The skeleton of Juravenator under UV light. If you look closely around the middle of the tail, you can see the traces of soft tissue. From Chiappe and Göhlich, 2010.
In 1861, as debates about evolution were brewing among naturalists, two important skeletons were discovered from the Late Jurassic limestone quarries of Germany. Both would be relevant to ideas about how birds evolved. Although not recognized as such until the late 20th century, Archaeopteryx was the first feathered dinosaur ever discovered and was a confirmation that birds had evolved from reptiles. The other creature, Compsognathus, represented a small, exceptionally bird-like dinosaur, and the anatomist T.H. Huxley took it as a proxy for the kind of animal from which birds originated. “There is no evidence that Compsognathus possessed feathers,” Huxley said during his 1877 American lecture tour, “but, if it did, it would be hard indeed to say whether it should be called a reptilian bird or an avian reptile.”
David Hone and colleagues published a paper showing how examining fossils under ultraviolet light can illuminate soft-tissue structures—like feathers—that would otherwise be hidden. Paleontologists Luis Chiappe and Ursula Göhlich applied the same technique to the Juravenator skeleton, and near the middle of the dinosaur’s tail they found an area of preserved soft tissue. The most easily seen parts of the soft tissue were patches of tiny bumps consistent with the skin impressions of other dinosaurs. Yet there were wispy protofeathers, too. Thanks to high-resolution photography, the remains of downy feathers were also detected, and these were similar to the structures that covered the body of a relative of Juravenator from China called Sinosauropteryx.
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Juravenator
was a small bipedal predator. Size of the juvenile type specimen, with a
human for scale - See more at:
http://www.fossilriver-thenovel.com/#sthash.qRxbHFb9.dpuf
Juravenator was a small bipedal predator. Size of the juvenile type specimen, with a human for scale |
The presence of both scaly skin and filamentous feathers makes Juravenator unique among feathered dinosaurs. This combination has not been seen before, but it is consistent with laboratory models of how feathers evolved from scaly skin. Furthermore, it appears that Juravenator was not wholly covered by a coat of fluffy feathers like baby chicks, perhaps indicating that feathery structures appeared on some parts of the bodies of dinosaurs before others. Frustratingly, the extent of soft-tissue preservation on the first Juravenator specimen is extremely limited, but further discoveries of this animal may help us better understand the origins of feathered dinosaurs.
