The lemur is a primitive primate that can be found
in Madagascar. The term Lemur not only applies to the typical lemurs but also
to the avahis, sifakas, indri, and aye-aye of Madagascar. The island country of
Madagascar is located on the southeastern coast of Africa. The island consist
of three parallel longitudinal zones-the central plateau, the coastal strip on
the east side, and the low plateaus and plains in the west. The steep eastern
plateau has numerous short, torrential rivers which discharge either into the
coastal lagoons or directly into the sea over waterfalls or rapids. The western
side of the plateau is crossed by longer and larger rivers, which bring large
deposits of fertile alluvium down into the plains. The island at one point was
covered with evergreen and deciduous forest, but now only little remains except
on the eastern escarpment and in some areas in the west. The forest was cut in
order to clear for rice fields, to obtain building materials, and to export
valuables such as ebony, rosewood, and sandalwood. A small part of the island
is covered with prairie grasses and bamboo or small thin trees. The south part
of the island is arid and grows thorn trees, giant cacti, dwarf baobab trees,
succulents and other drought-resistant plants. Due to the island's isolation
many primitive primates have survived and evolved into unique forms. It's been
estimated that about 40 species of lemurs live on Madagascar.
The lemur has a unique trait called a "dental
comb", which is formed by forward projecting lower incisors and canines.
The modified teeth are used by the lemurs for grooming similar to a hair comb
and feeding. The structure of the jaw has evolved independently in different
types of mammals through convergent evolution. In most mammals the toothcombs
include incisors only, but in lemuriform primates the jaw includes incisors and
canine teeth that tilt forward by a canine-shaped first premolar. The toothcomb
can also be used for food procurement and bark gouging. Due to the islands many
plants, trees and shrubs, the lemurs jaw has adapted to the surrounding
environment. The lemur has a wide variety of foods such as leaves, fruits,
buds, bark and shoots. Lemurs are also known to eat insects and even small
animals when fruits are not in season, and when conditions are really harsh lemur's
hibernate which helps contributes to their survival. The lemur has a dental
formula of 2.1.3.3, and has reduced
incisors and tooth comb when compared to the spider monkey.
The spider monkey is a smaller primate that can be
found in the forest areas of southern Mexico through central and South America
to brazil. The habitat of the spider monkey consist of tropical rainforests,
evergreen, semi deciduous and mangrove forest. The current forest where the spider
monkey's are located is in danger due to the removal of the forest to make way
for new farm land. The spider monkeys are well adapted to the high treetops as
they are strong and agile. The spider monkey has a wide variety of foods, such
as nuts, fruits, leaves, bird eggs, spiders and other insects. The spider
monkey or new world monkey, has a dental formula of 2.1.3.3 (two incisors, one
canine, three premolars, and three molars). The maxilla and mandible of the
monkey are equally the same, and the assortment of teeth allows the primates to
have a diverse diet. The incisors teeth of the monkey help with cutting into
food, and the canines are stabbing teeth that can be used as a weapon. The
premolars and molars are mainly used for shearing and crushing food. The spider
monkey has a unique dental formula which has evolved due to the environment the
primate lives in. The diet of the spider monkey has also contributed to the
evolution of the primates teeth, which is due to the lack of dietary
specialization and reflects the shape and size of the primates teeth. This type
of dentition was created from the varied diet of the primate, and has
contributed to their overall success during the last 50 million years.
The next primate is the baboon also known as the Old
World Monkey. There are 5 different species of baboons and each hierarchical
troop of baboons can have up to 300 members. Baboons can be found in the
savanna and semiarid environments in Africa to Arabia. Very few baboons can be
found in tropical forests. They have also been spotted in some open country
parts of Africa in the Sahara southward, and in southern Africa south of the
Zambezi River. These locations consist of a desert environment which is common
throughout the Sahara. The Sahara is bordered by the Atlantic Ocean, Atlas
Mountains, Red Sea and Mediterranean Sea. The baboon eats a variety of plants
and animals which includes grass and grass seed, fruits, pods, roots, and
tubers. They are also known to eat rodents, birds, gazelle fawns, and in some
parts of South Africa they kill lambs and are known as crop raiders. The
dentition formula for a baboon is 2.1.2.3, which is acquired from the primate
having a slightly different diet compared to New World Monkeys. The dental
pattern and formation of the jaw are similar to humans with some key changes.
The difference between humans and baboons is the more elongate arch form,
prominent maxillary canine crowns, and the second and third molar crowns are
greater size compared to the first molar crowns. The baboon males have powerful
jaws with longer canine teeth, which can be effective weapons in defense
against predators and competition with other males. This type of trait was
acquired from the environment the baboon lives in. Due to the primate's diet
which consist of eating other animals as compared to the New World Monkeys,
they have developed the longer canines which help killing the varied animals in
their diet. Since the monkey competes with other primates for the same
desirable foods this leads to the
killing of other monkeys, young chimpanzees and even flamingos. Therefore, the
dentition formula has evolved into a 2.1.2.3 pattern due the varied diet of the
baboon.
