A high-resolution growth series of Tyrannosaurus rex obtained from multiple lines of evidence
A high-resolution growth series of Tyrannosaurus rex obtained from multiple lines of evidence
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DOI：
10.7717/peerj.9192
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发表时间：
2020-06-04
期刊：
影响因子：
2.7
通讯作者：
Carr, Thomas D.
中科院分区：
文献类型：
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作者：
Carr, Thomas D.
背景资料：在复杂的多细胞生物的生长过程中，年龄、大小和形态以一种层次和协调的模式共同变化。在已灭绝的物种中，通过相对成熟度和年代年龄的定量分析，霸王龙雷克斯的生长受到反复关注。其生长序列表现为从幼年期的浅颅向成年期的深颅的极端转变，沿着牙齿数减少，生长曲线显示T.雷克斯与它的近亲相比有很高的生长速度。然而，单独地，这些数据集提供了一个不完整的图片之间的一致性年龄，大小和相对成熟度在这个范例物种。这项工作的目标是分析这些数据集一起使用支序分析，产生一个单一的假设的增长，包括所有的相关data.Methods：三个轴的增长一起使用支序分析进行了分析，基于一个数据集的1,850个形态特征和44个标本。在TNT v.1.5中，在新技术检索和传统检索下运行分析。结果：对所有标本进行初步分析，共获得50个最简约的个体发育图，一系列分析鉴定出13个最简约的个体发育图。在没有这些样本的情况下进行的分析恢复了一棵最吝啬的树（即，3，053步。发育图由21个生长阶段组成，除了第一和第三个阶段外，所有阶段都得到了明确优化的同形特征的支持。T.雷克斯个体发育可以分为五个离散的增长类别，诊断的实足年龄，形态，并在一定程度上，大小（在成年人中无信息）。拓扑结构显示，从浅到深头骨形状的转变发生在13至15岁之间，T。雷克斯在15岁到18岁之间被超越。虽然大小和成熟度在幼鱼和亚成体中是一致的，但在成体中没有发现一致性;例如，最不成熟的成体之一（RSM 2523.8）也是该物种中最大和最庞大的例子。在幼鱼和亚成体之间的过渡期出现的极端数量的变化表明，T。雷克斯表现出二次变态，类似于硬骨鱼性成熟时突然的个体发育变化。这些结果为测试成熟度与实足年龄、体型和质量之间的一致性以及将之前关于功能形态学的工作整合到严格的个体发生框架中提供了一个比较点。比较了T.雷克斯与外群类群的个体发育趋势，澄清了从共同祖先的初龙形目继承。
Background: During the growth of complex multicellular organisms, chronological age, size and morphology change together in a hierarchical and coordinated pattern. Among extinct species, the growth of Tyrannosaurus rex has received repeated attention through quantitative analyses of relative maturity and chronological age. Its growth series shows an extreme transformation from shallow skulls in juveniles to deep skulls in adults along with a reduction in tooth count, and its growth curve shows that T. rex had a high growth rate in contrast to its closest relatives. However, separately, these sets of data provide an incomplete picture of the congruence between age, size, and relative maturity in this exemplar species. The goal of this work is to analyze these data sets together using cladistic analysis to produce a single hypothesis of growth that includes all of the relevant data.Methods: The three axes of growth were analyzed together using cladistic analysis, based on a data set of 1,850 morphological characters and 44 specimens. The analysis was run in TNT v.1.5 under a New Technology search followed by a Traditional search. Correlation tests were run in IBM SPSS Statistics v. 24.0.0.0.Results: An initial analysis that included all of the specimens recovered 50 multiple most parsimonious ontograms a series of analyses identified 13 wildcard specimens. An analysis run without the wildcard specimens recovered a single most parsimonious tree (i.e., ontogram) of 3,053 steps. The ontogram is composed of 21 growth stages, and all but the first and third are supported by unambiguously optimized synontomorphies. T. rex ontogeny can be divided into five discrete growth categories that are diagnosed by chronological age, morphology, and, in part, size (uninformative among adults). The topology shows that the transition from shallow to deep skull shape occurred between 13 and 15 years of age, and the size of the immediate relatives of T. rex was exceeded between its 15th and 18th years. Although size and maturity are congruent among juveniles and subadults, congruence is not seen among adults; for example, one of the least mature adults (RSM 2523.8) is also the largest and most massive example of the species. The extreme number of changes at the transition between juveniles and subadults shows that the ontogeny of T. rex exhibits secondary metamorphosis, analogous to the abrupt ontogenetic changes that are seen at sexual maturity among teleosts. These results provide a point of comparison for testing the congruence between maturity and chronological age, size, and mass, as well as integrating previous work on functional morphology into a rigorous ontogenetic framework. Comparison of the growth series of T. rex with those of outgroup taxa clarifies the ontogenetic trends that were inherited from the common ancestor of Archosauriformes.