Mygdonia bison

Kostopoulos, Dimitris S., Maniakas, Ioannis & Tsoukala, Evangelia, 2018, Early bison remains from Mygdonia Basin (Northern Greece), Geodiversitas 40 (13), pp. 283-319 : 298

Among diachronous Mygdonia bison populations

KLT, TSR, KRI/KRM and APL cover a timespan from approximately 1.7 Ma to 1.2 Ma ( Fig. 1 ; see also Konidaris et al. 2015). Comparison of the biometrical and morphological features of the bison populations from these sites is feasible only among dental and postcranial remains (here restricted to metacarpals, as complete metatarsals are only known form APL), which point to the presence of a single species ( Figs 8; 9 ). Small differences between specimens from different sites appear meaningless when apply criteria of wear stage, ontogenetic age

or sexual bimodality, while others are of minor importance in the light of the known intraspecific variability of extant species; in most cases differences among samples do not exceed intrapopulation variability seen in the best documented APL sample ( Figs 8; 9 ). Some other differences may, however, due to the local evolution and adaptations of the Mygdonia population through time. Thus, dentitions from TSR, KRI and KLT show, less developed cement around the teeth than the APL bison, though samples from the former sites are rather limited for definitive conclusions. On the other hand, the small metacarpal sample from TSR indicates slightly smaller proportions at the average ( Fig. 9 ) than the bisons from the rest sites, while the distal trochlear condyle splaying of the metacarpals apparently increases from TSR to APL.

Estimated body mass based on metacarpals (ABME) gives a range of 553.1-584.3 kg for the three individuals from Tsiotra Vryssi, 541.7 kg for the single female of KRI and 632.8 kg for the single male of KRM, 439.9 kg for the single female and 575.3 kg for the single male of KTL, all values well within the estimated ranges for the APL bison ( Fig. 10A ). Body mass estimation based on M1 area ( Fig. 10B based on equation by Legendre, 1986) gave at average 650 kg for APL (n=11), 584 kg for KLT (n=4) and 595 kg for TSR (n=3); Kruskall-Wallis test shows no significant differences between pairs (APL-TSR, APL-KLT or TSR-KLT).

Figures

FIG. 1. — Geographic, geological, and chronological context of the fossiliferous sites from Mygdonia Basin yielding early Bison Hamilton Smith, 1827 and Leptobos Rütimeyer,1877-1878 remains. Abbreviations:Fm, Lithostratigraphic Formation; APL, Apollonia-1; TSR, Tsiotra Vryssi;KRI/KRM, Krimni;KLT, Kalamoto-2; GER, Gerakarou; Ol, Olduvai (geomagnetic field) reversal;Cb, Cobb mountain reversal; Jr, Jaramillo reversal.Map courtesy of D. Giusti (Eberhard Karls University of Tübingen, Senckenberg Center for Human Evolution and Palaeoenvironment).

FIG. 9. — Bivariate diagram of the bison metacarpal III+IV proportions (length [MLEN] against distal width [IDML]) from the Mygdonia Basin. Abbreviations: APL, Apollonia-1; TSR, Tsiotra Vryssi; KLT, Kalamoto-2; KRI/KRM, Krimni; R2, Pearson coefficient. The dotted line represents linear regression of the APL sample.

FIG. 10. — Box plots of the body mass (in kg) variation of the local samples of bisons from Mygdonia Basin, based on estimations from (A) the metacarpal III+IV (see Material & Methods) and (B) the M1 occlusal area (following estimation equation by Legendre 1986). Abbreviations:APL, Apollonia-1;TSR, Tsiotra Vryssi; KLT, Kalamoto-2;KRI/KRM, Krimni. For a detailed weight analysis according to age and sex of the Apollonia population see Appendix 4.