Professor Willie Anku is a theorist/ethnomusicologist who focuses on rhythmic theory and travels giving numerous international conferences. This is from his course I took at the University of Ghana-Legon, and here are some examples of notated rhythms he discusses.

A focus of his themes include categorizing rhythms within mathmetical frames and notes how different groups of people, i.e. Yoruba, Bembe, and Ewe, perceive the "1" or "western downbeat". He describes African music theoretically within cyclicality, time and circles. Here is a photo of the time cycle example below...

Here is a link to his full dissertation online.