Imagine crocodiles… falling from trees! Sounds like something out of a movie, right? But groundbreaking discoveries from 55-million-year-old fossils reveal a bizarre truth: ancient crocodiles in Australia, known as mekosuchines, were unlike anything we see today. These weren’t your average swamp-dwellers; some were terrestrial hunters, and others… well, they were “drop crocs,” ambushing prey from above.
Let’s rewind the clock. In the small town of Murgon, Queensland, researchers have been meticulously excavating a seemingly ordinary clay pit on a grazier’s land for decades. This site, one of Australia’s oldest fossil-bearing locations, offers a unique window into a time when Australia was still connected to Antarctica and South America, forming part of a supercontinent. It’s a treasure trove of information about life before Australia’s isolation.
Recently, an international team led by the Institut Català de Paleontologia Miquel Crusafont (ICP), in collaboration with UNSW Sydney, identified something extraordinary: the oldest crocodile eggshells ever found in Australia. These fragments, now formally named Wakkaoolithus godthelpi, belonged to mekosuchine crocodiles, a now-extinct group that dominated Australian waterways around 55 million years ago. Modern freshwater and saltwater crocodiles didn’t appear until much later, approximately 3.8 million years ago.
“These eggshells have given us a glimpse of the intimate life history of mekosuchines,” explains Xavier Panadès i Blas, the lead author of the study. “We can now investigate not only the strange anatomy of these crocs, but also how they reproduced and adapted to changing environments.” And this is the part most people miss: eggshells aren’t just fragile remnants; they’re time capsules of information.
But here’s where it gets controversial… Unlike their modern relatives, mekosuchines occupied a surprisingly diverse range of ecological niches. Some, as mentioned, were terrestrial hunters, stalking prey in the forests. Evidence for this comes from younger mekosuchine fossils found in 25-million-year-old deposits at the Riversleigh World Heritage Area.
“It’s a bizarre idea,” says UNSW paleontologist Professor Michael Archer, “but some of them appear to have been terrestrial hunters in the forests.”
And it gets even weirder. Some Riversleigh species, reaching lengths of up to five meters, were also semi-arboreal. “Some were also apparently at least partly semi-arboreal ‘drop crocs’,” Archer explains. “They were perhaps hunting like leopards — dropping out of trees on any unsuspecting thing they fancied for dinner.” Imagine that! Crocodiles behaving like leopards!
Panadès i Blas emphasizes the incredible value of eggshells in reconstructing ancient environments. “They preserve microstructural and geochemical signals that tell us not only what kinds of animals laid them, but also where they nested and how they bred,” he says. “Our study shows just how powerful these fragments can be. Eggshells should be a routine, standard component of paleontological research — collected, curated and analyzed alongside bones and teeth.”
The Murgon eggshells, studied under optical and electron microscopes, revealed that these crocodiles likely nested along the edges of a lake and adapted their reproductive strategies to changing conditions. Dr. Michael Stein suggests that as the region dried out, mekosuchines may have lost much of their inland habitat, forcing them into smaller waterways where they faced competition from newly arrived crocodiles and dwindling populations of their megafaunal prey.
The Murgon lake was surrounded by a dense forest, home to a fascinating array of creatures, including the world’s oldest-known songbirds, Australia’s earliest frogs and snakes, a variety of small mammals with South American connections, and one of the world’s oldest known bats. It was a biological hotspot!
Professor Archer describes the Tingamarra deposit at Murgon as a crucial piece of the puzzle in understanding life before Australia’s isolation. He recounts his experience uncovering a puzzling crocodilian jaw fragment in 1975. The jawbone looked reptilian but had teeth resembling those of dinosaurs. He sought the expertise of Professor Max Hecht, a reptile expert at the American Museum of Natural History.
“When he saw it, Max nearly dropped his coffee cup,” Archer recalls. “It closely resembled another kind of extinct croc with dinosaur-type teeth that had been found in South America. That was the first realization that crocodiles with teeth like this were also part of the older record in Australia.”
Archer and his team have been working at Murgon since 1983, often with the enthusiastic support of local residents. “That year, UNSW colleague Henk Godhelp and I drove to Murgon, parked the car on the side of the road, grabbed our shovels, knocked on the door and asked if we could dig up their backyard,” he says. After explaining the potential prehistoric significance of the site, the property owners readily agreed.
“From subsequent excavations, that’s where the eggshell pieces came from. And, quite clearly, from the many fascinating animals that we’ve already found in this deposit since 1983, we know that with more digging there will be a lot more surprises to come.”
But these fossil discoveries aren’t just about the past; they also offer valuable insights for modern conservation efforts. Archer has been involved in the ‘Burramys Project,’ aimed at saving the Mountain Pygmy-possum (Burramys parvus) from extinction. This alpine species is severely threatened by climate change. The project revealed that its ancestors thrived in lowland temperate rainforests for nearly 25 million years.
Based on this evidence, researchers concluded that the Mountain Pygmy-possum’s ancestors likely followed rainforest habitats uphill during a warm and wet phase in the Pleistocene Epoch. As the alpine climate cooled, the species developed survival strategies like hibernation.
A few years ago, Archer’s group collaborated with Trevor Evans of Secret Creek Sanctuary to establish a breeding program in non-alpine rainforest, supported by organizations like the Prague Zoo. Today, the Mountain Pygmy-possum population is thriving in that environment, validating the predictions derived from the fossil record.
“The Burramys Project is a demonstration that, at least in some cases, we can develop strategies to save endangered species,” Archer says. “Clues from fossil records matter, not just to understand the past, but also to help secure the future.” It’s a powerful reminder that understanding our planet’s history is crucial for protecting its future.
The newly named croc species, Wakkaoolithus godthelpi, honors the Wakka Wakka First Nations people, whose Country includes the fossil site, and Henk Godthelp, a longtime member of the UNSW paleontology team.
So, what do you think? Could understanding the past really be the key to saving species in the future? Are there other ways we can learn from fossils to address modern environmental challenges? And perhaps most importantly, does the idea of a crocodile dropping out of a tree change your perspective on these ancient creatures? Share your thoughts in the comments below!