Slime versus dinosaur

In 2005, researchers made headlines when they reported that they had found intact blood vessels from a 68-million-year-old Tyrannosaurus rex. The discovery raised hopes that paleontologists could get their hands on the flesh and blood of vanished animals. This week, however, other scientists challenged the results, arguing that the dinosaur flesh was in fact just coatings of young bacteria. But the original researchers stand by their results, calling the new argument weak. "There really isn't a lot new here," says Mary Schweitzer of North Carolina State University in Raleigh.