More than a decade of phylogenetic research has yielded a well-sampled, strongly supported hypothesis of relationships within the large ( > 4000 species) plant family Acanthaceae. This hypothesis points to intriguing biogeographic patterns and asymmetries in sister clade diversity but, absent a time-calibrated estimate for this evolutionary history, these patterns have remained unexplored. Here...

Evolutionary and biogeographic studies increasingly rely on calibrated molecular clocks to date key events. Although there has been significant recent progress in development of the techniques used for molecular dating, many issues remain. In particular, controversies abound over the appropriate use and placement of fossils for calibrating molecular clocks. Several methods have been proposed fo...

At the northern tip of Colombia, Jonathan Bloch hunts for fossils in the midst of spontaneous combustion fires, noxious gases laced with foul-smelling sulfur, rock-shattering explosions, and some of the largest machines in the world. “It is a weird place to work,” Bloch admits, an associate curator of vertebrate paleontology at the FloridaMuseum of Natural History, although he says he feels saf...

Evolutionary and biogeographic studies increasingly rely on calibrated molecular clocks to date key events. While there has been significant recent progress in development of the techniques used for molecular dating, many issues remain. In particular, controversies abound over the appropriate use and placement of fossils for calibrating molecular clocks. Several methods have been proposed for e...

The Triassic System in Arizona has yielded numerous world-class fossil specimens, including numerous type specimens. The oldest Triassic vertebrates from Arizona are footprints and (largely) temnospondyl bones from the Nonesian (Early Triassic: Spathian) Wupatki Member of the Moenkopi Formation. The Perovkan (early Anisian) faunas of the Holbrook Member of the Moenkopi Formation are exceptional...

Over half of all described species are insects, but until recently our understanding of the reasons for this diversity was based on very little macroevolutionary evidence. Here I summarize the hypotheses that have been posed, tests of these hypotheses and their results, and hence identify gaps in knowledge for future researchers to pursue. I focus on inferences from the following sources: (i) t...

Carboniferous strata in the Alborz mountains consist of calcareous rich fossils the main part of which is composed of rugose corals. There have been few studies carried out on corals so far. In this paper, a new subfamily, genus and eight new species of rugose corals from Mobarak limestones in the central Alborz mountains are introduced

Osedax is a recently discovered group of siboglinid annelids that consume bones on the seafloor and whose evolutionary origins have been linked with Cretaceous marine reptiles or to the post-Cretaceous rise of whales. Here we present whale bones from early Oligocene bathyal sediments exposed in Washington State, which show traces similar to those made by Osedax today. The geologic age of these ...