Mystery fossil #60 is...
Neogyps errans, a Pleistocene vulture from southern California
We said it was a neighbor of the toe of a dinosaur and we weren't kidding. It's the tarsometatarsus of an avian dinosaur (i.e., a bird) as viewed from the distal end (the bottom end in the photo at left). The photo at left shows both the anterior and posterior sides of the bone. The tarsometatarsus (fused metatarsals) articulates with the phalangeal bones (the toes).
This specimen of the Pleistocene vulture Neogyps errans was collected at the Rancho La Brea Tar Pits in Los Angeles County back in 1912-13. The bird may have become trapped in the "tar" when it swooped down to feed on some other poor creature that had been unable to extricate itself from the sticky stuff.
To be accurate, they really aren't "tar" pits they are asphalt pits. Asphalt, like the gooey substance at Rancho La Brea, occurs naturally, while tar is a man-made liquid produced by distilling such things as wood, coal, peat, or shale.
Find out more about the Rancho La Brea Tar Pits here or visit the George C. Page Museum website. Read more about fossil birds here.