Thursday, March 29, 2012

[Geology2] Ancient teeth

Size isn't everything -- it's how sharp you are
EurekAlert [USA], March 14, 2012

The tiny teeth of a long-extinct vertebrate -- with tips only two
micrometres across: one twentieth the width of a human hair -- are the
sharpest dental structures ever measured, new research from the
University of Bristol and Monash University, Australia has found. For
300 million years, Earth's oceans teemed with conodonts -- early
vertebrates that kept their skeleton in their mouth. Scientists know
that conodont elements worked differently from the teeth of other
animals: they are microscopic -- about 2 to 0.2 mm long -- and must have
had paltry muscles to move them, with no jaws to which they could
attach. Dr David Jones of Bristol's School of Earth Sciences, one of the
study's authors, said: "The first problem is: how do you analyse such
tiny teeth? The answer: with a very big machine. We created high
resolution 3D models of the conodont elements using x-rays from a
particle accelerator in Japan, using it like a giant CT scanner. These
virtual models were examined, leaving the original specimens untouched."

Some mammals used highly complex teeth to compete with dinosaurs: study
EurekAlert [USA], March 14, 2012

Conventional wisdom holds that during the Mesozoic Era, mammals were
small creatures that held on at life's edges. But at least one mammal
group, rodent-like creatures called multituberculates, actually
flourished during the last 20 million years of the dinosaurs' reign and
survived their extinction 66 million years ago. New research led by a
University of Washington paleontologist suggests that the
multituberculates did so well in part because they developed numerous
tubercles (bumps, or cusps) on their back teeth that allowed them to
feed largely on angiosperms, flowering plants that were just becoming


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