MAMMOTHS AND MASS EXTINCTION

Much ado about something - New evidence points to a celestial end for the wooly mammoth and many large mammals.

A swarm of comets that smacked North America 12,900 years ago wiped out the wooly mammoth and early Native American cultures, according to a soil study released Thursday.

The report in the journal Science focuses on tiny "nanodiamonds," crystals tied to past comet impacts, at six sites across the continent in a soil layer dated to the start of a 1,300-year-long ice age.

Geologists and archaeologists have long argued about what caused the extinction of dozens of large North American "megafauna" species, such as saber-toothed cats and mammoths. Was it environmental conditions, human intervention, competition for resources or a combination of factors? It seems a commet is to blame.

"What we're reporting is consistent with a major cosmic impact that had major consequences for the environment and Earth's climate," says study leader Douglas Kennett of the University of Oregon in Eugene.

"A swarm of comets" or carbon-rich meteorites either delivered or created the nanodiamonds in a fiery impact, the study suggests. The report relies on photomicrograph analyses of soil samples from Arizona, Minnesota, Oklahoma, South Carolina and two Canadian sites. Photomicrography captures images seen through a microscope.

"This is the 'smoking gun' evidence for a massive impact event 12,900 years ago that triggered the (ice age) and the extinction of the megafauna," says nuclear scientist Richard Firestone of the Lawrence Berkeley (Calif.) National Laboratory, who was not part of the study.

If true, the impact date coincides with the abrupt halting of deposits of "Clovis" Native American artifacts, distinctively fluted tools and arrowheads. Dozens of large animal species vanished then in North America. Kennett and other impact researchers have suggested a continent-wide wildfire may have contributed to the extinction of large North American creatures. In Europe, there were disruptions to the prehistoric culture and the demise there of species such as the cave bear and Irish elk.

Some scientists urge caution.

"We simply do not have conclusive evidence that nanodiamond materials aren't everywhere at many times," says geologist Nicholas Pinter of Southern Illinois University in Carbondale. "Tons of meteorite dust falls to Earth every year, after all."

Although more than 30 North American species died out about 12,900 years ago, about 50 large species died out a few centuries later in South America, and on some unpeopled Caribbean islands, species such as sloths survived an additional 6,000 years, says archaeologist Stuart Fiedel, author of Prehistory of the Americas. "Humans, not extraterrestrial objects," best explain the staggered extinctions in the New World, he says.

Kennett says future studies will show evidence of the nanodiamonds from Europe and further afield 12,900 years ago. Impact shock waves, debris and wildfires sparked by comets breaking apart in the atmosphere would have hit North America hardest, he says, but the effects would have been felt worldwide.

Fossil Mammals are the theme of the Eighth BC Paleontological Symposium being held at the University of British Columbia, May 14-18, 2009. Come and learn about the great mammals that roamed North America and hear the debates on their demise. Visit www.bcfossils.ca for more information

The story references an Irish Elk. A 12,000 year old specimen in the collections at UBC will be on display at the Symposium.

Ref: Dan Vergano

VOLCANIC DEMISE: THE TRIASSIC-JURASSIC EXTINCTION

Located as they are in Canada’s most active earthquake zone, the Queen Charlotte Islands have had their share of shake-ups and scourings. Many of the Islands’ hillsides are scarred by slides. But the rock beneath speaks of an even more violent past. Very few people know that the rock in the Queen Charlottes holds the key to a catastrophic event from eons ago.We’ve heard tales and seen images of the cataclysmic damage caused by meteriorites smashing into the Earth’s surface.

Until recently, it was a meteorite impact that was blamed for the worldwide Triassic/Jurassic Mass Extinction. This wholesale dying out of species occurred some 200 million years ago. New evidence challenges the meteorite theory. Experts now believe that tectonic forces may have caused hundreds of volcanoes around the world to erupt simultaneously. The subsequent showers of volcanic ash would have altered the composition of the atmosphere dramatically and plunged the world into near total darkness for years until it settled from the sky.

The picture painted of the sun flickering fitfully through inky clouds, paling against the torrents of glowing lava, while everywhere life is smothered, poisoned, or starved, rivals the most apocalyptic imaginings of Hollywood or religion. We know from worldwide evidence that the extinction was dramatic and affected upwards of 70% of the world’s biota.

Perhaps counterintuitively, for one might think of water as a refuge from fire, smoke, and lava, it was marine lifeforms that suffered the most. This is particularly well documented in the rocks of the Queen Charlottes, especially at Kennecott Point and Kunga Island.

Radiolarian microfossils – tiny, siliceous, single-celled microrganisms – tell the tale. In the Upper Triassic rocks, which predate the extinction by about 10 million years, radiolarians are preserved in hundreds of forms. Just above them, in the early Jurassic rock layers laid down about the time of the great die-offs, only a fraction of the previous number of forms are represented. The more recent Jurassic rock shows a rebound of radiolarian diversity (though of course, in different forms) — a diversity which continues to flourish and expand in today’s oceans.

Radiolarian microfossils – tiny, siliceous, single-celled organisms – tell the tale. These wee timekeepers have been living in the world’s oceans for about 600 million years. Because they occur in continuous and well-dated sequences of rock in the Queen Charlottes, these exquisitely beautiful microfossils act like a yardstick, helping geologists accurately date rock from around the globe.

In the Upper Triassic rocks, which predate the extinction by about 10 million years, radiolarians are preserved in hundreds of forms. Just above them, in the Early Jurassic rock layers laid down about the time of the great die-offs, only a fraction of the previous number of forms are represented.

The Queen Charlottes are most noted for their fossil ammonites, the coiled cousins to modern day nautilus. These perfectly preserved specimens tell of a deep water environment and warm tropical seas. The younger Jurassic rock shows a rebound of radiolarian diversity (though of course, in different forms) - a diversity that continues to flourish and expand in today’s oceans.

COASTAL WOLVES: GENETIC DIFFERENCES

Have you ever seen headless salmon littering the banks of rivers and streams during spawning season? Most who have generally blame our local bears for this selective dining. The real culprits are coastal wolves who gorge themselves on the nutrient-rich brains, leaving the rest to scavengers.

It seems this preference for fish and a redish tinge to their pelts set our local wolves apart. Coastal wolves, from Alaska and Vancouver Island, have not only adapted to their local environment but have evolved into something altogether new.

Think Darwin's finches.

Researchers from the Raincoast Conservation Foundation have published in this month's Journal of Biogeography, that our coastal wolves, "are like no other wolves." Well, we could have told them that, but no one listens until a paper gets published.

Grey wolves (Canis lupus), coastal wolves and our household pets (Canis lupus familiaris) share a common ancestry but at some point our coastal wolves have broken from the pack. With genetic differences that, "are striking and their ecology is very, very different."

So it seems everything old is new again.