Exploring Primate Skeletal Anatomy: A Comprehensive Lab Guide

LA 8: Primate Skeletal Anatomy Introduction In this Lab Activity you will apply what you have learned about primate skeletal anatomy to classify a series of primate skulls into their respective groupings. Primate anatomical comparisons like the ones you will be making here help us to identify what we humans share with the rest of the natural world, as well as what makes us unique – key information for understanding our origins and evolutionary history. Instructions The lab is divided into several “stations,” each with a set of specimen images and corresponding questions for you to answer. Station 1 – The Primate Order Use the images of Crania A and B provided below to answer questions 1 – 3. Be sure to use the appropriate anatomical and directional terms in your responses. Cranium A Cranium B 1. Compare Cranium A and Cranium B above and describe at least three differences you observe between them. Be as specific as possible in your descriptions, using the appropriate anatomical terminology. Cranium B has a relatively short rostrum and a plate that seperates the orbits from the temporal fossa. It has a reduced snout and a narrow interorbital breadth. Post orbital closer is also present. Cranium A has a relatively longer rostrum with no plate. It also has a postorbital

bar fused with the temporal fossa, It has a prognathic snout while no postorbital plate is present. 2. Based on the observations you recorded for #1, what behavioral differences can you infer between Cranium A and Cranium B? (Hint: think back to LA 7: Functional Anatomy to help you) Cranium B seems to have carnassial teeth to eat meat, while it lookd like cranium A has bunodont teeth to take in a variety of food. 3. Classify Cranium A and B as either “Primate” or “Non-primate.” Be sure to support your answer with at least two observed cranial characteristics. Cranium B is from a primate because it has an external auditory meatus and it’s eyes sockets are facing forward. Cranium A is not from a primte because it looks like all of its teeth are carnassial and it has a small brain case relative to the size of its face. Station 2 – Primate Suborders Use the images of Crania C – E provided below to answer questions 4 – 6, using the appropriate anatomical terminology. Cranium C

Cranium D Cranium E 4. Fill in Table 1 to identify key skeletal characteristics for Crania C – E. You will use these data to help you determine which suborder (strepsirhini or halporhini) each primate cranium belongs to. Table 1 Craniu m Braincase size relative to face (Smaller, Larger, or Proportional) Orbits (Enclosed or Unenclosed) Rostrum (“snout”) length (Short or Long) Toothcomb (Present/Abse nt) C Smaller Unenclosed Long Present D Larger Enclosed Short Absent E Proportional Enclosed Short Absent 5. Using information from Table 1, identify the primate suborder for Cranium C, D, and E. Cranium C: Cranium D: Cranium E: Strepsirrhini haplorhini haplorhini

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6. Strepsirhines are the only primates to possess a toothcomb. What are some possible behavioral inferences that can be made from this characteristic? In other words, what might the toothcomb be used for? The toothcomb can be used for grooming and to ontain gums and resins from trees. Station 3 – Primate Infraorders Use the images of Crania F – H provided below to answer questions 7– 8, using the appropriate anatomical terminology. Cranium F Cranium G Cranium H

7. Fill in Table 2 to identify key skeletal characteristics for Crania F – H. You will use these data to help you determine which primate infraorder (tarsiiformes, platyrrhini, or catarrhini) each cranium belongs to. Table 2 Cranium Orbits larger than braincase? (Yes or No) External Auditory Meatus (Cartilaginous or Bony) Dental Formula F Yes [not visible in photo] 2:1:3:3 G No Cartilaginous 2:1:3:3 H No Bony 2:1:3:3 8. Using information from Table 2, identify the primate infraorders for Cranium F - H: Cranium F: tarsiformes Cranium G: platyrrhini Cranium H: catarrhini Station 4 – Primate Superfamilies Use the images of Crania I and J provided below to answer question 9, using the appropriate anatomical terminology. Cranium I

Cranium J 9. Determine the primate superfamily for Cranium I and J below and identify at least one observed characteristic for each to support your answer. Craniums I is a Cercopithecoidea because is has four cusps instead of five.Cranium J is a hominoid because the molars are more round than Cranoum I. 10. Which cranium (A – J) do you think is the most “human-like”? Identify at least three shared traits you observed to support your answer. Cranium JI is most human like because the brain case is larger than the face and it has a different dental formula. Image Attribution Phil Myers on animaldiversity.org , licensed under CC BY NC SA 3.0

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