Evolution of antler types in New World deer (Odocoileinae) as inferred from molecular data.

Conventional systematics places the only antlerless deer, the Chinese water deer (Hydropotes) in a separate subfamily (Hydropotinae), on the assumption that the antlerless state represents the ancestral condition for deer generally. Molecular data indicate instead that Hydropotes is closely related to the roe deer (Capreolus), a species with simple branched antlers. One interpretation of the data is that the large, palmate antlers found in Old World deer (Cervinae) such as the fallow deer (Dama) and holarctic moose (Alces) and caribou (Rangifer) represent the ancestral condition, which has been modified to various multi-tined patterns in typical New World deer (including Blastocerus, Ozotoceros, & Odocoileus), and reduced in parallel to small "spikes" in South American Pudu and various lineages of Central & South American brocket deer (Mazama spp.).