The lesser ape also known as a gibbon, is a smaller
ape that is found in the tropical forests of Southeast Asia. The environment
where the gibbon can be found is generally composed of broad-leaved trees and
wet tropical uplands and lowlands. The rainforests are vegetation type
dominated by broad-leaved trees which form dense upper canopies and consist of
a diverse vegetation. The gibbons are omnivores, and their diet includes fruit,
leaves, flowers, seeds, tree bark, and tender plant shoots. They are also known
to eat insects, spiders, bird eggs, and small birds. The gibbon has a skull
that closely resembles the great ape. Their teeth also are similar to the great
ape, which consist a U-shaped dental arcade and a thin and light mandible. The
incisors are broad and flat, while the molars have low, rounded cusps with
thick enamel. They also have large, dagger-like canines in both upper and lower
jaw. The dentition formula for the gibbons is 2.1.2.3. The trait of the gibbons
dentition formula has adapted to its frugivorous environment.
The Chimpanzee is a species of apes that is most
closely related to humans. Chimpanzees can be found in tropical forests and
savannas of Africa from The Gambia to Lake Albert, Lake Victoria and Northwestern
Tanzania in the east. The tropical forest has a diverse array of vegetation,
and broad-leaved trees that form a dense upper canopy. The savanna has
vegetation that grows under hot seasonally dry climatic conditions, and has
open tree canopies. The chimpanzee consumes many types of fruits, leaves, figs,
nuts, flowers, insects and large animals they hunt and kill. Occasionally male
and female chimpanzee's take part in group hunting to kill small mammals like
bushpigs and antelope. The jaw of a chimpanzee is heavy and protruding, and the
canine teeth are large. Male chimpanzees have larger canines compared to
females, and use these in battle with other males during predation. The
dentition of the chimpanzee is similar to humans except for the larger canines.
The dentition formula for chimpanzees is 2.1.2.3/2.1.2.3 which equals 32 teeth.
This trait for the chimpanzee dentition formula has been acquired due to their
environment and their varied diet.
Due to the information I have collected it seems
that primate dentition is influenced based on the environment they are
presented with and their diet. The five groups of primates all have very
similar diets, and this could cause competition for food with other species.
The overall lack of dietary specialization in primates is reflected and
expressed in the size and shape of the teeth, because shape and size are
directly related to diet. Most of the primates have premolars and molars with
low, rounded cusps which allows them to process most types of food. The primates
have developed a dentition that has adapted to a varied diet and has
contributed to their overall success for millions of years.
Sources:
www.Lemurworld.com. BioExpedition Publishing, Web. 15 Sept. 2014
Colin Peter Groves. www.Britannica.com. Web. 16 Sept. 2014
Matthew Tschoegl. learni.st. Web. 15 Sept. 2014
www.angrydmonkey.com. Web. 15 Sept. 2014
Dr. Dennis O'Neil. anthro.palomar.edu. 1998-2014. Web. 16 Sept. 2014
Very detailed post! I'd have to agree with your conclusion that primates teeth have adapted to their environments. I always wonder if our teeth were once more like the chimpanzees or if they were more equipped for eating vegetarian. With all the health information and news emerging in the media lately, I can't help but wonder if our teeth adapted to eating meat originally or if they have adapted to eating meat. Some people protest that meat isn't good for our digestion and I'm curious to know if we adapted to eating meat because other options were scarce or if we were always equipped to eat meat, but modern processing of meat is what we are not supposed to consume.
ReplyDeleteExcellent description of the Lemur's environment, and I like how you touched upon the deforestation that can very much so contribute to the extinction of Lemurs. Also I didn't know that baboons could have troops that numbered in the hundreds. I also like that you brought up the comparison between canines of the male and female species of chimpanzees. I agree too that the environment and diets of all the listed primates has influenced their dentition patterns.
ReplyDeleteVery good discussion throughout of the environment of each primate. Well done.
ReplyDeleteGood connections made between the dental traits of the lemurs and spider monkeys and their environment, primarily of their diet. The shape of the teeth, their cusps, sheering complexes, flat surfaces will all reflect what these primates tend to eat.
Baboons are a little more difficult because the canine sometimes misleads people, but you did a good job of explaining the non-dietary function of that tooth. But one of the keys to understanding baboon dentition is recognizing just how broad their diet is... it is called "opportunistic", meaning that the eat what they can get and their dentition is generalized to support that important dietary adaptation.
The loss of the bicuspid tooth in old world monkeys and apes actually has nothing to do with diet. Think about what the jaw is attached to, the upper jaw in particular, and consider how the primate senses and evolved and changed to see if you can figure out why we have not only lost our third bicuspids but also our third molars (that wisdom tooth that can cause so much trouble).
Good description and connections made for the gibbon dentition.
Yes, the varied diet of the chimpanzees, much like that of the baboon, have led to the general pattern of dentition to allow for that wide range of food. Very similar to our own general dentition, actually.
Good post.
Graycee beat me to it, very detailed post! I really enjoyed reading it because I could visualize each primates environment. I also loved your pictures because it gave me visual proof of each similarity and each difference in all of the primates. I touched briefly on the environment in my post on the locomotor patterns but reading your post gave me a better sense of the way they live and survive which was awesome. Very well written and informative!
ReplyDelete