Final answer:
The BEST evidence of collective work by Paleolithic nomadic groups is a large bison kill site with evidence of butchering on thousands of bones.
Step-by-step explanation:
The BEST evidence that Paleolithic nomadic groups sometimes came together to work collectively is a large bison kill site with evidence of butchering on thousands of bones. This indicates that a large-scale hunt was undertaken by a group, as it is unlikely that a single individual could have hunted and butchered so many animals alone. Additionally, the presence of butchering evidence suggests that the animals were processed and distributed among the group, further supporting the idea of collective work.
Learn more about Paleolithic nomadic groups and collective work