【古生物学】獣脚類恐竜も軽快なフットワークで求愛行動をしていた

Dinosaurs may have engaged in mating displays similar to those of some species of ground-nesting birds, according to research published in Scientific Reports this week. The study presents fossils of large scrapes made by the feet of theropod dinosaurs and suggests they are similar to those made by some birds in ‘nest scrape display’ behaviour.

Martin Lockley and colleagues present evidence from four sites in Colorado of large scrape display traces found in Dakota Sandstone dating from the Cretaceous period (around 66-145 million years ago). The largest of the sites, covering an area of approximately 750 m2, revealed 60 scrapes which typically consist of parallel double troughs, comprised of well-defined scratch marks separated by a raised central ridge. The authors suggest that the variable size and depth of the scrapes could mean that different species of theropods used the sites.

The authors argue that evidence from these sites supports the hypothesis that the scrapes are examples of display arenas for courtship. They note that the scrapes bear a similarity to marks made by Atlantic puffins during breeding season and to scratches made by ostriches. While nesting colonies were not found in the areas studied, the authors suggest that the abundance of scrapes indicates that nest sites may have been established nearby.