Crocodiles: Modern Day Relics
From Archosaurs to Apex Predators
When you’re floating along the Adelaide River on a croc cruise and spot one of those big salties lurking just beneath the surface, it’s hard not to think of dinosaurs. Massive, armoured skins, cold-blooded beasts with a death stare that hasn’t changed in millions of years. But does that make crocodiles actual dinosaurs? Not quite — but they do have a tangled family tree worth digging into.
Both modern crocodiles and dinosaurs trace their lineage back to a group of prehistoric reptiles known as archosaurs, or “ruling reptiles.” These ancient crocodiles popped up around 250 million years ago in the early Triassic period, back when the Earth’s landmasses were still clumped together in the supercontinent Pangaea.
From there, archosaurs split into two major lineages:
- One branch led to modern birds and extinct dinosaurs.
- The other gave rise to crocodilian species — including ancient crocodiles, alligators, caimans, and gharials.
So, crocodiles and dinosaurs are more like distant cousins than siblings. Same sheep station, different evolutionary paddock.
What Makes a Dinosaur a Dinosaur
Crocodile Evolution: Survivors of Deep Time
Crocodilians have been kicking around for over 200 million years — and they’ve barely changed. That’s no small feat, considering they’ve outlived the dinosaurs and survived multiple mass extinctions. The fossil record shows remarkable consistency in body size evolution and anatomical traits.
Some prehistoric crocs were straight-up monsters:
- Deinosuchus riograndensis (roughly 80 million years ago during the Cretaceous period): This North American giant could grow up to 10 metres long and likely snacked on dinosaurs. The fossilised teeth and tooth marks on dinosaur bones don’t lie.
- Sarcosuchus, also known as Phobosuchus riograndensis or the “SuperCroc,” lived in what’s now Central Africa and South America. It was even larger than Deinosuchus and boasted one of the strongest bites in prehistoric reptiles.
Over time, some crocs moved into marine reptile territory, while others stuck to brackish water and riverbanks. Their saltwater tolerant physiology, including adaptations to salt water and brackish water, made them versatile apex predators.
Crocodile vs Dinosaur: What the Public Gets Wrong
While the term “prehistoric crocodile” gets thrown around a lot, these ancient creatures came in a range of forms — from extinct crocodilians to their evolutionary lookalikes:
- * Phytosaurs: Croc-like reptiles that lived before true crocodiles evolved. Think of them as false crocodiles — similar shape, but not in the crocodilian family tree.
- Notosuchians: Weird crocodilian species, including some with broad snouts, long snouts and even vegetarian habits.
- Thalattosuchians: Marine reptiles with streamlined bodies and paddle limbs for life in the water.
Many of these crocs were straight-up crazy — some were land animals, others swam like sharks. A few may have had olfactory chambers and light receptors to hunt like nocturnal predators.
Crocodile vs Dinosaur: What the Public Gets Wrong
The idea that crocodiles are dinosaurs comes up a lot — especially in pop culture. From schoolbooks to docos with snake venom and Snake Footage, people get tangled in the prehistoric web.
But here’s the lowdown:
- Modern-day crocodiles are not dinosaurs. They’re modern crocodilians — distant relatives.
- Birds are closer to dinosaurs than crocs are. In fact, birds are living dinosaurs.
- Crocodiles split off from the dino-bird branch before the main dinosaur boom in the Cretaceous period.
So while crocs have sharp teeth, a bite mark that’ll make you think twice, and a rubbery skin that looks like a prop from Jurassic Park, they’re not dinosaurs. They’re the cousins who never left the bush.
Crocodiles and dinosaurs are often grouped together because they both lived during the Mesozoic Era and share a common ancestor. But they are not the same type of reptile. Crocodiles belong to the Crocodylia order, while dinosaurs are a completely different group. This means they share some characteristics, like being cold-blooded reptiles and apex predators, but their evolutionary paths diverged millions of years ago.
Crocodiles and dinosaurs are often grouped together because they both lived during the Mesozoic Era and share a common ancestor. But they are not the same type of reptile. Crocodiles belong to the Crocodylia order, while dinosaurs are a completely different group. This means they share some characteristics, like being cold-blooded reptiles and apex predators, but their evolutionary paths diverged millions of years ago.
Modern Crocodiles and Alligators
Today’s croc family includes:
- Saltwater Crocodiles (Crocodylus porosus): Found in Northern Australia, these are the biggest crocodiles alive — and deadset predators.
- Freshwater Crocodiles (Crocodylus johnstoni): Smaller, less aggressive, but still no pushover.
- American Alligators and modern alligators: Broad snout and more chilled out.
Despite their fearsome rep, crocs are high-tech hunters:
- Valved hearts for underwater hunts
- Elongated snouts with sensory pits to detect ripples
- Tough hides with ancient flair — the kind that’s been around since the 14th century, if not earlier in folklore
They also shed the occasional crocodile tears — a quirk of their tear glands when digesting.
The diversity of modern crocodiles and alligators is proof of their long history. From the big crocodiles of the past to the smaller and more specialised ones we see today, crocodilians have adapted to many environments and challenges. This adaptability has made them one of the most successful predators in the animal kingdom.
Australia’s Crocodylian History
Australia wasn’t always dry red dirt and sheep stations. In the Miocene, tropical rainforests and rivers stretched across the continent. Perfect stomping ground for terror crocodiles and their kin.
Fossils show us a few Aussie locals:
- Quinkana: A rare land animal croc with slicing teeth and long hind legs — a true blue Aussie predator.
- Pallimnarchus: A massive prehistoric crocodile that ruled the river systems.
Today’s crocodiles dominate the Top End — from Kakadu to the Kimberley. Research from Gondwana Research, the Florida Museum of Natural History, and the University of California Museum of Paleontology has pieced together their ancient journey.
FAQ
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