8.6: Extant and Fossil Catarrhine Morphology (Worksheet)
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8.6: Extant and Fossil Catarrhine Morphology (Worksheet)
Opening the book…
Name: ______________________________
Section: _____________________________
Student ID#:__________________________
Section 1: Cercopithecoid vs Hominoid
Compare the crania of two catarrhine primates, Papio and Pan. List at least one difference you see in the:
shape and position of the orbits
nasal aperture and rostrum
neurocranium
Papio (Baboon)
Pan (Chimpanzee)
Other than body size, can you think of some other reasons why crania of these primates might look so different from each other?
Now compare the molars of Papio and Pan:
How many cusps do they each have on the upper M2 (second molar)?
Do you notice any differences in the shape of the teeth? What about their sizes?
What molar cusp pattern does each primate have?
What might be the function of these molar cusp patterns?
Papio (Baboon)
Pan (Chimpanzee)
Papio has very large canines, what purpose do you think this serves? What are the advantages and disadvantages of such big teeth?
Do you think the trait of large canines may have been the same throughout the evolutionary history of cercopithecoids?
How would you determine whether large canine size is a trait seen throughout the evolutionary history of cercopithecoids or if it is a recent development?
Section 2: Sexual Dimorphism: How Does Sex Influence Shape?
Examine the two crania of Papio: the larger is a male and the smaller is a female. Describe any other differences in their features that you see.
Male Papio (Baboon)
Female Papio (Baboon)
If you found two fossils with the features you identified in above for the male and female crania of Papio, would you think they were from the same genus? Would you assign them to the same species? What evidence would you use to support your classification of the fossils?
Section 3: How Do You Define an Ancestor?
Based on some of the features you have examined, what do you think the ancestor of Papio looked like? Which features of the cranium might look the same as the modern species? Which features might look different?
What do you think the common ancestor of Papio and Pan looked like? Are there any features that Papio and Pan have in common today that you think their ancestor might have shared? Might any features be absent?
Section 4: Putting Your Hypotheses to the Test: Fossil Evidence
Examine the hypothesized ancestor of cercopithecoids like Papio, Victoriapithecus (~19-12.5 MYA), from the early middle Miocene of East Africa. Did you identify any of the ancestral traits present in this specimen in your hypotheses from Section 3 for the ancestor of Papio? Which ones?
Do you think this fossil is likely to be the ancestor of Papio? Why or why not?
Now, look at the hypothesized ancestor for both Papio and Pan, Aegyptopithecus (~30-29 MYA), from the early Oligocene of Egypt. Did you identify any of the ancestral traits present in this specimen in your hypotheses from Section 3 for the common ancestor of Papio and Pan? Which ones?
Make the case for or against Aegyptopithecus as the ancestor for both catarrhines Papio and Pan. Use at least four shared traits to support your argument for Aegyptopithecus being an ancestor of Papio and Pan, OR use at least four independent traits to support your argument against Aegyptopithecus being an ancestor of Papio and Pan.
Figures and Lab Material
Anterior (forward-facing) and lateral (side) views of the skulls of: A - a female chimpanzee (Pan troglodytes) and B - a male chacma baboon (Papio ursinus). Comparative catarrhine morphology, a derived work by Zana Sims and Stephanie Canington is under a CC BY-NC 4.0 License. [Includes (A) Pan troglodytes [background removed] by Klaus Rassinger and Gerhard Cammerer, CC BY-SA 3.0. https://commons.wikimedia.org/wiki/File:Pan_troglodytes_01_MWNH_230.jpg; (B) Papio ursinus [background removed] by Klaus Rassinger and Gerhard Cammerer, CC BY-SA 3.0. https://commons.wikimedia.org/wiki/File:Papio_ursinus_02_MWNH_715b.jpg].Papio anubis (Olive baboon) adult male (left) and female (right) museum skull casts in A - anterior and B - oblique lateral views. Papio anubis sexual dimorphism, a derived work by Zana Sims and Stephanie Canington is under a CC BY-NC 4.0 License. [Includes Papio anubis male and female skull in (A) anterior view [contrast enhanced] by Emőke Dénes, CC BY-SA 4.0. https://commons.wikimedia.org/wiki/File:Papio_anubis_skulls.jpg; (B) oblique lateral view [contrast enhanced] by Emőke Dénes, CC BY-SA 4.0. https://commons.wikimedia.org/wiki/File:Papio_anubis_skulls_2.jpg].
To identify morphological features of the upper second molars (M2) of chimpanzees and baboons, we recommend that you access the following specimens on MorphoSource, an NSF-funded 3D scan data share website.
If it has loaded but the image does not appear on the screen, click out of the current tab you are working in (e.g., open a new tab) and then click back to MorphoSource. Sometimes, this allows the site to “refresh.”
When you see the specimen, note that the base of the tooth is empty and the visible features are on the occlusal surface.
You can zoom in on the 3D image for a better look at the features.
You can also rotate the specimen in any direction.
We recommend, if possible, that you open the baboon specimen in one tab and the chimpanzee in another tab. That way, you can move back-and-forth between the teeth to more easily note features.
