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Mammal Teeth and Skulls – Adaptations and Identification

Mammal Teeth and Skulls – Adaptations and Identification. Teeth. Placoderm.

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Mammal Teeth and Skulls – Adaptations and Identification

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  1. Mammal Teeth and Skulls – Adaptations and Identification

  2. Teeth

  3. Placoderm The placoderm is an extinct line of some of the first fish with jaws. This is an artist’s rendering of what it might look like based on fossil evidence. What looks like teeth in this picture are actually bony projections of the jaw. • The placoderms are found in the fossil record from the Silurian to the early Devonian periods during the Paleozoic era, 465mya-420mya. These fish had lots of hard, bony plates covering their body; which served as armor. The evolution of teeth in placoderms is an example of convergent evolution

  4. Tooth Types • Incisor • flat front teeth used for holding or picking something up • Canine • are the sharp “fangs.” They are next to the incisors and are used to cut into meat. • Premolar • are teeth used for cutting meat in carnivores (meat eaters) or for cutting and grinding plants in herbivores. • Molar • come after the premolars. They are usually flat and wide, and are used for grinding food.

  5. The presence of canines indicates if an animal is a carnivore (meat eater) or omnivore (eats meat and plants). • Premolars and molars with large flat grinding surfaces and small canines, indicate that an animal may be an herbivore (plant eater).

  6. Some animals have special incisors. These front teeth grow continuously during the life of the animal. If the animal does not use the wear them down by gnawing the teeth can grown right into the animals skull or jaw!

  7. Eye Sockets

  8. The placement of the eye orbits or sockets shows the lifestyle of the animal. Orbits that face forward give better depth perception and represent predators. Eye sockets facing to the side allow an animal to have a wider field of view. These animals are normally prey.

  9. Saggital Crest

  10. Some animals have an enlarged saggital crest. A ridge-like area on the top of the skull where jaw muscles attach. A larger saggital crest means that an animal will have larger jaw muscles, and will have a stronger bite. The herbivorous gorilla eats a lot of tough plant material, so it has a strong jaw to help it chew. The tiger is a carnivore. It use its strong jaw muscles to bite down on its prey to kill and to rip meat from the bones.

  11. Auditory Bullae

  12. The auditory bullae here are greatly inflated. The size inflation of the auditory bullae indicate how well an animal can hear. The larger the auditory bullae, the better the animal can hear. The extra air in the bullae act like a reverberating chamber; that is it makes the sound louder. These are small.

  13. Special Traits

  14. A rabbit skull is filled with an area that looks like bony webbing. This makes the skulls lighter making hopping from predators much faster.

  15. Text References • Linzey, D. and Brecht, C. 2000. American Beaver: Castor canadensis. All Taxa Biodiversity Inventory. Discover Life in America. November 1, 2003. http://www.dlia.org/atbi/species/animals/vertebrates/mammals. html • Schwartz, C. W. and Schwartz, E. R. 1981. The Wild Mammals of Missouri. University of Missouri Press, Columbia. • Vaughan, T. A., Ryan J. M., and Czaplewski, N. J. 2000. Mammalogy. Saunders College Publishing, Fort Worth. • Whitaker, J. O. 1996. National Audubon Society Field Guide to North American Mammals. Knopf, New York. • Whitaker, J. O. Jr. and Hamilton, J. W. Jr. 1998. Mammals of the Eastern United States. Cornell University Press, Ithaca.

  16. Image References • Ed Pivorun • Stephanie D. Stocks • Karen Hall • Patrick McMillan • Jennie Kill Bowden • James Kiser • Mike Moore • Howard Whiteman • Mammalian Jaw and Earbone Evolution Diagram Redrawn from Addison Wesley Longman, Inc 1999 • Fish and Wildlife Service Image Library http://images.fws.gov/ • The University of Michigan’s Animal Diversity Web http://animaldiversity.ummz.umich.edu/site/index.html • The Gaping Maws Image Library http://www.animalyawns.com/GapingMaws.htm

  17. Special Thanks to Stanlee Miller, curator of the mammal collection at the Campbell Museum of Natural History at Clemson University.

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