On the relationship between hypsodonty and feeding ecology in ungulate mammals, and its utility in palaeoecology
On the relationship between hypsodonty and feeding ecology in ungulate mammals, and its utility in palaeoecology
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DOI：
10.1111/j.1469-185x.2011.00176.x
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发表时间：
2011-08-01
影响因子：
10
通讯作者：
Janis, Christine M.
中科院分区：
文献类型：
--
作者：
Damuth, John;Janis, Christine M.
高冠（下齿）牙齿广泛存在于现存和已灭绝的食草哺乳动物中。现存的食草有蹄类动物（有蹄哺乳动物）有下齿动物的牙齿（一种衍生的条件），因此灭绝的下齿动物通常被认为是食草动物。因此，在过去的150年里，有蹄类动物的假说已经形成了广泛的古生态解释的基础，并在中新生代草原扩张的进化研究中占有突出地位。然而，在现存和灭绝的有蹄类动物中，牙齿磨损模式和牙齿脱落水平之间的不一致性导致一些研究人员拒绝将牙齿脱落作为古生物学中有用的预测工具，我们认为这种观点是错误的和过早的。尽管放牧和低密度动物之间的联系是公认的，但低密度动物与已知的有蹄类物种生态学之间的定量关系，对于解释化石记录至关重要，直到过去二十年才得到研究。此外，许多与理解假说有关的有蹄类生态学的文献尚未完全纳入古生物学家的观点。在这里，我们回顾了假说和有蹄类动物生态学之间关系的历史和现状，并重申了假说对我们理解有蹄类动物摄食行为的价值。我们还展示了土壤消耗，而不是草植物本身的消耗，可能是理解有蹄类动物饮食、栖息地和假说之间观察到的相关性的拼图中缺失的一块。此外，我们还展示了假说如何影响生活史策略，并解决了一些关于假说与预测灭绝物种饮食相关性的争议。这反过来又加强了假说在确定过去环境条件方面的效用，我们对古生物学中进化趋势的传统例子——马的假说进化及其与中新世北美草原扩张的关系——提供了一种修正的观点。
High-crowned (hypsodont) teeth are widely found among both extant and extinct mammalian herbivores. Extant grazing ungulates (hoofed mammals) have hypsodont teeth (a derived condition), and so extinct hypsodont forms have usually been presumed to have been grazers. Thus, hypsodonty among ungulates has, over the past 150 years, formed the basis of widespread palaeoecological interpretations, and has figured prominently in the evolutionary study of the spread of grasslands in the mid Cenozoic. However, perceived inconsistencies between levels of hypsodonty and dental wear patterns in both extant and extinct ungulates have caused some workers to reject hypsodonty as a useful predictive tool in palaeobiology, a view that we consider both misguided and premature.Despite the acknowledged association between grazing and hypsodonty, the quantitative relationship of hypsodonty to the known ecology of living ungulate species, critical in making interpretations of the fossil record, was little studied until the past two decades. Also, much of the literature on ungulate ecology relevant to understanding hypsodonty has yet to be fully incorporated into the perspectives of palaeontologists. Here we review the history and current state of our knowledge of the relationship between hypsodonty and ungulate ecology, and reassert the value of hypsodonty for our understanding of ungulate feeding behaviour. We also show how soil consumption, rather than the consumption of grass plants per se, may be the missing piece of the puzzle in understanding the observed correlation between diets, habitats, and hypsodonty in ungulates. Additionally, we show how hypsodonty may impact life-history strategies, and resolve some controversies regarding the relevance of hypsodonty to the prediction of the diets of extinct species. This in turn strengthens the utility of hypsodonty in the determination of past environmental conditions, and we provide a revised view of a traditional example of evolutionary trends in palaeobiology, that of the evolution of hypsodonty in horses and its correlation with the Miocene spread of grasslands in North America.