What interests you about Biological Anthropology? I ask because Anthropology as a whole is infected with Post-modernism and is strongly anti-science. Many areas of biological anthropology can be pursued with a Ph.D. in biology, physiology, anatomy, zoology, etc.
All programs that I know of in human/primate paleontology/evolution/biomechanics (only a subset of BA) accept students directly into the Ph.D program without a masters. The difficulty may be demonstrating your seriousness without a masters. You need to go beyond simply working for a professor in their lab. You need to read the primary literature in the field that you are interested in. Now. Or yesterday. Really, the reading should consume all your spare time. You want to begin to formulate some simple and independent projects that a professor can advise you on. This stuff takes time. Many start in High School. And many students that I know that are accepted into the top labs in organismal biology right after college have these kinds of experiences. If you cannot get a strong letter from a professor, and a professor writing "Frank is #1 i my class!" is not strong, then go get a masters degree or do post-bac work. Experience is what matters. That said, many admissions committees in departments are enamored by high grades at Ivy league schools.
Finally, to re-iterate what people have said above. Science graduate programs are not like going to law school or medical school. Although "programs" are ranked, these rankings are not very useful. You want to find 6 professors that you want to work with. That is, choose a lab, not a program. Asking a professor in your college in a related field is one way. A better way is reading the literature, getting to know the field, and identifying who you think is hot.
Perhaps the best way to chose a lab is to see where the hot young post-docs and professors got their Ph.Ds. A lot of that success can be directly due to a mentor and/or a culture of achievement in the department. Some top professors make lousy advisors - they simply give up on students after their first failure - and all students will fail at something. Others aren't great advisors because the lab has 35 people (students, post-docs, techs, visting faculty, etc.) and you are low on the priority. So look at where people are getting their degrees and there is probably something right about the departments/labs that produce a lot of hot young scientists.