Reconstructing Body Size in Extinct Crown Cetacea (Neoceti) Using Allometry, Phylogenetic Methods and Tests from the Fossil Record
Reconstructing Body Size in Extinct Crown Cetacea (Neoceti) Using Allometry, Phylogenetic Methods and Tests from the Fossil Record
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DOI：
10.1007/s10914-011-9170-1
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发表时间：
2011-12-01
影响因子：
1.9
通讯作者：
Sponberg, Simon N.
中科院分区：
文献类型：
--
作者：
Pyenson, Nicholas D.;Sponberg, Simon N.
现存的鲸目动物表现出几个数量级的种间大小，是有史以来最大的脊椎动物之一。然而，鲸目动物如何进化出不同的身体尺寸的细节仍然不清楚，因为它们缺乏传统上在其他脊椎动物化石中使用的基本形态指标。在这里，我们在系统发育的背景下，使用不同的回归方法对现存的头骨和长度数据重建了灭绝的冠群鲸类(Neoceti)的身体大小。因为大多数鲸类化石都是残缺不全的，我们开发了回归方程，根据保存在大多数头骨化石上的颅骨测量数据来预测总长度。所得到的回归方程是基于鲸目动物最现存的谱系(n=45个物种；272个标本)的头骨和长度数据的数据库，采样了所有现存的神秘属和所有主要的齿形纲分支。在建立预测方程时，我们比较了传统的物种数据回归和独立对比回归方法，以及单性状预测因子和一种结合了偏最小二乘多元回归和独立对比优势的新方法。最后一种方法利用了使用多个相关代理的预测能力。最后，我们使用罕见的保留全长的鲸目动物化石来测试我们的预测方程的性能，以仅根据头骨测量来重建身体大小。我们的结果表明，在偏最小二乘尺度研究中结合有关系统发育关系和多种头骨测量的信息可以提高重建身体大小的准确性，最显著的是通过减少超过70%的预测间隔。在这个经验的基础上，我们强调了新奥西特人身体大小演变的主要特征的轮廓，以及未来使用这些度量标准来解决古生物学问题的机会。
Living cetaceans exhibit interspecific size ranging across several orders of magnitude, and rank among the largest vertebrates ever. Details of how cetaceans evolved different body sizes, however, remain obscure, because they lack basic morphological proxies that have been traditionally used in other fossil vertebrates. Here, we reconstruct the body size of extinct crown group cetaceans (Neoceti) using different regression methods on extant skull and length data, in a phylogenetic context. Because most fossil cetaceans are fragmentary, we developed regression equations to predict total length based on cranial metrics that are preserved on most fossil crania. The resultant regression equations are based on a database of skull and length data from most extant lineages of cetaceans (n=45 species; 272 specimens), sampling all living mysticete genera and all major clades of odontocetes. In generating predictive equations, we compared both conventional species data regression and independent contrast regression methods, as well as single trait predictors and a new approach that combines the advantages of a partial least squares (PLS) multivariate regression with independent contrasts. This last approach leverages the predictive power of using multiple correlated proxies. Lastly, we used the rare occurrences of fossil cetaceans with preserved total lengths to test the performance of our predictive equations for reconstructing body size from skull measurements alone. Our results demonstrate that incorporating information about phylogenetic relationships and multiple cranial measures in PLS scaling studies increases the accuracy of reconstructed body size, most notably by reducing prediction intervals by more than 70%. With this empirical foundation, we highlight the outline of major features in the evolution of body size for Neoceti and future opportunities to use these metrics for paleobiological questions.