(CN) – A newly described fossil of the oldest known bird is the most senior specimen of the species found so far, according to a study published Friday in the journal PeerJ.
Roaming Earth roughly 150 million years ago, Archaeopteryx inhabited a subtropical landscape in Bavaria, Germany, characterized by reef islands and lagoons nestled within a shallow sea that was once part of the Mediterranean.
The new fossil, which is the 11th Archaeopteryx specimen found so far, has features that are distinct from other specimens found. The discovery will also enable researchers to differentiate between bird-like dinosaurs and their closest relatives.
“Specimens of Archaeopteryx are now known from three distinct rock units, which together cover a period of approximately 1 million years,” said lead author Oliver Rauhut, a paleontologist at Ludwig Maximilian University of Munich in Germany. “Among other things, they reveal that Archaeopteryx was very similar to advanced predatory dinosaurs in many respects.”
The study offers a diagnostic key that will enable researchers to reliably classify Archaeopteryx specimens, distinguishing them from their closest relatives, both basal birds and non-avian theropod dinosaurs.
While the fossil is 12th specimen attributed to Archaeopteryx, Rauhut and his team reported in 2017 that the first – the so-called Haarlem specimen, discovered in 1861 – does not actually belong to the species. Some researchers have questioned whether two other specimens are in fact part of the group, highlighting the need for a diagnosis to clearly identify Archaeopteryx fossils.
The fossil also demonstrates that known specimens span a considerable range of anatomical variation. Potential explanations for these differences range from intraspecific developmental polymorphism to evolutionary differentiation – the possibility that the fossils represent more than one species.
“The high degree of variation in the teeth is particularly striking – none of the specimens shows the same pattern of dentition as any other, which could reflect differences in diet,” Rauhut said.
The study compares the differences in the Archaeopteryx specimens to the variations in the beak shapes of Darwin’s finches on the Galapagos Islands.
The primordial birds might have also diversified into specialized forms on the islands of the Solnhofener Archipelago, making the Archaeopteryx fossils a Jurassic analog of Darwin’s finches.
All of the Archaeopteryx specimens have been found in the Altmuhl River valley in Bavaria.