Phylogeny of the giant deer with palmate brow tines Megaloceros from west and Sinomegaceros from east Eurasia

Abstract

Giant deer with palmate brow tines were placed either in a single genus, or those from west Eurasia were placed in Megaloceros and those from the east in Sinomegaceros, which implies local evolution. In order to see whether dispersals between the two areas may have occurred, we studied the morphology and interpreted the phylogeny of these deer. The phylogenetic model proposed does not support any dispersals between east and west after the appearance of the first species of each genus, but it does support the recognition of two separate genera. The ecological significance of some of the morphological characters is interpreted. Thicker molar enamel, reduced posterior molars, larger premolars and a P 4 with a lesser degree of “molarisation” suggests that Megaloceros savini adapted to a diet that includes coarser and harder food. Elevated mandibular condyles, thin molar enamel, and P 4 that are predominantly “molarized” suggest that Megaloceros giganteus and Sinomegaceros yabei shifted towards grazing larger quantities of not very hard food. Very robust metapodials evolved several times in western Eurasian giant deer: during the Early Pleistocene in the Megaloceros solilhacus group, not later than the late Middle Pleistocene in M. giganteus and it increased in the Late Pleistocene M. giganteus. Since the character did not evolve in the east Eurasian giant deer, it might be related to some aspect of the west Eurasian environment, that was not present in east Eurasia.