locomotor adapataions

This section will assist in identifying the primary types, often called patterns, of locomotion used by primates. Primate locomotion can be broken into four major categories of movement: Vertical Clinging and Leaping (VCL), Quadrupedalism, Brachiation (Suspension), and Bipedalism. Within these major categories are subcategories of even more specialized movement types. You will become familiar with each of the major categories and the general body features associated with it.

Vertical Clinging and Leaping

Vertical Clinging and Leaping (VCL) is a highly specialized locomotion strategy used by a small number of primates. VCL requires many skeletal specializations in order for this locomotion strategy to work. Tarsiers are one type of VCL primate whose name actually comes from their elongated tarsals bones used for jumping (see examples below).

Exercise 4

Vertical Clinging and Leaping

Observe the following features on the Indri skeleton below and fill out the table in the lab.

Quadrupedalism vs Brachiation

Quadrupedalism is the most common form of locomotion observed in primates. Quadrupedalism can be used on land (terrestrial) as well as in the trees (arboreal). Some primates have a distinct method of moving through the trees called Brachiation (suspension). Brachiation is the ability to use the arms to swing beneath branches as the primary means of locomotion.

Quadrupedalism

Brachiation

Exercise 5

Quadrupedalism vs Brachiation

Examine the photos to observe some of the anatomical characteristics associated with Quadrupedalism and Brachiation.

Bipedalism

Bipedalism is likely the most familiar locomotion strategies for humans, as it is the locomotion strategy you used to walk to class today. While we are not the only animal to practice bipedalism, we are the only primate to be habitually bipedal.

Take a look at the gifs. Chimpanzees can walk bipedally, but it is awkward. Chimpanzees' preferred locomotor pattern is quadrapedalism, while humans' preferred locomotor pattern is bipedalism.

Exercise 6

Bipedalism

Compare humans to our closest living relative, the chimpanzee, to identify anatomical changes associated with bipedal locomotion.

Human

Chimpanzee

It is fairly easy to identify a primate’s locomotion based on observation. However, what if you are only dealing with a skeleton and cannot simply observe the animal’s movement? Using the measurements of four bones (the humerus, radius, femur, and tibia) and a simple mathematical equation, we can usually predict the pattern of locomotion used by a primate. In fact, we already met this equation in the last segment of the course, the intermembral index:

The intermembral index of an animal is basically a ratio comparing the length of the arms to the length of the legs, which reflects the locomotion pattern.

Exercise 7

Intermembral Index

Follow the directions below to find the intermembral index of five primate species.

Using the data from the table to calculate the intermembral index for each species. Compare the index you calculated to this chart to identify the locomotion pattern for each species.

Don't forget to finish the Concept Review and Concept Applications on the Lab Document!

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