Teeth, tusks, and mammoth clues

By Sam Reynolds

A friend of mine produces and sells scrimshaw, engraved artwork on ivory or bone. He makes most of his money at craft fairs. There he patiently explains again and again to mortified fair-goers that the tusks he works on are not from elephants, but from mammoths. “Mammoths that lived at least several thousand years ago”, he politely clarifies—”Not the modern mammoth of today.”

Mammoth ivory—which is sometimes mislabeled fossil-ivory—is by no means ubiquitous. However there is a continuing supply of it, especially from the permafrosts of Siberia, where tusks are often treated as a raw material commodity, not as paleoecological specimens. Mammoth molars and tusks are essentially unregulated largely because they are distinct from contemporary elephant ivory, which is illegal save for a few exceptions. Though still recognizable as ivory, the teeth have often undergone partial diagenesis, consisting of both original and some fossilized material. Sometimes they are preserved nearly perfectly, with little more than staining. In either case, they tend are original material—and provide plentiful and accurate chemical snap-shots of the lives of their proboscidean owners. From a site in Switzerland, Mammoth teeth dated 45,000 years old contained oxygen-18 isotopes that indicated the average air temperature there was 4ºC cooler than today (Heuser, 2010). Teeth can also be analyzed for dietary information through values of carbon-13 and nitrogen-15.

Mammoth tusking showing characteristic banded patterning. Taken from the blog of Charlotte Bailey, a fossil-trader and educator; http://www.rocks-fossils.com.

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The Hyper-Disease Hypothesis: Did Humans Bring About Doomsday for the Megafauna of the Pleistocene?

By Erika Lyon

It is a concern that we are entering Earth’s 6th mass extinction.  Mass extinctions occur when a large number of species die off in a short amount of time relative to background extinction rates (to read more about extinctions, click here).   Some of the major questions being asked include what are the mechanisms behind extinction events and could humans possibly cause a mass extinction?  One of the more recent extinctions in geologic time that may provide some insight into these questions is the Pleistocene megafaunal extinction that occurred in North America.  Three hypotheses have been made on the cause of the Pleistocene extinction, which include: 1) vegetation and climate change, 2) over-hunting by humans, and 3) the introduction of disease brought into North America by humans, the last of which is known as the hyper-disease hypothesis (MacPhee and Marx 1997; Lyons et al. 2004).  Continue reading