Equus suessenbornensis from Akhalkalaki (Georgia, Caucasus): a review with new insights on the paleoecology, paleobiogeography and evolution of the palearctic large-sized equids during the Early - Middle Pleistocene Transition

Equus suessebornensis is one of the most intriguing species of the Early and Middle Pleistocene Eurasian Equus. Although it was described from the Middle Pleistocene site of Sussenborn, in recent years its biochronological correlation has been extended to the Early Pleistocene, raising a debate in the scientific community. In this contribution, we provide a complete ontogenically-based description of the Akhalkalaki E. suessenbornensis samples, and we compare it by multivariate and statistical analyses with the Early and Middle Pleistocene European fossil record. Moreover, we provide new paleoecological insights utilizing body mass, mesowear and net primary productivity estimates. Our outcomes provide a new perspective on the E. suessenbornensis morphology and variability, but also new interpretations for its paleoecology, biochronology, paleobiogeography and evolution. Eventually, these results provide a reassessment of equid evolution during the Early - Middle Pleistocene Transition in Western Eurasia, a critical period for the dynamics of the Quaternary faunas and paleoenvironments.

Automated summary

This study provides a comprehensive description of the Akhalkalaki E. suessenbornensis samples and compares them with the fossil record of Early and Middle Pleistocene Europe. New insights into the morphology, variability, paleoecology, biochronology, paleobiogeography, and evolution of E. suessenbornensis are presented using ontogenically-based analysis and paleoecological estimations. These findings contribute to a reassessment of equid evolution during the Early-Middle Pleistocene Transition in Western Eurasia.