One difference between our dentition is that though non-human apes have canines in the same place as humans, their canines are much larger than ours. We also have baby teeth, or “milk teeth,” that we loose when the adult teeth come in. Plants want animals to eat their fruits because, in doing so, animals eat the seeds of the fruit and then disperse them far away from the parent plant.Apes (humans included) all have the same dentition pattern, which is a fancy way of saying we have the same number of teeth, and in the same order, across the board.
Fewer primates are gummivores, who specialize in eating gums and saps, so we will not discuss the adaptations for this dietary type in great detail. The most common dietary types among primates are those whose diets consist primarily of fruit ( frugivores), those who eat mostly insects ( insectivores), and those who eat primarily leaves ( folivores). That is, two primates living in the same forest may be eating the same foods but in vastly different proportions, and so we would categorize them as different dietary types. While all primates eat a variety of foods, what differs among primates are the proportions of each of these food items in the diet. Primates are known to eat a wide range of plant parts, insects, gums, and, rarely, meat. Teeth also tell us directly about an organism’s diet. This is not always the case, however, as you will see when you read about the teeth of lemurs and lorises. Canines are often easy to distinguish because they are usually much longer and more conical than the other teeth. Molar cusps can also vary between taxa in how they are arranged, as you will learn more about later in this chapter. There is even one extinct primate ( Oreopithecus) who had six cusps on its molars. Depending on the species of primate and whether you’re looking at upper or lower teeth, molars can have between three and five cusps.
Molars are bigger, with a larger chewing surface, and so have more cusps. Premolars are smaller than molars and, in primates, often have one or two cusps on them. Cusps are the little bumps (which in some species can be quite sharp) that you can feel with your tongue on the surface of your back teeth. Premolars and molars can be differentiated by the number of cusps that they have. You can recognize incisors because they often look like spatulas with a flat, blade-like surface. To determine the dental formula, you need to be able to identify the different types of teeth. Many have fewer teeth, however, and some have a different dental formula on the top than they do on the bottom. Some early fossil primates had a dental formula of 2:1:4:3, but among the living primates, none have more teeth than can be found in a 2:1:3:3 dental formula.
(The first number represents the number of incisors, followed by the number of canines, premolars, and molars). This dental formula is written as 2:1:2:3. You can see that in half of the mandible, there are two incisors, one canine, two premolars, and three molars. For example, Figure 5.5 shows half of the lower teeth of a human. The dental formula tells you how many incisors, canines, premolars, and molars are in each quadrant of the mouth (half of the top or bottom). We determine the number of each type of tooth an organism has by its dental formula.
With the four types of teeth labeled, you can determine that the dental formula is 2:1:2:3.Īs discussed before, primate taxa can vary in the numbers and forms of teeth they have. \): This drawing shows half of the human mandible.
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