# Osteology of the Feeding Apparatus of Chilean Flamingo Phoenicopterus chilensis (Aves: Phoenicopteridae)

## TL;DR

This paper describes the skull structure of the Chilean Flamingo, focusing on how its unique bill is adapted for filter feeding.

## Contribution

The study provides a novel detailed osteological analysis of the Chilean Flamingo's feeding apparatus.

## Key findings

- The skull's frontal region and elongated upper jaw are adapted for filter feeding.
- The mandible's low mechanical advantage supports rapid, repetitive movements.
- The tubular cavity between the rami aids in tongue movement for efficient water pumping.

## Abstract

Flamingos (Phoenicopteridae) feed using a uniquely adapted bill that extracts small particles from the water and sediments. This study provides a detailed osteological description of the skull of the Chilean Flamingo (Phoenicopterus chilensis), with particular emphasis on feeding‐related features. The skull exhibits a broad, flattened frontal region that articulates with an elongated upper jaw, which is deflected ventrally at approximately 45° and aligns seamlessly with the laterorostrally curved mandible, forming a configuration well suited for filter feeding. The mandible exhibits a low mechanical advantage, indicating an adaptation for rapid and repetitive movements rather than forceful biting. Jaw muscle attachment sites, including the fossa subtemporalis, fossa temporalis, and fossa ventralis palatini, are reduced, suggesting the presence of relatively small muscles that favor speed and precision.

1. The skull features a broad, dorsoventrally flattened frontal region articulating with an elongated upper jaw that is complemented by the mandible's downward bend along its proximal half.

2. The low mechanical advantage in the mandible is attributed to the reduced and shallow insertion areas of the adductor muscles, which are positioned close to the jaw joint.

3. The tubular cavity formed between the rami provides suitably space for tongue movements, enhancing the efficiency of the water‐pumping system during filter feeding.