Fossil Friday – wildfires

A large wildfire, called the “Lake Fire“, is currently burning in the San Bernardino National Forest. Even though the fire is about 50 km north of Hemet, smoke from the fire is clearly visible from the Western Science Center.

Wildfires such as this are widespread in Southern California during the summer, driven by dry vegetation and frequent afternoon and evening winds. The regularity of these fires is evident in the fleet of Cal Fire aerial tankers based at the Hemet Airport, which are currently making regular flights to combat the Lake Fire:


Anthropogenic climate change and the ongoing drought have resulted in ideal conditions for wildfires in this area, but wildfires are not a new occurrence in California. In fact, a quick records search of the Diamond Valley Lake fossil collection housed at the museum turned up at least 80 Pleistocene specimens that show evidence of burning. The DVL fossils all predate the arrival of humans in California, so these aren’t animals that were cooked for food. They represent animals that were exposed to wildfire at or fairly close to the time of death.

In some cases the evidence for burning is subtle, but in others there is no room for doubt:

   

Above are two views of the left tibia (shin bone) of the camel Camelops. Most of the bone is missing, with only the distal end preserved (there is also a box full of associated fragments). The bone is completely burned, inside and out, and has almost a charcoal-like texture on the surface. The burning extends to the broken surface, so presumably the bone was broken when it burned. It’s possible that the bone had been exposed on the ground for awhile and had already started cracking up when the fire came through, but it’s also possible that a relatively fresh bone cracked and broke due to the heat from the fire. Regardless, specimens like this show that, much like today, wildfires were a regular occurrence in Southern California during the Pleistocene. 

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