Divergence time estimation
Introduction The photosynthetic stramenopiles (Ochrophyta)  constitute a highly diverse clade within Heterokonta, a clade that also includes a number of heterotrophic lineages such as plant molds and aquatic pseudofungi [e.g. 2] ,  . The majority of published molecular phylogenetic analyses have indicated that the photosynthetic and non-photosynthetic stramenopiles form a monophyletic taxon  ,  ,  ,  ,  ,  ,  . Heterokonts are typically characterized by the presence of a flagellum with tripartite tubular hairs (stramenopiles) and a smooth flagellum (i.e. lacking mastigonemes), although these are secondarily reduced or lost in some lineages  . The closest living relative of the heterokont eukaryotes has traditionally remained unclear.
+ Author Affiliations Abstract Carbonaceous cherts of the Tarahumara Formation, exposed near Huepac, Sonora, Mexico, contain abundant diatom frustules occurring as benthic filamentous colonies. Stratigraphic and paleontological observations indicate that Tarahumara sediments accumulated in a nonmarine setting; radiometric ages on encompassing volcanic rocks delimit their depositional age to ca. 70 Ma. Tarahumara fossils therefore extend the paleontological record of nonmarine diatoms from middle Eocene to Late Cretaceous.
+ Author Affiliations An improved Bayesian method is presented for estimating phylogenetic trees using DNA sequence data. The birth-death process with species sampling is used to specify the prior distribution of phylogenies and ancestral speciation times, and the posterior probabilities of phylogenies are used to estimate the maximum posterior probability (MAP) tree.
1. Introduction 2. Material and methods
+ Author Affiliations * Correspondence to be sent to: Department of Biology, Galton Laboratory, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK; E-mail: firstname.lastname@example.org . Received January 14, 2009.
1. Introduction 2.