Take a moment to scream at the top of your lungs. Finished? You just produced a sound that is a fraction of the volume that a howler monkey – the world's loudest land animal – can belt out.
Thanks to super-sized vocal chords and a hyoid bone that contains a pocket of air – with the exception of the skull, bones with air pockets are rarely seen except in dinosaurs – the howler monkey can easily make itself heard some three miles away. These monkeys live in the forests of eastern Bolivia, southern Brazil and Paraguay, and northern Argentina.
