A collection of fossils that are approximately 160 million years old have painted an new picture of the Jurassic period.
The assemblage, named the Daohugou Biota after a Chinese village near one of the major fossil sites, includes fossils belonging to rare creatures that walked on Earth millions of years ago including the oldest known gliding mammal, the oldest dinosaurs preserved with feathers, and a pterosaur that represents an important transitional form between two major groups.
"The Daohugou Biota gives us a look at a rarely glimpsed side of the Middle to Late Jurassic - not a parade of galumphing giants, but an assemblage of quirky little creatures like feathered dinosaurs, pterosaurs with 'advanced' heads on 'primitive' bodies, and the Mesozoic equivalent of a flying squirrel,” Dr. Corwin Sullivan, lead author of the study, said in a statement.
The findings, published in the Journal of Vertebrate Paleontology, shows that the fossils collected from sites in western Liaoning Province and adjacent parts of northeastern China are linked by shared amphibian, mammal, and reptile species.
Most of the fossils belong to vertebrate specimens with nearly-complete skeletons of animals with soft tissue like feathers, fur, skin and gills. Their remarkable condition is credited to volcanic ash they were found in.
“The new paper (of which I am an author) reviews the evidence establishing the geological age of these older fossils, and more importantly, suggests that they can be considered part of a new fauna,” Dr. Dave Hone writes in an article for The Guardian. “These older specimens come from a number of different localities, but they can be linked together by the presence of a salamander species.”
Using radiometric dating for numerous archeological sites, researchers found the fossil of the aquatic salamander Chunerpeton, is about 160 million years old. This allowed scientists to use the species as a marker to see what specimens belong to the new fauna based on their age.
The latest findings are poised to challenge or at least match the famous Jehol Biota – an ecosystem belonging to 60 species of plants, nearly 1000 species of invertebrates, and 140 species of vertebrates found in northeastern China.
“Just as over the last 20 years the Jehol has produced some astonishing finds (giant feathered tyrannosaurs, gliding dinosaurs, badger-sized carnivorous mammals, seed-eating birds) and in huge numbers, the Daohugou Biota is now threatening to do the same,” Hone writes. “It is of an important time, is already producing important specimens and new species, and the links to the Jehol provide the opportunity for much greater depth of understanding of transitions in a narrow geographical location over time.”
Dr. Paul Barrett, dinosaur researcher at the Natural History Museum, London, who was not involved in the study says the findings can aid in understating vertebrate evolution.
"Daohugou is proving to be one of the key sites for understanding the evolution of feathered dinosaurs, early mammals, and flying reptiles, due largely to the fantastic levels of preservation,” Barrett said. "Many of the fossils are stunning and offer vast amounts of information. There are only a handful of similar sites elsewhere in the world and this article represents the first comprehensive attempt to draw all of the relevant information together into a single benchmark paper."