Teeth of the Kayentatherium reptile species

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Did You Know…

…that We Can Determine What Fossil Animals Ate By Analyzing Their Teeth?


One of the most fascinating areas in the evolution of animals is the transition from reptiles to mammals. There are numerous hybrids that, due to constantly evolving scientific knowledge, are switched back and forth between these two classifications or should really be included in both at the same time. One of the disputed families is that of the Tritylodontidae. Following the initial discovery of their fossilized teeth in 1847 and 1866 in Württemberg, Germany, this was considered the oldest family of mammals.

Their skulls are actually very mammal-like, and their dentition resembles that of present-day rodents. However, the teeth themselves look completely different. Due to the similarity in their diets, the teeth of the Tritylodontidae and rodents developed parallel to each other, but today’s rodents are not descendants of this family of fossil animals.Various other characteristics – in the lower jaw joint, the auditory ossicles, or the shoulder girdle, for example – indicate that Tritylodontidae are actually reptiles.

To find out what food this family of animals preferred, the teeth of the Kayentatherium species were examined at the Steinmann Institute at the University of Bonn with the aid of a ZEISS zoom microscope for large object fields. This new system enables scientists to create very high-resolution images with an outstanding depth of field. Accordingly, they were able to photograph key areas on the dental surfaces. These “facets” are formed during the process of chewing due to the contact of the teeth in the upper and lower jaws, causing these areas to be ground smooth and reflect light.

There are also scratches on the facets indicating the movements of the lower jaw during chewing. By analyzing these scratches, we can draw conclusions about the chewing cycle and the animal’s preferred diet. The diet of the Kayentatherium consisted exclusively of plants. In this respect they are similar to modern-day rodents, which also feed primarily on plants. However, while rodents move their lower jaw from back to front, the Kayentatherium always chewed from front to back. Crowned with steeply-angled, sharp edges arranged in pairs, one behind the other, the molars were extremely effective in breaking down food. While it is not possible to say which types of plants the Kayentatherium ate, its habitat at the time gives us a few clues. It was largely covered with Equisetum, a horsetail plant that blanketed the ground like grass.

 

16 January 2013