dinosaur soft tissues are biofilms, shows study~~~>>>

Structures too common to be preserved tissue Gas bubbles indicated methane producing bacteria

Paleontologists in 2005 hailed research that apparently showed that soft, pliable tissues had been recovered from dissolved dinosaur bones, a major finding that would substantially widen the known range of preserved biomolecules.

But new research challenges that finding and suggests that the supposed recovered dinosaur tissue is in reality biofilm — or slime.

Opinion changed

“I believed that preserved soft tissues had been found, but I had to change my opinion,” said Thomas Kaye, an associate researcher at the Burke Museum of Natural History and Culture at the University of Washington. “You have to go where the science leads, and the science leads me to believe that this is bacterial biofilm.”

The original research, published in Science magazine, claimed the discovery of blood vessels and what appeared to be entire cells inside fossil bone of a Tyrannosaurus rex.

The scientists had dissolved the bone in acid, leaving behind the blood vessel- and cell-like structures, according to a University of Washington press release.

But in a paper published in PloS One, a journal of the open-access Public Library of Science, Kaye and his co-authors contend that what was really inside the T. rex bone was slimy biofilm created by bacteria that coated the voids once occupied by blood vessels and cells.

He likens it to what would happen if you left a pail of rainwater sitting in your backyard. After a couple of weeks you would be able to feel the slime on the inner walls of the bucket.

“If you could dissolve the bucket away, you’d find soft, squishy material in the shape of the bucket, and that’s the slime,” Kaye said. “The same is true for dinosaur bones. If you dissolve away the bone, what’s left is biofilm in the shape of vascular canals.”

In addition to the acid bath procedure used in the previous work, Kaye added examination by electron microscope before the bones were dissolved.

The researchers found that what previously had been identified as remnants of blood cells, because of the presence of iron, were actually structures called framboids, microscopic mineral spheres bearing iron.

“We determined that these structures were too common to be exceptionally preserved tissue. We realized it couldn’t be a one-time exceptional preservation,” Kaye said.

Gas bubbles

Using an electron microscope, the researchers saw coatings on the vascular canal walls that contained gas bubbles, which they associated with the presence of methane-producing bacteria. In addition, they found small troughs, or channels.

Study at high magnification revealed the channels had rounded bottoms and bridged each other, indicating they were organically created, likely by bacteria moving in a very thick solution.