Assignment: Platyrrhini And Catarrhini

Assignment: Platyrrhini And Catarrhini

Station 1: What defines a primate? (0.6 pt.)

A college happened upon a mystery skull while looking through a mammalian skeletal collection. She thinks it may be a primate and comes to you for your expert opinion. She cannot mail you the skull so she emails youaeveral photos. Examine the photos below. Use the list of primate features (found in the lab reading for this week) to help you make the distinctions. Assignment: Platyrrhini And Catarrhini

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Station 2: Dentition (2 pts.) Different primate clades can be identified by their dental formulae. Primates have 2 incisors, and 2-3 premolars (except the aye-aye, which has a very unusual dentition). Most other mammals have either more or fewer teeth. For the following questions, first determine the dental formula, then consider the cusp pattern.

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1. Write the dental formula for each of the craniums or mandibles provided:

A)

B)

C)

D)

E)

2. Answer the following questions using the above dental formulae and the written/illustrated materials provided:

a) Which specimen is not a primate? How do you know?

b) Which specimen is a New World monkey? How do you know?

c) Does specimen “E” have the bilophodont or Y-5 molar cusp pattern? Based on this cusp morphology and its dental formula, what primate group does this specimen belong to?

d) Which mandible is human? What traits did you use to make your identification?

e) Which specimens are apes? How do you know? (Hint: you are an ape)

Station 3: Strepsirrhini and Haplorhini (2 pts.)

Using the handouts, images, and websites, complete the following table illustrating some of the important morphological differences between each primate group.

Strepsirrhine: http://eskeletons.org/boneviewer/nid/12540/region/skull/bone/cranium  http://humanorigins.si.edu/evidence/3d-collection/primate/loris-malaysia-usnm-84389  http://humanorigins.si.edu/evidence/3d-collection/primate/loris-malaysia-usnm-84389-0  Haplorrhine: http://eskeletons.org/boneviewer/nid/12538/region/skull/bone/cranium

http://humanorigins.si.edu/evidence/3d-collection/primate/gorilla-rwanda-usnm-396937-beringeicranium

with primitive primates in a grade called “Prosimia.” They are now grouped with monkeys and apes in a

Examine the tarsier skull (http://www.eskeletons.org/boneviewer/nid/12544/region/skull/bone/cranium) and study the table. Tarsiers can be placed in the prosimian grade or in the haplorhine clade. Name one primitive, prosimian feature that tarsiers retain and one derived, haplorhine feature that they possess. Add which of these features is a synapomorphy, and which is a symplesiomorphy.

Prosimian feature:         Haplorhine feature:

2) Does the mystery skull at this station belong to a strepsirrhine or a haplorhine primate? List at least one trait which helped you determine this.

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Station 4: Platyrrhini and Catarrhini (1.6 pts.)

The Haplorhine suborder is divided into two infraorders: Anthropoidea (Monkeys and Apes) and Tarsiiformes (tarsiers). Anthropoidea is further divided into two parvorders: Platyrrhini and Catarrhini. Platyrrhines are native to Central and South America (the ‘New World’) and Catarrhines are native to Africa, Europe, and Asia (the ‘Old World’).

Platyrrhine: http://eskeletons.org/boneviewer/nid/12546/region/skull/bone/cranium  Catarrhine: http://eskeletons.org/boneviewer/nid/12547/region/skull/bone/cranium   http://humanorigins.si.edu/evidence/3d-collection/primate/baboon-usnm-258502 http://humanorigins.si.edu/evidence/3d-collection/primate/baboon-usnm-258502-0

1) Based on what you’ve learned so far, identify what group the following “mystery primate” skulls belong to. To receive credit, list the character(s) you used to make your identification.

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A) Is “A” a platyrrhine or catarrhine? How do you know?

B) Is “B” a platyrrhine or catarrhine? How do you know?

2) What advantages might there be to having a prehensile tail for an arboreal primate?

Station 5: Cercopithecoidea and Hominoidea (1.8 pts.)

Within Catarrhini are the two superfamilies Cercopithecoidea (Old World monkeys) and Hominoidea (apes). Use the table below to describe the features of each in relation to the other.

Cercopithecoid: http://eskeletons.org/boneviewer/nid/12547/region/skull/bone/cranium  http://humanorigins.si.edu/evidence/3d-collection/primate/baboon-usnm-258502 http://humanorigins.si.edu/evidence/3d-collection/primate/baboon-usnm-258502-0 Hominoid: http://eskeletons.org/boneviewer/nid/12549/region/skull/bone/cranium

http://humanorigins.si.edu/evidence/3d-collection/primate/siamang-indonesia-usnm-114497

1) Which two traits in the above table would be the most useful for determining if an animal was a cercopithecoid or a hominoid in the fossil record? Hint: think about discrete (traits which are either present or absent) vs. continuous traits.

2) List one human autapomorphy – a trait that humans have to the exclusion of all the other primates. Hint:

think about what makes humans unique within the order Primates.

Exercise 2: Systematics and Primate Phylogeny (2 pts.)

Below is a hypothetical phylogeny for six different taxa (A–F). In the phylogeny, the appearance of a new character is represented as a number in a circle. For instance, Character 3 evolved sometime after the common ancestor of Taxa D, E, and F diverged from the common ancestor these taxa share with Taxon C. Character 3 would therefore be a shared, derived trait, or synapomorphy of taxa D, E, and F.

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A) Which character is a synapomorphy of E and F?

B) Is Character 1 a synapomorphy or a symplesiomorphy for taxa C and D?

C) Is Character 1 useful for reconstructing the relationship between C and D? Why or why not?

D) Of the 5 characters listed, which represents an autapomorphy?

Study the primate phylogeny in your textbook and fill in the blanks below. Be mindful of spelling: some names are very similar, but have different meanings!  If you are having difficulty filling out the phylogeny, you may print out the last page, neatly handwrite the answers in the blanks, and paste a picture of the phylogeny back into the document.