Courtesy Photo by Heather Rousseau ©Denver Museum of Nature and ScienceThe last talk I attended at the Geological Society of America (GSA) convention this past week was one of my favorites. It was an update of the Snowmastodon Project given by Kirk Johnson, chief curator at the Denver Museum of Nature and Science (DMNS). Just one year ago, a construction worker bulldozing for a dam-building project at the Zeigler Reservoir near Snowmass Village in Colorado unearthed a mammoth tusk. Paleontologists and archaeologists from the Denver museum were called in, and excavation of a small portion of the drained reservoir bottom soon got underway. The museum crew worked for just one month, until November 14, 2010, when snowfall halted the project. Then last spring scientists returned to the site and were allowed just 51 days to excavate the fossil deposits before the Snowmass Water and Sanitation District resumed their expansion work on the reservoir.
This time more research experts from the US, Canada, and England joined the dig along with a slew of interns and volunteers, totaling some 233 people working on the project. Over the next seven weeks excavation at the Zeigler Reservoir site progressed at a frantic pace. According to Johnson, anywhere from 15 to 90 diggers were on site each day digging out fossils from the ancient peat and mud deposits, from what once were the shores of a small glacial lake. Despite the short window of opportunity, the sheer number and diversity of fossils from the dig site has been truly remarkable.
Courtesy Dantheman9758 at en.wikipediaOf the nearly 5000 bones and skulls exhumed from the Snowmass fossil site, more than 60 percent were of mastodons (Mammut americanum) representing at least 30 individuals in various stages of life. The other 40 percent of the fauna included mammoths (Mammuthus columbi), camels, horses, giant bison (Bison latifrons) and ground sloths (Megalonyx jeffersonii), otters, muskrats, minks, bats voles, chipmunks, beavers, bats, rabbits, mice, salamanders, frogs, lizards, snakes, fish, and birds, and iridescent beetles. No large carnivore remains were found in the deposits, and human remains were absent as well, although archaeological techniques were used during the dig just in case any were uncovered.
Flora from the prehistoric tundra environment included pollen, green leaves and cones, and tree logs, some with their bark still intact.
So far, age estimates for the deposits range between 43, 000 to 130,000 years old although further dating tests should narrow that down.
The talk included several photos of what Johnson termed “Flintstone moments”, i.e. shots of field workers posing with massive mammoth or mastodon femurs or tibia. And Johnson marveled at the incredible state of preservation of many of the fossils displayed. Some of the bones, he said, still emitted a very strong funk.
In terms of sheer number of bones and ecological data, Snowmastodon ranks up there as probably one of the best high altitude Ice Age ecology sites in the world, and certainly the best mastodon fossil site. A team of researchers at the DMNS lab will spend the next year and a half cleaning, cataloging, and analyzing all the fossils found at the Snowmass dig site, water was to be reintroduced into the reservoir on Oct. 13. Despite the loss of the site, the field crew did a tremendous job in the time they were given to excavate the fossil-rich site. And Kirk Johnson didn’t hide his excitement. In closing his talk, he said “It was one hell of a year!”
A new abundant source of viable DNA has been discovered in the preserved hair of woolly mammoths, those great ancient elephants that once roamed the Pleistocene landscape.
The new “life molecule” source opens a whole new world of study of not only mammoths, but a whole array of extinct mammalian species including musk ox, wooly rhinoceros, and even ancient man.
Prior to the discovery - the results of which appear in Science magazine - researchers regarded hair shafts as a poor source for mitochondrial DNA. Researchers used to glean the DNA by extracting it from the ground-up bone material or preserved muscle. Unfortunately, that DNA is susceptible to rapid breakdown soon after death due to bacteria contamination and exposure to the elements.
“DNA from hair is very clean because it has been encapsulated in keratin, a kind of plastic membrane that protects the hair and the DNA,” explained Thomas Gilbert, one of the study’s authors and a researcher at the University of Copenhagen in Denmark. The research team included scientists from Penn State, and an international consortium of scientists and museum curators.
