Dinosaurs from chickens??

It's provably impossible to get from dinosaurs to birds via any combination of mutation and selection.

But an actual tyrannosaur from modern bird DNA seems a bit silly to me,

Shirakawasuna wrote:

But an actual tyrannosaur from modern bird DNA seems a bit silly to me,

They've actually managed to sequence some of the proteins from that tyrannosaur leg bone you might have read about with the soft tissue inside, and the proteins were all but identical to those of a chicken.

Dinosaur Soft Tissue Sequenced; Similar to Chicken Proteins
Scott Norris
for National Geographic News
April 12, 2007

Ancient collagen—the main protein component of bone—has been extracted from the remains of a 68-million-year-old Tyrannosaurus rex, according to two new reports.

The new studies provide strong support for the hotly debated claims that organic material previously extracted from the T. rex's leg bone is original dinosaur soft tissue that somehow escaped fossilization.



Now, for the first time, scientists have obtained partial protein sequences from the soft tissue remains.

"The sequences are clearly from T. rex," said John Asara of Harvard Medical School in Cambridge, Massachusetts, who led one of the studies.

In addition, both studies found similarities between the dino sample and the bone collagen of chickens, providing molecular support for the hypothesis that modern birds are descended from dinosaurs.

Until now the dino-bird connection has been entirely based on physical similarities in fossils' body structures (related: "Earliest Bird Had Feet Like Dinosaur, Fossil Shows" [December 1, 2005]).

In a related study, a team led by Mary Higby Schweitzer of North Carolina State University conducted tests that also revealed the presence of collagen in the T. rex remains.

In one experiment, antibodies that normally react in the presence of chicken collagen reacted strongly to the dinosaur protein, suggesting a similar molecular identity.

Multiple Tests

For the protein sequencing study, Asara's team isolated seven fragmentary chains of amino acids—the building blocks of proteins—from the T. rex specimen.

The results are by far the oldest such data ever recovered. Previously, the earliest protein sequence data came from a 300,000-year-old mammoth specimen.

Asara's team extracted the amino acids using a highly refined version of the analytical technique known as mass spectrometry......

The new studies provide strong support for the hotly debated claims that organic material previously extracted from the T. rex's leg bone is original dinosaur soft tissue that somehow escaped fossilization...

gunga may be confused in thinking that"if its old, its gotta be really hard rock". Not true at all, some of the rocks of the Early Ordovician are still clays and are used for making brick. Chalk cliffs of Cretaceous (chalk) ages are just that, chalk, not consolidated and indurated. Many early formations contain minerals that are soft and unstructured, they can retain an almost paleo soil appearnce. The same is with many deposits of minerals, petroleum like tar, Permian coal layers with actual paraffin wax layers, and resins and organic fluids of ages that go back over 400 million years. The act of consolidation and induration involves a process like "cooking" by differential P/T and uniaxial compression. If such cooking does not occur, then many deposits of organic acids or waxes or even soap like materials can be left as fossil evidence. Animal fossils are usually produced by chemical replacement nmechanisms.As Thompson et al found, the lack of complete replacement of the material within the upper leg bones was a function of a chemical reaction that had only achieved a certain level of completeness

When gunga lets us know that he doesnt understand paleo material science, he tries to pooh pooh what he doesnt understand. Fortunately hes realktively safe because noone has the time or inclination to do a detailed explanation of mechanisms. However, I can assure him that Ill try to let him know at least where hes dead wrong.