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- Scientists just identified a dinosaur tail preserved in amber. What is amber? Take a look at our study guide for some help.
- Amber is a substance created by resin, a type of liquid produced by trees. (Resin is not sap, another type of liquid created by trees.) Resin, a protective substance, oozes out of trees when they are cut or threatened by insects or fungi. Dripping resin can sometimes trap seeds, feathers, and even animals such as ants or mosquitoes in its viscous goo.
- Not all resin becomes amber. Organic substances such as resin are usually broken down by weather (such as extreme temperature changes or rain) and decomposers in the food web (such as bacteria and fungi). For resin to become amber, it must resist such decay. It must also undergo tremendous pressure, similar to the process that creates petroleum from other organic substances. Seams or globules of amber are mostly pressurized beneath tons of marine or terrestrial sediment.
- Most organisms trapped in amber are small insects, such as flies or ants. How did a dinosaur get stuck?
- The whole dinosaur didn’t get stuck—just its tail did. (Ouch.)
- It was probably a small dinosaur to start with—scientists think it was a juvenile coelurosaur, which was about the size of a sparrow.
- The baby dinosaur was probably dead when resin dripped down and covered the tail. (The skin on the tail is desiccated, indicating it had shriveled before encapsulation in the resin.) However, “there are signs the dinosaur still contained fluids when it was incorporated into the tree resin that eventually formed the amber. This indicates that it could even have become trapped in the sticky substance while it was still alive.” (Ouch.)
- How do scientists know the specimen is the feathered tail of a dinosaur, and not the feathered tail of a bird?
- telltale tail. The sample tail has “eight vertebrae from the middle or end of a long, thin tail that may have been originally made up of more than 25 vertebrae.” The tails of modern birds do not have spine-like vertebrae. They have a single set of fused vertebrae called a pygostyle.
- telltale feathers. Feathers in the sample lack the amazing geometry of modern bird feathers: the well-defined central shaft (rachis), branches, sub-branches, and hooks that latch the structure together and allow the bird to fly.
- According to Nat Geo News, the open, flexible structure of the feathers would not allow the dinosaur to fly. Why have feathers if you can’t use them to fly (or swim)?
- The brown-and-white dinosaur feathers “may have served a signaling function or played a role in temperature regulation.”
- Why is this discovery so important?
- Well, “this is the first time that scientists are able to clearly associate well-preserved feathers with a dinosaur.”
- The discovery provides insight into the evolution and morphology of feathers. The discovery supports the “barbule-first” theory, in which the fine tiers of feathers, called barbs and barbules, evolved before the strong central shaft of the rachis.
Nat Geo: Beach Awash in Amber study guide
(extra credit!) Current Biology: A Feathered Dinosaur Tail with Primitive Plumage Trapped in Mid-Cretaceous Amber