Kalimantsia sp.

Antoine, Pierre-Olivier & Sen, Sevket, 2016, Rhinocerotidae and Chalicotheriidae (Perissodactyla, Tapiromorpha), Geodiversitas 38 (2), pp. 245-259 : 256-257

Kalimantsia sp.

( Fig. 4 )

Chalicotherium goldfussi – Nicolas 1978: 456.

MATERIAL EXAMINED. — MNHN.F.TRQ670, left M2 (lingual fragment); TRQ671, right M fragment (protocone);TRQ669, phalanx II, right digit 4 (hand).

COMPARATIVE DESCRIPTION

Upper dentition

The upper molar MNHN.F.TRQ670 is broken, lacking most of the labial part ( Fig. 4A ). Yet, it was probably as wide as long in occlusal view (estimated dimensions: W = 39.0; L = 41.0), as usual in Chalicotheriinae (except Kalimantsia from the late Miocene of Bulgaria; Geraads et al. 2001) but contrary to Schizotheriinae and Kalimantsia (molars more elongated mesio-distally; Anquetin et al. 2007). A dilambdodont pattern is still discernable for the ectoloph (forming a W-shaped shearing crest in occlusal view), allowing for a referral to Chalicotheriidae ( Coombs 1989) . Lingual cusps are almost unworn. In occlusal view, the anterior side is convex and oblique distolingually, with a protocone much displaced distally with respect to the paracone. The former is located at mid-length of the tooth, as in Anisodon sp. from Vathylakkos ( Bonis et al. 1995; Anquetin et al. 2007). The protoloph is low and thin, running only from the mesiolabial edge to the small paraconule, and then interrupted lingually, contrary to what occurs in Schizotheriinae. The protocone is totally isolated from other cusps in TRQ670 and TRQ671, as in all Chalicotheriinae . The lingual opening of the deep and wide median valley coincides with a concave inflection of the occlusal outline, as observed in all molars of Kalimantsia ( Geraads et al. 2001) . There is no lingual cingulum (TRQ670 and TRQ671). The metaloph is transversely oriented. Yet, the hypoconule is located distolabially with respect to the hypocone. The hypocone and hypoconule are equally developed and separate by a shallow groove at this early stage of wear. The short crest distolabially oriented running from the hypocone (posthypocrista) would confer a crescent-like shape to the metaloph at more advanced stages of wear, as in M2-M3s of Kalimantsia ( Geraads et al. 2001) . The postfossette is deep and narrow transversely, crescent-like in occlusal view and it opens distolabially. The distal cingulum is low and restricted to the bottom of the distal valley.

Phalanx

The phalanx MNHN.F.TRQ669 ( Fig. 4 A-D) is fully developed and belongs to an adult individual (fused epiphyses). The proximal facets are biconcave and elongate sagittally ( Fig. 4D ). They are separated by a smooth ridge and forming a c. 60° angle in plantar view, which allows for identifying it as a phalanx II (only one proximal facet on the phalanx I whereas the phalanx III is a claw in chalicotheriids; Coombs 1989). There is no trace for coalescence with the phalanx I (thus forming a “duplex”), which discards any referral to Schizotheriinae (see Coombs 1989; Saraç & Sen 2005). On the other hand, such morphology matches that of most Chalicotheriinae . The shaft is long, transversely compressed ( Fig. 4C ), and symmetrical in anterior view (L = 54.5; APD = 48.5; TD = 31). These features are consistent with a phalanx II from the manus, as hind limb phalanges are much shorter proximodistally in chalicotheriids, and more particularly in chalicotheriines ( Coombs 1989; Guérin 2012). The distal facet is concave transversally, with a deep U-shaped profile, and regularly convex dorso-ventrally ( Fig. 4B ). When compared to the mounted hand of Anisodon grande from Sansan ( Guérin 2012: fig 5), TRQ669 best matches the second phalanx of a right digit 4.

DISCUSSION

The isometric dimensions of the upper molar (not elongated mesiodistally), the presence of an interrupted protoloph on it, and the absence of a duplex (unfused phalanx) allow for discarding the occurrence of a schizotheriine chalicotheriid in Küçükçekmece. On the other hand, all these features are observed in the chalicotheriines Chalicotherium , Anisodon , and Butleria ( Zapfe 1989; Bonis et al. 1995; Anquetin et al. 2007; Guérin 2012). Molars are more elongate mesio-distally in the chalicotheriine Kalimantsia (M2 of the holotype: 43*37; Geraads et al. 2001) and in all schizotheriines (e.g., Ancylotherium ; Geraads et al. 2001). The relative size of the dental-postcranial chalicothere remains is compatible, so that a single chalicotheriine taxon may occur in Küçükçekmece. The presence of a paraconule on the M2 from Küçükçekmece discards any referral to Anisodon sivalense among chalicotheriines ( Anquetin et al. 2007). The protoloph is extremely reduced with respect to M2s of Chalicotherium goldfussi from La Grive and Anisodon grande from Sansan ( Anquetin et al. 2007). The distally-displaced position of the protocone is consistent with what is observed in both Anisodon sp. from Vathylakkos and Kalimantsia ( Geraads et al. 2001; Anquetin et al. 2007). The presence of a well-developed hypoconule, of a crescent-like metaloph, of a disto-labially oriented narrow post-fossette, and of a lingual inflection in occlusal view concur to a referral to Kalimantsia bulgarica , even if the tooth from Küçükçekmece is less elongated mesio-distally than the M2 from the holotype of Kalimantsia .

Figures

FIG. 4. — Tapiromorph perissodactyls from the upper Miocene locality of Küçükçekmece, Thrace, Turkey, Kalimantsia sp.: A, TRQ670, left M2 in occlusal view; B-D, TRQ669, phalanx II, right digit 4 (hand) in medial (B), anteroproximal (C), and posterior views (D). Scale bar: 20 mm.