A lot can be learned from a mammoth molar

During the most recent Ice Age, this slice of North America was a prime stomping....

  During the most recent Ice Age, this slice of North America was a prime stomping ground for mammoths.The giant elephant-like beasts were heavily concentrated in the central and northern Puget Sound lowlands.Why they became extinct is still a mystery.Molars of the Columbian mammoth are the most common mammoth remains found in Washington. In fact, the Columbian mammoth — which foraged grasses along meadows, bogs and ponds 1.6 million to 10,000 years ago — is the state fossil. Scientists still have much to learn from fossil remains, said Bax Barton, a paleontology researcher at the University of Washington’s Burke Museum of Natural History and Culture. Barton recently examined a fossilized molar unearthed on a rocky Hat Island beach by Patti McClinchy of Everett. Here is a Q&A with Barton.

Q. What did you do with Hat Island mammoth molar?

A. First I confirmed that the molar was indeed from a mammoth, and not from some other similar animal (modern elephant, or mastodon, or gomphothere, etc.). Having established that it was a mammoth tooth, I next carried out a "morphometric analysis," which allows me to determine the position (and number) of the molar in the mammoth molar dental sequence, and its placement in the mouth [Is it an upper or lower molar? From the left side or right, etc.?]. Since mammoth molars vary in size and shape for each different mammoth species, the results of this analysis allow me to determine which mammoth the molar came from (of four possible North American species of mammoth), and the terminal age for the mammoth (its age at death).

Q. What did you learn?

A. The molar from Gedney Island is a lower right-side fifth molar from a Columbian mammoth (genus=Mammuthus, species=columbi). It's not possible to sex (male or female?) the mammoth based on the molar alone, so this could have been either a male or female. Whichever, based on the wear on the occlusal (chewing) surface of the molar this critter was roughly 21 years of age at death (+/- 3 years). In modern African elephants a 21-year-old animal is classified as a "subadult" ... something like a 'late teen' in human years. The molar is missing 2 or 3 plates off of the front, otherwise it is a fairly typical find of its type for the greater Puget Sound-Gulf of Georgia area.

Q. What other information might be derived from the specimen?

A. There is much that can be learned from the laboratory analysis of mammoth molars. With some careful sampling we could date the molar, using AMS radiocarbon dating, and have the molar subjected to stable isotope analysis. The radiocarbon analysis would tell us when the mammoth lived, and the isotope analysis (on carbon, nitrogen, oxygen, and strontium isotopes) would indicate the ancient temperature, precipitation, and diet associated with this mammoth. The strontium analysis can suggest whether this mammoth remained local (within the Puget lowlands) throughout the year, or perhaps migrated seasonally between the lowlands and the outer Washington coastal zone. It is usually just the cost of these procedures that prohibits our analysis of such finds. The cost for all of this analysis would be about $1,000 per molar, and most people are not able to pay this much, even though they often wish they could, both for reasons of curiosity and for a desire to contribute to our scientific knowledge of these animals. As with the Gedney molar, we have dozens of other suitable mammoth bones and molars that could profitably be scientifically analyzed if we had the funds to do it. This is one area where a wealthy benefactor could make a definite scientific contribution by funding laboratory analysis on mammoth finds from the local area, state or region.

Q. How common were these animals in the Northwest and when were they around?

A. Because of their overall size (they are relatively large and easy to see compared to the bones of lesser critters), mammoth bones and molars are one of the most often reported vertebrate fossil finds from this state. Beginning in about 1870 with the first noted finds, and continuing up to the present day, there have been roughly 400-plus mammoth finds in the state. No totally accurate count of these finds exists, but based on the numbers of finds reported each year this estimate is probably a minimal guess. The number of finds suggests that, seasonally at least, mammoths may have been quite common on the local Ice Age landscape, although for biological and ecological reasons they were probably outnumbered by other herbivores, and they would have certainly been outnumbered by contemporary populations of rodents like mice and voles. However, mice and vole bones/teeth are tiny and easily overlooked, and are therefore rarely reported. In general, because so few of these finds in our region have been accurately studied and dated, we have very limited knowledge of the dates for these animals. Mammoths first migrated into North America from Eurasia (across the Bering land bridge) roughly 1.5 million years ago. So in theory at least, the earliest mammoth from the state might well date to that age ... although sediments of this age are rarely exposed and/or studied and vertebrate finds from this early are accordingly quite rare. Similarly, we are not certain when the last mammoths inhabited the state. In general, mammoth finds from this state become rare in sediments more recent than about 13,000 years ago. But their chronological distribution in the state varies by region ... mammoths in the Puget lowland were probably gone by roughly 17,000 years ago, while mammoths in eastern Washington seem to have been present as late as approximately 13,000 years ago. We need much more analysis of these finds and sites before we will be able to answer for certain such questions as when the first mammoths arrived in our area, and when the last mammoths left.

