who's tooth
Response to: Who's Tooth is it Anyway? Julie Kazimiroff, dental professor at NYU College of Dentistry, attempts to cover the issue of cusp patterns with respect to relatedness among the hominoids. She starts off by posing a question regarding the 5 cusp (Y-5) molar pattern present in extant primates. To begin with, she emphasizes the importance of teeth to phylogenetics, as they are often times all that survives from an organism. DNA is brought into the paper to explain how testing techniques have been utilized to enhance the answering of relatedness questions, particularly in terms of chimps, apes and humans. In her title she mentions Dryopithecus, an early "dental ape" thought to be an early hominoid. Dr
The fossil record has been used to trace the evolution of mammals to primates, and dentition has played a major role in this. What this paper ends up doing is answering the question by stating that all cusp patterns originated with this group of reptiles. It basically provided an overview of the tritubercular theory and traced primate cusp patterns back to reptilian origins and eventually to the first time the familiar Y-5 pattern shows up, with the finding of an early hominoid, Dryopithecus ( according to this paper). The article goes beyond primates in addressing the question however, as reference to reptiles and the idea that their triangular molars ( 3 cusps) are considered to be principle cusps that have evolved over time as mammals began to emerge, carrying and modifying the cusps and patterns according to species divergences in response to both internal (genetics and behavior) and external ( environmental and dietary factors). In tracking an answer to the question posed, it appears that it lies in the study of mammalian molarization. In tracing the pattern, it was determined that it could be found in not only extant groups of primates, but in extinct groups such as those ancestral to the great apes and gibbons also. ------------------------------------------------------------------------**Bibliography**. Therapsida, an early group of reptiles which followed a mammalian direction, had a triangular crown with three cusps, which led to the tritubercular theory that stated all mammals developed their cusp patterns from this pattern. By combining the fossil evidence provided by the molar pattern data with the molecular data, it was determined that the gibbons was the earliest branch of the Hominoidea, and all primates are related through this pattern. It was here that a pattern emerged which seemed to define what was characteristic of primates, the Dryopithecus pattern, that of the Y-5 cusp pattern. yopithecus possessed the Y-5 cusp pattern found among the extant primates, and this paper seems to indicate that it actually may be the origination of such a pattern in terms of the beginning of the hominoid lineages. It is argued that this is the root of the patterns seen in the primates, the Y-5 or Dryopithecus pattern, originating from the reptilian 3 cusp pattern.
Common topics in this essay:
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Acceptance Essays
