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On September 7th 2022, I was out waiting for flash floods near a wash in Tucson I won't disclose. After trekking back and forth to my truck a few times I just happened to glance down at one point and notice a mammoth tusk eroding out of a hill. 

I had done some reading after moving to Tucson and knew that there were a lot of Pleistocene sediments around southern Arizona, so it's always in the back of my mind when I'm out hiking that a site might turn up. This one caught me by surprise. 

Discovery image with growth rings highlighted.

What tipped me off right away was the growth rings visible in the tusk as it was eroding out of the hill. The tusk is essentially sliced into a cross section and you can make out the individual growth rings inside of it. As a mammoth grows it adds rings to its tusks. 


I reached out to Pima County to report the site, who got in touch with Ian Milliken from the University of Arizona. Ian led a team that excavated the site. They didn't recover a lot of material. A decent size section of tusk and some large rib fragments. There is likely more material at the site, but the skeleton is very disarticulated and spread out. It would require a lot of damage to the landscape in order to retrieve the rest of the bones. The bones were also not in great condition, indicating some weathering before burial. I was invited to view what they recovered which is now housed at the UofA paleo lab. 

Bone fragments and tusk section from the site.


Close up shot of the tusk.


Unfortunately there isn't a lot of money in paleo available to fund further research on the site. The mammoth was likely a young Columbian Mammoth that occupied the region before the first human occupation occurred mid to late Pleistocene. 

It is very important to report sites like this to the proper authorities. Had it been in better condition or more material easily recovered, it would have warranted more scientific investigation. It is also illegal to remove vertebrate fossils from public lands and the penalties are severe. 

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