Oldest fossil of 'missing link' dinosaur discovered in Germany

This may be the oldest known specimen of Archaeopteryx. Credit: Oliver Rauhut et al., PeerJ, https://doi.org/10.7717/peerj.4191

Germany's Bavaria region is known today for its green hills and valleys, studded with whimsical castles and breweries. During the Jurassic period, most of this landscape was under a shallow sea, located much closer to the equator, with coral reefs and a chain of subtropical islands populated by dinosaurs.

Scientists in Bavaria have identified a new fossil from this long-gone era: what may be the oldest known specimen of Archaeopteryx— once thought to be the feathery link between dinosaurs and modern birds.

The discovery of the 150-million-year-old fossil highlights the diversity of known Archaeopteryx specimens, which may have belonged to several species, like "a Jurassic analog of Darwin's finches," said study leader and paleontologist Oliver Rauhut, of the Bavarian State Collections for Paleontology and Geology in Munich. [Images: Dinosaurs That Learned to Fly]

The sites in southern Germany where Archaeopteryx fossils have been found were once islands in a chain known as the Jurassic Solnhofen archipelago.

When the first Archaeopteryx fossils were discovered in the 19th century, paleontologists recognized the finds' mix of avian and reptilian features — such as feathers and a full set of teeth — and declared these raven-size creatures the earliest known birds. That title was undermined after fossils discovered more recently in Asia suggested that Archaeopteryx was just one of many bird-like dinosaurs to roam the planet.

In 2010, a private collector found an Archaeopteryx specimen at Gerstner Quarry, where tourists can dig for fossils, just outside of the Bavarian village of Schamhaupten, north of Munich. The collector alerted Rauhut, who then analyzed the fossil.

Scientists sometimes use fossils of extinct mollusks called ammonites as guides to gauge which geologic period a nearby specimen comes from. Based on the ammonites found near the Schamhaupten Archaeopteryx, the researchers think this specimen dates to the boundary between the Kimmeridgian age and the Tithonian age, around 152 million years ago, during the Jurassic period, the scientists said. That might make it the oldest of the 12 fossils that have been classified as Archaeopteryx.

"Specimens of Archaeopteryx are now known from three distinct rock units, which together cover a period of approximately 1 million years," Rauhut, who is also a professor at Ludwig-Maximilian University in Munich, said in a statement. Rauhut added that the specimens also show a great deal of diversity in their physical characteristics, which suggests that the fossils could represent more than one species.

"The high degree of variation in the teeth is particularly striking," Rauhut said in the statement, and the arrangement of teeth is different in every specimen, "which could reflect differences in diet." He said the situation was "very reminiscent" of the finches Charles Darwin studied on the Galapagos Islands, which showed diversity in their beak shapes and famously helped inspire his theory of evolution by natural selection.

Rauhut added that Archaeopteryx could have diversified into several species on the islands of the Solnhofener archipelago.

The findings were described online Jan. 26 in the journal PeerJ.

Original article on Live Science.