Ancient 'Drop Croc' Eggshells Unearthed in Queensland Reveal Tree‑Hunting Crocodiles

Ancient crocodile eggshells shine new light on unusual tree‑hunting 'drop crocs'

Scientists report the discovery of what appear to be Australia’s oldest crocodile eggshells, recovered from a rancher’s backyard near Murgon in southeast Queensland. The shells are attributed to mekosuchine crocodiles, a diverse group that dominated parts of Australia about 55 million years ago — long before modern saltwater and freshwater crocodiles arrived on the continent.

According to the study, published in the Journal of Vertebrate Paleontology, some mekosuchines reached at least 5 metres in length and show anatomical features consistent with terrestrial or arboreal ambush hunting. Australian researchers have nicknamed them "drop crocs" — a playful reference to the mythical "drop bear" — because they may have leapt or dropped from elevated perches to catch prey.

'It’s a bizarre idea. But some of them appear to have been terrestrial hunters in the forests,' said Michael Archer, a professor at the University of New South Wales and a coauthor of the study. 'They were perhaps hunting like leopards — dropping out of trees on any unsuspecting thing they fancied for dinner.'

An international team led by the Institut Català de Paleontologia Miquel Crusafont in Barcelona excavated and analysed the fossil eggshells. The material preserves fine microstructural and geochemical signals that can identify the type of animal that laid them and reveal details about nesting locations and breeding behaviour, said lead author Xavier Panadès i Blas.

These microscopic and chemical features make eggshells valuable for reconstructing life history traits and reproductive strategies of extinct animals. As Panadès i Blas explained, the shells 'tell us not only what kinds of animals laid them, but also where they nested and how they bred.'

The fossils were recovered from deposits near the town of Murgon — about a three‑and‑a‑half‑hour drive from Brisbane — where researchers from UNSW have been excavating since 1983. Archer recalled the excavations began informally: he and a colleague knocked on a homeowner’s door, asked to dig, and were welcomed when the residents learned their yard sat on a rich fossil deposit.

Coauthor Michael Stein, a research associate at UNSW, said mekosuchines likely disappeared from Australia roughly 3,000 years ago. He suggested a combination of habitat change (loss of inland wetlands to drying), increased competition from other predators, and dwindling prey may have driven their decline.

Not everyone is ready to assign the eggshells to a specific species based on eggs alone. Paleontologist Dean Lomax, who was not involved in the study, cautioned that identifying an extinct animal from eggshells is challenging. However, he said the case is strengthened because the eggshells came from the same geological layer and locality as known mekosuchine fossils from the same period.

'Matching the fossil eggshells and the croc that laid them can provide new information,' Lomax said. 'It will help us understand not only how they reproduced and where they laid their eggs, but also the lifestyle of these unusual crocs.'

Altogether, the find adds important new evidence about mekosuchine biology and behaviour and underscores that long‑running, small‑scale excavations can still yield surprising insights into prehistoric ecosystems.