概述

齿式

表示 哺乳动物 异型齿的 排列顺序和数目的公式.哺乳动物的牙齿，由前至后依次分化为 门齿，以“Ｉ”表示、 犬齿，以“Ｃ”表示、 前臼齿，以“Ｐ”表示、 臼齿以“Ｍ”表示.左右两侧数目相同，取其一侧，并以横线分隔开 上颌和下颌，即齿式为ＩＣＰＭMＩＣＰＭ.把具体动物各类牙齿的数目填入相应的M代号位置上，则可看出该动物的齿式和计算出它的总齿数.如马的齿式为３１３３０３３MMMM３１３３＝４０。牛的齿式为０M３１３３＝３２，即牛M上颌无门齿及犬齿.鼠的齿式为１００３M１００３＝１６。猴和人齿式M均为２１２３MMMM２１２３＝３２。哺乳动物的齿型和齿数在同种个体中是M稳定的，因此，齿式是哺乳动物 分类学的重要依据之一.Special-shaped teeth, said the order of mammals, and number of formulas. Mammalian teeth, followed by the former to the later differentiation into incisor, to "I" said the canines, in order to "C" said, pre-molar, in order to "P", said molars with "M" said. the same number of left and right, whichever side, and separated by horizontal upper and lower jaw, or tooth of ICPMMICPM. to the specific types of animals, the number of teeth, fill in the corresponding position of M-code , you can see the animal's teeth, and calculate its total number of teeth. such as the horse's teeth for 3133033MMMM3133 = 40. Cattle teeth for 0M3133 = 32, that is, no one to turn cow teeth and the maxillary canines M. Rat tooth formula 1003M1003 = 16. Monkey and human tooth-type M are 2123MMMM2123 = 32. Mammalian tooth type and number of teeth in the same kinds of individuals is the M stable, therefore, tooth mammals one of the important basis for taxonomy.