KENNEWICK -- Scientists now know how old a mammoth skeleton is that is being dug up just south of Kennewick -- 17,450 years.
That makes it a fairly recent skeleton for a North American mammoth. Columbian mammoths roamed the area from about 400,000 to 11,000 years ago, dying out with 90 percent of other large mammals at the end of the last major Ice Age.
The animal is older than Kennewick Man, whose 9,300-year-old skeleton was found on the banks of the Columbia River in 1996. The two would have missed each other by about 8,000 years.
The age of the mammoth skeleton was determined through radiocarbon dating and is believed to be accurate to plus or minus 25 years, said George Last, a senior research geologist at Pacific Northwest National Laboratory in Richland.
It's not uncommon to find mammoth bones in the Ice Age flood deposits of Eastern Washington.
However, few have been excavated and studied to the exacting scientific standards that modern paleontolgy and archaeology require, according to the MCBONES Research Center Foundation of the Coyote Canyon Mammoth Site near Kennewick.
Researchers, who are also collecting other animal bones and plant seeds as the mammoth is excavated, are trying to capture data to show how plants and animals changed over time.
"The purpose of the dig is to get a record of life, which will reflect climate," said Gary Kleinknecht, educational director for the research foundation and a social studies teacher at Kamiakin High in Kennewick.
The dig could yield clues about why large mammals died out at the end of the last ice age -- whether because of disease, predators such as humans or how the climate changed, Last said.
But more immediately, they are finding out more about the mammal discovered south of Kennewick.
The skeleton is that of an adult mammoth -- not a teenager and not a senior citizen, Kleinknecht said.
He -- or she, the gender has not been determined -- did not have much arthritis in its bones.
As a full-grown mammoth, it would have stood 10 to 13 feet tall at the shoulder, making it larger than the modern-day Asian or African elephant.
Scientists also know it was buried mostly intact rather than his bones scattered around, because the skeleton was found largely intact. The excavation so far has reached its right ribs, with its left ribs still buried in the dirt.
The right ribs are jumbled and there are bite marks on them, leading researchers and volunteers to believe an animal might have fed on the carcass before it was buried.
At this point, they've come up with three hypotheses about how the mammoth came to be buried south of Kennewick, Last said.
The mammoth died during the time of the Missoula floods, when 40 to 100 floods swept across Eastern Washington between 15,000 and 20,000 years ago and a temporary lake built up over the Tri-City area as water backed up behind the Wallula Gap.
Most animals lived in low lands near water, and the mammoth found near Kennewick could have been washed away by the flood waters anywhere from North Idaho to the Tri-Cities, Kleinknecht said.
Then the carcass could have settled on the shoreline of the lake, only to be covered with sediment during the next flood.
Or perhaps the animal was an early resident of the Tri-City area that came down to get a drink from the temporary lake and become mired in the mud, Last said. His carcass then would have been buried when another flood came along.
The third hypothesis is the most recently developed, because of what's being found at the dig site.
Underneath the bones are angular granite rocks believed to have floated into the region encased in ice that then melted here during the Ice Age floods. That raises the possibility that the mammoth carcass also floated into the Tri-Cities area encased in an ice sheet that extended into Canada.
The mammoth was discovered in 2000, and between then and the establishment of MCBONES in 2008 and the purchase of the land, some bones, including the lower jaw, ended up in private hands.
The scientific dig began in fall 2010 with one month of excavation, and last year, with the first full dig season, more than a dozen ribs, vertebrae and a couple of foot bones were unearthed. A tail bone and shoulder bone had been found earlier.
Other animal bones also believed to be ancient have been uncovered. They include a foot bone from a camel plus remains of snails, snakes, spiders and beetles.