Hyomandibula

The hyomandibula, commonly referred to as hyomandibular [bone] (Latin: os hyomandibulare, from Greek: hyoeides, "upsilon-shaped" (υ), and Latin: mandibula, "jawbone"), is a set of bones that is found in the hyoid region in most fishes.

It is commonly suggested that in tetrapods (land animals), the hyomandibula evolved into the columella (stapes).

The first set of these elements surrounded the mouth to form the jaw.

There is ample evidence[3] that vertebrate jaws are homologous to the gill arches of jawless fishes.

The upper portion of the second embryonic arch supporting the gill became the hyomandibular bone of jawed fishes, which supports the skull and therefore links the jaw to the cranium.