National Geographic : 1986 Jan
FOLLOWING HIS TEAM up a limestone ridge in Queensland's far northwest on an invigorating May morning, paleontolo gist Michael Archer paused for a tardy col league. Looking at the rock beneath his feet, he nearly collapsed with excitement. The ground bristled with the teeth and jaws of fos sil mammals that lived 15 million years ago. His shout brought team members, who, de spite prickly spinifex grass, crawled around a ten-square-meter area and spotted fragments of 100 mammals representing some 30 species never seen before. It was one of the final days of the 1983 four-week field season, Archer's fourth year exploring Riversleigh Station, a cattle ranch half the size of Delaware. Earlier discoveries were mostly turtles, crocodiles, and birds. Particularly startling among the new finds were two species of bats that resem bled those in well-dated deposits in France, a boon to fixing fossil chronology in Australia. In 1984 and 1985 the research group- Incredible carnivorous kangaroo (Ekaltadeta ima) wrestles a python (Montypythonoides riversleighensis), one of many in the deposits. Scoring on the marsupial's teeth indicates it crunched bone. Bobcat-size marsupial lions (a new species of Wakaleo) stabbed with long, powerful incisors. Large claws on the thumbs could rend prey; the opposable first toes on the rear feet suggest that the animals could climb like opossums. A primitive ratkangaroo (Wabularoo naughtoni), which browsed on undergrowth, possessed such unusualjaws that it was assigned to a new subfamily (Bulungamayinae). It is one of a dozen new kangaroo species found so far.