Sentence:  The late Eocene was a fascinating time with respect to community changes among terrestrial organisms. Among the mammals, for example, the greatest worldwide ordinal (26 total) and <WSD>familial</WSD> (about 120, plus bats and modern-type whales) diversity occurred. 
Meaning of the word marked with <WSD> tags:  Of or pertaining to any grouping of things referred to as a family.