How did the crocodiles survive the asteroid that killed the dinosaurs? – Éamonn, age 5, Western Australia
Hello Éamonn! This can be a nice query, and one many scientists have requested.
There are two predominant causes. First, crocodiles can stay for a really very long time with out meals. Second, they lived in locations that had been the least affected when the asteroid hit Earth.
When the asteroid hit earth
About 66 million years in the past, dinosaurs dominated Earth. However then an enormous asteroid, greater than 9 kilometres vast, slammed into the shallow sea close to what’s now Mexico.
The explosion from this was so big, it led to international earthquakes, tidal waves, bushfires and even toxic rain.
Additionally, the asteroid hit at one of many worst potential locations, the place the rocks may simply be “exploded” (or vapourised). This threw up large quantities of mud into the sky, blocking out the Solar for a lot of months and sending Earth into a protracted, darkish and freezing winter.
With out daylight, the inexperienced vegetation died, adopted by the plant-eating animals that ate them to outlive, and the meat-eaters that ate the plant-eaters.
Curious Youngsters: What impact did the asteroid that worn out the dinosaurs have on vegetation and bushes?
Scientists assume three-quarters of all of the totally different sorts (species) of animals on Earth had been worn out – together with most dinosaurs.
However some managed to outlive for a spread of causes.
One essential group of dinosaurs sailed via, helped by their means to fly and discover meals in faraway locations. Their feathers protected them from the chilly, and their beaks allow them to eat buried seeds discovered close to useless vegetation.
Amazingly, these dinosaur survivors are nonetheless with us at present. We name them birds!
How small birds developed from large meat consuming dinosaurs
Crocodiles had some keys to survival
Crocodiles had been one other group that famously survived the asteroid. Clearly they will’t fly, don’t have feathers, and don’t eat seeds! However they’d different secrets and techniques to success.
Firstly, crocodile our bodies use little or no power. They lie round rather a lot, breathe slowly and also have a very gradual heartbeat. That is how they will maintain their breath underwater for greater than an hour.
It additionally means they will go with out meals for months, and generally greater than a 12 months. This could have been very useful when meals (akin to different animals) turned laborious to seek out as soon as the asteroid hit.
Dinosaurs, alternatively, had been typically extra energetic, which suggests they wanted extra power – particularly meat-eaters like Velociraptor. With out meals, they might have died shortly.
Crocodiles additionally lived in locations the place dropping inexperienced vegetation didn’t make an enormous distinction. Consider a forest or a grassland (the place many dinosaurs lived): if the vegetation there die, then all of the animals that want them die too, together with the meat-eaters that are left with no meals.
However the crocodile survivors largely lived in locations like rivers, lakes and coasts. The animals dwelling in these locations don’t want inexperienced vegetation as a lot. Lifeless vegetation and animal materials washes in from surrounding land, which is eaten by tiny creatures, that are then eaten by bigger creatures together with crocodiles.
So not like dinosaurs dwelling on the land, crocodiles in a river wouldn’t have starved as quickly because the inexperienced vegetation died.
Our mammalian ancestors additionally survived
The same purpose helps clarify why human beings’ ancestors additionally survived the asteroid impression. These had been the small mammals that lived close to the top of the age of dinosaurs, which ultimately gave rise to all of the totally different sorts of mammals round at present (together with people).
They had been primarily small, rat-like issues that scurried about within the useless leaf litter on the bottom, consuming bugs and worms. These tiny creatures relied not on dwelling inexperienced vegetation, however on useless leaves and bark falling from the bushes, or being blown and washed in from elsewhere.
So similar to the crocodiles, our tiny ancestors survived the asteroid partly as a result of they didn’t rely closely on dwelling vegetation. A very good factor too: these fortunate survival abilities are the rationale you and I are right here at present!