21 March 2011

Columbian mammoth unearthed in fossil trove

Agence France-Presse
After three years' back-breaking work archaeologists are finally, painstakingly revealing the face of Zed, the ice age mammoth, unearthed in the so-called La Brea Tar Pits, one of the world's most famous fossil sites.
Colombian mammoth fossil

Assistant lab supervisor Trevor Valle works on a tusk belonging to 'Zed', a Colombian mammoth fossil discovered eighty percent complete, in the laboratory at the Page Museum at the La Brea Tar Pits. Credit: AFP PHOTO/ ROBYN BECK

LOS ANGELES: After three years’ back-breaking work archaeologists are finally, painstakingly revealing the face of Zed, the ice age mammoth, unearthed in the so-called La Brea Tar Pits, one of the world’s most famous fossil sites.

The 80% complete skeleton is the prize find in a fossil treasure trove discovered on a Los Angeles building site in June 2006, when workmen digging for a new parking lot stumbled on the prehistoric beast’s skull. The size and width of Zed’s teeth indicate that he was a male, and wear patterns on his teeth suggest that he was between 48 and 50 years old when he died.

“The Zed deposit was actually found by a bulldozer, by a piece of heavy equipment that took off the top six inches of his skull,” said Trevor Valle of the Page Museum. “But at least they stopped before they went any further. It was better to hit a somewhat simpler area of the head than say take out the teeth or the tusks.”

In the company of saber-toothed cats

In fact the semi-articulated, largely complete skeleton of an adult Columbian mammoth (Mammuthus columbi) is only a tiny part of a huge haul of ancient bones and fossils found during work on the underground parking lot at the LA County Museum of Art (LACMA).

Saber-toothed cats – including the only specimen found with its mouth closed – giant jaguars and long-tailed weasels are among the thousands of animal remains found in the La Brea Tar Pits.

The ‘Tar’ refers to the highly viscous asphalt geological layer which helped preserve the fossils for so many millennia – and in fact which caught many of the unsuspecting animals in its sticky embrace in the first place.

Setting up work in the park

“It only takes an inch and a half to two inches to totally immobilise an animal the size of a horse,” explained John Harris, the British chief curator of the Page Museum.

Animals which happened to step in it “got stuck like flies on flypaper. If they were lucky they would die of hunger and thirst in a few days. If they were unlucky they’d be torn apart by a saber-toothed cat”, he added.

Once the workers had stumbled upon the fossils in the underground parking lot, they had to decide what to do with them. Rather than stop building work, they decided to pack up all the bones into vast wooden crates, and take them to a nearby park, behind the Page Museum, where archaeologists could sift through them at their leisure.

Only museum with sifters on display

Collectively the trove of 16 40,000-year-old fossils from the Late Pleistocene period is known as ‘Project 23’ – after the number of timber boxes they are stored in.

The Page prides itself on being perhaps the only museum where people can see the sifters – a small army of red-clad assistants crouched over in the boxes – the cleaners like Valle in a glass-walled lab, and the finished displays, all in one place.

Excavators use small hand tools such as dental picks, chisels, hammers, and brushes to remove the matrix (dirt) surrounding the bones. This matrix is kept and will be cleaned at a later date and eventually sorted for microfossils in the lab.

“People can come past and look through the fence and see excavators taking the fossils out of the ground,” said Harris. “Then they can walk across the park to the museum, and they can see the bones actually being prepared and cleaned, and being placed on display, so you get the whole experience,” he added.

Juvenile mammoth a possibility

For Valle, a bear of a man covered with tattoos and sporting a colourful pony-tail, it couldn’t be more exciting – especially as he has worked on every single piece of Zed that has come out of the ground. “It’s just ridiculously cool. I’m cleaning a mammoth head, how neat is that?” he said. “When we recover a fossil from them, we’re the first humans to lay eyes on that animal.”

So why the name Zed? It was chosen by Harris, as the British version of the last letter of the alphabet. “He’s the last best mammoth we think we’ll ever recover here, so Zed.” said Valle.

But, he added, Zed may not be the last of it after all. “In fact there’s a possibility that we may have a juvenile mammoth in one of the boxes, so we’re starting the alphabet over, and we’re going for ‘Alfie’,” he said.


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