“The largest trench identified by the team is 40 centimetres deep, and oval-shaped with a diameter of 2 metres. [...] According to team member Martin Lockley of the University of Colorado Denver, the trenches could have enabled [dinosaur] females to select their mates depending on who had the physical strength to dig most impressively – an important skill for building nests.”
▻https://www.newscientist.com/article/dn28736-dinosaurs-took-part-in-building-competitions-to-attract-female