The 50-foot-thick (16 meters) layer of limestone that held these fossils dates back to when south China was a large island just north of the equator with a tropical climate. A smattering of fossil land plants suggest this marine community lived near a conifer forest.
The fossils are exceptionally well-preserved, with more than half of them completely intact, including soft tissues. Apparently they were protected across the ages by mats of microbes that rapidly sealed their bodies off from decay after death.
“Soft tissues can give us more profound information about larger patterns of evolution and relationships, such as the feathers on dinosaurs,” Benton said. “Soft tissues in some of the marine creatures may help us understand diet and locomotion.”
Ninety percent of the fossils are bug-like creatures, such as crustaceans, millipedes and horseshoe crabs. Fish make up 4 percent, including the “living fossil” known as the coelacanth, which is still alive today nearly 250 million years later. Snails, bivalves (creatures including clams and oysters), squid-like belemnoids, nautilus-like ammonoids and other mollusks make up about 2 percent of the fossils.
The largest creature the scientists found was a thalattosaur, a marine reptile about 10 feet (3 meters) in length, which would have preyed on the larger fishes there, which reached lengths of about 3 feet (1 m). Other predatory marine reptiles the scientists found include dolphin-bodied ichthyosaurs.