If the guys on "CSI" and "Law and Order" can use dental records to identify human individuals, why not extend the same logic to animals? That's exactly what scientists have done. To be absolutely sure which animal you're dealing with, you have to compare their molars. Since the two species eat their meals in different habitats, their teeth have evolved over the years to suit the specific vegetable matter they consume.
The wallaby lives in bushy forest areas where it dines on mostly leaves. Because the wallaby has to crush and grind up leaves in its mouth, it needs flat teeth. Unlike the kangaroo, it doesn't do much cutting, so its crowns are less pronounced. However, the wallaby does retain a single cutting tooth on the top of its mouth for any occasional cutting needs. It also keeps its premolars; the kangaroo sheds its premolars.
The kangaroo, which lives in more open treeless areas, chomps on mostly grasses. Because the kangaroo has to slice up stalks of grass in its mouth, it needs teeth that can accomplish the task. The kangaroo's teeth are curved with cross-cutting ridges for cutting and shearing grass. Its molars have higher crowns than wallaby teeth.
Are you still wondering whether Rocko is a kangaroo or a wallaby? Next time you're watching "Rocko's Modern Life," peer inside his mouth and check out his molars. If his creators know their stuff, you should see flat teeth and a sharp cutting tooth; Rocko is a wallaby. You'll also notice he's noticeably smaller than his buddies on the show, another telltale sign that he's a member of the wallaby species.
To learn more about kangaroos and wallabies and some other intriguing animals, investigate the links on the following page.
Related HowStuffWorks Articles
More Great Links
- Australia Zoo. "Mammals: Kangaroos vs. Wallabies." Feb. 3, 2006. (Feb. 12, 2008)http://www.australiazoo.com.au/our-animals/animal-diaries/index.php?diary=872
- Fountain, Lesley. "America Zoo: Brush-tailed Wallaby." 2005-2006. (Feb. 13, 2008)http://www.americazoo.com/goto/index/mammals/25.htm
- Microsoft Encarta Online Encyclopedia 2007. "Marsupial." (Feb. 12, 2008) http://encarta.msn.com
- Myers, P. "Macropodidae." Animal Diversity Web. 2001. (Feb. 13, 2008) http://animaldiversity.ummz.umich.edu/site/accounts/information/Macropodidae.html
- National Geographic Kids. "Eastern Gray Kangaroo." 1996-2008. (Feb. 12, 2008)http://animals.nationalgeographic.com/animals/mammals/gray-kangaroo.html
- National Geographic Kids. "Wallaby." 2008. (Feb. 12, 2008)http://animals.nationalgeographic.com/animals/mammals/wallaby.html
- Thomas, Oldfield. "Catalogue of the Marsupialia and Monotremata in the collection of the British Museum (Natural History)." London: Order of the Trustees, 1888.
- Tyndale-Biscoe, Hugh. "Life of Marsupials." Australia: Csiro Publishing, 2005.
- Wilson, Don E. and DeeAnn M. Reeder, eds. Mammal Species of the World. A Taxonomic and Geographic Reference (3rd Ed). Johns Hopkins University Press. (Feb. 13, 2008)http://www.bucknell.edu/msw3/