A new paper published in the Journal of Vertebrate Paleontology describes 30 Jurassic creatures – five salamanders, one anuran, two lizards, 13 pterosaurs, five dinosaurs, and four mammals – of the so-called Daohugou Biota, a fossil assemblage named after a village near one of the major localities in Inner Mongolia, China.
Over the last two decades, huge numbers of fossils have been collected from the western Liaoning Province and adjacent parts of northeastern China, including exceptionally preserved feathered dinosaurs, early birds, and mammals. Most of these specimens are from the Cretaceous Period, including the famous Jehol Biota.
However, in recent years many fossils have emerged from sites that are 30 million years earlier, providing an exceptional window on life during the Jurassic period, about 160 million years ago.
The new study shows that several of these Jurassic sites are linked together by shared species and can be recognized as representing a single fossil fauna and flora – the Daohugou Biota. It contains superbly preserved specimens of a diverse group of amphibian, mammal, and reptile species.
The Daohugou Biota dates from a time when many important vertebrate groups, including our own group, mammals, were undergoing evolutionary diversification. It makes a contribution to our understanding of vertebrate evolution during this period, with such notable creatures as the oldest known gliding mammal, another early mammal that may have swum with a beaver-like tail, 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,” said lead author Dr Corwin Sullivan from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China.
Almost more impressive than the diversity of the biota is the preservation of many of the vertebrate specimens, including complete or nearly-complete skeletons associated with preserved soft tissues such as feathers, fur, skin or even, in some of the salamanders, external gills.
“The Daohugou amphibians are crucially important in the study of the phylogeny and early radiation of modern amphibian groups,” said co-author Dr Yuan Wang, also from the Institute of Vertebrate Paleontology and Paleoanthropology.
“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. 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,” said Dr Paul Barrett from the Natural History Museum, London, who was not involved with the study.
Because the Daohugou Biota and the much better studied Jehol Biota are similar in preservational mode and geographic location, but separated by tens of millions of years, they give paleontologists an outstanding, even unique, opportunity to study changes in the fauna of this region over a significant span of geological time and an important period in vertebrate evolution.
“The Cretaceous feathered dinosaurs of northeastern China have been astonishing paleontologists and the public for almost two decades now, and the Daohugou Biota preserves their Jurassic counterparts in the same region. As prequels go, it’s pretty exciting,” Dr Sullivan said.
Corwin Sullivan et al. 2014. The vertebrates of the Jurassic Daohugou Biota of northeastern China. Journal of Vertebrate Paleontology, vol. 34, no. 2; doi: 10.1080/02724634.2013.787316