The team’s process works this way: hair samples are first washed with a special concoction containing bleach that removes any contaminating bacteria that may be present on the strands. Next, enzymes are used to break down the protective proteins (e.g. keratin) that encase the hair, subsequently releasing the DNA from the long-dead hair cells. Two types of DNA can then be retrieved. Mitochondrial DNA that holds data about the species migration, and nuclear DNA that carries information about the evolutionary relationship between different species.
Hair strands were taken from nearly a dozen mammoths dug up across northern Siberia, and ranging in age from 12,000 to 50,000 years old. One of the specimens tested was from the very first recorded mammoth discovered in the permafrost in 1799. Known as Adams’ mammoth, it had spent two centuries stored at room temperature in the backroom of a Russian museum.
Scientists think the process may prove valuable using other keratin-based body parts such as horns, hooves, antlers and feathers. That would open up a whole new world of possibilities for extracting usable DNA from the loads of material stored in the backrooms of museums around the world, material that until now considered useless as DNA sources.
Researchers hope this new DNA source will help answer such questions as why the wooly mammoth and other Pleistocene animals went extinct, or unravel the complexities of relationships between species. But the new source could also aid present-day crime scene investigators.
“It is not only interesting in relation to the past, but also to the present in e.g. forensics,” said Eske Willerslev, an expert in ancient DNA at the University of Copenhagen. “But some development is needed yet for the method to be 100 per cent usable in that context. But it is only a question of time and refinement.”
Whatever the case, these new DNA sources open up a whole world of possibilities in the fields of paleontology and genetics.
"Think about all the extinct furred animals that are displayed on museums around the world,” Tom Gilbert mused. “There is a lot of work waiting for us."
A new theory suggests that a blast from space 13,000 years ago may have been responsible for changes in Ice Age human cultures, and for wiping out most of North America’s large mammals, a fate similar to what large dinosaurs may have met 65 million years earlier.
The extraterrestrial blast from a large object, such as a comet or asteroid, colliding with Earth would have caused a significant climate cooling over the North American continent lasting for centuries.
According to Dr. Richard Firestone of Lawrence Berkeley National Laboratory, in California, the source of the collision may have originated from a supernova explosion that occurred about 250 light years from Earth.
“Our research indicates that a 10-kilometer-wide comet, which may have been composed from the remnants of a supernova explosion, could have hit North America 13,000 years ago,” says Firestone. “This event was preceded by an intense blast of iron-rich grains that impacted the planet roughly 34,000 years ago.”
Firestone and co-researcher Alan West say evidence of the supernova’s initial shockwave can be found in tiny impact craters in 34,000 year-old mammoths tusks. The two men theorize the tiny craters are the results of iron-rich grains traveling at 10,000 kilometers per hour slamming into the enamel.
Other evidence supports the comet impact theory. Sediment layers at some 22 prehistoric sites across the continent, show high of levels of iridium, along with concentrations of tiny diamond chips called nanodiamonds. There’s also a black layer of high carbon content that researchers argue could be the remains from wildfires ignited by the blast that swept across the continent.
No crater is known but scientists suggest that ice sheets present at the time may have been thick enough to act as a buffer against the collision.
It’s also possible the space rock exploded in the atmosphere but even then a shockwave of intense heat that would have wiped out everything in its path for miles around, and would have caused immediate and long-term damage to any existing human cultures. Glacial ice would have melted and surged into the North Atlantic, changing currents and effects on climate for centuries.
Such an event seems to coincide with the onset of what’s known as the Younger Dryas Episode, a period of significant environmental changes, Paleolithic cultural development, and mega-fauna extinctions.
All the large mammals that once populated the North and South Americas disappeared suddenly right about the estimated time of the extra-terrestrial impact.
"All the elephants, including the mastodon and the mammoth, all the ground sloths, including the giant ground sloth - which, when standing on its hind legs, would have been as big as a mammoth," said Professor James Kennett, from the University of California in Santa Barbara.
"All the horses went out, all the North American camels went out. There were large carnivores like the sabre-toothed cat and an enormous bear called the short-faced bear."
The effects of such a sudden extinction would certainly impact human populations as well. And that seems to be what happened. A number of prehistoric cultures such as the Clovis seem to have disappeared around the same time.
The new theory will be presented and hashed out this week at the American Geophysical Union's Joint Meeting in Acapulco, Mexico.
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