Mongolian Site A Fossil Gold Mine Skeltons Of Rodent-Size Mammals Found Among Dinosaur Fossils

In a finding that could shed light on the early evolution of mammals, scientists have uncovered exquisitely preserved skeletons of previously unknown, shrewlike creatures that lived during the age of the dinosaurs.

Even tiny ear bones are present in the 80-million-year-old fossils, found in Mongolia’s Gobi Desert, said researcher Michael Novacek.

Five skeletons were found together in a nest, Novacek said. No such complete specimens of this kind of mammal had been found before from that time period, he said.

The creatures, about 6 inches long from nose to the tip of the tail, represent a previously unknown species, Novacek said.

The find is “a tremendous discovery,” commented William Clemens, curator of mammals at the Museum of Paleontology at the University of California at Berkeley.

The fossils were unearthed last summer at a site that had made headlines a few months before, when researchers announced that a 1993 expedition had found a remarkable collection of well-preserved fossils.

A summary of findings so far at the site is presented in today’s issue of the journal Nature by scientists including Novacek, curator of vertebrate paleontology at the American Museum of Natural History in New York.

Researchers last summer also found the first known skull of a turkey-size flightless bird called Mononykus, and eight skeletons of two-legged dinosaurs called oviraptors, including one unusually big one measuring about 10 feet from its head to the tip of its whip-like tail, Novacek said.

In all, the site so far has produced complete or partial skeletons of more than 100 dinosaurs and skulls of more than 400 mammals and lizards, many with skeletons attached.