Major cranial changes during Triceratops ontogeny
Major cranial changes during Triceratops ontogeny
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DOI：
10.1098/rspb.2006.3643
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发表时间：
2006-11-07
影响因子：
4.7
通讯作者：
Goodwin, Mark B.
中科院分区：
文献类型：
--
作者：
Horner, John R.;Goodwin, Mark B.
这是对三角龙的第一次颅骨个体发育评估，三角龙是众所周知的白垩纪晚期恐龙，以三个角和巨大的顶骨鳞片褶边为特征。我们的分析是基于10个头骨的生长序列，从38厘米长的婴儿头骨到大约2米长的成人头骨。四个生长阶段对应于一套个体发育特征，表达于眶后角、褶边、鼻角、鼻外缘角和鼻部。卵后角在个体发育早期是直的，幼年时是向后弯曲的，亚成虫是直的，成虫是向前弯曲的。婴儿褶边的后缘是深扇形的。在早期幼体中，褶边边缘被17-19个三角形的头状花序装饰。在亚成人中，枕叶背侧受压，在成人中，枕叶强烈受压并拉长，在老年人中，枕叶最终合并到后褶边。生长阶段内和生长阶段之间的个体发育趋势包括：后褶边由扇形变为波浪状和光滑；枕骨上孔与枕骨枕骨大孔的渐进式排除；眶后角基部的内部凹陷；鼻中线缝合闭合；鼻壁和鼻翼的融合；鼻壁扩张形成形态多变的鼻角。我们假设角的方向和枕部形状功能的变化使幼鱼的视觉识别得以实现，并标志着它们达到性成熟。
This is the first cranial ontogenetic assessment of Triceratops, the well-known Late Cretaceous dinosaur distinguished by three horns and a massive parietal-squamosal frill. Our analysis is based on a growth series of 10 skulls, ranging from a 38 cm long baby skull to about 2 m long adult skulls. Four growth stages correspond to a suite of ontogenetic characters expressed in the postorbital horns, frill, nasal, epinasal horn and epoccipitals. Postorbital horns are straight stubs in early ontogeny, curve posteriorly in juveniles, straighten in subadults and recurve anteriorly in adults. The posterior margin of the baby frill is deeply scalloped. In early juveniles, the frill margin becomes ornamented by 17-19 delta-shaped epoccipitals. Epoccipitals are dorsoventrally compressed in subadults, strongly compressed and elongated in adults and ultimately merge onto the posterior frill margin in older adults. Ontogenetic trends within and between growth stages include: posterior frill margin transitions from scalloped to wavy and smooth; progressive exclusion of the supraoccipital from the foramen magnum; internal hollowing at the base of the postorbital horns; closure of the midline nasal suture; fusion of the epinasal onto the nasals; and epinasal expansion into a morphologically variable nasal horn. We hypothesize that the changes in horn orientation and epoccipital shape function to allow visual identity of juveniles, and signal their attainment of sexual maturity.