“生长标度”定义了在研究腕足动物异速生长时所需的个体生长发育定量指标，其数值大小受到壳长、壳宽、壳厚以及相对应权重的共同控制。将腕足动物待研究性状的测量值与其生长标度作为两个变量进行二元回归分析，可判断该性状是否存在与腕足动物个体发育不等的生长速率，即异速生长。该指标对凯迪期(Katian)(晚奥陶世)腕足动物无洞贝类 Rongatrypa xichuanensis的定量分析表明，该种腕足动物的壳宽与个体发育保持同步，壳长呈负异速生长，壳厚呈正异速生长，指示出该种生物在生长过程中总体向横宽方向伸展，并伴随着壳体的加快增厚。

The term "Growth metric" is introduced in this paper to measure the degree of ontogeny for research about the allometry of brachiopods. The metric is calculated by length, width and thickness of shell with their separate weights. Regression analysis for the measurements together with growth metric of some shell’s dimensions of brachiopods can provide evidences for existence of allometry for the fossil population. A case study on Rongatrypa xichuanensis, a Katian(Late Ordovician) atrypide species, indicated that isometry of shell width, negative allometry of shell length and positive allometry of shell thickness can be detected by the statistics study on growth metric for the species.

国家自然科学基金(41530103)；中国科学院先导专项 B计划(XDB26000000)；现代古生物学和地层学国家重点实验室基金联合资助；本文是IGCP 653项目(The Onset of the Great Ordovician Biodiversification Event)的阶段成果