Q. What caused the extinction of mammoths?

A.This remains a mystery and the fact of the matter is that we do not know for certain the cause of their extinction. There are dozens of theories about this, but only two that most scholars consider likely. Many believe that mammoths were done in by climate change and habitat destruction or fragmentation. Others believe that mammoths were hunted to extinction by early Paleoindians. Both of these theories, if carried to extremes, are probably overly simplistic, and it may well be that a combination of these factors (climate/habitat change and over-hunting) contributed to their extinction. Archaeological evidence for such hunting is found at some mammoth sites in the Desert Southwest and High Plains of the United States, but to date, no such evidence has been found at mammoth sites in the Pacific Northwest or with consistency throughout the rest of North America. Before we can demonstrate that climate/habitat change did in the mammoths we would need to fully document just what climate and habitat conditions they required for survival. To date this has not been documented for these animals, in spite of the fact that mammoth finds are plentiful throughout North America. This of course suggests that even a random, isolated find, such as the Gedney Island mammoth molar, when fully scientifically analyzed might well make an important contribution to our understanding of the demise of these magnificent mammals.

Q. Can you suggest any resources where people can learn more about mammoths?

A. Apart from many Web sites that are available on mammoths, probably the best single book on mammoths is "Mammoths" by Adrian Lister and Paul Bahn (1994), which is readily available through most library systems. Many museums and university geology departments in the state have mammoth finds on display, too many to list separately here. For Washington State finds, two of my articles in the journal Washington Geology (published in 1998 and 1999) list many sites and discuss their importance.

Q. Do you have any interesting mammoth trivia to share?

A. Not sure about trivia, but I can dispel the three most commonly held, and cited, myths about mammoths. These are ... that mammoths and mastodons were the same critters (and therefore these names can be used interchangeably) those mammoths were ancestral to modern elephants ... and that any mammoth found in North America (or the Pacific Northwest) must have been a woolly mammoth. Mammoths and mastodons were separate animals and not closely related at all. Both are found in Washington State. They seem to have occupied different habitat niches. Mammoths were grazers (like modern cows) feeding predominantly on grasses and herbs; mastodons were browsers (like modern moose) feeding mostly on leaves and water plants. While it is true that mammoths were a type of ancient elephant, both mammoths and modern elephants evolved contemporaneously about 7 million years ago in Africa. Mammoths were more closely related to Asian elephants, rather than modern African elephants, but mammoths were sister species of both modern types of elephants and ancestral to neither. Four main types of mammoths are found in North America: woolly mammoths, Columbian mammoths, imperial mammoths, and southern mammoths. In general, woolly mammoths had a more northerly distribution on this continent. They are rarely found south of a line stretching from South Dakota to West Virginia, and have never been documented from sites west of the Rocky Mountains. The other three species of mammoths have a continent-wide distribution and are found on both sides of the Rockies. This means that, in spite of endless newspaper headlines trumpeting the latest Pacific Northwest mammoth find as yet another "woolly" mammoth, none of the hundreds of mammoth finds from Washington, Oregon, Idaho, Northern California, and western British Columbia are woolly mammoths, and all must therefore be finds of one of the other three types of North American mammoths. Put plainly, woolly mammoths are not found in Washington, and that is part of the reason that Columbian mammoths are our state fossil (and not woolly mammoths). Indeed, the commonest mammoth found in our state is the Columbian, although there are also a few finds of imperial mammoths as well from the state.