Of The Tooth Enamel Of Small Equus Of The “ Tarpan ” Group And Their Possible Phylogenetic Connections, Fossil Imprint 77 (1), pp. 55-72 : 57-58

Tarpan ( Equus gmelini ANTONIUS, 1912 )

In nature, this species was widely distributed across the steppes of Europe and Asia, from the early Holocene to the end of the 19 th century. The history of the species, its taxonomic status and systematic position are still the subject of scientific discussion ( Gromova 1949, Bibikova 1972, Bibikova and Belan 1979 , 1981, 1984, Kosintsev 2015, Сroitor 2018).

The position of many authors on the division of the species under the general name of “tarpan” into separate taxonomic groups, possibly with the rank of subspecies, is generally accepted, and at the same time somewhat debatable: steppe – Equus gmelini gmelini ANTONIUS, 1912 and forest – Equus caballus var. sylvatica according to Vetulani 1928, (= Equus gmelini sylvaticus according to Kuzmina 1997 = Equus caballus gmelini ANTONIUS forma silvatica VETULANI according to Jaworska et al. 2020) From these taxonomic groups, the conclusion is clear – today the systematics, taxonomy and nomenclature of abovementioned representatives of the genus Equus is relatively ambiguous and debatable ( Kuzmina 1997, Kosintsev and Bachura 2013, Seetah et al. 2016, Cucchi et al. 2017, Croitor 2018). In Southeast Europe, the species Equus gmelini is known from the Holocene, apparently as a migrant from Asia.

In our research, we did not deal with the taxonomy and systematics of tarpans, but assumed that Equus gmelini is an extinct species ( Gromova 1949). It includes two ecological types: steppe, Equus gmelini gmelini , and forest, Equus gmelini sylvaticus . For formal reasons, these taxa can be considered at the subspecies level. There was an assumption that the konik polski (Polish konik), a Polish native horse breed ( Equus caballus ), is closely related phylogenetically to the forest type of tarpan ( Gladenko 1976). However, later studies did not confirm this theses. Konik polski shows a great resemblance to the extinct wild tarpan, but it is not genetically the same breed ( Fornal et al. 2020). Our goal was to study the ultrastructure of the enamel of their teeth, conduct a comparative analysis of the data obtained with species close to the tarpan, and formulate appropriate conclusions.

The studies of Gromova (1949), Bibikova (1972) and later Belan ( Bibikova and Belan 1981 , 1984) revealed the distinctive features of the tarpan species, Equus gmelini , based on the morphology of the skull, teeth and bones of the postcranial skeleton. The authors noted that this species was smaller than the others, with relatively shorter maxillary teeth, an elongated m3 talonid, a shortened protocone, and an enlarged distal part of the first phalanx. This sets it apart from other related forms – Equus caballus LINNAEUS, 1758 , Equus latipes GROMOVA, 1949 and Equus scythicus RADULESCU et SAMSON, 1962 .

A more complete description of tarpan osteomorphology was provided by Roman Croitor ( Croitor 2018). He noted differences in the proportions of the skull, in particular the first and second phalanges (phalanxes), in individual elements of the dentition. The horses from Botai culture in Kazakhstan are related in origin with Equus przewalskii ( Orlando et al. 2008) . It is supposed that E. przewalskii is a feral form of the domesticated E. caballus derived from Botai ( Levine 1999, Gaunitz et al. 2018). But this opinion was recently questioned by Taylor and Barrón-Ortiz (2021), who suggest that Botai horses represent rather wild than domesticated form.

The species tarpan, Equus gmelini ANTONIUS, 1912 , inhabited the territory of south-eastern Europe, was adapted to the barren conditions of the steppe and led a herd lifestyle ( Bibikova and Belan 1981 , 1984, Conti et al. 2010, Kosintsev and Bachura 2013, Kosintsev 2015). As a steppe form of the southern part of Europe ( Italy, Ukraine), its main feed was halophytes, which are characterized by high osmotic pressure in cells and the presence of phytoliths ( Burke et al. 2003). The last of these is an important indicator of the process of biting and chewing food, and thus the process of abrasion of teeth and enamel ( Erickson 2014). Bibikova and Belan (1981, 1984) in their works justify the osteological differences of tarpan from the comparative forms of wild small horses, and suggest the history of their origin as a separate phylogenetic branch of equines in the Pleistocene of Europe. In this region, cabbaloid horses are known from the Middle Pleistocene (Galerian) and are well represented by Late Pleistocene or Holocene forms such as Equus ferus germanicus , Equus ferus gallicus and Equus ferus gmelini ( Conti et al. 2010) . According to these authors, the tarpan was domesticated during the eneolite, and is known as Equus caballus .

In the Holocene sites Myrne, Kamiana Mohyla and Hirzhevo, osteological remains of tarpan Equus gmelini were not particularly numerous (in total 75 bones are known), but were reliably defined. This is evidenced by data from Bibikova and Belan (1981, 1984), who show that at that time, there were no Equus latipes (extinct) and no domesticated Equus yet, which also proves the authenticity of the remains in favor of the distinctiveness of the tarpan species. In addition, the aforementioned authors provided diagnostic differences between tarpan and similar forms. DNA analysis of equines and the related process of their domestication provide variable and perhaps questionable data on phylogeographic content ( Jansen et al. 2002, Viltsrup et al. 2013). A short description is given of the Holocene Ukrainian sites in which the remains of the tarpan species were found.

Myrne locality

This is known primarily as a monument of archaeological culture of the Stone Age in the south-western region of Ukraine ( Kiliya district , Odesa region). It belongs to the Late Mesolithic ( Grzebenik’s archaeological culture), which is 8,500 –9,000 years old (Sapoznikov and Sapoznikova 2011). The list of fauna species at this site includes aurochs, tarpan, European wild ass, saiga antelope, red deer, wild boar, wolf, fox, European badger, hare and marbled polecat, all with dominance of the steppe representatives ( Bibikova and Belan 1981 ) .

Kamiana Mohyla locality

This is known as a natural and historical multilayered monument of Ukraine from different epochs of the Holocene (Melitopol district, Zaporizhia region of Ukraine). An unusual accumulation of large stone slabs and hard sandstones (sediments of the Sarmatian Basin) with a height of up to 12 m covers almost 3 hectares of land near the Molochna River. This proved a relatively convenient place in steppe Ukraine for periodic human settlement starting in the Late Paleolithic. On the rocks of the caves and grottoes of this tomb, paintings and drawings (petroglyphs) were made of various animals, including tarpans, and the settlers here contributed to the accumulation of large bones, mainly large mammals. Horse osteological materials have been classified as being tarpan ( Equus gmelini ). The remains of species such as horses, deer and antelopes are also known in the area (Sapoznikov and Sapoznikova 2011).

Hirzhevo locality

This locality is in the Velyko-Mykhailivskyi district of Odesa region of Ukraine, and is characteristic of the stage of natural and societal development of the first half of the Holocene, the early Neolithic, which is 7,000 years old – and the emergence of the Samchyn culture (Sapoznikov and Sapoznikova 2011). According to the data collected by Bibikova and Belan ( Bibikova and Belan 1979 , 1981, 1984) in Hirzhevo, the remains of species such as auroch, tarpan and the European wild ass are known, while neither the presence of domesticated animals nor the morphological changes found in the process of the domestication of wild fauna were detected. This means that the horse remains genuinely do belong to the tarpan Equus gmelini .