Rare glimpse of feathered dinosaur tail
In recent decades, it’s become increasingly clear that modern-day birds are related to dinosaurs. And, while specimens of amber containing the remnants of feathered dinosaurs have been found before, an amber specimen described on December 8, 2016 in the peer-reviewed journal Current Biology is said to be the most useful yet. The researchers who studied it said it will help:
… to fill in details of the dinosaurs’ feather structure and evolution, which can’t be determined from fossil evidence.
Researchers at the Royal Saskatchewan Museum (RSM) in Canada, who studied the amber specimen, said that while the feathers aren’t the first to be found in amber, earlier specimens have been difficult to definitively link to their source animal. They said the feathers definitely are those of a dinosaur, not a prehistoric bird. Ryan McKellar of RSM said:
The new material preserves a tail consisting of eight vertebrae from a juvenile; these are surrounded by feathers that are preserved in 3D and with microscopic detail. We can be sure of the source because the vertebrae are not fused into a rod or pygostyle as in modern birds and their closest relatives. Instead, the tail is long and flexible, with keels of feathers running down each side.
The amber specimen did not come from Canada, but instead was discovered in an amber market Myitkyina, Myanmar in 2015. The first author on the study – Lida Xing from the China University of Geosciences (Beijing) – noticed the specimen at the market. Those who found it originally might have imagined the inclusion was some kind of plant. The amber was destined to become a curiosity or piece of jewelry, if Xing had not recognized its scientific potential. The researchers’ statement said:
… the specimen represents the feathered tail of a non-avialan theropod preserved in mid-Cretaceous amber about 99 million years ago. While it was initially difficult to make out the details of the amber inclusion, Xing and his colleagues relied on CT scanning and microscopic observations to get a closer look.
The feathers suggest that the tail had a chestnut-brown upper surface and a pale or white underside. The specimen also offers insight into feather evolution. The feathers lack a well-developed central shaft, or rachis. Their structure suggests that the two finest tiers of branching in modern feathers, known as barbs and barbules, arose before a rachis formed.
The researchers also examined the chemistry of the tail inclusion where it was exposed at the surface of the amber. The analysis shows that the soft tissue layer around the bones retained traces of ferrous iron, a relic left over from hemoglobin that was also trapped in the sample.
McKellar lauded the value of amber as a supplement to the fossil record, saying:
Amber pieces preserve tiny snapshots of ancient ecosystems, but they record microscopic details, three-dimensional arrangements, and labile tissues that are difficult to study in other settings. This is a new source of information that is worth researching with intensity and protecting as a fossil resource.
Bottom line: A Chinese paleontologist stumbled on a piece of amber in Myanmar that turns out to contain feathers from a dinosaur.