New rodent discovery leads to new mammal family

April 23, 2005

Researchers in mammalogy from London, Vermont, Wisconsin, and Gloucestershire, UK have just discovered a new species of rodent that is unlike anything previously identified.

In a new study published in Systematics and Biodiversity, researchers describe a new rodent species called the Laotian Rock Rat. It was found for sale as meat at a marketplace in Laos. The researchers brought it to London for a closer look at its skeleton and DNA.

Researchers found that the specimen was not particularly related to anything currently known. The group had to describe a new family of mammals for this single species. The last time a new mammal family was created to accommodate a new species discovery was in 1974 when the bumblebee bat was discovered.

The closest relatives to Laotian rock rats are a group of rodents that includes porcupines and guinea pigs, but this relationship is a rather distant one. The researchers think the Laotian rock rats may have split off from common ancestors a long time ago, with porcupines and guinea pigs evolving after that split.

The authors hope that by studying Laotian rock rats, they can solve an old puzzle. How did guinea pigs and their relatives get to South America at a time when it was surrounded by water? Until these rock rats came along, the only Old World relatives of guinea pigs were ones found in Africa or both Africa and Asia. This led some scientists to think that guinea pig ancestors got to South America from Africa across the Atlantic Ocean. Others insisted that they went through Asia and North America first. Understanding how the guinea pig's new Asian relative is connected to the rest of the family may help to explain this mystery.