Tag Archives: Pleistocene

Giant sloth.

Timeline for giant sloth extinction rewritten by new analysis

The giant sloth may have lived in the slow lane, but it went extinct much faster than previously estimated, a new study reports.

Giant Sloth Bones.

Lithic tool associated with giant ground sloth bones.
Image credits Gustavo Politis, Pablo Messineo.

Researchers at the National University of Central Buenos Aires, Olavarría, Stafford Research, and La Brea Tar Pits and Museum, report that the giant sloth went extinct before the Holocene, the current geological period.

Dirty collagen

Prior research had found that the giant sloth disappeared during the Pleistocene, the geological epoch spanning from about 2.5 million to 11 thousand years ago — the last period of repeated glaciations to grip the Earth (right before the Holocene). However, there was also some evidence pointing to the survival of this species in certain pocket areas (of today’s Pampas, Argentina) up to the Holocene.

The present study comes to invalidate that hypothesis: the giant sloths went completely extinct before the onset of the Holocene, it explains. This new paper used a more stringent testing technique to date the remains of giant sloths found at the Campo Laborde dig site in Argentina. The team recovered collagen from the remains — they note that a single bone had recoverable collagen — that they dated using the radiocarbon technique and used to establish the new timeline for the sloths’ extinction.

The study also provides a glimpse into what went wrong with earlier dating attempts: the collagen used in the current study had been heavily contaminated with compounds leaching from the soil around it. Earlier dating efforts had not taken this contamination into account, they explain, which fouled the results. The team used chemical purification techniques to clean up the collagen before running their analysis, and then extracted specific amino acids that could only have come from the sloth itself, the team explains.

Giant sloth.

Giant sloth.
Image credits Eden, Janine and Jim / Flickr

Their analysis shows that the giant sloth went extinct around 10,570 years ago. This would push the timeline of their disappearance out of the Holocene (previous research found that the animals went extinct around 9,730 years ago, which is during the Holocene).

It’s a distinction that might sound pedantic, but it’s actually quite significant. Humans are currently considered the driving force behind the extinction of many ancient megafauna species, including the giant sloth. The new findings don’t exonerate our ancestors, but they do suggest that they were only part of the problem; their hunting of the giant sloths certainly helped, but it likely happened during a time when the species was buckling, likely under environmental strain from changing climate patterns.

The findings also raise the possibility that other species of huge mammals, especially those in South America (but possibly other places around the globe as well) didn’t make it to the Holocene either. If the collagen in the remains those studies were based on is found to be contaminated, the findings could be off the mark by thousands of years.

The paper “A Late Pleistocene giant ground sloth kill and butchering site in the Pampas” has been published in the journal Science Advances.

Incredible cave lions found preserved in Siberian permafrost

Paleontologists have unearthed two spectacular cave lion cubs, preserved by the permafrost in the Sakha Republic, also known as Yakutia.

These cubs suffered a tragic fate, but they will now be admired by the entire world. Picture: Academy of Sciences of Yakutia

The last glacial period, popularly known as the Ice Age, was the most recent glacial period within the Quaternary glaciation occurring from 100,000 to 12,000 years ago. At the end of this ice age, several species couldn’t adapt to the changing conditions and went extinct – the so-called sabre-tooth cat, wooly mammoth and cave bears among them.

Another, perhaps less known species that went extinct at the end of the ice age was the cave lion. Cave lions looked more like today’s tigers, although genetic analysis revealed that they are more related to modern lions than tigers. These active carnivores probably preyed upon the large herbivorous animals of their time, including horses, deer, reindeer, bison and even injured old or young mammoths. Some cave paintings show them hunting together in a pack, and likely took cover in caves – hence the name. Most of their bones were found in caves, and there is a pretty good fossil record of them. However, these are the most well preserved fossils ever found. They may very well be the best preserved fossils in the world.

‘The find is sensational, no doubt,’ said a source close to the discovery. It is known the remains are free of dangerous infections such as anthrax following initial microbiological analysis, but no other significant details or pictures will be released before the official presentation, which will take place sometime in November.

Along with the lions, scientists also found other animals, incredibly well preserved by the permafrost. Pictures: Academy of Sciences of Yakutia, RGO

Like many other animals, they went extinct at the end of the ice age, but their case is a bit more mysterious – they had all the chances to survive the environmental change. They had few, if any predators, they were smaller than herbivores and better prepared for warmer temperatures and were not prone to getting bogged down in swamps, like wooly mammoths or rhinos. These cubs might answer that question.

Paleontologists also made other remarkable findings in the area, which will be presented together at the same presentation in November.

 

ancient mammoth

Diversity is what helped mammals survive through deep time

ancient mammoth

After the great dinosaur extinction some 65 million years ago, mammals finally had their big shot as numerous niches became free for the taking. Thus, from mouse size, some mammal species surfaced which were as large as a bus, the so called mammal megafauna, like mammoths, giant sloths or saber-tooth tigers. However, a dire trial of their own was to come. Through out millions of years, mammals were challenged by a series of alternating climate cycles. According to a recent study by scientists at Vanderbilt University, diversity was the key to their survival.

The study focused on the various ups and downs in range and diversity of families of mammals that inhabited the continental U.S. during  the period that began with the Eocene and ended 12,000 years ago with the terminal Pleistocene extinction. The scientists involved in the study looked at a myriad of fossil records, however its almost impossible to distinguish highly related species between one another, so instead they concentrated on performing a family-level analysis. They analyzed 35 different families, such as Bovidae (bison, sheep, antelopes); Cricetidae (rats, mice, hamsters, voles); Equidae (horses, donkeys); Ursidae (bears); Mammutidae (mammoths); and Leporidae(rabbits and hares).

What their analysis showed was that the range and distribution of mammalian families stayed surprisingly consistent, despite major climate changes through out the 56 million year period, which saw temperature differences of several degrees, in alternating warm/cold cycles, and finally ended with the Ice Ages that alternated between relatively cold glacial and warm interglacial periods.

“These data clearly show that most families were extremely resilient to climate and environmental change over deep time,” said Larisa R. G. DeSantis, assistant professor of earth and environmental studies at Vanderbilt University who directed the study.

The scientists’ research shows that families retained more or less similar niches through out millions of years and is consistent with the idea that family members may inherit their ranges from ancestral species. However, the biggest takeaway is the fact that the researchers observed a highly important link  between a family’s diversity and its range – the greater diversity a family has, the better the stability and range.

“Diversity is good. The more species a family has that fill different niches, the greater its ability to maintain larger ranges regardless of climate change,” says DeSantis.

Mammals have demonstrated a remarkable ability to adapt to their environmental conditions, re-sizing and migrating easily. Understanding how mammalians have adapted through out deep geological time is highly important to understanding how they will adapt in the future, especially considering that one in four species of land mammals in the world faces extinction.

“Before we can predict how mammals will respond to climate change in the future, we need to understand how they responded to climate change in the past,” says DeSantis.

“It is particularly important to establish a baseline that shows how they adapted before humans came on the scene to complicate the picture.”

The findings were published in the journal PLoS One

source: Futurity  / image credit : Wikimedia Commons.