Final answer:
The folded nasal passages of ankylosaurids may have functioned as resonating chambers, which are part of the nasal cavity. These structures could have modified sounds for communication and were also involved in warming and filtering the air for efficient respiration. This adaptation likely arose through natural selection.
Step-by-step explanation:
The folded nasal passages of ankylosaurids may have functioned as resonating chambers. These structures are part of the nasal cavity, which, in modern animals, is involved in the process of breathing by allowing the passage of air into the respiratory system where it is warmed, humidified, and filtered. In the context of dinosaurs, like ankylosaurids, it is hypothesized that these complex nasal passages could have played a role in vocalization or other forms of communication by modifying the sounds that the animals made. The nasal conchae, bony structures present in the nasal cavity, increase the surface area for warming and humidifying the air before it reaches the lungs. This protects the lung tissue and helps to ward off infection. Birds, which descended from dinosaurs, have a flow-through respiratory system—similar to what is believed for dinosaurs—where the air moves unidirectionally from air sacs into the lungs, promoting efficient respiration. This is one of the many features that has been subject to natural selection over the course of evolution. The specific adaptation of the folded nasal passages in ankylosaurids could indeed have been shaped by the forces of natural selection, contributing to their survival and fitness within their environment.