Thriving rodent population in prehistoric Africa could shed light on human evolution

WASHINGTON - Rodents have been one of the most common mammals in Africa for the past 50 million years. From deserts to rainforests, they flourished in prehistoric Africa, making them a stable and plentiful source of food.

Now, rodent fossils are proving useful in shedding light on human evolution.

A new study has pointed out that rodents were diverse and abundant in prehistoric Africa when our human ancestors evolved.

“Rodents are often known in abundance, and there are many different kinds from a number of famous hominid and hominoid localities. Many paleoanthropologists are very interested in the faunal and ecological context in which our own species evolved,” said palaeontologist Alisa J. Winkler, an expert on rodent and rabbit fossils and a research professor at Southern Methodist University.

Rodents - rats, mice, squirrels, porcupines, gerbils and others - are the largest order of living mammals, constituting 42 percent of the total mammalian diversity worldwide.

Their review documents more than 130 formally named genera in ‘Fossil Rodents of Africa’, the first comprehensive summary and distribution analysis of Africa’s fossil rodents since 1978.

“At many of the sites, identification of Africa’s rodents provides important collaborating information on the ecology of the locales and on environmental change through time,” noted the authors.

The diversity of ancient Africa’s rodents most likely has been underestimated, they said. Just how much is not known, though, because the quantity of rodent fossils being discovered far exceeds the handful of scientists who specialize in identifying and studying the specimens.

That diversity continues to expand. R. Lavocat carried out the last exhaustive analysis of Africa’s rodents in 1978. At that time, scientists recorded 54 genera, 76 fewer than those documented by Winkler in her analysis.

Winkler and her colleagues summarized the distribution and ecology of existing rodent families, as well as the systematics, biochronology and paleobiogeography of rodent families in Africa’s fossil record.

The diversity they document reflects ‘the wide variety of habitats present on the continent’ and paints a picture of Africa’s paleoecology.

Given the huge rodent diversity in modern Africa, “it is likely that such an extensive fauna was also present in the past,” the scientists concluded.

The analysis is a chapter in the new scientific reference book ‘Cenozoic Mammals of Africa’ (University of California Press, 2010), the first comprehensive scientific review of Africa’s fossil mammals in more than three decades. (ANI)