1 . Imagine a warm spring day 66 million years ago. These could have been the very last moments of the dinosaur era when a city-sized asteroid struck Earth, killing off three quarters of all species on the planet. According to a study published in Nature on Feb 23,the asteroid hit in springtime.
Scientists have long been confused over the time of year the asteroid hit, and how some animals managed to survive while dinosaurs didn’t, according to USA Today.
Researchers in 20l9 discovered fossilized fishes in North Dakota that died shortly after the asteroid hit Earth. They examined the fossils with a particle accelerator and found out there was seasonal growth on the bone. All fish bone cell densities and volumes can indicate the season. Because the accelerator also could capture the sizes, researchers were able to determine when in the year the asteroid hit, Dennis Voeten told USA Today.
“I think spring puts a large group of the late Cretaceous biota in a very unprotected spot because they were out and about looking for food, tending to offspring after the winter,” Melanie During, the main author of the study.
In the Southern Hemisphere, it was autumn. Therefore, life in the Southern Hemisphere was a lot more prepared for this event.
It is unclear whether small animals in the Northern Hemisphere actually did worse than those in the south. There is evidence that Northern Hemisphere turtles were wiped out in the asteroid strike, after which their habitats were later repopulated by turtles from the south, Voeten told The Guardian.
Nothing much larger than a house cat survived the asteroid impact and many species would have been killed whenever it hit, Daniel Field, a professor at the University of Cambridge, told The Guardian.
1. Which probably helps find the time of year the asteroid hit?| A．The types of fossilized fishes. | B．The location of fossilized fishes. |
| C．The number of fish fossils in the area. | D．The volume and density of the fish bone cells. |
| A．The season of the hit. | B．The size of asteroid. |
| C．The group size of species. | D．The body shape of animals. |
| A．Chances of survival depended on it where the species lived at the time. |
| B．Many species could have survived the asteroid strike but for the season. |
| C．Many species had little chance to survive even if it was a different season. |
| D．Animals from the Southern Hemisphere were less affected by asteroid strikes. |
| A．The Science behind the Asteroid | B．Occurrence of the Natural Disaster |
| C．The Effect of Dinosaurs’ Extinction | D．New Research on the Asteroid Strike |
