BIOGEOGRAPHIC AND EVOLUTIONARY SIGNIFICANCE OF TURRITELLID GASTROPODS FROM THE MIOCENE OF NORTHERN COLOMBIA
Turritellid gastropods are diverse and abundant Neogene fossils across the southern Caribbean, especially in Panama and Venezuela. Much less has been known about the group in Colombia, where previous work suggested only 2-3 species per formation. As part of a wider study of Neogene turritellids in the region, we have begun an intensive examination of turritellid species from the Jimol and Castilletes formations. Preliminary results indicate that the Jimol contains as many as 4 turritellid species, including Turritella coccoditana, T. curamichatensis, T. larensis, and T. matarucana. The Castilletes may contain as many as 8-10 species, including Turritella altilira, T. berjadinensis, T. coccoditana, T. cornellana, T. falconensis, T. gatunensis, T. gilbertharrisi, T. larensis, T. matarucana, and T. montanitensis. Most of these species are also known from Panama and/or Venezuela, and their presence in northern Colombia therefore fills in geographic and stratigraphic gaps in their known ranges. Species for which apical whorls are preserved (T. gatunensis and T. matarucana so far) are consistent with most fossil and Recent turritellid species: relatively small paucispiral protoconchs suggestive of short-term planktonic development.