Fossil sites sometimes resemble a living room table where half a dozen different jigsaw puzzles have been thrown: It is often difficult to determine which bone belongs to which animal. Together with colleagues from Switzerland, researchers from the University of Bonn have presented a method that allows for a more emphatic answer to this question. Their results are published in the journal Electronic paleontology.
Fossilized dinosaur bones are relatively rare. But if any of them are found, then most often it is in large quantities. “Many sites contain the remains of dozens of animals,” says Professor Dr. Martin Sander of the Institute of Earth Sciences at the University of Bonn.
If the researcher is lucky, the bones are still arranged exactly like in a living dinosaur. Some even are still attached to each other at their joints. Often, however, they were loosened and dispersed by scavengers and flowing water before being implanted in the soil. “It is very difficult to allocate this pile of hundreds of fossilized bones to the individuals from whom they originally came,” stresses Sander, who is also a member of the interdisciplinary research of the “building blocks of matter and fundamental interactions”.
This is because the “long bones” of the arms and legs, like the thigh bone, look remarkably similar even in different types. This means that even experts are often unable to determine if the femur is a fossil from a diplodocus or a brachiosaurus. Even if this could be confirmed, the fossils may have produced many diplodox specimens that may belong to them.
Sander and PhD student Kylie Wirma and Yand have now shown how to achieve this. They used dinosaur bones from the US state of Wyoming as a test tool. It was excavated and partially incorporated into skeletons by a team from the Aathal Dinosaur Museum in Switzerland shortly before the turn of the millennium.
Digging into bones that are 150 million years old
The Swiss researchers made their discoveries available to paleontologists in Bonn to conduct the study. He drilled, drew, Yand, and Sander into 150-million-year-old bones and examined the extracted core under a microscope. “This allows us to know how old the animal in question was when it died,” explains Wiersma Weand. For one thing, young bones are better than old bones. This means that after ossification they have more cavities in which blood vessels were. Second, the bone continues to grow in batches. “We often see distinct annual rings that resemble what we see in trees,” the researcher says.
Often an estimate of age makes it possible to rule out that the bone belongs to a specific skeleton. “If the left femur is 10 years older than the right femur, then we have a problem,” Sander says succinctly. There were no such discrepancies in the findings examined for the sake of the study. “However, we did find bones that were previously attributed to two different animals, but which belong to the same skeleton.”
The study addresses a problem that has begun to have a scientific focus in recent years: With so many dinosaur skeletons housed in museums and collections around the world, it remains unclear whether their bones come from one or more individuals. This combination is often made deliberately during fitting, since dinosaur skeletons are rarely fully preserved. Therefore supplementing the missing bones with finds from other samples is a common practice and, in principle, not a big deal as long as it is recorded. However, the most important thing is when researchers combine discoveries without their knowledge, and then these discoveries come from different species or animals of different ages.
When the original diplodocus has very short legs
This becomes especially important when the skeletons are called type specimens. This is because these are considered the “standard” for the corresponding types, similar to the prototype scale. But what if, for example, the original Diplodox program had the lower legs of a younger (and therefore smaller) Diplodox sample? Sander notes that “some of the conclusions we make about her mobility and her lifestyle may be wrong.” “So our research also helps combat the redundancy crisis that is so cited in science.”
Together with Kayleigh Wiersma-Weyand and lead student Nico Roccazzella, he will soon use this method to take a closer look at a popular exhibition: the “Arapahoe”, the tallest dinosaur skeleton in Europe, which is currently on display at the Koenig Museum in Bonn.
the post: Kayleigh Wiersma-Weyand, Aurore Canoville, Hans-Jakob Siber and Martin P. Sander: Skeletal Unity Hypothesis Testing using Bone Tissue: The Case of Surobod Remnants from Howe-Stephens and Howe Scott Quarries (Morrison Formation, Wyoming, USA); Electronic paleontology; DOI: https: /
Prof. Dr. Martin P. Sander
Institut für Geowissenschaften
Phone + 49- (0) 228-733105
email: [email protected]