Equus (S.) ovodovi, Eisenmann & Sergej, 2011
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publication ID |
https://doi.org/ 10.5252/g2011n3a5 |
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persistent identifier |
https://treatment.plazi.org/id/038687D0-9626-FFAF-39A1-FA1CFBE4FA08 |
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treatment provided by |
Marcus |
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scientific name |
Equus (S.) ovodovi |
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sp. nov. |
Equus (S.) ovodovi n. sp.
HOLOTYPE. — Palatal fragment, with P3/-M1/ of both sides ( IAES 21 ).
ETYMOLOGY. — In honour of Professor N. D. Ovodov, of the Institute of Archeology and Ethnography (Novosibirsk) who excavated the Proskuriakova cave in 1973-1974.
MATERIAL EXAMINED. — Enumerated above and described below. Besides Proskuriakova cave, fossils possibly belonging to the same species were found in late Pleistocene alluvial deposits of “Pred-Altai plain” (Upper Ob) and in Altai caves where they can be traced up to the end of Pleistocene ( Vasiliev et al. 2006).
TYPE LEVEL. — Late Pleistocene.
TYPE LOCALITY. — Proskuriakova cave, Khakassia, western Siberia.
DIAGNOSIS
Slender Equus slightly larger than the extant E.hemionus onager ;cheek teeth relatively small;shallow postprotoconal grooves on the upper cheek teeth; shallow lingual grooves, elongated double knots and metaconids on the lower cheek teeth; deep vestibular grooves on the lower molars; occasional presence of a pli protostylid on P/2; deep diaphyses on the MC and MT.
GENERAL DESCRIPTION
The Simpson’s ratio diagram ( Fig. 1 View FIG ) where E. hemionus onager is the reference zero line, compares MT length, distal articular breadth, depth of the diaphysis (respectively MT1, MT11, MT4), size of P3/-P4/ (Psize),size of M1/-M2/ (Msize), protocone length of P3/-P4/ and of M1/-M2/ (Pprot.; Mprot.), in E. (S.) ovodovi n. sp. of Proskuriakova to the same dimensions in E. hemionus onager (zero line), in E. (S.) altidens Reichenau, 1915 (Süssenborn) , and in three forms of E. hydruntinus .
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It shows slight size differences inside the Proskuriakova material, particularly in the length of the premolar’s protocones ( Fig. 1 View FIG [Pprot.]; Table 1). There is also a difference between the MT1-MT4- MT11 proportions between the “large” and “small” forms but since there is only one large MT (no. 6, with a damaged distal end), this does not seem very reliable).
More important are the differences between E. (S.) ovodovi n. sp. and both E. hemionus and E. hydruntinus :
– unlike E. hemionus onager teeth are relatively small and diaphyses are deep on the metatarsals;
– unlike E. hydruntinus protocones are relatively long.
The smaller form has proportions close to E. (S.) altidens from Süssenborn, Germany, a species c. 0.6 Ma old ( Maul et al. 2000).
Upper cheek teeth ( Table 2)
The enamel is simple, the plis caballin – when present – are small; the postprotoconal grooves are shallow. Size and shape of the protocones are very variable: short, pointed, and humped ( Figs 2 View FIG ; 3C View FIG ) like in some Sussemiones and E. andium Branco, 1883 ( Fig. 4 View FIG ) or flat and long ( Fig. 3I View FIG ).
Lower cheek teeth ( Tables 3; 4)
Small or large, the lower cheek teeth ( Fig. 5 View FIG ) differ from hemiones by deep vestibular grooves on the molars, and from E. hydruntinus , by assymetric double knots. Some resemble to middle Pleistocene species ( Fig. 6 View FIG ) found at Süssenborn and Akhalkalaki ( Georgia), or to some E. (Amerhippus) santaeelenae Spillmann, 1938 of Tarija, Bolivia.
Third metacarpals
The material is very poor ( Table 5) but it is possible to reconstruct the approximal length ( Fig. 7).
Size and proportions look similar ( Fig.8 View FIG )to the MC fragments found in the Mousterian ofTsopi, Georgia ( Gabunia & Vekua 1989; Vekua pers. com. 1995).
Tsopi yielded also a deciduous upper series, a fragment of M3/, and several associated lower cheek teeth ( Gabunia & Vekua 1989). One of these, a lower molar, is very interesting: it bears an ectostylid, and has a very deep vestibular groove reminding of some Sussemiones ( Fig. 9). No other photographs are available.
Third metatarsals
MT no. 6 is more robust than the others and has a very developed keel ( Table 6; Fig. 10 View FIG ).
The size of MT no. 6 is close to the mean of E. hipparionoides Vekua, 1962 MT from Akhalkalaki ( Fig. 11 View FIG ) but the latter is closer by proportions to the smaller MT from Proskuriakova: deep diaphysis like MT no. 6 and 7 (measurement 4), and probably large distal articular breadth (distal end damaged) like MT no. 9 (measurement 11).
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REMARKS
Note that molecular analyses were performed on samples ACAD2302 (MT no. 9), ACAD2303 (MT
no. 12), and ACAD2305 (fragment of juvenile MT no. 14) belonging to the smaller form.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.