2022-01-04 10:44:35
Those who visit La Rioja, a region in the north of Spain famous worldwide for its good wines, little can imagine that there were times when instead of huge expanses of vineyards, there were large swampy areas, huge and shallow lakes that coexisted with open spaces. slightly elevated where giant ferns and plants abounded that now would seem to us from another world. When the water level dropped, the shores were visited by a huge variety of creatures, most of them dinosaurs, which dug their paws into the mud and left their footprints in it. Due to chance, some of those footprints were trapped there and were preserved as rock for more than 120 million years. Now, little by little, those footprints of disappeared creatures are coming to light spread over more than a hundred sites in La Rioja. The paleontologists who study these footprints, call them footprints, try to reconstruct to some extent the life and behavior of the creatures that created them.
Pablo Navarro Lorbés and Angélica Torices, our guests at Talking to Scientists, are two of those paleontologists. Pablo Navarro is doing his doctoral thesis at the University of La Rioja under the supervision of Angélica Torices and both, together with an international group of researchers, have published in the journal Scientific Reports the results of the study of two traces of theropod dinosaurs that are preserved in one of the deposits close to the Rioja population of Igea.
Just like we do when we walk or run with our bare feet across the wet sand of a beach and leave a stamp of our movement on them, those two dinosaurs left information about the way they moved in their footprints. When walking slowly, the footprints we leave are closer to each other, we support the entire sole of the foot more evenly and the depth of the tread is not very great, on the other hand, when running, the stride is longer and the footprint is uneven . Thus, the analysis of the footprints with the appropriate tools provided by science makes it possible to extract information about the movement and speed of the creature that left them, be it human or dinosaur. Scientists have even developed mathematical formulas that allow data such as stride length, footprint size, and others to be related to the animal’s speed.
The dinosaurs that left their footprints on Igea were bipedal, their feet had three elongated toes, like those of birds, although much larger. After all, theropods include both carnivorous dinosaurs, such as the famous Tyrannosaurus or the velociraptor, as well as modern birds, which are their modern descendants.
Dinosaur footprints have been discovered all over the world and, so far, the analyzes carried out reveal that the vast majority of them belong to animals moving slowly, walking, a small part were created by trotting animals and very few were generated by running. This is what makes the two tracks analyzed in the Igea sites so special, both animals moved very fast. The trace called La Torre 6A contains five footprints that show a tridactile footprint that is longer than it is wide and an average length of 32.8 cm. The average distance between two consecutive footprints is 2.6 meters and the stride (distance between two footprints of the same foot) is 5.2m. The La Torre 6B trail is made up of 7 footprints, somewhat shorter in length, with a deeper impression of the fingers and a stride that exceeds 5 and a half meters.
The authors calculate that the theropod that left track 6A was running at a speed between 23.4 and 37.1 km/h, while theropod 6B was going even faster, between 31.7 and 44.6 km/h. These velocities are among the three highest estimated for theropod tracks.
The tracks were probably made by the same species of theropod, although the interviewees indicate that it is not possible to specify their species. They possibly belong to medium-sized and very agile dinosaurs, possibly from the families of spinosaurids or carcharodontosaurids.
I invite you to listen to Pablo Navarro-Lorbés, a doctoral student at the University of La Rioja, and Angélica Torices, director of the Department of Paleontology at the same university and professor at the Complutense University of Madrid.
Reference:
Navarro-Lorbés, P., Ruiz, J., Díaz-Martínez, I. et al. Fast-running theropods tracks from the Early Cretaceous of La Rioja, Spain. Sci Rep 11, 23095 (2021). https://doi.org/10.1038/s41598-021-02557-9
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