Implications of age variation and sexual dimorphism in modern equids for Middle Pleistocene equid taxonomy
Article first published online: 28 DEC 2010
Copyright © 2010 John Wiley & Sons, Ltd.
International Journal of Osteoarchaeology
Volume 23, Issue 1, pages 1–12, January/February 2013
How to Cite
van Asperen, E. N. (2013), Implications of age variation and sexual dimorphism in modern equids for Middle Pleistocene equid taxonomy. Int. J. Osteoarchaeol., 23: 1–12. doi: 10.1002/oa.1231
- Issue published online: 24 JAN 2013
- Article first published online: 28 DEC 2010
- Manuscript Accepted: 5 NOV 2010
- Manuscript Revised: 28 OCT 2010
- Manuscript Received: 29 JUN 2010
- age variation;
- sexual dimorphism;
Interspecific variation in the equid lineage is limited when compared with other large mammal lineages, while a considerable amount of intraspecific ecomorphological variation occurs. This has led to considerable debate regarding the taxonomic status of palaeontological and archaeological equid remains. The possible confounding impact of sex and age variation on analyses of archaeological equid remains has so far remained untested. This could be especially problematic when it is unknown whether an assemblage contains more than one equid species, breed or hybrid. Here, sex and age variation in modern equid species is examined and compared to variation in Pleistocene equid assemblages from northwest Europe. Sex variation in the longbones of modern equid species was found to be lower than variation over time. Similarly, age variation in dental elements of the same species is predominantly lower than diachronic variation, although caution needs to be taken when an archaeological assemblages consists mostly of elements at a similar wear stage.
To assess whether late Middle Pleistocene caballoid horse fossils should be assigned to multiple species or be considered to form a monospecific group, the coefficients of variation for measurements on fossil horse remains were compared with those for modern equid specimens. Results indicate that the fossil assemblages are similarly variable to samples of modern material. Taken as a whole, the late Middle Pleistocene caballoid horse lineage is equally variable to an assemblage of modern ponies of a variety of different breeds. This implies that the variation observed between samples dating from different parts of the Middle Pleistocene can be characterised as intraspecific variation within a single species reflecting ecomorphological adaptations to the changeable Pleistocene climate. Copyright © 2010 John Wiley & Sons, Ltd.