Washington, August 5 : Tiny fossilized teeth discovered from an open-pit coal mine in Gujarat, India, could be the oldest Asian remains ever found of anthropoids, taking the primate timeline back by almost 10 million years.
The discovery was made by Sunil Bajpai, an earth scientist at the Indian Institute of Technology (IIT) who directed excavations at the Vastan lignite coal mine in western India that unearthed the fossils.
"It's certainly the oldest anthropoid from Asia and India," said Richard Kay, a Duke professor of evolutionary anthropology, who is corresponding author of a report to be published online during the week of Aug. 4 - 8 in Proceedings of the National Academy of Sciences (PNAS).
Previous fossil evidence shows primates were living in North America, Europe and Asia at least 55 million years ago. But, until now, the fossil record of anthropoid primates has extended back only 45 million years.
"We're going back almost 10 million years before any previously described Asian anthropoid," said co-author Blythe Williams, a Duke visiting associate professor of evolutionary anthropology.
"The new fossils from India are exciting because they show that the anthropoid lineage is much more ancient than we realized," he added.
In addition to stretching the primate timeline, the specimens represent a new genus as well as a new species of anthropoid, which the researchers have named Anthrasimias gujaratensis by drawing from the Greek word for "coal," Latin for "monkey" and the Indian State of Gujarat where the teeth were found.
Bajpai's Indian team managed to find and remove the tiny Anthrasimias tooth specimens from a strata in the coal mine while "really gigantic trucks" scooped up coal above them.
The teeth were dated by identifying microscopic marine plankton fossils of known age in nearby rock layers.
Just 9-thousandths of a square inch in size, the teeth are about 54.5 million years old and suggest these early primates were no larger than modern dwarf lemurs weighing about 2 to 3 ounces.
Studies of the shape of the teeth suggest these small animals could live on a fruit and insect diet, according to the researchers.
The PNAS report describes tooth structure differences that would separate Anthrasimias from two other ancient lines of primates whose remains have been found at the same level of the Vastan mine.
Of the three lines, Williams and Kay believe only Anthrasimias's is part of the anthropoid lineage that evolved into modern monkeys, apes and humans.
"It's certainly the oldest anthropoid from Asia and India," said Kay.