On allometric equations for predicting body mass of dinosaurs
On allometric equations for predicting body mass of dinosaurs
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DOI：
10.1111/j.1469-7998.2009.00665.x
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发表时间：
2010-04-01
影响因子：
2
通讯作者：
Janacek, G. J.
中科院分区：
文献类型：
--
作者：
Cawley, G. C.;Janacek, G. J.
帕卡德和他的同事使用异速生长模型研究恐龙体质量的预测，倡导通过直接优化算术轴上的最小二乘准则来估计参数，而不是基于对数轴上的线性最小二乘回归的传统方法。我们考察了支持每种方法的统计学假设，发现帕卡德的方法在概念上并不令人满意，因为它假设给定的长骨周长身体质量的绝对变异性而不是相对变异性，这在生物学上是不可信的。因此，他们提出的方法对大型哺乳动物的小相对误差过于敏感；由于最大的(大象)因其大骨周长而相对较轻，由此产生的模型严重高估了小型哺乳动物的身体质量，并可能大幅低估恐龙的身体质量。然而，还必须注意的是，传统模型的误差条已经表明了身体质量的实质性不确定性，例如，迷惑龙的身体质量可能高达63公吨，或低至23公吨，模态值为38公吨。
Packard and colleagues investigate the prediction of the body mass of dinosaurs, using allometric models, advocating parameter estimation via direct optimization of a least-squares criterion on arithmetic axes rather than the conventional approach based on linear least-squares regression on logarithmic axes. We examine the statistical assumptions underpinning each approach, and find the method of Packard to be conceptually unsatisfactory as it assumes absolute rather than relative variability in body mass for a given long-bone circumference, which is biologically implausible. Their proposed approach is thus unduly sensitive to small relative errors for large mammals; as the largest (the elephant) is comparatively light for its large-bone circumference, the resulting model grossly overestimates the body mass of small mammals and is likely to substantially underestimate the body mass of dinosaurs. It is also important to note, however, that the error bars for the conventional model already indicate substantial uncertainty in body mass, such that for example, the body mass of Apatosaurus louisae may be as high as 63 metric tonnes, or as low as 23 metric tonnes, with a modal value of 38 metric tonnes.