Samotherium cf. major Bohlin, 1926

Kostopoulos, Dimitris S. & Saraç, Gercek, 2005, Giraffidae (Mammalia, Artiodactyla) from the late Miocene of Akkaşdağı, Turkey, Geodiversitas 27 (4), pp. 735-745 : 742-743

Samotherium cf. major Bohlin, 1926

MATERIAL EXAMINED AND MEASUREMENTS (in mm). — Distal part of tibia (AK2-506): DT dist = 106.6, DAP dist = 76.0; part of tibia (AK4-203): DT diaph = 70.0, DAP diaph = 52.5; talus (AK7-28): L lat = 109.5, DT dist = 74.0; (GOK-198): L lat = 105.2, L med = 92.0, DT dist = 68.6; cubonavicular (AK11-65a): DT max = 88.7, DAP max = 77.0.

DESCRIPTION AND DISCUSSION ( FIG. 7 )

The presence of a second large giraffid in Akkaşdagwı is poorly but certainly documented by a few postcranial elements. Although the absolute dimensions of the available specimens are slightly smaller than those of Helladotherium , their proportions and some morphological characters clearly separate them from this genus: the lateral malleolus surface of the distal tibia is reduced (large in Helladotherium ); the proximal trochlea of the talus ( Fig. 8 ) is moderately unequal (clearly asymmetrical in Helladotherium ); the proximolateral tuberosity of the calcanear facet is weak (usually strong in Helladotherium ); the medial ridge of the plantar trochlea is continuous (presence of notch in Helladotherium ) and presents a large, shallow and round imprint at its lateral base (absent in Helladotherium ) ( Fig. 7 ); the cubonavicular is longer transversally than anteroposteriorly (squarish in Helladotherium ). This set of morphological features is indicative of Samotherium ( Bohlin 1926; Geraads 1974; pers. data). The type species Samotherium boissieri Forsyth- Major, 1888 ( Geraads 1994), originally known from the late Miocene deposits of Samos island ( Greece), appears to present a great size variabili- ty. Based on the works of Bohlin (1926) and Şenyürek (1954), Geraads (1994) refined the specific status of Samotherium from Samos, recognizing two species, S. boissieri Forsyth-Major, 1888 and S. major Bohlin, 1926 , the latter one considered as a successor of the former. We also consider the classical Samotherium stock from Samos as certainly bi-specific. Study of the Forsyth-Major collections (MGL, BMNH), as well as of the new material collected during the last years ( Koufos et al. 1997; and pers. data) allow us to recognize two forms of certainly different stratigraphic origin, similar but not identical in cranial morphology and different in size. According to the new available magnetostratigraphic data ( Kostopoulos et al. 2003), the fossiliferous levels yielding S. boissieri (“Stefano”, Qx, Q4) are certainly older than those with S. major (“Andriano”, Q1).

In comparison to the known Samotherium species, the Akkaşdagwı form appears dimensionally closer to the large samotheres referred to S. major ( Fig. 8 ) from the upper horizons of Samos, VAT, and KTA,B ( Geraads 1978, 1994) and it could be referred to as Samotherium cf. major .

Figures

FIG. 7. — Samotherium cf. major, Akkaşdağı, Turkey, right talus AK7-28, posterior view. Scale bar: 4 cm.

FIG. 8. — Scatter diagram “Llat against DTdist” of talus of Helladotherium sp., Akkaşdağı, Turkey (GOK-197) and Samotherium cf. major, Akkaşdağı, Turkey (AK7-28, GOK-198) in comparison with Helladotherium from several sites, Samotherium major from Samos (MGL collection), Kemiklitepe A,B (KTA,B), Taşkınpaşa (TAS), Samotherium sp. from Kemiklitepe D (KTD) and Samotherium boissieri from Samos (BMNH and MGL collections) (data from Şenyürek 1954; and pers. data).