The Palaeomerycidae – an extinct family of horned ruminants that lived in Eurasia during the middle Miocene, and which were thought to be related to deer – are actually in the same clade as giraffes, according to a new research.
Both giraffes and deer have horns and are ruminant herbivores with more than one stomach. However, based on the shape of the Palaeomerycid’s horns (as well as other features), the animal may be more closely related to giraffes, rather than deer.
Researchers found the fossils of Xenokeryx amidalae in Spain. This particular species of Palaeomerycid roamed the Earth about sixteen to eleven million years ago, during the Miocene period.
In the new paper – published December 2 in the journal PLOS ONE – the researchers stated that Xenokeryx amidalae was part of the clade Giraffomorpha. Xenokeryx amidalae has a total of three horns, two of which are smaller and are situated in front of the animal’s had, and a larger T-shaped horn in the back of its head. According to researchers, the front horns have a similar structure to that of giraffes; they are ossicones.
Ossicones grow separately when the animal is young and they only fuse to the skull once the animal reaches adulthood. They can be described a detachable units.
Study author Israel M. Sánchez, of the National Museum of Natural Sciences in Madrid, said that no one really knew where Palaeomerycids belonged within the evolutionary tree of ruminants. They were previously linked to the Dromomerycids in North America, a group of ruminants that are thought to be distant relatives of deer.
Dr. Nikos Solounias, an expert in modern and paleo ungulate anatomy and biology in the Division of Palaeontology at the American Museum of Natural History, said that the new evidence separates the Eurasian animals from those that lived in North America. According to Dr. Solounias, the similarities between the two occurred due to convergent evolution.
Convergent evolution can be described as a type of independent evolution in which species of different lineages develop similar features.
Based on its physical characteristics, the researchers classified Xenokeryx amidalae as member of the clade Giraffomorpha. This process of classification is also called cladistics. The giraffe expect said that the new study certainly shows that Xenokeryx amidalae and giraffes are in fact related.
Image source: www.giraffopia.com