Decennatherium rex: Ancient Giraffe Relative, Once Roamed Iberian Peninsula

Saturday, November 11, 2017

Decennatherium rex

A new large species of giraffid being named Decennatherium rex has been discovered by Dr. Maria Rios from the National Museum of Natural History of Spain and co-authors.

Decennatherium rex lived during the late Miocene epoch, approximately 9 million years ago, in what is now Spain.

The animal belongs to the family Giraffidae (giraffids), a group of ruminant artiodactyl mammals that includes modern day giraffes and okapis.

“Giraffids were much more diverse and widespread in the past, with more than 30 fossil species described,” Dr. Rios and colleagues said.

“For the past decades a number of studies intended to resolve the phylogenetic relationships of giraffids, but due to the lack of fossilized skulls no clear consensus was reached regarding the phylogenetic relationships amongst the different members of the family.”

“The exceptionally complete remains of Decennatherium rex allow us to improve and reassess giraffid systematics, offering a lot of new data, both anatomic and phylogenetic, on the large late Miocene giraffids.”

Skeletal and life reconstructions of an adult female Decennatherium rex. Image credit: Oscar Sanisidro.

The paleontologists conducted a phylogenetic analysis to help elucidate evolutionary patterns.

“The results suggest that the genus Decennatherium may have been the most basal branch of a clade of now-extinct giraffids containing both sivatheres, the largest known giraffids, and samotheres, whose appearance was somewhere in between that of okapis and giraffes,” they said.

“All giraffids in this group feature four horn-like skull protuberances known as ossicones, two over the eyes and two larger ridged ossicones at the back of its head.”

Decennatherium rex was likely the earliest-evolving example of this ossicone layout.”

“The inclusion of this species in the sivathere-samothere clade would extend its timespan back to the early late Miocene and its range as far as the Iberian Peninsula, making the clade one of the most successful and long-lived of all the giraffids.”

The discovery of Decennatherium rex is reported in the journal PLoS ONE.


M. Ríos et al. 2017. A new giraffid (Mammalia, Ruminantia, Pecora) from the late Miocene of Spain, and the evolution of the sivathere-samothere lineage. PLoS ONE 12 (11): e0185378; doi: 10.1371/journal.pone.0185378