Lab Write Up

The tooth formula is a shorthand technique that biologist use to keep track of the teeth on a particular jaw. The formula consisted of two lines, top jaw and bottom jaw, which were used to count how many incisors, canines, premolars, and molar teeth a species had. Species A, Odocoileus virginiaus (white-tailed deer), had a tooth formula of 0033/3133. On the top jaw, the deer had zero incisor and canine teeth but have three of both the premolars and molars. On the bottom jaw, the deer had three incisors, one canine, three premolars, and three molars. Species B, Canis latrans (coyote), had a tooth formula of 3142/3143.

On the top jaw, the coyote had three incisors, one canine, four premolars, and two molars. On the bottom jaw, the coyote has three incisors, one canine, four premolars, and three molars. Both the deer and coyote skull were long and skinny towards the nose and mouth.

The coyote skull had a much rounder nose than the deer. Species C, Homo sapiens (human), had a tooth formula of 2122/2122. On both the top and bottom jaws, there were two incisors, one canine, two premolars, and two molars. In comparison to the deer and coyote skull, the human was an outcast. The human skull was a short distance from the back of the skull to the front. The human skull was very different in bone structure and longer in height than the deer and coyote skulls.

The tooth width from the deer, coyote, and human had a wide range in variety (Figure 1). There was a direct relationship between premolars one and two

Figure 1. Different tooth types in deer, coyote, and human compared by tooth width (cm). using the deer and human. The coyote had much smaller premolars than the deer and human. Figure 1 shows how similar the tooth width of a deer and coyote are. The cusps on the molars were very similar between the coyote and the human. The coyote and human molar cusps were very similar in molars one and two.

In Figure 1, the human and coyote tooth width are almost displayed the same. On molar three, the cusp sizes were very similar between the deer and coyote. The jaw length of a deer, 6.151 cm, is closest to a coyote, 5.507 cm, making the molars towards the back of the jaw more similar to each other than humans. Figure 1 gives a visual on the numbers for data and comparisons.

The tooth sharpness of each animal depended on the type of diet each animal had (Figure 2). The premolars had a linear pattern between the three animals.

Figure 2: Different tooth types of deer, coyote, and humans compared by tooth sharpness (deg.). Coyote’s had the sharpest premolars, deer’s in-between, and human’s with the dullest premolars. Figure 2 compares the degrees of each premolar and each time, the pattern was followed. The molars had no relationship between each animal. Molar one cusp one and two are most closely related in both deer and humans. Molar two cusps one and two are most closely related to deer and human out of the three animals.

The cusps were similar but have about a ten-degree sharpness difference. The molars and cusps human’s and deer’s and human’s were similar but have about a twelve-degree difference between sharpness. In the second molar of the human, the cusps were less sharp than the deer. Figure 2 displays that there was no pattern between the molars of the three animals.

Taking the calculated number of tooth width and dividing it by the matching jaw length found relative tooth width (Figure 3). Relative tooth width displays the tooth width relative to the length of the jaw. The jaw length of a deer was 6.151 cm,

Figure 3: Displays three different animals and how their tooth width is related to their jaw length. which was the longest jaw out of all species compared in this experiment. The coyote had a jaw length of 5.507cm while the human had a jaw length of 2.932 cm. Premolar one of the deer was most similar to the coyote. Premolar’s 1, 2, and 3 were in proportion between the human and deer. The relative tooth width of the deer was very close in range while the coyote was not. By looking at Figure 3, this can be determined. The human has the highest relative tooth width out of the three species being compared.