Irish elk
It has been historically thought that, because both have palmated antlers, the Irish elk and fallow deer ("Dama" spp.) are closely related, this is supported by several other morphological similarities, including the lack of upper canines, proportionally long braincase and nasal bones, and proportionally short front portion of the skull. In 2005, two fragments of mitochondrial DNA (mtDNA) from the cytochrome b gene were extracted and sequenced from 4 antlers and a bone, the mtDNA found that the Irish elk was nested within "Cervus," and were inside the clade containing living red deer ("Cervus elaphus"). Based on this, the authors suggested that the Irish elk and red deer interbred. However, another study from the same year in the journal "Nature" utilising both fragmentary mitochondrial DNA and morphological data found that the Irish elk was indeed most closely related to "Dama". The close relationship with "Dama" was supported by another cytochrome b study in 2006, a 2015 study involving the full mitochondrial genome, and by a 2017 morphological analysis of the bony labyrinth. The 2006 and 2017 studies also directly suggest that the results of the 2005 cytochrome b paper were the result of DNA contamination.