Interview: New insights into what dinosaurs looked like

December 8, 2016

The discovery brings researchers closer to answering the question whether all dinosaurs were feathered or not.

The newly discovered dinosaur tail was preserved in amber about 99 million years ago. One year ago, a researcher from the China University of Geosciences found the specimen at an amber market in Myanmar. In its lifetime, the dinosaur was the size of a sparrow and likely belonged to the same group as Tyrannosaurus and modern birds, the researchers report in their new study. We speak about it with one of the study’s authors, Ryan McKellar from Royal Saskatchewan Museum in Canada.

ResearchGate: Where was this piece of amber found?

Ryan McKellar: This specimen comes from the Kachin State of Myanmar. It was mined from a region that has been producing amber for sculptures and carvings for two-thousand years, and that has been a major focus for fossil insect studies over the last twenty years. Dr. Xing, the lead researcher on this project, discovered the specimen while touring amber markets in Myanmar in 2015, and the Dexu Institute of Palaeontology was able to purchase the sample for their research collection.

Artist rendition of the coelurosaur with its feathered tail. Credit: Chung-tat Cheung.
Artist rendition of the coelurosaur with its feathered tail. Credit: Chung-tat Cheung.

ResearchGate: What’s special about it?

McKellar: This is the first time that we have skeletal material from a dinosaur (other than birds) reported from amber. We can tell that the tail belonged to a dinosaur outside of the group that contains Archaeopteryx and modern birds, because the vertebrae have not fused together to form a stiff rod. The tail is flexible and composed of a series of elongate, cylindrical vertebrae. The feathers also support a particular pathway for the evolutionary development of these structures.

ResearchGate: What do you know about the dinosaur this tail was once attached to?

McKellar: We know that we are dealing with a small individual (sparrow-sized), that was probably a juvenile, and that it fits into a broad grouping of dinosaurs called Coelurosauria, the large group that contains everything from Tyrannosaurus to modern birds. Most members of this group are thought to be bipedal carnivores. The individual that the tail came from would have had rows of feathers coming off the sides of its tail, and this part body would have been fuzzy looking, with pale or white feathers on the underside of the tail, and brown feathers on the upper surface. If this sort of plumage ran the entire length of the tail, it seems unlikely that the animal would have been an active flyer.

Tip of the feathered disosaur tail in amber. Royal Saskatchewan Museum (RSM/ R.C. McKellar)
Tip of the feathered disosaur tail in amber. Royal Saskatchewan Museum (RSM/ R.C. McKellar)

ResearchGate: What do amber-encased fossils tell us that traditional fossils don’t?

McKellar: Amber specimens provide us with a lot more fine detail than compression fossils, and they preserve objects in 3D. This allows us to examine things like the finest branching structures in feathers, how they insert into the skin, how pigments were distributed in the feathers, and if other animals lived in the same habitat.

ResearchGate: How does one examine such a specimen?

McKellar: Much of the analytical work that went into this specimen used a synchrotron (a very bright light source) to scan the sample with x-rays in order to created CT scans for 3D imaging, or chemical maps in order to look at preservation conditions. We also used some unusual microscope and microphotography rigs to capture images of the specimen and study visible features that are only a few micrometers in size.

ResearchGate: Did all dinosaurs have feathers?

McKellar: At this point, there is strong evidence that many theropod dinosaurs had feathers at some point during their life, and there is mounting evidence that feathers or other outgrowths of the skin may have been present within a wider range of dinosaurs (like ceratopsians). The more well-preserved specimens that are found and studied, the closer we get to providing a solid answer to this question.

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