Crocodiles survived the asteroid strike that wiped out the dinosaurs 66million years ago due to ‘snappy evolution’ that saw the animals flourish on land AND in the oceans
- Experts studied over 200 skulls and jaws of crocodiles and their extinct species
- Some extinct crocodile groups evolved very fast over millions of year
- Today’s crocodiles and alligators evolved steadily for the last 80 million years
It’s a mystery that has baffled scientists for years – why did crocodiles survive the asteroid strike that wiped out the dinosaurs 66 million years ago?
Now, researchers believe they may have the answer, and it all comes down to aptly named ‘snappy evolution.’
In a new study, scientists suggest that crocodiles underwent rapid evolution that meant the creatures could flourish on land and in the oceans.
Dr Stephanie Pierce, Associate Professor of Organismic and Evolution Biology at Harvard University, said: ‘Ancient crocodiles came in a dizzyingly array of forms. They were adapted to running on land, swimming in the water, snapping fish, and even chewing plants.
‘Our study shows that these very different ways of living evolved incredibly fast, allowing extinct crocodiles to rapidly thrive and dominate novel ecological niches over many millions of years.’
In a new study, scientists suggest that crocodiles underwent rapid evolution that meant the creatures could flourish on land and in the oceans. Pictured is a modern crocodile
HOW DO CROCODILES AND ALLIGATORS DIFFER?
Snout: Alligators have wider, U-shaped snouts, while crocodile are more pointed and V-shaped.
Smile: Crocodiles look like they’re flashing a toothy grin when their snouts are shut.
Alligators teeth are hidden as their upper jaw is wider than their lower.
Home: Crocodiles live in saltwater habitats, while alligators prowl freshwater marshes and lakes.
In the study, researchers from the University of Bristol and Harvard University studied over 200 skulls and jaws of crocodiles and their extinct species, spanning 230 million years.
The team analysed how the shape of the skulls and jaws varied between species, and studied how fast crocodile groups changed with time.
Their findings suggest that some extinct crocodile groups, including dolphin-like thalattosuchians and land-dwelling notosuchians, evolved very fast over millions of year.
These species also underwent huge changes to their skulls and jaws, becoming almost mammal-like at times.
And while today’s crocodiles, alligators and gharials are often referred to as ‘living fossil’, the researchers suggest that this isn’t the case, and that there is ‘no evidence for a slow-down in their evolution.’
Instead, the team believes that today’s crocodiles, alligators and gharials evolved steadily for the last 80 million years.
Dr Tom Stubbs, who led the study, said: ‘Crocodiles and their ancestors are an incredible group for understanding the rise and fall of biodiversity.
A fossil of a land-dwelling crocodile from the Cretaceous. Notosuchians had diverse diets, including insect-eating and plant-eating
This tiny skull belonged to an early ancestor of crocodiles which lived on land and had a diverse diet
‘There are only 26 crocodile species around today, most of which look very similar. However, there are hundreds of fossil species with spectacular variation, particularly in their feeding apparatus.’
While scientists have long believed that dramatic shifts in habitat and diet can trigger rapid evolution, this is the first time it has been shown in crocodiles.
Professor Micahel Benton, who also worked on the study, said: ‘It’s not clear why modern crocodiles are so limited in their adaptations.
While scientists have long believed that dramatic shifts in habitat and diet can trigger rapid evolution, this is the first time it has been shown in crocodiles. Pictured is an extinct ocean-going crocodile from the Jurassic
‘If we only had the living species, we might argue they are limited in their modes of life by being cold-blooded or because of their anatomy.
‘However, the fossil record shows their amazing capabilities, including large numbers of species in the oceans and on land.
‘Perhaps they only did well when world climates were warmer than today.’
KILLING OFF THE DINOSAURS: HOW A CITY-SIZED ASTEROID WIPED OUT 75 PER CENT OF ALL ANIMAL AND PLANT SPECIES
Around 65 million years ago non-avian dinosaurs were wiped out and more than half the world’s species were obliterated.
This mass extinction paved the way for the rise of mammals and the appearance of humans.
The Chicxulub asteroid is often cited as a potential cause of the Cretaceous-Paleogene extinction event.
The asteroid slammed into a shallow sea in what is now the Gulf of Mexico.
The collision released a huge dust and soot cloud that triggered global climate change, wiping out 75 per cent of all animal and plant species.
Researchers claim that the soot necessary for such a global catastrophe could only have come from a direct impact on rocks in shallow water around Mexico, which are especially rich in hydrocarbons.
Within 10 hours of the impact, a massive tsunami waved ripped through the Gulf coast, experts believe.
Around 65 million years ago non-avian dinosaurs were wiped out and more than half the world’s species were obliterated. The Chicxulub asteroid is often cited as a potential cause of the Cretaceous-Paleogene extinction event (stock image)
This caused earthquakes and landslides in areas as far as Argentina.
But while the waves and eruptions were The creatures living at the time were not just suffering from the waves – the heat was much worse.
While investigating the event researchers found small particles of rock and other debris that was shot into the air when the asteroid crashed.
Called spherules, these small particles covered the planet with a thick layer of soot.
Experts explain that losing the light from the sun caused a complete collapse in the aquatic system.
This is because the phytoplankton base of almost all aquatic food chains would have been eliminated.
It’s believed that the more than 180 million years of evolution that brought the world to the Cretaceous point was destroyed in less than the lifetime of a Tyrannosaurus rex, which is about 20 to 30 years.