Modified from labs by Henry M. McHenry, University of California, Davis
Time needed: 50-60 minutes
Supplies Needed
Primate and non-primate skeletons and skulls. These can be real, casts, or images. A list is provided below.
Labels for the skeletons and skulls (e.g., Primate or Strepsirrhine)
Resources for students to look up specific examples of Platyrrhines (e.g., Rowe. 1996. The Pictorial Guide to Living Primates)
Student worksheet (attached)
Readings
Etting, Stephanie. 2019. Chapter 5: Meet the Living Primates. Explorations.
Introduction
People belong to the zoological orderPrimates, which is one of the many orders within the class Mammalia. This lab gives students the opportunity to observe characteristics of the skeleton that differentiates primates from other mammals and compare primates to one another.
Before beginning, students should consider the following conceptual questions: What can bones tell us about the animal to which they belonged? Specifically, what might the skeleton tell us about:
what the animal ate?
its mode of locomotion?
the environment it lived in?
its behavior?
Bones can reflect the lifestyle of primates, and the characteristics they share are likely reflective of early primate ancestors. For example, most primates move about in trees by grasping with their feet and hands. Primatologists believe the common ancestor of all living primates was an arborealclimber with prehensileextremities who relied on vision more than olfaction (smell). This ancestor may have had some depth perception, made possible by the overlapping visual fields of forward-facing eyes, and hands with the ability to manipulate objects. Thus, physical traits that help us distinguish primates from other mammals include:
a generalized skeletal structure for arboreal life;
convergent eyes (forward facing);
eye orbits with a postorbital bar or plate;
reduced snout length (related to less reliance on smell);
opposablethumbs and big toes;
flattened nails instead of, or in addition to, claws;
a larger brain size;
differences in tooth morphology (reflects variable diets);
and prehensile (grasping) hands and feet.
Steps
Before beginning this lab, the instructor should select skeletal materials, casts, or images of skeletal materials for students, and arrange them at various stations. All skeletal materials should be labeled with cards/small labels with terms that match the student worksheets (e.g., Primate, Strepsirrhine). Alternatively, virtual images can be
linked to the student worksheet to create a virtual lab. Materials include non-primate, nonhuman primate, and primate skulls and articulated skeletons. Specifically:
Station 1: (a) primate (e.g., monkey) articulated skeleton, and (b) non-primate (e.g., cat or dog) articulated skeleton. Preservation should be good enough to see nails/claws.
Station 2: (a) non-primate (cow or pig) skull with teeth, (b) dog skull with teeth, (c) monkey skull with teeth, and (d) human skull with teeth. Be sure that the surfaces of the teeth are visible in addition to the eye orbits (e.g., the mandible can be separated from the skull or there are multiple images to depict various views).
Station 3: (a) strepsirrhine (e.g., lemur) and (b) haplorrhine (e.g., monkey).
Station 4: (a) tarsier. Because this station asks students whether the tarsier is more like a strepsirrhine or haplorrhine for given traits, they should have either completed Station 3 or have access to comparative materials at this station too. Additionally, because tarsiers are small, it can be difficult for students to clearly identify some of the traits, and it can be useful to also provide a diagram with a closer view.
Station 5: (a) New World monkey skull and (b) catarrhine skull (preferably an Old World monkey). Be sure to use adult primate skulls so that students can accurately compare their dental formulas. Additionally, this station requires photographs of these primates so that students can compare nose shapes and look up examples of different types of New World monkeys.
Station 6: (a) Old World monkey articulated skeleton, (b) ape articulated skeleton, and (c) human articulated skeleton. This station also asks students to compare molar cusp patterns, so it can be useful to also have separate skulls or photos of dentition.
Station 7: No skeletal materials are required. However, students should have completed Stations 3 through 6.
The instructor should choose to assign this lab as an individual or small group activity.
An introduction to encourage students to think about “form and function” of the skeleton would be helpful. Additionally, students should be encouraged to think broadly (incorporating what they already know about animals, what they eat, and how they move), especially when answering questions at Stations 1 and 2. Instructors should be sure students are familiar with the traits in the lab (e.g., foramen magnum, tooth comb, Y5 or bilophodont molar cusp patterns) or are given resources to identify these traits at the various stations.
The lab consists of seven “stations.” Stations 1 and 2 focus on “form” and “function” of the skeleton, while stations 3 through 6 focus on the organization of the primate taxonomy. Students will rotate through stations filling out tables and answering questions on their worksheets. Instructors may assign some or all stations. Stations can be
completed in any order, however Station 7 requires the completion of stations 3 through 6 first.
Station 1: Students compare primate and non-primate postcrania and relate the form of the skeletons to their function.
Station 2: Students compare primate and non-primate teeth and crania and relate the form of the skeletons to their function.
Station 3: Students compare strepsirrhines and haplorrhines.
Station 4: Students identify tarsier traits and evaluate their classification.
Station 5: Students compare New World monkeys to catarrhines.
Station 6: Students compare a cercopithecoid to two hominoids (an ape and human).
Station 7: Students construct a primate order phylogeny based on the information from Stations 3 through 6.
Instructors should have students report to the class on their answers for some/all of the stations. For example, each group could complete a small table for one station on the board. While some parts of the tables are more open-ended, there are some traits that instructors will want to be sure students identified correctly.
Conclusion
By completing this lab, students learn to distinguish primate and non-primate body forms and functions, with a focus on postcrania, teeth, and eye orbits. Students learn how to differentiate the primate suborders (Haplorrhini and Strepsirrhini) and to describe the unique characteristics of tarsiers, New World primates, and Old World primates. By the end of this lab, students will have acquired a robust understanding of primate classification.
Adapting for Online Learning
This activity could be easily adapted to online classes by linking to 3-D images of primates at educational sites (e.g., eSkeletons) and students could share their results in an assignment, virtual meeting (e.g., Zoom), or on an LMS discussion board.
For Further Exploration
David Attenborough. 2003. “Episode 9: The Social Climbers.” The Life of Mammals (Film) eSkeletons. Department of Anthropology, University of Texas at Austin. http://www.eskeletons.org/
Rowe, Noel. 1996. The Pictorial Guide to Living Primates. Charlestown: Pogonias Press.
References
Etting, Stephanie. 2019. “Chapter 5: Meet the Living Primates.” In Explorations: An Open Invitation to Biological Anthropology,edited by Beth Shook, Katie Nelson, Kelsie Aguilera, and Lara Braff. Arlington, VA: American Anthropological Association. http://explorations.americananthro.org/
