Sr age: 11.2-15 Ma
50 coral species recorded in total.
Contrasting earlier statements diversity and fanal tunover rates high in the middle Miocene.

Ref. 1902 recorded only 5 genera and 8 species of corals.

Abstract of ref. 1862:
Caribbean coral reefs were widespread, well developed, and highly diverse during the Late Oligocene. In contrast, the Early Miocene was marked by decline in both reef building and reef-coral diversity. Increasing planktonic productivity has been implicated in this regional collapse of the coral reef ecosystem. Reduction of extensive reef development makes it difficult to find early Neogene corals to sample, but the abundant and well preserved corals from the Tamana Fm. of Trinidad are one exception. The goal of this study was to more fully document this important fauna and better constrain the timing and effects of the Oligocene/Miocene biotic transition. Large new collections from the Tamana Fm. indicate that extinction was nearly complete and that recovery of coral species diversity was well under way by the beginning of the Middle Miocene. A total of 33 species were recovered from the Tamana Fm. Thirteen of these species are first occurrences (40 percent), but only four are last occurrences (12 percent). Three of the four last occurrences have only been recognized from the Tamana Fm., and may represent taxonomic uncertainty. The first occurrences include taxa destined to be major constituents of Miocene and Pliocene coral communities, including several species of Montastraea, Caulastraea portoricensis, Agaricia undata, and Siderastrea siderea. In spite of this increasing diversity, significant reef tract development did not return to the Caribbean until after a major episode of extinction during Plio/Pleistocene time. This second extinction decimated the diverse Late Pliocene fauna, and is associated with oceanographic changes caused by the emergence of the Isthmus of Panama and intensification of northern hemisphere glaciation. Therefore the Oligocene/Miocene transition was characterized by a decline in both reef building and reef-coral diversity but the Plio/Pleistocene transition was associated with decreasing diversity and increasing reef development. Both reef coral diversity and reef-tract development are strongly influenced by oceanographic conditions, but their responses are not in phase.