A solid background in biology will only help you excel in the field of physical anthropology.  This does not demand a degree in biology, however if you plan to prepare with adequate coursework in biology (a&p, zoology, population biology, evolutionary biology, etc .... and all of the prereqs) then you might as well go for the biology degree or at least a minor.  Prior to getting my BA in physical, I had two years as a biology major at a community college and was taking pre-med classes while completing the BA at a 4-year institution.  Heavy emphasis on the biology ....

Good luck whatever you choose to do ....

It may not be necessary, but will definitely help - and keep in mind that not all Physical Anthro is bones as many people think.  Several of my grad school cohort ended up going to work for the CCC and various state health agencies with degrees in Physical anthro - so the more well rounded your background in a range of biological, health, medical, statistical analysis.... etc. fields  - the better off you will be in school.  Osteology and A&P are classes you should definitely take at the undergrad level if they are available -

Good luck