Wednesday, July 9, 2014

Comparative Primate Blog


Lemurs are only found on the African island of Madagascar. The forest of Madagascar are often covered with epiphytes, mosses, and lichens. . Lemurs evolved to an arboreal lifestyle (living and feeding off of trees) when separated during early primate evolution. They don’t have a large amount competition for food. A lemurs diet consist typically of fruit, leaves, tree bark, and sap.  The dental formula for a Lemur is 2:1:3:3  Lemurs have 2- incisors,1- canines,3- premolars, and 3-molars in the upper and lower jaws of both the right and left sides, which totals 36 teeth. Since Lemurs have multiple teeth morphologies their dentition is considered to be heterodnet. Prosimians (a type of primate that include lemurs) have a tooth comb which is six teeth that are closely pushed together. Fruit eating Lemurs use their tooth-comb to pick out seeds from fruit. Leaf eating Lemurs have smaller tooth-combs then fruit eating Lemurs. 




Spider monkeys inhabit Central America, South America, and Mexico. All three regions have tropical environments. It is also home to the Amazon Rainforest. Spider Monkeys, like the Lemur, live an arboreal lifestyle. Spider monkeys stay near the tops of canopy trees. The trees serve as a defense from predators below. The spider monkeys diets consist mostly of fruit, bird eggs, insects, and seeds. Spider monkey teeth have evolved to adapt to their arboreal living;  for example, using their incisors to pick fruits off of trees.  The dental formula for a spider monkey is 2:1:3:3  They have 2 incisors, one canine, 3 pre molars, and 3 molars. Spider monkeys differ from Prosimians, in regard to their jaw and teeth. They have no hypoconulids(the distal, or fifth, cusp of a lower molar tooth)  on the first 2 lower molars. 






Baboons live mainly in Africa. Baboons generally prefer semiarid habitats, like savannas, but some live in tropical forests. The major requirements for any habitat seem to be water sources and safe sleeping places—either in tall trees or on cliff faces. Baboons eat fruits, grasses, roots, bark, and seeds. Baboons also eat rodents, birds and other meats. Since, baboons have such a varied diet, they are considered omnivorous. They have broad incisors, molars with high crowns, and low cusps. Baboons have powerful jaws, as well as long teeth. This trait helps to defend against predators, as well as compete for food. Baboons dental formula is 2:1:2:3. Baboons have 2 incisors, 1 canine, 2 premolars, and 3 molars. 









Southeast Asia is home to gibbons. The climate is warm, humid, and could be generally characterized as monsoonal. The trees of the region are tropical, and are abundant in fruit. Gibbons spend most of their time in trees and feed on fruit trees. They specifically enjoy eating figs, but also eat tree bark and leaves. Gibbon’s dental formula is 2:1:2:3, just as the baboons are. Gibbons have shortened jaws with long canine teeth. Their teeth also resemble that of great apes.










Chimpanzees inhabit both tropical forest and bordering savannas in Africa. The savannas have scattered trees with an arid climate. Chimpanzees are omnivores. While the vast bulk of the chimpanzee's diet is made up of plant foods including fruits, seeds, nuts, leaves and flowers, they will also eat insects and even larger animals that they have hunted and killed themselves. Chimpanzees have 32 teeth; 16 on upper jaw and 16 on bottom jaw. They use their molars to grind fruits and leaves. Their dental formula is 2.1.2.3, 2 incisors, 1 canine, 2 premolars, and 3 molars,  just as gibbons and baboons. 






Since they need to crush and grind leaves, animals that have a plant based diet, tend to have more molars which means a dental formula typically of 2:1:3:3.  Animals like the lemur and the spider monkey live in tropical rain forest and inhabit trees. Their plant based diet is abundant in their habitat which allows them to be less aggressive. However, animals that have a meat based diet, tend to be more aggressive because they must compete with other carnivorous animals.  Examples of these animals are chimpanzees, baboons and gibbons.  These animals also tend to have larger incisors and less molars which is typically a dental formula of  2:1:2:3. 

2 comments:

  1. Great post! I would have liked to know right at the beginning what traits you were comparing across the groups, but i figured it out eventually. This is all so informative. The visual graphics made it enjoyable to read along to. Well done!

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  2. Let me address your summary first.

    So far, you are the only student to try to figure out why New World Monkeys and prosimians have three premolars and Old World monkeys and apes have only two. Your argument makes sense based upon the primates we are comparing, but let me throw a wrench into it. Gorillas are completely folivourous. No meat eating whatsoever. Orangutans are also only vegetarians. So how to explain the loss of premolars?

    It is more likely that it has nothing to do with diet and everything to do with changing reliance upon the sense of smell. There is a trend toward greater reliance upon vision and less upon sense of smell in primates. As the nose because less important and the eyes gained importance, the nose reduced in size. The nose and the upper palate are directlye connected, so as the nose shrunk, the jaw shrunk as well. Hence the reduction in tooth number because there wasn't enough room for more.

    Back to the primates:

    Good discussion on the lemurs. Aside from the toothcomb, can you explain any unique tooth morphologies that help with their diet?

    Same issue: Can you connect the structure of the teeth with their diet? They have a very broad diet. How is that reflected in their teeth?

    Good catch noting that teeth in the baboon reflect more than diet, in terms of their defensive methods.

    Connections between tooth shape and gibbons' diet? You make this connection must better when you talk about how the back molars are used for grinding plant fibers and fruit. Chimps tend to have lower cusps (flatter) on their molars which is helpful for an organism that is predominantly a plant eater.

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