The extremely well-preserved remains of a 66-million-year-old hadrosaur, known as a "dinosaur mummy," have just yielded soft-tissue skin structures and organic molecules, according to a new study.
While research on other dinosaurs has led to the identification of organic material linked to bones, co-author Roy Wogelius told Discovery News that "this is the first dinosaur to reveal intact skin structure and associated organic molecules."
Wogelius, a senior lecturer at the University of Manchester, added, "We (also) seem to have some original organic material within the tendon."
The existing "skin," as described in a Proceedings of the Royal Society B paper this week, consists of a mixture of the original cellular components mixed with mineralized material.
"Imagine putting a bunch of grapes into a runny cement," he said. "If you let the cement set, and cut a cross section years later, you'd see a beautiful cast of a bunch of grapes --whether the grapes survived the process or not. Based on our observations and analysis, we think a mineralizing fluid acted very quickly to make a solid mineral (calcium carbonate or calcite) cast of the skin cells."
Wogelius and his colleagues conducted infrared imaging, amino acid analysis and high-temperature breakdown studies that show the organic materials taken from the hadrosaur are "completely different from the organics present as background in the surrounding geological sediment."
Their remarkable preservation is due to the dinosaur's quick burial. Shortly after the hadrosaur's death near a sandy river channel, the researchers believe its body was covered in a waterlogged setting that prohibited contact with atmospheric oxygen. This led to rapid mineralization that appears to have outpaced tissue decay.
The scientists can also tell that the dinosaur's skin was probably very thick.
Wogelius said it was "at least 3.55 mm (.14 inches) thick at the base of the tail — much more than twice as thick as human skin, and that's at a place where the skin was probably quite thin anyway."
He therefore thinks the dinosaur's skin would have been much thicker, perhaps like that of an elephant.
The study further determined the organic skin molecules are consistent with molecules found in crocodile claws and bird feathers and strengthens the evolutionary link between the dinosaurs and those animals.
The hadrosaur, nicknamed "Dakota," was found in southwestern North Dakota in 2004. It was removed from its "rock tomb" just last year.
In addition to its intact skin structures, the dinosaur possesses an exceptionally well-preserved tendon, which even shows small canals that once conducted blood and other substances into the hadrosaur's bones.
Yet another specimen in surprisingly good condition is "Leonardo," a 77-million-year-old duck-billed dinosaur, whose remains first came to public light in 2002.
Cory Coverdell, a field instructor at Montana's Two Medicine Dinosaur Center, told Discovery News, "Leonardo is very special, because 70 percent of the body is covered with mineralized skin and possible fossilized organs are within the remains."
Organic molecules have not yet been found in Leonardo, however, and Coverdell is "skeptical that organic molecules could have been identified in Dakota, since these usually are due to contamination."
Despite these advancements, Wogelius concedes that it is "not likely" that DNA could be extracted from a dinosaur, mummified or not.
Looking for the building blocks of protein "is hard enough," he explained. "Finding intact DNA is so unlikely that we are not focusing on that as a concept."
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