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Four major characteristics shared by all organisms in Platyrrhine are long-sharp nails, wide nostrils, move by climbing, and they have long tails.

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Major Characteristics of Marmoset Monkeys

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Major Characteristics of Marmoset Monkeys

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Marmoset monkeys live in a rain forest habitat. They are found in the Amazon River Basin and in rain forests all over Brazil. Physical characteristics of marmoset monkeys are black and grey fur with black fur over head and neck, white ear tufts in adults and juveniles, and the tail has alternating white wide dark bands and pale narrow bands. Their behavioral characteristics are that they are highly social, found in small groups, and older offspring help to rear new born offspring off of the mother.

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Major Characteristics of Spider Monkeys 

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Major Characteristics of Spider Monkeys 

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Spider monkeys live in evergreen forests, and mangrove forests. They are found in eastern South Africa, north of the Amazon River. Physical characteristics of spider monkeys include slender body and limbs, long-narrow head, nostrils are far apart, and thumbs are not opposable. Behaviorally, spider monkeys are sociable, live in groups of 30, wander independently, a female is always with her offspring, and they use trees for sleeping.

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Howler monkeys live in tropical areas. They can be found throughout jungles in South America. Physically, howler monkeys are the loudest of all monkeys, have a strong tail, and a big lower jaw. Behavioral characteristics of these monkeys include calling out from ten miles away, using their tails to move from branches, and live in groups of 10-15.

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Common Name - Marmoset Monkey

Kingdom - Animalia

Phylum - Chordata

Class - Mammalia

Order - Primates

Family - Callitrichidae

Genus - Callithrix

Species - Callithrix jacchus

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Common Name - Howler Monkey

Kingdom - Animalia

Phylum - Chordata

Class - Mammalia

Order - Primates

Family - Atelidae

Genus - Alouatta

Species - Alouatta arctoidea

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Common Name - Spider Monkey

Kingdom - Animalia

Phylum - Chordata

Class - Mammalia

Order - Primates

Family - Atelidae

Genus - Ateles

Species - Ateles fusciceps

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56 mya

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48 mya

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30 mya

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18 mya

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8 mya

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The five fossils are evidence for evolution in new world monkeys. The body shape and the skull size/shape has changed over time. The Plesiadapis fossil shows how this primate's limbs are shorter. Whereas the Notharctus and Pronconsul shows that the limbs are longer. This can be due to the fact that these monkeys had to jump or climb more and needed longer, more muscular legs to do so. In the Aegyptopithecus and Sivapithecus fossils, the skulls are shown. In the Aegyptopithecus, the skull protrudes out further. Whereas the Sivapithecus shows a skull that does not protrude as far.

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Anatomy and Physiology of New World Monkeys

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Anatomy and Physiology of New World Monkeys

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New World Monkeys all have a tail. Although the tails are different sizes and have a different shape to them, they all all used for the same thing. New World Monkeys use their tail to grasp onto trees and move around in the trees. Also, New World Monkeys all have long-lanky arms, but the arms are different sizes depending on the monkey.The long arms are also for moving swiftly from branch to branch. The tail and arms are an example of a analogous structure. They have the same function, but a different structure. This shows that the monkeys faced similar environmental pressures.

A homologous structure of the monkeys would be their skull shape. The species have a big forehead, flat naval cavities, two eye sockets. All the New World Monkeys share these characteristics in their skull shape. This shows that the monkeys have evolved from a common ancestor.

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New World Monkeys evolved from Old World Monkeys 37 mya. The New World Monkeys have evolved a new set of functional genes : DRB11 and DRB*W12. The DRB*W13, *W14, *W15, *W17, *W18, and W*19 only belong to the Cebidae family, which includes Capuchin Monkeys and Squirrel Monkeys. But DRB*W16 has only been documented in the Callitrichidae family, which includes Marmoset Monkeys. This evidence shows that the New World Monkeys have similar DNA, with slight differences.

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These karyotypes compare different types of Marmoset monkeys.

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This karyotype is showing a translocation, but it also shows that the Howler Monkey should have 50 chromosomes.

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The number of chromosomes can range from 16 in a titi monkey and 62 in a woolly monkey. Marmoset monkeys and howler monkeys have differences and similarities in chromosomes. The howler monkey has between 48 and 50 chromosomes. The Marmoset monkey has 42 to 44 chromosomes. The karyotype also shows that there are 2 sex chromosomes. The difference in the number of chromosomes show that the species are different. But, the similarity of the number of sex chromosomes show that they are similar. So, these monkeys are pretty closely related.

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The type of speciation that is at work in New World Monkeys is gradual equilibrium. The evolution of New World Monkeys occured over a long period of time. These monkeys had a long evolution time.

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The type of evolution that is at work in New World Monkeys is divergent evolution. Divergent evolution occurs when two or more related species evolve from a common ancestor. First, Old World Monkeys and New World Monkeys evolved from the same ancestor. So, Old World Monkeys and New World Monkeys diverged. But, New World Monkeys also diverged between themselves into the 150 species.

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Geographic isolation is at play between New World Monkeys. New World Monkeys are located in Central and South America and Mexico. Old World Monkeys are located in tropical Africa and Asia. This separation of the two types of monkeys has resulted in an inability to exchange genetic material. Which makes New World Monkeys different.

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Microevolution is at work in New World Monkeys between howler monkeys. It was studied that howler monkeys with small molars have decreased fitness than those with large molars. This shows selection on molar size. These results provide support for the assumption that molar size is under natural selection.

Another example of microevolution is found in spider monkeys. Spider monkeys do not have thumbs because they move around trees with their tails and their long limbs help them pick fruit. Because the spider monkeys do not need thumbs, they have evolved to not have them.

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Darwin's theory of descent with modification is at shown in New World Monkeys. Descent with Modification simplify means passing traits from parent to offspring. Traits from different monkeys were passed down to their offspring. For example, spider monkeys do not have thumbs. So, the spider monkeys will pass that trait down to their offspring. Also, howler monkeys with large molars have the best fitness and therefore survive and pass their traits down to their offspring.

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Another one of Darwin's theories of evolution includes natural selection. Natural selection is how descent with modification occurs. New World Monkeys demonstrate directional selection. Directional selection occurs when an extreme phenotype is favored, causing allele frequency to shift overtime. In the case of howler monkeys, a howler monkey will either have small or large molars (which are two extremes of a trait). This separates these two traits into two distinct groups and the monkeys with the larger molars will be more likely to survive. The same goes for the spider monkeys without a thumb. Directional section is most shown throughout the new world monkeys.

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This phylogenetic tree shows the how related different species are.

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https://www.ncbi.nlm.nih.gov/pubmed/8505064

http://www.charlotteobserver.com/news/science-technology/article9097880.html

https://www.ncbi.nlm.nih.gov/pubmed/12952624

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185867

https://www.nature.com/scitable/knowledge/library/macroevolution-examples-from-the-primate-world-96679683

http://www-personal.umich.edu/~phyl/anthro/platy.html

http://www.wildernessclassroom.com/wilderness-library/spider-monkey/

https://animalsake.com/characteristics-of-new-world-monkeys