Humans belong to the Order Primates (one of the 18 Orders of the Class Mammalia). This lab will outline what distinguishes primates from other mammals and from one another. As you go through this lab, please read through the descriptions at each station, and look closely at the embedded images. Take some time to rotate them, zoom in on different features, and look carefully at the characteristics that differentiate separate taxa within the primate order. As you go through the lab, fill out the charts and answer the reflection questions on your answer sheet, and then submit your answers through Blackboard.
NOTE: Before completing this lab, please watch the lab terminology introduction video here:
By the end of this lab you should be familiar with the following terms (explained in the video):
- postorbital closure
- foramen magnum
- generalized vs. specialized dentition
- grooming claw
- dental comb
- fused/unfused mandible
- canine diastema
- prehensile tail
- molar pattern (Y5 vs bilophodont)
- dental formula
Station 1: What is a Primate?
Primate Characteristics include:
- Tendency toward erect (upright) posture
- Flexible, generalized limb structure
- Grasping hands and feet
- Five digits on hands and feet
- Opposable thumbs, opposable big toes
- Nails instead of claws
- Tactile pads (fingers, toes, and sometimes tail)
- Generalized but heterodont teeth (incisors, canines, premolars, molars)
- Eyes facing forward, depth perception through stereoscopic vision
- Bony protection of the eye (post-orbital bar or post-orbital enclosure)
- Visual information from each eye processed in both hemispheres of brain
- Decreased sense of smell (olfaction)
- Expansion and increased complexity of neocortex; larger brain size
- More efficient placenta, longer gestation length, reduction in litter size
- Delayed maturation, extended lifespan
- Greater dependence on flexible, learned behavior
Many of these characteristics can be related to one particular life-style that was peculiar to the ancestor of all living primates and is typical of most primates today – getting about in trees by grasping with the feet and hands. The common ancestor of all living primates was an arboreal climber, with prehensile extremities, and it probably relied on its eyes for predation on insects.
Based on the above-specified characteristics, fill out the chart below.
Look at the four “mystery skulls” below. Using what you now know about the physical characteristics that differentiate primates from non-primates, fill out the chart with analyses of those characteristics, and see if you can figure out which specimens are part of our order.
Station 1 Reflection Questions
Based on your observations, are any of the casts primates? Why?
For each of the casts, observe the teeth – what diets are suggested by the teeth of each cast?
Exercise 3: Primate Taxonomy
There is a blank version of this taxonomic tree uploaded on blackboard with your lab document. Please DO NOT fill it out by copying this chart here. Rather, please fill in the blanks on the chart as you go through the lab, and pay attention to the taxonomic splits and the variation in features that correlate with each division. At each station, I have indicated in bold, red font which taxonomic differentiation you will be analyzing. Then come back here at the end to check and see if you’ve filled out your taxonomy correctly. This is for your own practice only (note: makes a great study guide!), I will not be grading this form. (Click the image below to link to the zoomed in version).