Weighing a dinosaur is no easy task. These extinct creatures were massive, and for the most part, all that remains are their bones, as their organs and skin have long since disappeared. However, new research has found more than one way to measure the mass of these creatures.

In a paper published recently in Biological Reviews, scientists evaluated the two existing ways that calculate how much a Tyrannosaurus rex (翻王龙) might have weighed. Led by Nicolas Campione from the University of New England, they examined an extensive database of dinosaur body mass estimates from as far back as 1905, with weight estimates for an individual ranging from 3 tons to 18 tons.

In an essay published by The Conversation, Campione explains that for years, scientists followed two rival (对立的) approaches for calculating a dinosaur’s weight. These methods were long thought to be at odds with each other, but Campione’s team found that both techniques are actually quite accurate.

Using limb circumference (肢体周长) to work out an animal’s mass is already widely used across a variety of modern land animals. The same method can be applied to dinosaurs. Researchers essentially measure the bones in living animals, such as the femur (股骨) in an elephant’s leg, and compare that figure to a dinosaur’s femur.

The second method involves calculating the volume of 3D reconstructions of dinosaurs, which serve as approximations (近似值) of what the creature would have looked like when it was still alive. Occasionally, these methods have come to very different conclusions.

David Evans, a researcher at the Royal Ontario Museum in Toronto, says it’s important to use both methods because dinosaurs, like humans, did not come in one neat package. “There will always be uncertainty around our understanding of long-extinct animals, and their weight is always going to be a source of it,” he says in a statement. “Our new study suggests we are getting better at weighing dinosaurs, and it’s paving the way for more realistic dinosaur body-mass estimation in the future.”

Despite heavy illegal hunting of rhinos, South Africa’s Kruger National Park is still a natural paradise. One of the largest remaining lion populations in Africa lives there. Yet there is something the local animals fear even more than the big cats.

Liana Zanette of Western University in Ontario and her colleagues were able to show that animals react most strongly to human voices and flee in response. For their experiment, the team placed camera traps and loudspeakers at water holes in the national park, which allowed the researchers to influence and record the behavior of a total of 19 mammal species. They played the animals sounds of normal conversations of humans in four South African languages, dogs barking, gunshots and lion sounds.

The study group found that animals were twice as likely to flee and yacated an area faster when they heard human voices than when they heard lions or gunshots. This was true for 95 percent of the animal species observed, including giraffes, leopards, hyenas, zebras, kudu, warthogs, impalas and rhinos. Only elephants were significantly more likely to run from lions than from humans.

The same was true of the time that animals spent at water holes: they usually stayed longer when lion sounds were played to them than when human voices were heard. Wild dogs, leopards and buffalo were the only animals who stayed at water holes longer when they heard humans, and the difference was not statistically significant for these species. “There is a notion that animals get used to humans when they are not being hunted. But we’ve shown that’s not the case,” Clinchy says. “Fear of humans is deeply rooted and common, so we need to seriously address it for conservation reasons.”

The team is now investigating whether its customized sound systems can be used to help endangered species, such as the southern white rhino, away from known poaching(偷猎) areas in South Africa. Initial tests of keeping rhinos away from such areas through the use of human voices have been successful.

With the global warming reaching catastrophic levels, this dramatic climate change is causing the warming up and melting of the Arctic, which has led to other potential dangers for nature there.

The danger is for an increase of pollution as well as exploitation (开采) by resource companies which are looking to drill in the area and approaching new sources of oil, gas minerals and hydropower. Shell has already revealed its plans to drill in the area, and so are other oil and gas drilling companies.

These new sources of fossil fuels will further increase harmful greenhouse gases causing permanent damage to the atmosphere, the weather and to the world and its population. The small and unique population and ecosystems of the Arctic are also threatened by the new dangers of pollution.

Recently Shell said that it is currently stopping is planned project for drilling in the Chukchi Sea, but unfortunately, the dangers are not all gone for this environmentally sensitive area. Another oil drilling company— Italian Eni has announced a 5.5 billion dollar oil drilling project for the Norwegian Arctic area.

Already, the impact on the environment in the Arctic is becoming evident and is being documented. The tundra (苔原) is disappearing rapidly as the frost is melting. The Inuit hunters are worriedly watching the sea ice disappearing, which is making sea animals such as seals change their behaviors and habits.

Overall, the climate changes in the area are now being considered as unpredictable and can cause a serious threat to the infrastructure (基础设施), the local people and the over 21,000 Arctic animal species.

With the increase of global temperature levels by an average of 2 degrees Celsius, this tendency is spreading to the Arctic as well. The level of the sea has risen by about 8cm since 2000. With the melting of the permafrost (永久冻土) in the area, a massive release of methane (沼气) in the atmosphere is expected, which can have a serious effect on the global weather.