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Dec. 05, 2011

Cool Craniums

by Science Friday Education

Click to enlarge images
Bones are a critical part of vertebrate anatomy because they provide structure and serve as an anchor for musculature. Certain bones of the skeletal system can be used to determine aspects of an animal’s biology, such as its locomotion, feeding behavior, and ecological niche.
In this activity, students will observe three “mystery” mammal skulls and compare and contrast the features of each skull. Students will learn the anatomical terms for skull features such as orbits, nasal passages, and foramen magnum. Students will learn how these features relate to physical characteristics or behaviors of each animal. Students will use their observations and recordings to attempt to identify each skull, and will discuss how these physical characteristics helped the animal survive in its environment.
 
Grade Level: 6th – 8th grade
Subject Matter: Life Sciences
National Standards: NS.5-8.1, NS.5-8.3
 
Using CT scans, DigiMorph, a project at The University of Texas at Austin, has compiled hundreds of 3-D visualizations of fossils, skeletons and other specimens. Tim Rowe, director of DigiMorph, and Richard Ketcham, director of the High-Resolution X-ray Computed Tomography Facility at UT-Austin, share highlights from the collection, including the famous hominid fossil, “Lucy.”
 
Activity Materials
3 mammal skulls – from an herbivore, carnivore and omnivore*
3 small stickers - to be used as labels
1 permanent marker
Pens or pencils – one for each student
Skull Identification Worksheet – download one copy for each student from the template at the end of this lesson.
*Purchasing skulls can be expensive. The following are low-cost sources or alternative suggestions for mammal skulls:
  1. Search online for discounted skulls. All three types of skulls can be purchased for less than $100 at: http://www.boneroom.com/bone/smallmamskulls.htm
  2. Contact your local natural history museum, science center, education centers, or government wildlife or customs agencies that may lend out skulls for educational purposes.
  3. In some states, the National Park Service provides traveling trunks that include skull specimens: http://www.nps.gov/learn/trunks.cfm
  4. Ask your local butcher shop to donate leftover animal skulls. (These may require cleaning.)
  5. Conduct the activities using one of the following online sources for skull images:
 
Vocabulary
Biped: animal that primarily walks on two legs.
Quadruped: animal that primarily walks on four legs.
Orbits: eye sockets.
Dentition: arrangement of teeth.
Nasal passage: passageway through the nose.
Foramen magnum: the large opening in the skull through which the spinal cord enters.
Diurnal: animal that is mostly active during the day.
Nocturnal: animal that is mostly active at night.
Binocular vision: visual ability to use both eyes to focus and track an object.
Monocular vision: visual ability to use eyes separately to see a wide field or view.
Depth perception: visual ability to see and judge the distance of an object.
 
What To Do
Prep: Use the stickers and marker to label each skull from 1 – 3. Create a version of the Skull Identification Worksheet that can serve as your answer sheet fora the identity of each skull.
  1. Start the lesson by having the students watch the SciFri Video, “Bones Come to Life with 3-D Scans.” Begin a discussion with students on why scientists study bones. What can the features of a bone tell us about the animal from which it came? Why do students think that it is important for scientists to study skulls from different animals? Inform students that they will observe three mystery skulls and attempt to identify what animal the skull is from.
  2. Divide students into three groups and hand out one skull per group, along with copies of the Skull Identification Worksheet, one to each student. Inform students that they will begin by making observations only. They should record their observations for each column in the Observation section on the Worksheet. Review each column in the Observation section with students:
  • Orbits – Describe where the eye sockets are located. Are they directly in front or more towards the sides of the skull? Do the eye sockets appear proportional in relation to the size of the skull?
  • Dentition – Are the majority of the teeth sharp and pointed, mostly flat, or a combination of both?
  • Nasal passages – Is the nasal passage long or short?
  • Foramen Magnum – Would the spinal cord enter the skull from the bottom or from the back of the skull?
Have groups rotate through all three skulls, until the Observation section on the Worksheet is completed for all three.
  1. Tell students that now they will make predictions based on their observations. Review each column in the Prediction section of the worksheet:
  • Is the animal diurnal or nocturnal?
  • Does the skull appear to be that of a carnivore, a herbivore or an omnivore?
  • Is the skull that of a biped or quadruped animal?
  • Is the animal a predator, or more likely to be preyed upon by a predator?
Students can discuss each of their observations as a group and use their observations to help them make predictions. Have students discuss how their observations relate to the behavior or characteristics of the animal. What connections can they identify between these physical characteristics and animal behaviors? Students should record their explanations for each answer in the Prediction section of the Worksheet.
 
