Lemurs are primates that belong to the Order Primates and Suborder Strepsirhini. They live only on the island of Madagascar and adjacent islands off the east coast of Africa. They are called arboreal, which means that they live in trees, but they do come down to the floor once in a while. Because they are very adaptable to their environment, they live everywhere, including the rainforests and hot/dry areas..jpg)
Lemurs have a unique derived trait called a "dental comb" formed by forward projecting lower incisors and canines. As heterodents, their dental formula is 
, which means that they have 2 incisors, 1 canine, 3 premolars, and 3 molars. Their bottom incisors and canine teeth provides grooming and feeding for the organism. They groom with their teeth to get rid of debris in their furs and excess hair. Because Lemurs live in an environment with trees, most of them are herbivores and they have developed projecting lower incisors and canines to be able to open seeds and eat other plants. Although most Lemurs are herbivores, some are omnivores that eat insects, eggs, and lizards. Because of their omnivores feeding, their premolars have become sharp to assist them in eating insects.
2. Spider Monkey
Spider Monkeys are part of the group called the New World Monkeys, and are one of the three major informal groups of the biological Order Primates. They live in the rainforests of Central and South America in the highest part of the rainforest canopies. Like the Lemurs, Spider Monkeys are arboreal, which means that they live in the trees.
New World Monkeys have the dental formula of , which means that they have 2 incisors, 1 canine, 3 premolars, and 3 molars. As they live in the trees, they are naturally safe from land predators. Because they are arboreal, they eat plants, seeds, insects, and lizards. But it is interesting to see them not eating small prey despite their sharp canine teeth. I assume this is because they do not want to hunt for small preys on the ground due to the possible dangers of predators.
3. Baboon
Baboons belong to the group of Old World Monkeys, also known as the Family Cercopithecidae. They reside on the main continent of Africa. Unlike their tree-dwelling counterparts, this organism is highly adaptable and can live in a variety setting. Because of their diverse habitat, their diet may differ from eating plants and seeds to small quantities of meat, such as antelope and fish.
Baboons have the dental formula is 
, consisting of 2 incisors, 1 canine, 2 premolars, and 3 molars. Unlike the past two organisms analyzed, Baboons differ by having only 2 premolars. Although I was unable to find enough resources to explain this, I am guessing this is because their jaws are not big enough to carry the third premolar. Humans have the same problem, as many take out their third premolar, commonly known as the "wisdom tooth," to prevent their jaws from being deformed and disoriented. I believe they have sharper teeth built for eating meat because it may be hard to find plants and seeds on a dessert of Africa.
4. Gibbon
Gibbons are known as the Lesser Ape, and belong to the Family Hylobatidae. They are currently considered endangered and inhabit the subtropical rainforests. They are arboreal, meaning that they live on the trees and diets have been fit to match their habitat.
This organism has the dental formula of , same as the Baboon. With 2 incisors, 1 canine, 2 premolars, and 3 molars, they eat mostly fruits. The environment is able to provide abundance of fruits for the Gibbons, and because of this, Gibbons are mostly herbivores. Like the Baboons, I believe that they do not have the third premolar because of the orientation and the size of the jaw.
5. Chimpanzee
Unlike the Gibbons, Chimpanzees are known as the Great ape, and belong to the Family Hominidae. While Lesser Apes are relatively small in size and weight, Great Apes are big and heavy. They are native to Africa including Guinea to Western Uganda and Tanzania. They also inhabit rainforests and grassy lands of the Savannah.
Chimpanzees have the dental formula that is the same with Gibbons and Baboons. Having a very sharp canine teeth, they are able to prey on creatures like birds and occasionally, on other monkeys. With the molars and premolars, they are able to eat ripe fruit and small insects. Their dental orientation and size are the closest to human, and because of this, they have a wide variety of diet.
Conclusion: Looking at five different categories of Primates, I was able to see the effects of the environment on to the organisms. These organisms develop distinct dental formulas for better chance of survival in their habitat. Herbivores such as Lemurs and Spider Monkeys will have one more premolar to aid them on eating plants, seeds, and insects. Omnivores such as Baboons, Gibbons, and Chimpanzees lose one premolar because they have very sharp canine teeth to prey on small organisms. Because they do not eat on seeds and little insects as much as the first two organism, they do not have an extra premolar. If the organism lives on the trees, most of them will be eating plants and insects while others will add on meat to their diet. It will be interesting to see additional effects of the environment other than the differences in the dental orientation of the organisms.
I apologize for the disfigured picture of the Dental Formula. Lemurs and Spider Monkeys have the formula of 2,1,3,3 while the other three have the formula of 2,1,2,3.
ReplyDeleteNo problem on the dental formula. That doesn't transfer well into Google.
ReplyDeleteYou do a very good job attempting to be complete in your dental description and drawing those connections with environmental factors, which includes not only food but also issues of defense.
Just a couple of points:
You speculate on the canines in spider monkeys being for defense purposes but then don't raise this issue in baboons, who have much larger (and sexually dimorphic) canines.
With regard to the drop from three premolars to two:
"I am guessing this is because their jaws are not big enough to carry the third premolar. "
Exactly! Good insight. But in the case of the human "wisdom" teeth, that is the loss of a molar, not a pre-molar, but the cause is the same, the reduction in jaw size which reduces the number of teeth the jaw can hold. What caused the jaw to shrink in size?
Can you make clearer connections between gibbon and chimpanzee tooth morphology and their diet? You did this better with earlier primates but leave out some of this information here.
In your summary, you change your possible explanation of the loss of pre-molars. It isn't diet related, it is related to jaw-reduction size. Including the issue of tooth shape (morphology) with regard to molar cusps and its relationship to diet would have been helpful.
Great post! I obtained a lot of information that I did not know before about these primates.
ReplyDeleteI think the formulas were an interesting addition to your blog post--it seems that Google isn't too interested in that though!
I'm slightly puzzled, however. I never knew that Spider Monkeys could use their teeth as a defense mechanism, but at the same time I know that they do not have the largest canines among primates. Do other primates also use their teeth in protective ways? Maybe a little elaboration on that part would have answered some unanswered questions.
For my post I wrote about diet, which is definitely related to how teeth have evolved to handle various foods. One thing I find incredibly interesting is the retention of large, sharp canines in species that are primarily fruit and plant eaters. Even baboons, who have more of a utilitarian reason for those huge teeth, are mostly grass eaters in spite of the disproportionate number of photos on the internet of them tearing up baby gazelles. They ARE definitely intimidating though.
ReplyDeleteThank you for the feedback everyone! I really appreciate it.
ReplyDeleteProfessor Rodriguez, I really can't think about the reason for a small jaw of certain primates. Would you like to explain? I am very curious about it.
Josh, it does seem like Google didn't like my images of the dental formula... Why would they do this to me? Anyway, thank you for pointing out the canine teeth in primates. I am sure the primates I have analyzed above could all use their canine teeth as a defense mechanism because it could cause unwanted injuries to the predator. I apologize of the confusion.
Kathryn, I do agree with you, and I was amused at the exact same thing. While looking for pictures to show the dental structure of the primates, I have noticed that most of them have very intimidating canine teeth. Despite the size and sharpness of them, most of them were omnivores that tend to prefer eating plants instead of meat.