thumb|Hemimandible of [[Trimerorhachis; the splenial (labeled "sp") is visible on the interior surface]]
thumb|Skull and jaws diagram of the primitive [[Synapsida|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.
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