Here's why:
* Mummification: The tar pits acted like a natural preservative. The thick, sticky tar trapped animals, preventing them from decomposing fully and preserving their bones, soft tissues, and sometimes even fur and skin.
* Other fossil types: While the tar pits primarily produce mummified fossils, some bones may also be mineralized (turned to stone) through the process of fossilization. However, the preservation of soft tissues is a hallmark of the La Brea tar pit fossils.
