The Elastic Tissue of T. rex

Fig. 2

Mary Schweitzer is one of the few paleontologists looking for the preservation of anything other than the highly mineralized fossil bones that form the foundations of vertebrate paleontology. If anything her quest is a challenging one. Sixty Five million years is a long time and not much is left of the soft tissue, which often decays in the first few weeks after death. But in todays issue of Science she and several collegues have isolated microstructures which have cell-like morphology within vessels that may represent blood vessels and blood cells. Although the article includes the conservative statement "reveals transparent flexible vessels in what remains of the cortical bone matrix, represented by a brown amorphous substance."

Schweitzer, Mary H., Wittmeyer, Jennifer L., Horner, John R., Toporski, Jan K.
Soft-Tissue Vessels and Cellular Preservation in Tyrannosaurus rex
Science 2005 307: 1952-1955

Summer Dedication for John Day Fossil Beds National Monument

A formal dedication of the new Thomas Condon Paleontology Visitor Center at John Day Fossil Beds is planned for August 13th, 2005. For more information on this event contact joda_paleontology@nps.gov, or visit the John Day Fossil Beds National Monument website.

Old Fishy Bits from the Big Horn Basin of Wyoming

The Bighorn Basin is best known for its Paleocene and Eocene mammal fossils, yet on the highway west of Buffalo an outcrop of early Palaeozoic rocks exhibit a fragmentary record of early fish evolution. In a recent article in Palaeontology (vol. 48) Ivan Samson and M.Paul Smith revisted the site to discover a fauna of late Ordovician jawless fish. The fauna is composed of fragmentary remains of Astraspis and Eroptychius, biostratigraphically constrained by a diverse sample of conodonts. These early fish fragments (osteoderms) enable a better understanding of the paleogeography of the shelf margin of the Williston Basin and the paleoecology of an ancient Ordovician sea.

Molecular Clock Fossil Calibration Consistency

Molecular clocks are a controversal subject among paleontologists. They often conclude on rather different results then studies based souly on the fossil record. An example is the proposed early diversification for plancental mammals during the late Mesozoic, rather than a later diversification supported the fossil record. Molecular clocks depend on two assumuptions: 1) clock-like DNA substitution rates and 2) accurate fossil calibration points. A recent article by Near, Meylan and Shaffer in the journal "The American Naturalist" took a look at fossil calibration points in a clade of fossil turtles. They developed a method to assess the consistency of fossil calibration points by cross comparison of various nodes in a cladogram. This unique method may provide a useful tool to help resolve the differences between molecular clock age estimates and fossil record estimates.

Near TJ, Meylan PA, Shaffer HB. 2005. Assessing concordance of fossil calibration points in molecular clock studies: An example using turtles. AMERICAN NATURALIST 165 (2): 137-146.