Tooth eruption in the Early Cretaceous British mammal Triconodon and description of a new species
Tooth eruption in the Early Cretaceous British mammal Triconodon and description of a new species
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白垩纪早期英国哺乳动物三角齿兽的牙齿萌出和新物种的描述
DOI：
10.1002/spp2.1329
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发表时间：
2020
影响因子：
2.3
通讯作者：
Hautier, ed., Lionel
中科院分区：
文献类型：
--
作者：
Jäger, Kai R. K.;Cifelli, Richard L.;Martin, Thomas;Hautier, ed., Lionel
Triconodon mordax，来自多塞特郡Purbeck群的最低白垩纪（Berriasian）部分，以记录牙齿萌出和替换方面的个体发育系列标本而闻名。基于四个标本的显微计算机断层扫描，我们将一个下颌骨称为一个新物种，Triconodon averianovi，它不同于T.mordaxin，具有更细长，弯曲的c; p4明显低冠，具有细长的主尖和较小的副尖;以及具有弱扣带的磨牙，m4明显较小，具有弱尖a和c.T. mordaxis，颏孔数量和后颌形态可变。扫描显示比以前认为的Triconodon更早的发育阶段（早期萌出的P3），并显示前磨牙的顺序前后替换;目前尚不清楚P1 - 2是否被替换。扫描也支持了早期的假设，即m4在生命晚期爆发。M4矿化的发生可能与P3的喷发同时发生，随后P4置换DP4，C喷发。M4在冠状突的舌侧内发育，远高于牙排。它保持在原位，随后通过下颌骨后部异常延长和局部生长而被容纳在活动牙列中。这种模式在一些较晚的三齿龙科中可以看到，似乎是该家族所独有的。
Triconodon mordax, from the lowest Cretaceous (Berriasian) part of the Purbeck Group, Dorset, is known by an ontogenetic series of specimens that document aspects of tooth eruption and replacement. Based on micro‐computed tomography of four specimens we refer one mandible to a new species,Triconodon averianovi, which differs fromT. mordaxin having a more slender, curved c; p4 notably low crowned with slender main cusp and smaller accessory cusps; and molars with weak cingula, m4 being notably smaller with weak cusps a and c.T. mordaxis variable in the number of mental foramina and posterior jaw morphology. Scans reveal an earlier developmental stage (p3 in early eruption) than previously recognized forTriconodon, and demonstrate sequential, anteroposterior replacement of premolars; it remains unclear whether p1–2 were replaced. Scans also support an earlier hypothesis that m4 erupted late in life. Onset of m4 mineralization is likely to have coincided with eruption of p3, followed by replacement of dp4 by p4 and eruption of c. The m4 developed within the lingual side of the coronoid process, well above the tooth row. It remained in position and was subsequently accommodated in the active tooth row through unusually prolonged and localized growth of the posterior part of the mandible. This pattern is seen in some later triconodontids and appears to be unique to the family.
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