The above is a picture of the skull of an Irish Elk.
According to National Geographic News a study in Nature has linked Irish Elk to Fallow Deer:
Scientists at University College London studied DNA and skeletal remains of the extinct giant deer, or Irish elk, to construct its family tree. This is the first time this method has been used to reveal an extinct animal's living descendants, according to the study team.
The researchers found that the giant deer, which stood seven feet (two meters) tall at the shoulder, is closely related to the modern fallow deer, a much smaller species that still inhabits the former haunts of its Ice Age relative throughout Europe.
The giant deer (Megaloceros giganteus) roamed Europe and Central Asia alongside humans until its extinction some 8,000 years ago. The animal was just one of a number of colossal deer species that no longer exist today.
The team identified skeletal features that are unique to both fallow and giant deer. They also found that the vertebrae of the fallow deer were once adapted to support very large antlers.
Further evidence of a close ancestral link came from mitochondrial DNA taken from both animals' bones. Mitochondrial DNA is passed down through generations from mothers to their offspring.
The NGN article also contains an interesting discussion on using a similar techniques with Homo floresiensis:
Recent technological advances have raised hopes that scientists may be able to pinpoint our own closest relatives in the human family tree.
Researchers are currently trying to extract the DNA of Homo floresiensis, whose remains were found last year on the island of Flores in Indonesia.
Nicknamed "the Hobbit" because of its tiny stature, H. floresiensis is believed to have diverged from modern humans some two million years ago.
However researchers are skeptical about whether techniques that worked for extinct Ice Age animals like the giant deer will work on this diminutive species of human, which lived only some 18,000 years ago.
The problem, says Ian Barnes, is that the remains come not from Ireland or Siberia, as in the case of the giant deer, but from a tropical island.
"DNA degrades over time, and like any chemical reaction, it will degrade faster if the temperature's higher," he said. "The problem with a lot of the remains that we are asked to look at is that they've been at too high a temperature for too long a period of time.
"Our best estimate is that there won't be any DNA surviving in that [H. floresiensis] material."