Prefrontal_bone
The prefrontal bone is a bone separating the lacrimal and frontal bones in many tetrapod skulls. It first evolved in the sarcopterygian clade Rhipidistia, which includes lungfish and the Tetrapodomorpha.[1] The prefrontal is found in most modern and extinct lungfish, amphibians and reptiles. The prefrontal is lost in early mammaliaforms and so is not present in modern mammals either.[2]