After stumbling upon a handful of tiny teeth in Israel's Negev Desert, a team of international researchers has discovered a new species of rodent - Sayimys negevensis - that has been extinct for more than 18 million years.
The new species also reveals a dispersal route used by mammals and other species between Eurasia and Africa in the Early Miocene, which took place approximately 23 million to 16 million years ago.
The newly discovered route solidifies Israel's unique paleographic position and reveals it as the piece that holds together the Levantine corridor that connects Eurasia with North Africa.
S. negevensis is a distant rodent on the evolutionary tree that eventually evolved into the present-day gundi, a tiny rodent also referred to as a "comb-rat" due to the comb-like bristles located on the two middle toes of its hind feet.
"It is a pivotal species that bridges the gap between an array of primitive ctenodactylines and the most derived, Early Miocene and later, gundis," the researchers wrote.
Gundis are the last known descendants of the Ctenodactylidae family, whose earliest ancestors existed in Asia approximately 40 million years ago.
The new species, S. negevensis, was named after the Negev locality where it was found. Currently, Israel is the only location along the Eastern Mediterranean where fossil evidence of the Early Miocene has been found.
"The fossil sites of Israel are in a unique position to offer data on the early times of the large waves of faunal exchanges that took place around 19 million years ago between Eurasia and Africa," said Raquel Lopez-Antoñanzas, first author of the study and a senior researcher at the University of Bristol.
Israel was more connected to Africa during the early Miocene, and most animals discovered in the area originated from Africa. Conversely, the extinct S. negevensis is one of the few species discovered in the country to have Eurasian roots.
"The new Israeli species is closer in morphology to nearly coeval species found in Pakistan, therefore demonstrating that mammals were already using the Levantine corridor to travel between Eurasia and Africa in the Early Miocene," said Rivka Rabinovich, co-author of the study and a member of the Institute of Earth Sciences and the National Natural History Collections at the Hebrew University of Jerusalem.
The findings were published in the April 6 issue of PLOS ONE.
