"Dinosaurs would not have become extinct had it not been for a catastrophic asteroid strike, researchers have said, challenging the idea the animals were already in decline. About 66m years ago, during the late Cretaceous period, a huge space rock crashed into Earth, triggering a mass extinction that wiped out all dinosaurs except birds. However, some experts have argued the dinosaurs were already in decline."
"Dr Andrew Flynn, the first author of the research at New Mexico State University, said: I think based on our new study that shows that, at least in North America, they weren't going towards extinction. Writing in the journal Science, Flynn and colleagues report how they dated a unit of rock called the Naashoibito Member in the San Juan basin using two methods. The first involved analysing the ratio of two argon isotopes within crystals found in the rock."
The Naashoibito Member in the San Juan basin was dated using argon isotope ratios in crystals and magnetic polarity alignment of particles. The dating indicates the rock section with the youngest dinosaur fossils formed at most about 350,000 years before the mass extinction 66 million years ago. The extinction event occurs essentially in the middle of a short reversed polarity interval. Non-avian dinosaurs in southern North America appear to have been diverse and not part of a uniform, continent-wide declining fauna immediately prior to the asteroid impact. Some dinosaur species were common to both northern and southern North America.
Read at www.theguardian.com
Unable to calculate read time
Collection
[
|
...
]