Splenial

Hemimandible of Trimerorhachis; the splenial (labeled "sp") is visible on the interior surface

Skull and jaws diagram of the primitive synapsid Dimetrodon, showing location of the splenial

The splenial is a small bone in the lower jaw of reptiles, amphibians and birds, usually located on the lingual side (closest to the tongue) between the angular and surangular.<ref>Romer, A. S. (1956). Osteology of the Reptiles. 772 pp. Chicago & London.</ref><ref>Watson, D. M. S. (1912). LXVII.—On some reptilian lower jaws. Journal of Natural History, 10(60), 573-587.</ref>