ABSTRACT
The echinoid genus Clypeaster appears to have reached the Caribbean area only in mid-Oligocene times. Its apparent explosive radiation there during mid-Tertiary times is, however, a human artefact resulting mainly from underestimation of the morphological variation within Clypeaster species. The Miocene species C. concavus and C. cubensis appear to be ancestral to the distinctive Recent Caribbean type species C.rosaceus. Trends within this lineage, particularly variation in test shape, test construction and tuberculation pattern, indicate progressive adaptation to an epifaunal mode of life, possibly prompted by the Miocene expansion of seagrass communities in the Caribbean.
