The jaw apparatus of the Late Cretaceous heteromorph ammonoid Pravitoceras
The jaw apparatus of the Late Cretaceous heteromorph ammonoid Pravitoceras
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晚白垩世异形菊石Pravitoceras的颌器
DOI：
10.1017/jpa.2015.27
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发表时间：
2015
影响因子：
1.4
通讯作者：
A.
中科院分区：
文献类型：
--
作者：
Tanabe;K.;Tsujino;Y.;Okuhira;K. and Misaki;A.
在日本西南部上白垩纪Izumi群的两只异形氨类Pravitoceras sigmoidale Yabe， 1902 （Nostoceratidae, Ancyloceratina）标本的体内发现了保存完好的aptychus型上下颌。它们在整体形态上与其他已知的蝶角亚目和双角亚目ammonoids相似，表明这些类群的颌部特征在形态上具有稳定性。上颚和下颚大小相等，喙状吻部突出，这表明该物种的下颌器官可能具有咬伤和切割猎物的功能。
Well-preserved upper and lower jaws of the aptychus-type found inside the body chambers of two specimens of the heteromorph ammonoid Pravitoceras sigmoidale Yabe, 1902 (Nostoceratidae, Ancyloceratina) are described from the Upper Cretaceous Izumi Group in Southwest Japan. They are similar in overall morphology to those of other nostoceratid and diplomoceratid ammonoids currently known, suggesting the morphological stability of the jaw features among these taxa. The equal size of the upper and lower jaws with beak-like rostral projection suggests that the jaw apparatus of this species might function to bite and cut up prey.