Prosimians’ Start Is Updated

A small collection of 40-million-year-old teeth and jaw fragments suggests that one line of primates developed much longer ago than researchers had previously believed. The fossils, discovered in the Fayum desert region of Egypt, represent at least two early animals -- a small bushbaby called Saharagalago and a loris-like species called Karanisia.

Bushbabies, lorises and lemurs, collectively called toothcombed prosimians, represent one of the three main groups of primates. The others are anthropoids, a grouping that includes monkeys, apes and humans, and tarsiers.

The toothcombed prosimians received their name because they use their teeth to groom their peers. Teeth from the new fossils, discovered by a team from Duke University and the Egyptian Geological Museum, clearly show the grooves produced by grooming. The oldest previously known grooved teeth from prosimians were observed in 17-million to 20-million-year-old fossils found in East Africa.

Genetic studies had previously suggested that the toothcombed prosimians split off from other primate lines much earlier than was indicated by existing fossils. The new find, reported in Thursday’s issue of Nature, confirms the genetic evidence.

“The early evolutionary history of these toothcombed primates has long been the most mysterious phase of early primate evolution,” said Duke anthropologist Erik Seiffert, one of the paper’s authors.

“Finally ... fossils have been found that shed important light on this issue.”