Morphometry of upper cheek teeth of cave bears (Carnivora, Ursidae)

Abstract

Univariate and multivariate statistics were applied to analyse the morphometrical variability of 4920 upper cheek teeth (P4, M1 and M2) of cave bears from 123 geographical sites (180 samples) of different Pliocene – Pleistocene ages. The analysed specimens included those belonging to the big cave bears Ursus kudarensis, U. deningeri, U. spelaeus (three subspecies) and U. kanivetz (including U. ingressus), as well as the small cave bear U. rossicus. The information‐theoretical parameters (Shannon entropy and orderliness (Von Foerster, 1960: On self‐organizing systems and their environments. In Self‐Organizing Systems, 31–50. Pergamon Press, London) were used to estimate tooth diversity in different teeth, different taxa and in selected local chrono‐populations. Multivariate allometry coefficients (Klingenberg, 1996: Multivariate allometry. In Advances in Morphometrics, 23‐49. Plenum Press, New York) were used to describe the relationships of different ‘parts’ of a tooth and to compare allometric patterns amongst species or selected local samples. A multivariate analysis showed a significant overlap of the size/shape parameter ranges in deningeroid and spelaeoid bears within morphological spaces. Within the cave bear lineage, the Deninger's bear has the greatest morphological diversity index (entropy) of all the teeth overall, and the lowest diversity is observed in the final taxon of this lineage – U. kanivetz (=ingressus). The P4 and M2 diversity showed multidirectional correlations with elevation above sea level amongst several ‘local’ populations of Late Pleistocene cave bears. The morphological disparities between the studied taxa are in close agreement with the distances in the available schemes of genetic differentiation based on ancient mitochondrial DNA. The split of U. kudarensis and U. deningeri has a good bootstrap support, which corresponds to the hypothesis about their parallel evolution. The small cave bear U. rossicus is placed between U. arctos and U. deningeri. The phylogenetic signal is more pronounced in the variability of teeth in comparison with other skeletal remains of cave bears (cranium, mandible, or metapodial bones).

Morphometry of lower cheek teeth of cave bears (Carnivora, Ursidae) and general remarks on the dentition variability

“…The results of univariate and multivariate analyses (Figs , Data S2: Tables S2A, S2C, S2E, S2G) of the variability of the size/shape of the crowns of the lower cheek teeth indicate a significant overlap of the parameters in the different evolutionary lineages of deningeroid and spelaeoid bears ( U. deningeri , U. kudarensis , U. savini , U. rossicus , U. spelaeus , U. kanivetz (= ingressus )). The ‘phylogenetic signal’ in the morphometric variability of cheek teeth in the lower row is less pronounced than in the upper row (Baryshnikov & Puzachenko ). In the multidimensional morphological space the ranges occupied by ancestral potential taxa ( U. minimus , U. etruscus ) or brown bear ( U. arctos ) also overlap markedly with the areas occupied by cave bears (to a lesser extent the size and, to a greater extent the shape of the tooth crowns).…”

“…Based on the previous results (Baryshnikov & Puzachenko ), the morphometric analysis in this work was carried out without dividing the sample into males and females.…”

“…The usage of models of morphological spaces (Baryshnikov & Puzachenko : data S3) allows us to compare the entropy or derived parameters of samples, which include different elements with different sets of measurements, i.e. such as different cheek teeth.…”

“…Therefore, in order to compare correctly samples with different numbers of elements, it is necessary to calibrate the values of entropy or other derived parameters. The calibration of H (or R ) is in accordance with the following transformation: H cal = ( H − ( a + b log 10 N )) + ( a + b log 10 N cosnt ), where N cosnt = 50 (Puzachenko ; see also Baryshnikov & Puzachenko : data S3).…”

“…Here, we present the second part of a new analysis of a morphometric study of cave bear cheek teeth, with the use of methods of multivariate statistics. The previous study (Baryshnikov & Puzachenko ) focused on the upper tooth row and demonstrated the effectiveness of the used statistical techniques.…”