Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA.
Science. 2012 Oct 5;338(6103):98-101. doi: 10.1126/science.1224495.
Mammalian grinding dentitions are composed of four major tissues that wear differentially, creating coarse surfaces for pulverizing tough plants and liberating nutrients. Although such dentition evolved repeatedly in mammals (such as horses, bison, and elephants), a similar innovation occurred much earlier (~85 million years ago) within the duck-billed dinosaur group Hadrosauridae, fueling their 35-million-year occupation of Laurasian megaherbivorous niches. How this complexity was achieved is unknown, as reptilian teeth are generally two-tissue structures presumably lacking biomechanical attributes for grinding. Here we show that hadrosaurids broke from the primitive reptilian archetype and evolved a six-tissue dental composition that is among the most sophisticated known. Three-dimensional wear models incorporating fossilized wear properties reveal how these tissues interacted for grinding and ecological specialization.
哺乳动物的研磨齿由四种主要组织构成，这些组织磨损方式不同，形成粗糙表面以粉碎坚韧的植物并释放营养物质。尽管这种齿型在哺乳动物中（如马、野牛和大象）反复进化，但在鸭嘴龙类恐龙组（Hadrosauridae）中，这种类似的创新在更早的时候（约 8500 万年前）就出现了，这为它们在 3500 万年的时间里占据了欧洲大陆巨型食草动物的生态位提供了动力。这种复杂性是如何产生的尚不清楚，因为爬行动物的牙齿通常是由两种组织构成的结构，大概缺乏用于研磨的生物力学特性。本文作者展示了，鸭嘴龙类从原始的爬行动物原型中分化出来，进化出了六种组织的牙齿组成，这在已知的牙齿结构中是最复杂的之一。结合了化石磨损特性的三维磨损模型揭示了这些组织如何相互作用进行研磨和生态特化。
