Croft said that although it probably ate fruits and nuts and spent much of its time foraging among the trees, like its modern relatives, its durable teeth indicate that it may also have ventured into more open areas. Forested habitats no longer exist in the Quebrada Honda area.
Quebradahondomys potosiensis is a rat-sized relative of extant spiny rats, which are mostly tree-dwelling relatives of guinea pigs and chinchillas that have spiny coats and tails that easily break off to help them escape from predators. Currently, spiny rats are found throughout Central America and most of South America.
The molar teeth, which are shaped like a "3" or an "E", are typical of a particular subgroup of spiny rats and indicate the extinct rodent fed on a leafy diet. The researchers say it was at least partially arboreal and may have been living in the same trees among which Mesoprocta hypsodus foraged on the ground.
In addition to the two new species above, Croft's group found a number of fossils from the genus Acarechimys.
The remains indicate the animal was about hamster-sized, lived in rocky or bushy environs and fed on leaves and seeds.
Fossils from the genus have been found from Colombia to the southern tip of Argentina, but close analysis is needed to break them down into species. The researchers hope to work with others to define species found.
The most common fossils at the site are from relatives of chinchillas, all of the genus Prolagostomus. They were found in such high numbers that the researchers believe the animals were highly social and, like some of their current relatives, lived in communities much as prairie dogs do today.
Again, closer analysis of known fossils from here and other locations is needed to determine species. St
|Contact: Kevin Mayhood|
Case Western Reserve University