Godfrey Laurie R, Samonds Karen E, Wright Patricia C, King Stephen J
Department of Anthropology, University of Massachusetts at Amherst, Amherst, MA 01003, USA.
Folia Primatol (Basel). 2005 Mar-Apr;76(2):77-99. doi: 10.1159/000083615.
Schultz's rule (as reconstructed by Smith) states that there is a relationship between the pattern (or relative order) of eruption of molar versus secondary (replacement) teeth and the overall pace (or absolute timing) of growth and maturation. Species with 'fast' life histories (rapid dental development, rapid growth, early sexual maturation, short life spans) are said to exhibit relatively early eruption of the molars and late eruption of the secondary replacement teeth (premolars, canines, incisors), whereas species with 'slow' life histories are said to exhibit relatively late eruption of the molars and early eruption of the secondary dentition. In a recent review, B.H. Smith noted that primates with tooth combs might violate this rule because tooth combs tend to erupt early, regardless of the pace of life history. We show that exceptions to Schultz's rule among lemurs are not limited to the relative timing of eruption of the tooth comb. Rather, among lemurs, some species with extremely accelerated dental development exhibit a pattern of eruption of molars and of secondary teeth in direct opposition to the expectations of Schultz's rule. We focus particularly on the pattern (order) and pace (absolute timing) of dental development and eruption in Avahi and Lepilemur - two relatively small, nocturnal folivores with rapid dental development. These taxa differ markedly in their eruption sequences (the premolars erupt after M2 and M3 in Lepilemur but not Avahi ). We offer an explanation for the failure of Schultz's rule to predict these differences. Schultz's rule presumes that eruption timing is dependent on the size of the jaw and that, therefore, molar crown formation and eruption will be delayed in species with slow-growing jaws. We show that a variety of processes (including developmental imbrication) allows the crowns of permanent teeth to form and to erupt into jaws that might appear to be too small to accommodate them.
舒尔茨法则（由史密斯重构）指出，臼齿与恒牙（替换牙）的萌出模式（或相对顺序）和生长及成熟的整体速度（或绝对时间）之间存在关联。具有“快速”生活史（牙齿快速发育、生长迅速、性成熟早、寿命短）的物种据说臼齿萌出相对较早，而恒牙（前磨牙、犬齿、门牙）萌出较晚；相反，具有“缓慢”生活史的物种据说臼齿萌出相对较晚，而恒牙萌出较早。在最近的一篇综述中，B.H. 史密斯指出，具有梳齿的灵长类动物可能违反这一法则，因为梳齿往往萌出较早，与生活史的速度无关。我们发现，狐猴中舒尔茨法则的例外情况不仅限于梳齿萌出的相对时间。相反，在狐猴中，一些牙齿发育极度加速的物种，其臼齿和恒牙的萌出模式与舒尔茨法则的预期直接相反。我们特别关注了毛耳鼠狐猴和鼬狐猴这两种相对较小的夜行性食叶动物的牙齿发育和萌出模式（顺序）及速度（绝对时间），它们的牙齿发育都很快。这两个分类群在萌出顺序上有显著差异（鼬狐猴的前磨牙在M2和M3之后萌出，而毛耳鼠狐猴不是）。我们对舒尔茨法则未能预测到这些差异给出了解释。舒尔茨法则假定萌出时间取决于颌骨的大小，因此，颌骨生长缓慢的物种中臼齿牙冠的形成和萌出会延迟。我们发现，多种过程（包括发育重叠）使得恒牙牙冠能够在看似太小而无法容纳它们的颌骨中形成并萌出。
