卵齿，指卵生羊膜动物（如鸟类）在出卵壳前，上喙先端形成硬化的角质物。卵齿苦地胆（学名：Ajuga 纤毛纲 var. ovatisepala）是唇形科筋骨草属筋骨草的变种。

卵生羊膜动物（如鸟类）在出卵壳前，上喙先端形成硬化的角质物。由于早成雏在胚胎发育中吸收了大量的钙质，使卵壳薄而脆弱。雏鸟较容易用卵齿在气室附近啄破卵壳，然后用喙逐渐扩大裂缝，用身体向上顶卵壳的钝端，使卵壳破裂而出壳，一般雏鸟出壳后数小时卵齿即脱落，只有等一些鸟类保留一周以上。

oviparous amniotes (such as 巴尔的摩金莺队) in the out of egg shell prior to the formation of hardened horny beak tip material. nestling in the embryonic development due to absorption of a lot of 钙, so that egg-shell thin and fragile. Nestlings easier to use eggs teeth in the gas chamber near the pecking broken egg shells, then use the beak gradually expanding cracks in the body upward with the top of the blunt end of egg shells, so that rupture of the hatched egg shells. usually a few hours after the eggs hatched chicks tooth that is off, only the owl and some birds retain more than one week. Related term: Amphibians | 鳄科 Lizard |