A mitochondrial DNA study of cave bears suggest that cavemen hunted them to extinction.

Now an international team of scientists analyzing DNA in 17 newly identified fossils of cave bears has revealed the decline started 50,000 years ago, “much earlier than previously suggested, at a time when no major climate change was taking place, but which does coincide with the start of human expansion,” said researcher Aurora Grandal-D’Anglade at the University of Coruña in Spain.

The scientists compared 59 DNA sequences from cave bear mitochondria – the powerhouses within their cells – with 40 modern and fossil DNA samples from brown bears (Ursus arctos) to find out why the former went extinct while the latter did not.

Their findings suggest that cave bear genetic diversity – a clue to how many there were – began declining 50,000 years ago. Other fossil evidence reveals they ceased to be abundant in Central Europe roughly 35,000 years ago. (Diversity of genes can provide indirect evidence for the number of breeding individuals, because with more bears mating more genes are thrown into the mix, and vice versa.)

“This can be attributed to increasing human expansion and the resulting competition between humans and bears for land and shelter,” Grandal-D’Anglade explained.

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A series of coprolites (fossilized poop) have been found showing bite marks from an ancient species of shark. But why were they biting poop? I thought this was an interesting article to read and I enjoyed how it reveals the researchers’ thought-process and shows you how they reached their conclusions.

The coprolite that had been severed, given the label CMM-V-3245, was not especially helpful in identifying the biter, but the other coprolite (CMM-V-2244) preserved a row of tooth marks. The scientists made a silicone cast of the impressions to see if the punctures held any clues as to the identity of the biter. What they found was that the animal that had made them had a single row of asymmetrical teeth, and while there were as many as eight shark genera with this characteristic, most of these were deemed “innocent” on the basis of anatomical peculiarities. The best fits for the tooth marks were the genera Physogaleus and Galeocerdo (which, in fact, might be synonymous), sharks that, like their living relative the tiger shark (Galeocerdo cuvier) possessesed asymmetrical teeth in the shape of a bent A.

With the list of potential culprits successfully narrowed down Godfrey and Smith were left with the question of how the bite marks had been made. Even though coprolites are relatively common at the Calvert Cliffs site, no one had ever found a shark-bitten piece of shit before, so they had no other reference to go by. They ultimately settled on several possible scenarios.

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Humans were responsible for driving an ancient giant species of turtle to extinction almost 3,000 years ago.

It is one of the first cases that clearly shows that humans played a role in the demise of the giant, extinct animals known as “megafauna”.

An Australian research team discovered turtle leg bones – but not shells or skulls – on an island of Vanuatu.

The bones date to just 200 years after humans’ arrival, suggesting they were hunted to extinction for their meat.

However, the turtles lived far longer than other megafauna – which included the famed woolly mammoth; while Australian megafauna is thought to have died out almost 50,000 years ago, it appears that these turtles survived for far longer – until the arrival of a people known as the Lapita.

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A new study suggests that woolly mammoths became extinct because of dwindling grasslands, not because of human interference.

“What our results have suggested is that the changing climate, through the effect it had on vegetation, was the key thing that caused the reduction in the population and ultimate extinction of mammoths and many other large herbivores,” he said.

Professor Huntley and his colleagues created a computer simulation of vegetation in Europe, Asia and North America over the last 42,000 years.

They did this by combining estimates of what the climate was like during this period with models of how various plants grow under different conditions.

They found that the cold and dry conditions during the ice age, with reduced concentrations of carbon dioxide, didn’t favour the growth of trees.

So instead of forests there were vast areas of pasture, which was ideal for large herbivores, such as woolly mammoths. But as a result of a warmer, wetter climate and rising concentrations of carbon dioxide at the end of the ice age, trees emerged at the expense of the grasslands.

“During the height of the ice age, mammoths and other large herbivores would have had more food to eat,” said Professor Huntley.

“But as we shifted into the post-glacial stage, trees gradually displaced those herbaceous ecosystems and that much reduced their grazing area.”

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Ancient reptile footprints have been found along the Bay of Fundy shoreline in New Brunswick, Canada.

“These are quite remarkable,” he said Thursday. “It’s not just one set of footprints. The slabs are covered with footprints.”

Miller said he actually had his back to the slab and was examining plant fossils when the footprints were discovered.

Falcon-Lang said he was looking for something else, and only discovered the prints after he tripped and fell, scraping his knee.

“I still have the scars to prove it,” he said.

The footprints are quite small — only about four centimetres long. Falcon-Lang said the reptile that made them would have been about 20 centimetres long and resembled a gecko.

He said it is probably an early reptile called Hylonomus. Fossil skeletons have been found in adjacent Nova Scotia.

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