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Evolution

The fossil history of the Rubiaceae goes back at least as far as the Eocene. The geographic distribution of these fossils, coupled with the fact that they represent all three subfamilies, is indicative of an earlier origin for the family, probably in the Late Cretaceous or Paleocene. Although fossils dating back to the Cretaceous and Palaeocene have been referred to the family by various authors, none of these fossils has been confirmed as belonging to the Rubiaceae.

The oldest confirmed fossils, which are fruits that strongly resemble those of the genus Emmenopterys, were found in the Washington and are 48–49 million years old. A fossil infructescence and fruit found in 44 million-year-old strata in Oregon was assigned to Emmenopterys dilcheri, an extinct species. The next-oldest fossils date to the Late Eocene and include Canthium from Australia, Faramea from Panama, Guettarda from New Caledonia, and Paleorubiaceophyllum, an extinct genus from the southeastern United States.

Fossil Rubiaceae are known from three regions in the Eocene (North America north of Mexico, Mexico-Central America-Caribbean, and Southeast Pacific-Asia). In the Oligocene, they are found in these three regions plus Africa. In the Miocene, they are found in these four regions plus South America and Europe.