New Fossil Sheds More Light on Oldest Known Ancestor of Giant Panda

An 11.6 million year old giant panda’s cousin, described earlier this year and attributed to the genus Agriarctos, has been re-evaluated and considered to be distinct enough to separate it into its own genus.

This is an artist’s reconstruction of Kretzoiarctos beatrix, formerly known as Agriarctos beatrix (SINC)

In May 2012, Dr Juan Abella and colleagues from the Spain’s National Museum of Natural Sciences and the Catalan Institute of Paleontology announced the discovery of a new fossil species of bear that roamed what is now Spain in the Miocene period.

On the basis of fossil teeth found at the Nombrevilla 2 site in the province of Zaragoza, the species was assigned to the genus Agriarctos and named A. beatrix. The discovery was described in a paper in the journal Estudios Geológicos.

In a new study, published November 14 online in the journal PloS ONE, Dr Abella’s team describes a newly found jaw fossil from the Vallès-Penedès Basin and suggests that the species is distinct enough as to be attributed to a different genus.

“The new genus we describe in this paper is not only the first bear recorded in the Iberian Peninsula, but also the first of the giant panda’s lineage,” Dr Abella said.

For the new genus, the name Kretzoiarctos was chosen to honor the paleontologist Miklós Kretz (arctos being Greek for bear).

According to the team, Kretzoiarctos beatrix bears the characteristics of a bear adapted to eating tough plant material like bamboo. The giant panda, native to certain parts of China, is the only living member of this unique bear family with these dietary habits.

“This new genus represents the oldest and most basal member of the ursid clade currently represented by Ailuropoda, thus being of utmost significance for understanding the origin of the giant panda lineage from both a chronological and paleobiogeographic perspectives,” Dr Abella and his colleagues reported in the PloS ONE paper.

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Bibliographic information: Abella J et al. 2012. Kretzoiarctos gen. nov., the Oldest Member of the Giant Panda Clade. PLoS ONE 7 (11): e48985; doi: 10.1371/journal.pone.0048985