The tar in the La Brea Tar Pits is a fossil fuel that began forming hundreds of million years ago from the bodies of marine organisms. During the last ice age, a few tens of thousands of years ago, mammals like mammoths and sabertooth cats, became trapped in the tar, leaving their bones behind. The mammals became trapped in the tar that already existed, and were not in fact part of what created it.
The tar located in the La Brea tar pits is today a fossil fuel that began its formation many hundreds of millions of years ago from the bodies of marine organisms. During the last ice age that ended a few tens of thousands of years ago, some animals got trapped in the tar and left their bones behind. They are not something that created it but only got trapped in preexisting tar.
