21 décembre 2015

Vaisseaux sanguins de dinosaures!

Quelle fascinante découverte:

Researchers have confirmed that vessel-like structures found in an 80-million-year-old dinosaur fossil are indeed blood vessels from the original animal, and not the result of biofilm or other contaminants.

(...) The vessels were first spotted in a demineralised a piece of leg bone from a Brachylophosaurus canadensis – a 9-metre-long hadrosaur that roamed Montana around 80 million years ago – by molecular palaeontologist Tim Cleland while he was still a graduate student.

(...) Now a researcher at the University of Texas at Austin, Cleland and his team have since managed to identify several distinct proteins trapped inside the vessels, including myosin, which is found in the smooth muscles that make up the walls of blood vessels.

To make sure that what they were seeing really did belong to a dinosaur, the team then compared the proteins in the fossilised blood vessels to those found in the relatives of dinosaurs, such as chickens and ostriches. Amazingly, the peptide sequences found in both the ancient and modern samples matched those found in the blood vessels. 

"This study is the first direct analysis of blood vessels from an extinct organism, and provides us with an opportunity to understand what kinds of proteins and tissues can persist and how they change during fossilisation," said Cleland. "This will provide new avenues for pursuing questions regarding the evolutionary relationships of extinct organisms, and will identify significant protein modifications and when they might have arisen in these lineages."

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