Did Ancient Tree-Climbing Crocodiles Roam Australia?

Recent discoveries in Queensland, Australia, have unveiled the oldest known crocodile eggshells, estimated to be around 55 million years old, which may have belonged to a unique group of tree-climbing crocodiles dubbed "drop crocs." This significant find not only sheds light on the ancient lifestyle of these mekosuchine crocodiles but also highlights the rich prehistoric biodiversity of the region when Australia was part of a supercontinent.

Last updated: 12 October 2023 (BST)

What’s happening now

Scientists have made a remarkable discovery of 55-million-year-old eggshells in Queensland, Australia, which are believed to belong to a long-extinct group of crocodiles known as mekosuchines. These findings were published in the Journal of Vertebrate Paleontology, providing new insights into the behaviour and habitat of these ancient reptiles. The eggshells were found in a sheep farmer's backyard, where palaeontologists have been excavating for decades. The research suggests that some mekosuchines, referred to as "drop crocs," may have exhibited arboreal behaviours, climbing trees to hunt prey below.

Key takeaways

• The eggshells are the oldest known from crocodiles, dating back 55 million years.
• Mekosuchines are a unique group of crocodiles that lived in inland waters of ancient Australia.
• The term "drop crocs" describes their possible hunting strategy, similar to leopards.

Timeline: how we got here

The journey to this discovery spans several decades, with significant milestones including:

• 1983: Prof Michael Archer and colleagues began excavating a clay pit in Murgon, Queensland, which became known for its rich fossil deposits.
• 2000s: Ongoing excavations led to the discovery of younger mekosuchine fossils in Queensland.
• 2023: Recent analysis of the previously found eggshells confirmed their age and species, leading to their publication in a scientific journal.

What’s new vs what’s known

New today/this week

The recent analysis of the eggshells has confirmed they belonged to the mekosuchine group, broadening our understanding of their behaviour and habitat. The concept of "drop crocs," which suggests these creatures may have hunted from trees, is a new perspective that adds complexity to their ecological roles.

What was already established

Previously, scientists had identified younger mekosuchine fossils and established their presence in Australia long before modern crocodiles arrived. The excavation site in Murgon was already noted for its diverse prehistoric fauna, including some of the world's oldest known songbirds, frogs, and bats.

Impact for the UK

Consumers and households

While the discovery itself may not directly impact UK consumers, it contributes to the global understanding of evolutionary biology and the history of species. Such findings can influence educational content and awareness regarding prehistoric life.

Businesses and jobs

The implications for tourism and educational sectors could be significant, as discoveries like these can attract researchers, students, and tourists interested in palaeontology and natural history. This can potentially lead to job creation in these areas.

Policy and regulation

The findings could inform conservation efforts and policies regarding fossil sites in Australia, underscoring the importance of protecting such significant archaeological and geological treasures.

Numbers that matter

• 55 million years: Age of the discovered eggshells, marking the oldest known crocodilian eggs.
• 5 metres: Estimated maximum length of mekosuchine crocodiles.
• 270 km: Distance from Brisbane to the excavation site in Murgon.

Definitions and jargon buster

• Mekosuchines: An extinct group of crocodiles that lived in inland waters of ancient Australia.
• Drop crocs: A colloquial term for mekosuchines that are believed to have hunted from trees.
• Palaeontology: The scientific study of the history of life on Earth through the examination of plant and animal fossils.

How to think about the next steps

Near term (0–4 weeks)

Further studies will likely emerge as researchers continue to analyse the eggshells and other fossil materials from the site. This could lead to new insights into the behaviour and ecology of mekosuchine crocodiles.

Medium term (1–6 months)

We can expect additional publications detailing the findings from the Murgon site, possibly uncovering more information on the environmental conditions of prehistoric Australia and the various species that coexisted with mekosuchines.

Signals to watch

• New fossil discoveries or analyses from the Murgon site that could offer further insights into the mekosuchines.
• Research outputs from related palaeontological studies that may provide context for the findings.

Practical guidance

Do

• Stay informed about palaeontological discoveries and their implications for understanding biodiversity.
• Encourage educational initiatives that promote awareness of prehistoric life and its relevance today.

Don’t

• Underestimate the importance of fossil discoveries in informing our understanding of evolutionary history.
• Dismiss the potential for further discoveries in known fossil sites.

Checklist

• Check for updates on the Murgon excavation site and related research studies.
• Engage with educational materials on prehistoric species and their habitats.
• Support conservation efforts that protect fossil sites and promote research.

Risks, caveats, and uncertainties

While the discovery of the eggshells is significant, there remain uncertainties regarding the exact behaviours of mekosuchines and their ecological roles. Ongoing research may yield new findings that could shift current understanding. Furthermore, the terminology used to describe these creatures, such as "drop crocs," is based on hypotheses that need further evidence to confirm their behaviours and lifestyles.

Bottom line

The discovery of 55-million-year-old crocodile eggshells in Queensland highlights the fascinating evolutionary history of crocodiles in Australia. This find not only sheds light on the mekosuchines but also emphasizes the importance of ongoing palaeontological research in understanding our planet’s prehistoric life. As scientists continue to explore and excavate fossil sites, the potential for further groundbreaking discoveries remains high.

FAQs

What are mekosuchines?

Mekosuchines are an extinct group of crocodiles that lived in the inland waters of ancient Australia, notable for their unique adaptations.

What are "drop crocs"?

"Drop crocs" is a colloquial term for some mekosuchines believed to have hunted by dropping from trees onto their prey.

How old are the discovered eggshells?

The discovered eggshells are approximately 55 million years old, making them the oldest known from crocodiles.