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Dinosaurs struggled to survive for tens of millions of years before extinction event

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MIAMI — Dinosaurs struggled to survive for tens of millions of years before they finally went extinct, an event widely blamed on the environmental fallout from an asteroid strike, researchers say.

The argument offers the latest salvo in a long-running debate among scientists over the state of dinosaur health in their final years on Earth — some say they were flourishing, while others say they were strongly in decline.

For the study in the Proceedings of the National Academy of Sciences, researchers combed through fossil records from around the world and performed a statistical analysis showing that various species of dinosaurs were going extinct at a faster pace than new ones were emerging for a period of at least 40 million years prior to the cosmic debris that smashed into what is modern-day Mexico.

“We were not expecting this result,” lead author Manabu Sakamoto, a paleontologist at the University of Reading, said.

“While the asteroid impact is still the prime candidate for the dinosaurs’ final disappearance, it is clear that they were already past their prime in an evolutionary sense.”

For instance, long-necked vegetarian sauropod dinosaurs — the largest land animals known to exist — were in the fastest decline, the study found.

But the ropods, the group that includes the iconic, meat-eating Tyrannosaurus rex, were disappearing at a more gradual pace.

Factors in their struggle likely included the break-up of continental land masses and sustained volcanic activity, the study said.

Then, a giant asteroid collided with the Earth — known as the Chicxulub impact in Mexico — 66 million years ago, causing a massive dust storm that blocked the Sun and led to a period of global cooling and widespread plant deaths.

Without trees and vegetation, an important food and shelter source disappeared, and so did the dinosaurs.

“This suggests that for tens of millions of years before their ultimate demise, dinosaurs were beginning to lose their edge as the dominant species on Earth,” Dr Sakamoto said.

Even more, the research offers a look into the future. With many species already struggling due to human-driven climate change, those on the edge may be completely wiped out in the event of a disaster.

“Our study strongly indicates that if a group of animals is experiencing a fast pace of extinction more so than they can replace, then they are prone to annihilation once a major catastrophe occurs,” Dr Sakamoto said.

“This has huge implications for our current and future biodiversity, given the unprecedented speed at which species are going extinct owing to the ongoing human-caused climate change.”

AFP

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Tourist arrivals jumped 73.5 percent in July

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KATHMANDU — Tourist arrivals to Nepal jumped 73.5 percent in the month of July, according to statistics released by Nepal Tourism Board (NTB).

The NTB said that this increment is because of a sharp increase in the number of travellers from countries like India, China, the US and the UK. The growth in the numbers has also been attributed to Indian pilgrims visiting Mount Kailash Mansarovar in Tibet, via Nepal.

The statistics show that Nepal received a whopping 73,285 international tourists in July—a time of the year that is considered to be an off-season for tourists due to the monsoons. With July’s figures, the number of foreign tourists visiting Nepal in the first seven months (January–July) of 2018 reached 593,299, which is an increase of 18 percent as compared to the same period last year.

Total 18,385 Indian tourists visited Nepal via air transport, which is up 80.4 percent compared to the same period last year.

After India, Nepal received the highest number of visitors from China. The Chinese tourist numbers have more than doubled to 13,123 in the month of July. This is a 125.4 percent growth in comparison to the arrivals in the same month last year.

Overall arrivals from SAARC countries registered a growth of 66 percent, in comparison to the same month last year. However, arrivals from Bangladesh declined by nine percent. Arrivals from rest of the Asian countries have also recorded a robust growth of 86.2 percent.

Visitors from Japan and South Korea to Nepal also increased by 36 percent and 21.9 percent respectively.

Likewise, an overall increase of 54.1 percent in July has been recorded from European source markets. However, arrivals from Austria declined by 72.6 percent.

The number of visitors from the US and Canada have also grown by 79.6 percent and 73.3 percent respectively.

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