HERE IN THE ORDOVICIAN, GONE IN THE DEVONIAN: DISSECTING THE GLOBAL DIVERSIFICATION TRAJECTORY OF TENTACULITOIDS

Throughout the history of life, various taxa have survived through repeated perturbations while others, some of which were once quite species rich, have not. These taxa are often thought of enigmatic, yet they can reveal more than previously thought about Phanerozoic marine diversification if studied within environmental and geographic contexts. Tentaculitoids have long been regarded as one such group. There has never been a definitive diversity study of tentaculitoids at any scale, and paleoecological / paleogeographic analyses for the group are almost entirely lacking in the literature.

To better understand the history of tentaculitoids, particularly geographic constraints on tentaculitoid distributions and morphology; we have begun an investigation of their evolutionary history, through global scale assessments of environmental and geographic distributions. The investigation involves the use and continued augmentation, and analysis of data contained in the Paleobiology Database (http://paleodb.org).

As of December 2007, there were only 511 occurrences of tentaculitoids in the Paleobiology Database, gleaned from 120 publications. Our ongoing assessment of the paleontological literature suggests that certain aspects of tentaculitoid diversity, such as the documentation of only one genus in the Ordovician, may relate to the paucity of tentaculitoid literature accessed thus far, inconsistency in systematic identification, and the lack of documentation of certain geographic areas because of stratigraphic biases. In this presentation, we provide an updated, though still preliminary assessment of the global diversification and paleogeographic distribution of tentaculitoids.