Advances in molecular biology and genetics are revealing that many recognized crocodylian species are complexes of two or more cryptic species. These discoveries will have a profound impact on interpretation of the crocodyliform fossil record. Our understanding of ranges of intraspecific variation in modern crocodylian morphology may be based on multiple species and thus express both intraspecific and interspecific variation. This raises questions about our ability to recognize modern species in the fossil record, and it also indicates that specimens from disparate localities or horizons may represent not single widespread species, but multiple related species. Ranges of variation in modern species require a thorough re-evaluation, and we may have to revisit previous perceptions of past crocodyliform diversity, rates of evolution or anagenetic lineages in stratigraphic succession. These challenges will not be unique to those studying crocodyliforms and will require sophisticated approaches to variation among modern and fossil specimens.

中文翻译：

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化石记录中的现代神秘物种和鳄鱼生物多样性

分子生物学和遗传学方面的进展表明，许多公认的鳄类物种是两个或多个隐性物种的复合体。这些发现将对鳄形化石记录的解释产生深远的影响。我们对现代鳄鱼形态的种内变异范围的了解可能基于多种物种，因此表达了种内变异和种间变异。这引起了人们对我们在化石记录中识别现代物种的能力的质疑，并且还表明来自不同地区或地平线的标本可能不代表单个广泛分布的物种，而是代表多个相关物种。现代物种的变异范围需要进行全面的重新评估，我们可能不得不重新审视以前对过去鳄形生物多样性的认识，地层演替中的演化速度或抗神经系。这些挑战将不是那些研究鳄形动物的人所独有的，并且需要复杂的方法来区分现代和化石标本。