- Prefrontal bone
The prefrontal bone is a
bone separating the lacrimal andfrontal bone s in manytetrapod skull s. It first evolved in thesarcopterygian clade Rhipidistia , which includeslungfish and theTetrapodomorpha .cite_book |last=Cloutier |first=Richard |coauthors=& Ahlberg, Per E. |year=1996 |chapter=Morphology, characters, and the interrelationships of basal sarcopterygians |editor=Stiassny, Melanie L.J.; Parenti, Lynn R.; & Johnson, G. David (eds.) |title=Interrelationships of Fishes |location=San Diego |publisher=Academic Press |pages=445-479 |isbn=978-0126709513] The prefrontal is found in most modern and extinct lungfish,amphibian s andreptile s. It is very small, fused to the frontals or lost in many groups ofcoelurosauria ntheropod dinosaur s and is completely absent in their modern descendants, thebird s. The prefrontal was also lost in earlymammaliaform s and so is not present in modernmammal s either.cite_web |url=http://www.palaeos.com/Vertebrates/Units/Unit420/420.100.html#Mammaliformes |title=Mammaliformes |publisher=Palaeos: The Trace of Life on Earth |accessdate=2008-01-25]References
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