the.com/howler monkey

means A large Central and South American primate known for its deafening, roaring calls that travel for miles through dense rainforest, used to mark territory and avoid physical confrontation with rival troops.

from Straightforwardly descriptive — 'howler' names the sound, and the sound is the whole point. The genus name, Alouatta, comes through French/Latin-adjacent naturalist tradition, but the common English name is simple observation: early naturalists and travelers in Central and South American forests kept hearing a roar that seemed far too enormous for the small, shadowy creature making it, and named the animal exactly what it does. The call itself is possible thanks to an oversized, horseshoe-shaped hyoid bone that acts like a natural amplifier — nature's own built-in megaphone.