Difficulties in detecting convergent   ecomorphs without the use of molecular data are particularly pervasive in   anuran amphibians because their body plan is remarkably conserved. For example,   despite the fact that Archaeobatrachia and Neobatrachia diverged about 200   million years ago (mya) (12), superficial examination shows no striking   morphological fixed differences between these two groups. This situation is   diametrical to that, e.g., of mammals, whose orders underwent extensive   remodeling of morphological and physiological character complexes in a much   shorter time (10, 12, 13). Hence, most conspicuous morphological features are   usually used in anuran systematics despite their possible adaptive   properties.

在没有使用分子数据的情况下，检测生态形态趋同的困难在无尾两栖动物中尤其普遍，因为它们的身体结构非常保守。例如，尽管距今约2亿年前（12），始蛙亚目(Archaeobatrachia)和新蛙亚目(Neobatrachia)就发生了分化，但外形研究显示这两者之间没有明显的稳定形态差异。这种情况与哺乳动物的情况正好相反，例如，哺乳动物的目级类群在更短的时间内（10、12、13）经历了形态和生理特征复合物的广泛重塑。因此，最显著的形态特征通常用于无尾类系统学，尽管它们可能具有适应性。