Classification lab: Mammal Skulls
Introduction: Humans have always been in awe of the natural world around us. For many
biologists the key to understanding wildlife of all forms is to first classify them into groups with
common form and function. In this case form refers to the physical shape of an organism and
function refers to what it does or how it acts. Once organisms are classified similarities can be
seen with many benefits. Take for example chronic wasting disease (CWD). The first step to
containing and/or curing this disease is to first classify it or compare it to other known illnesses
to find out how it is transferred. Only then can the search for a cure begin.
There are many ways to classify organisms and many philosophers and scientists have devised
their own system. Carl Linneaus created a system known as binomial nomenclature (a two-word
naming system) to identify organisms. His system became the most widely used (and is still
today) because it had the ability to expand and accommodate new species as they were being
discovered and was based on Latin – which is the basis for many European languages as well as
being widely used by many scientists.
Classification helps to identify organisms and then discover their natural history, for example
their habitat, food sources, travel routes etc.. To help identify and then classify an animal a tool
called a dichotomous key is used. When a dichotomous key is used a series of yes and no
questions is asked based on physical features of an organism that divides a group of organisms
into two (always two – remember the prefix “Di”). Eventually, a group is broken down until it
contains only one member which can then be assigned a name. The name may be based on Latin,
the name of the discoverer, a feature of that organism or a specific area it lives.
Examples: Beaver – Castor canadensis (named after the castoreum or reproductive gland)
Grey Wolf – Canis lupus – (named after the large canine teeth)
Black bear – Ursus americana (Ursus is Latin for bear - Ursa major – the big dipper)
Rhinoderma darwinii- Darwin’s Frog (named after Charles Darwin)
Linnaea boreali – An arctic plant discovered by and named after Linneaus on a trip to
Lapland (between Finland and Sweden)
Mountain vole – Microtus montanus (named because it lives in mountainous areas)
Barren ground caribou – Rangifer arcticus (named because it lives in arctic regions)
Materials: Three mammal skulls and the mammal skull identification key
Procedure:
1) Read page one on how to use the key, the definitions of different kinds of teeth
and where to find them.
2) Count the total number of teeth in the upper jaw on both sides and including any
spaces that may have contained teeth that have fallen out.
3) Use the key and create your own abbreviated key with the attached form. In
other words each line that you use from the key record in your data table. You
and your group must each identify three skulls – use one data table for each
skull.
Data table Begin Here:
Line #
Description
Go to
Order/Genus/Specie
Line #
Description
Go to
Order/Genus/Specie