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New rodent’s link to fossil family

10 March 2006

Laonastes, the rock-dwelling new species of rodent. © Mark A Klingler/CMNH

Laonastes, the rock-dwelling new species of rodent, belonging to an extinct rodent family. © Mark A Klingler/CMNH

A new genus and species of rodent from southeast Asia, described last year, is now believed to be a surviving member of an extinct family of rodents.

The rodent was known to locals as the Kha-nyou, but was new to science, being the only new family of mammals to have been discovered in the last 30 years.

Scientists found that the kha-nyou, Laonastes aenigmamus, may belong to the extinct rodent family Diatomyidae that lived around 11 million years ago.

Comparing living and fossil rodents
Lateral view of Laonastes aenigmamus skull © The Natural History Museum, London 2005

Lateral view of Laonastes aenigmamus skull © The Natural History Museum, London 2005

Mary Dawson, of the Carnegie Museum of Natural History, Pittsburgh and Laurent Marivaux, of the Université Montpellier, visited the Natural History Museum in London to study the skeletal remains of the Laonastes specimens so that they could consider possible relationships with fossil rodents.

Dawson and her colleagues found many similarities between the Laonastes specimens and a subsequently discovered, well-preserved fossil specimen of an ancient rodent, Diatomys from China. They concluded that both belonged to the extinct family of rodents Diatomyidae.

Lazarus effect
Fossil skull of ancient rodent Diatomys from China © Mark Klingler/AAAS/Science

Fossil skull of ancient rodent Diatomys from China © Mark Klingler/AAAS/Science

The research is an excellent example of the Lazarus effect where living examples are discovered of an animal group that was thought to be extinct. This is extremely rare amongst mammals, especially for a family of rodents that was believed to have been extinct for so many million years.

'This is a fascinating, exciting and important new theory supported by convincing evidence', said Paula Jenkins, mammalogist at the Natural History Museum. 'The idea of Laonastes as an example of the Lazarus effect is incredibly exciting and inspiring.'

Laonastes joins the tarsier, flying lemurs and tree shrews as examples of ancient mammal groups that were once widespread but now survive as relicts in areas of southeast Asia.

BBC article, 7 Apr 2006, reports that Laonastes may be more common than previously thought .