  1. Challenge students to identify the animal for each skull, and to write their guess under the numbered skull on the Worksheet. Ask them to explain why they think the skull came from the animal that they have identified. Did shape, size, or certain characteristics on the skull help them to identify the skull?
  2. Inform students of the identity of each skull. Review the answers for each column on the Worksheet. Were students surprised by the identity of any of the skulls? Were some of their predictions on the animal’s behavior or characteristic correct even if they were not able to identify the animal accurately? Why is it important to study bones and fossils? How do the characteristics of the skull help the animal to survive in its environment?
What’s Happening?
Comparing and contrasting features of various animal skulls can reveal a great deal about the behaviors or characteristics of the animals, even though the living animals are no longer present. Studying skull form and function is essential to understanding mammal classification, adaptation, and evolution.
 
In this activity, students observe anatomical features found on the skulls of omnivorous, herbivorous and carnivorous mammals. These features can be used to determine behaviors characteristic of each mammal. Skull dentition can reveal whether the animal is a carnivore, herbivore, or omnivore. A long or large nasal passage suggests an animal with a strong sense of smell, while short nasal passages suggests an animal with a poor sense of smell. The large hole at the base of the skull (foramen magnum) is indicative of biped or quadruped locomotion. If the foramen magnum is located at the bottom of the skull, then that animal was most likely a biped. If the foramen magnum is located at the back of the skull, the animal was most likely a quadruped.
 
The size and location of the orbits, or eye sockets, also can reveal much about an animal. Large orbits allow for greater light perception, and can indicate a nocturnal animal with sharp eyesight. Eyes that are located in the front of the skull allow an animal to focus on an object with both eyes (binocular vision). Such an animal also has the ability to judge distance (depth perception). Both are useful physical features for a predator to use in tracking and hunting prey. Eyes that are located towards the side of the skull indicate an animal with monocular vision. Animals with monocular vision are able to see in all directions, making them better able to watch out for predators.
 
Topics for Science Class Discussion
  • Are there any other features on the skull that can be studied to find out more about the animal’s characteristics or behaviors?
  • How would a human skull compare to any of these mammal skulls?
  • What are some types of careers that benefit from the study of skulls or skeletal structures?
Extended Activities and Links
Assign each student an extinct animal and a living animal. Students should research all of the physical characteristics that led to each animal’s survival or extinction. Have students present their findings to the class.
Have students sketch a “super animal” that has what they think are the best physical characteristics for survival. Challenge each student with these questions once their sketch is completed:
  • Could their animal survive in varied environments such as the desert, the Arctic, or a rainforest?
  • Would their animal maintain a balanced ecosystem or would it exhaust its resources?
  • Is their animal able to defend or protect itself?
Allow other students to challenge or ask questions on the survival characteristics of each animal.
View 3-D images of biological specimens on Digimorph’s website:
http://www.digimorph.org/
 
Try this lesson to learn more about dentition and skulls:
http://www.brandywinezoo.org/games/teeth_bones.pdf
 
View and compare skull and skeletal features from the primate family:
http://www.eskeletons.org/
 
Explore this interactive website on skulls from the California Academy of Sciences:
http://www.calacademy.org/exhibits/skulls/
 
 

 

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