Fossilized backbones initially identified as woolly mammoths have been re-identified as belonging to an entirely different animal, specifically whales. The bones, two epiphyseal plates from a mammalian spine, were discovered in 1951 by archaeologist Otto Geist during an expedition north of Fairbanks in the Alaskan interior, a region known as Beringia.
Geist's initial classification as woolly mammoth (Mammuthus primigenius) was based on the bones' appearance and location, as Late Pleistocene megafauna bones are common in the region, and the size suggested an elephantid origin. The bones were archived at the University of Alaska's Museum of the North for over 70 years.
Radiocarbon dating, enabled by the museum's 'Adopt-a-Mammoth' program, revealed the bones to be approximately 2,000 to 3,000 years old. This age contradicted the woolly mammoth timeline, as mammoths are believed to have gone extinct around 13,000 years ago, with a few isolated populations persisting until about 4,000 years ago. A finding of mammoths dating to the Late Holocene in interior Alaska would represent the youngest mammoth fossil ever recorded, several thousand years younger than existing evidence for mammoths in eastern Beringia.
Further analysis involved examining carbon and nitrogen isotopes. The bones exhibited higher levels of nitrogen-15 and carbon-13 isotopes than expected for a terrestrial animal like a woolly mammoth. These isotopes are more commonly found in marine environments, suggesting a marine origin for the specimens. No eastern Beringian mammoth fossils have previously displayed such a chemical signal, given the inland location.
Both mammoth and whale experts concluded that a definitive identification based solely on physical appearance was impossible. Ancient DNA analysis was pursued, and although nuclear DNA was too degraded, mitochondrial DNA was successfully extracted. This DNA was compared with that of a Northern Pacific Right whale (Eubalaena japonica) and a Common Minke whale (Balaenoptera acutorostrata), confirming the specimens' identity as whales.
The re-identification of the bones led to a new mystery: how the remains of two whales, over 1,000 years old, came to be located more than 400 kilometers (250 miles) from the nearest coastline in interior Alaska. Researchers have proposed several explanations:
- Inland whale incursion: This theory suggests whales may have entered ancient inlets and rivers. However, this is considered unlikely due to the large size of the whale species and the small size of Alaska's inland water bodies.
- Human transport: Ancient humans might have transported the bones from a distant coastline. While documented in other regions, this has not been recorded in interior Alaska.
- Scientific error: A mix-up during the early 1950s when Otto Geist donated numerous specimens to the university is also considered a possibility, given his collections originated from various parts of Alaska.
The ultimate resolution of how the whale bones reached interior Alaska may remain unknown. However, the effort has conclusively ruled out these specimens as contenders for the last mammoths.