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Australia's oldest crocodile eggshells hint at tree-climbing 'drop crocs'
Scientists have identified Australia's oldest known crocodile eggshells, dating back 55 million years, which may belong to an extinct group of tree-climbing predators dubbed "drop crocs." The discovery, made in a Queensland sheep farm, was detailed in the Journal of Vertebrate Paleontology this week.
Extinct mekosuchines and their hunting tactics
The eggshells are linked to mekosuchines, a long-vanished crocodile lineage that thrived in Australia's inland waters when the continent was still connected to Antarctica and South America. Unlike modern crocodiles, these creatures-some reaching five meters in length-may have hunted from trees, ambushing prey like leopards, according to researchers.
"It's a bizarre idea," admitted Prof Michael Archer, a palaeontologist at the University of New South Wales and co-author of the study. "But some mekosuchines were likely terrestrial hunters, lurking in forests and possibly dropping onto unsuspecting animals."
Decades-old find, newly analyzed
The eggshells were unearthed decades ago in Murgon, a rural town 270 km northwest of Brisbane, but only recently examined with assistance from Spanish scientists. The site, a former clay pit, has yielded fossils since the 1980s, revealing a prehistoric ecosystem teeming with early songbirds, frogs, snakes, and mammals with South American ties.
"This forest was home to the world's oldest-known songbirds, Australia's earliest frogs and snakes, and one of the oldest bats," said Dr Michael Stein, another co-author.
From backyard digs to global significance
Prof Archer recalled the site's humble origins: in 1983, he and a colleague "knocked on a farmer's door, explained the potential fossils beneath their sheep paddock, and were welcomed to dig." The area, once a lush forest, continues to surprise researchers. "With more excavation, we'll find even more," he predicted.
Evolutionary context
Mekosuchines dominated Australia's waterways millions of years before modern saltwater and freshwater crocodiles arrived around 3.8 million years ago. Younger mekosuchine fossils, dated to 25 million years old, were previously found elsewhere in Queensland, reinforcing theories about their semi-arboreal behavior.
