|The computer model of the dinosaur tail used and a diplodocide
Image Credit: Simone Conti / Zachi Evenor
An international research team with the participation of the Department of Biology at the University of Hamburg has analyzed the mobility of dinosaur tails using computer models and methods from engineering. According to a study published in Scientific Reports, the researchers found that these tails could be moved more than 100 kilometers per hour. Unlike previously assumed, however, they did not reach supersonic speed.
Diplodocids were large herbivorous dinosaurs with long necks and long tails. In a previous study, it was believed that a hypothetical structure at the end of a diplodocid's tail, similar to the end of a whip, could move faster than the speed of sound (340 meters per second) and produce a supersonic bang.
To test this hypothesis, the international research team simulated the movements of the tail of diplodocids using a model based on five fossil diplodocid skeletons. The virtual tail model is over 12 meters long, would weigh 1,446 kilograms in real terms and consists of 82 cylinders, which are supposed to represent vertebrae and are attached to an immovable, virtual basin.
“Research was quite a challenge, because we had to tackle the problem with two methods, that are normally used in aerospace technology: multi-body simulation and the estimation of the resilience of the materials”, reports the first author of the study, Simone Conti from the Universidade NOVA de Lisboa and the Politecnico di Milano.
The researchers now tested whether their model tail would withstand the stress of moving quickly enough to create a supersonic bang. For this purpose, the base of the tail was moved in an arc, so that a whip-like movement was created. They found that the thin tail could not move at a top speed of 340 meters per second without tearing.
They then examined three different hypothetical structures one meter long, which were attached to the end of the model tail and were supposed to mimic the end of a whip. The first structure consisted of three skin and keratin segments, the second of braided keratin threads and the third of soft tissue, the shape of which was modeled on a medieval tool, the flail. The result: None of the structures was able to withstand the stress of movement at 340 meters per second. Both different analyzes showed that the tail end of diplodocids could not reach supersonic speed.
The simulations suggest that the tails of the diplodocids could only reach a top speed of 33 meters per second (more than 100 kilometers per hour). While this is very fast, it is more than ten times slower than the speed of sound and therefore too slow to create a supersonic bang, which contradicts the previous study.
“So, although the Diplodocid tails could not be moved quickly enough to create a supersonic bang, they are likely to be used as defense weapons or in the fight with other Diplodocids. Whether this was in a territorial fight or in the competition for reproductive partners remains speculative, of course,” says paleontologist Dr. Emanuel Tschopp, Alexander von Humboldt Research fellow at the Department of Biology at the University of Hamburg and co-author of the study.
Multibody analysis and soft tissue strength refugee supersonic dinosaur tail, S. Conti, E. Tschopp, O. Mateus, A. Zanoni, P. Masarati, and G. Sala, Scientific Reports
Source/Credit: University of Hamburg