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. 2026 Jun 14;16(1):21401.
doi: 10.1038/s41598-026-57113-0.

Scythicorhinus vekuai gen. nov. et comb. nov. (Mammalia, Rhinocerotidae) from the Pliocene of Georgia and its implications for the early evolution of Coelodonta and Stephanorhinus

Oleksandr Kovalchuk  1   2 , Antonio Borrani  3 , Paweł Mackiewicz  4 , Zoltán Barkaszi  5   6 , Chiara Capalbo  7 , Svitozar Davydenko  8 , Anastasiia Dubikovska  5   8   9 , Urszula Ratajczak-Skrzatek  10 , Maxim Sinitsa  11 , Krzysztof Stefaniak  10 , Maciej T Krajcarz  12 , Paul P A Mazza  7
Affiliations

Scythicorhinus vekuai gen. nov. et comb. nov. (Mammalia, Rhinocerotidae) from the Pliocene of Georgia and its implications for the early evolution of Coelodonta and Stephanorhinus

Oleksandr Kovalchuk et al. Sci Rep. .

Abstract

The taxonomy of Eurasian rhinoceroses has long been complicated by extensive homoplasy, incomplete fossil records, and shifting diagnostic criteria, particularly affecting the genera Dicerorhinus, Dihoplus, Pliorhinus, Rhinoceros, and Stephanorhinus. Rhinocerotid material from the Late Pliocene locality of Kvabebi (Georgia), previously referred to Pliorhinus miguelcrusafonti, is re-evaluated here using an expanded morphological dataset and phylogenetic analyses. The results consistently recover the Kvabebi rhinoceros as a distinct dicerorhinine lineage positioned close to the divergence between Coelodonta and Stephanorhinus. On the basis of its unique combination of cranial, dental, and postcranial characters, and its stable phylogenetic placement outside both Coelodonta and Stephanorhinus, the Kvabebi material is provisionally assigned to Scythicorhinus vekuai (Tsiskarishvili, 1987) gen. nov. et comb. nov. Although alternative placements within the early Coelodonta-Stephanorhinus radiation cannot be statistically rejected, a close relationship with Stephanorhinus miguelcrusafonti is strongly unsupported. Two fragmentary maxillae from Berehove (Crimea, Ukraine) are also examined and are tentatively referred to Scythicorhinus vekuai, pending the discovery of more diagnostic material. Discrete-character and morphometric analyses indicate that both the Kvabebi and Berehove rhinoceroses fall outside the observed morphological variation of Coelodonta and Stephanorhinus, supporting their distinction at the generic level, albeit provisionally given the limited and partially worn material. The results further support rejection of Pliorhinus as a valid genus. Overall, this study refines the systematic framework of late Neogene rhinocerotids and underscores the importance of expanded comparative datasets for resolving evolutionary relationships within this highly homoplastic group.

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Conflict of interest statement

Declarations. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Schematic map indicating the geographic placement of the studied localities.
Fig. 2
Fig. 2
Remains of the Berehove rhinoceros: (a–c) – right maxilla NMNHU-P UN-1501/1 in labial (a), lingual (b), and occlusal view (c); (d,e) – fragment of left maxilla NMNHU-P UN-1501/2 in lingual (d) and occlusal (e) views. Scale bar: 10 cm.
Fig. 3
Fig. 3
Reconstruction of the skull of Scythicorhinus vekuai gen. nov. et comb. nov. Not to scale.
Fig. 4
Fig. 4
Selected cranial and dental characters of Scythicorhinus vekuai gen. nov. et comb. nov. illustrating features that differentiate it from Coelodonta and/or Stephanorhinus (see Table S6 for full character-state distribution). Illustrated are the skull in lateral (A), dorsal (B) and ventral (C) views, and the upper cheek-tooth row in occlusal view (D). Scale bar: 10 cm.
Fig. 5
Fig. 5
Phylogenetic consensus tree inferred from morphological character data using three analytical approaches. Clades are color-coded according to synapomorphies and inferred relationships, including the calibrated tree. Node support values are shown as: (1) number of methods (out of three) supporting each clade; (2) posterior probabilities (MrBayes); (3) SH-aLRT and bootstrap (BS) values (IQ-TREE); (4) relative Bremer support, jackknife, BS, and symmetric resampling values (TNT). Posterior probabilities < 0.5 as well as jackknife, BS, and symmetric resampling values < 50% are shown by a dash (“–”).
Fig. 6
Fig. 6
Preferred (t1) and alternative (t2, t3, t4) placements of the Kvabebi and Berehove rhinoceroses on maximum parsimony (MP), Bayesian Inference (BI), and maximum likelihood (ML) trees. The accompanying table reports tree length (TL); p-values from the Templeton test (TT) and Winning-sites (WST) tests; Bayes Factor (BF); log likelihood (logL); bootstrap proportion via RELL method (bp-RELL); and p-values from the weighted Shimodaira-Hasegawa (WSH), Expected Likelihood Weight (ELW), and approximately unbiased (AU) tests. BF are expressed as differences in log marginal likelihood relative to the best topology (t1). Values < 0.05 and BF > 3 are highlighted in red font. BF values of 1–3 indicate positive support, 3–5 strong support, and > 5 very strong support for the best tree.
Fig. 7
Fig. 7
Percentages of discrete character-state differences and phylogenetic distances (BI and ML trees) among selected rhinoceros taxa: Ce – Ceratotherium, Di – Diceros, Co – Coelodonta, Sv – Scythicorhinus vekuai, St – Stephanorhinus. Thick line: median; box: interquartile range; whiskers: range excluding outliers.
Fig. 8
Fig. 8
LDA plot of Scythicorhinus vekuai (Sc_ve) compared with Stephanorhinus (A) and Coelodonta (B) species: Stephanorhinus etruscus (St_et), S. hemitoechus (St_he), S. hundsheimensis (St_hu), S. kirchbergensis (St_ki), Coelodonta antiquitatis (Co_an) and C. nihowanensis + C. thibetana (Co_ni_th). Percentages of variance explained by the first two discriminant functions (F1 and F2) are indicated.
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