New species of ancient rodent discovered in the Negev

A mere handful of tiny teeth found in the Negev desert allowed an international research team to discover a new species of rodent that has been extinct for around 18 million years.

The researchers explain that the discovery of Sayimys negevensis enables a new understanding of how mammals and other species were dispersed between Eurasia and Africa in the Early Miocene, a period 23 million to 16 million years ago.

It also illustrates how crucial Israel's paleogeographic position is as a key point in the Levantine corridor connecting Eurasia with North Africa.

The research, published in the scientific journal PLoS ONE accessible here and announced in a Hebrew University press release on Wednesday, describes the Sayimys negevensis as a forerunner of the present-day gundi or "comb-rat" – a small rodent with comb-like bristles sprouting from the two middle toes of its back 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 in the article.

Ctenodactylidae are a family of rodents who first appeared in Asia around 40 million years ago, with gundis constituting their last descendants. Currently they are found living in groups on rocky outcrops in deserts in East and North Africa.

The name Sayimys negevensis references the Negev where the ancient species was found, and Israel is indeed the only site along the Eastern Mediterranean stretching from Anatolia to the Sinai where Early Miocene fossil sites have 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 Dr. Raquel Lopez-Antoñanzas, a senior researcher at the University of Bristol, who led the research.

Back in the Early Miocene, Israel was more firmly attached to Africa according to the researchers, and many local mammals at the time were of African origin. Sayimys negevensis is one of the few species found in Israel with Eurasian affinities.

"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 research co-author Dr. Rivka Rabinovich, of Hebrew University's Institute of Earth Sciences and the National Natural History Collections.

The new rodent's discovery is part of an international focus on Israel's Early Miocene fauna and the country's paleogeographic implications.

This focus is being led by Dr. Rivka Rabinovich, Dr. Rani Calvo of the Israel Geological Survey and Dr. Ari Grossman of Midwestern University in Glendale Arizona. Other international experts taking part in the research include Dr. Raquel López-Antoñanzas, Dr. Fabien Knoll of the University of Manchester and Dr. Gideon Hartmann from the University of Connecticut.


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