Scientific discovery shows ‘drop crocs’ once existed in Australia
Ancient crocodiles that may have ambushed prey by dropping from trees have been identified through fossilised eggshells found in Queensland, suggesting a prehistoric predator ready to pounce
READING LEVEL: ORANGE
An ancient crocodile that hunted in trees has been uncovered by palaeontologists* examining fossilised eggshells.
Australia’s “drop bear” myth is well known as a tall tale told to gullible* tourists on their first visit Down Under.
But it turns out the popular fiction might not be so completely unrealistic, with scientists recently finding evidence of a five-metre-long “drop crocodile” that lived 55 million years ago.
The group of palaeontologists unearthed Australia’s oldest crocodile eggshells at a dig site in inland Queensland, finding they belong to mekosuchines*, an ancient crocodile that’s now long-extinct*.
“It’s a bizarre idea,” said palaeontologist Professor Michael Archer. “But some of them appear to have been terrestrial* hunters in the forest. They were perhaps hunting like leopards — dropping out of trees on any unsuspecting thing they fancied for dinner”.
MEET THE MEKOSUCHINES
While freshwater and saltwater crocodiles only arrived in Australia around 3.8 million years ago, mekosuchines would have dominated the continent’s inland waters 55 million years ago.
They grew up to five metres long, and some were “at least partly semi-arboreal (or partially tree-dwelling),” Professor Archer said.
The study explains how mekosuchines filled strange ecological* niches*.
“These eggshells have given us a glimpse of the intimate life history of mekosuchines,” said lead author Dr Xavier Panadès i Blas.
“We can now investigate not only the strange anatomy of these crocs, but also how they reproduced and adapted to changing environments.”
Historically significant, this information might also help us understand how species can adapt to ongoing changes in the environment.
WHERE WERE THE FOSSILS FOUND?
The fossils were discovered in the town of Murgon in Queensland, a rural township about three hours northwest of Brisbane.
Scientists have been digging there for decades in a clay pit that was once a lake. Over nearly half a century, the site has become a place of rich discovery.
Excavation has found evidence of Australia’s oldest-known mammals from the Tertiary period (55 million years ago).
Soft-shelled turtles and Australia’s oldest-known frogs lived in the area, as well as Australia’s oldest bat*.
The world’s earliest-known songbirds were also known to have lived there, making researchers think they might have evolved in Australia.
WHAT CAN EGGSHELLS TELL US?
Evidently, quite a lot.
After being examined under optical* and electron* microscopes, the shell fragments suggested that the mekosuchine crocodiles would have laid eggs on the margins of the lake.
This laying behaviour suggests adaptability in their reproductive strategy amid changing conditions.
“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,” Dr Blas said of the eggshell discovery.
“Our study shows just how powerful these fragments can be. Eggshells should be a routine, standard component of palaeontological research — collected, curated* and analysed alongside bones and teeth.”
POLL
GLOSSARY
- palaeontologist: someone who studies fossils as a way of getting information about the history of life on Earth
- fossilised: process of organic material becoming a fossil over time
- gullible: naive easily fooled, tricked or easily able to believe something that isn’t true
- extinct: no longer existing, an animal or planet species that has completely died out
- mekosuchines: scientific name Kambara implexidens, from the early Eocene of Queensland (period of time between about 56.5 and 35.4 million years ago), was an ancient group of primitive Gondwanan crocodiles
- terrestrial: land-based, relating to the planet Earth, or living or existing on land rather than in the sea or air
- ecological: relating to ecology, the scientific study of the relationships between the air, land, water, animals, plants, usually of a particular area
- niches: places, situations, spaces that are small, limited, specialised, suitable or appropriate, like a particular organism’s function within an ecosystem
- Australia’s oldest bat: the scientific name is Australonycteris clarkae, also of the Eocene of Queensland, not just the oldest bat of the Southern Hemisphere and one of the oldest in the world
- optical: relating to light or the ability to see something
- electron: a tiny particle of matter that is smaller than an atom and has a negative electrical charge
- microstructural: relating to the structure of a material that can be seen under a microscope
- geochemical: relating to the chemical substances in the Earth’s crust
- curated: carefully selected and organised
EXTRA READING
Wait, what? You can keep a croc?!
Crocodile safety as teen survives
Crocs in swimming pool surprise
QUICK QUIZ
- What did palaeontologists examine that provided such rich insights?
- Where were the fossils discovered?
- Name three other prehistoric animals that lived in the area at the same time?
- How long ago did saltwater and freshwater crocodiles arrive in Australia?
- Where would the mekosuchine crocodiles have laid their eggs?
LISTEN TO THIS STORY
CLASSROOM ACTIVITIES
1. Drop bear crocodile
Draw a visual representation of what you think this mekosuchine crocodile hunting from trees might have looked like. You could even add some humour in with some speech bubbles on what a poor unsuspecting creature below might be thinking.
Time: allow 15 minutes to complete this activity
Curriculum Links: English, Science, Visual Arts, Personal and Social, Critical and Creative Thinking
2. Extension
What and how do they get all this information from eggshells?
Why do you think Murgon in Queensland is so full of these palaeontological treasures?
Time: allow 5 minutes to complete this activity
Curriculum Links: English, History, Science, Personal and Social, Critical and Creative Thinking
VCOP ACTIVITY
Read this!
A headline on an article – or a title on your text – should capture the attention of the audience, telling them to read this now. So choosing the perfect words for a headline or title is very important.
Create three new headlines for the events that took place in this article. Remember, what you write and how you write it will set the pace for the whole text, so make sure it matches.
Read out your headlines to a partner and discuss what the article will be about based on the headline you created. Discuss the tone and mood you set in just your few, short words. Does it do the article justice? Will it capture the audience’s attention the way you hoped? Would you want to read more?
Consider how a headline or title is similar to using short, sharp sentences throughout your text. They can be just as important as complex ones. Go through the last text you wrote and highlight any short, sharp sentences that capture the audience.