Despite their extinction millions of years ago, Triceratops continue to incite controversy. In the latest chapter, researchers present further evidence that three genera thought at one time or another to be distinct  Triceratops, Torosaurus, and Nedoceratops  actually represent different individuals that all belong to the Triceratops genus.

The work, led by John Scannella of Montana State University and published in the Dec. 14 issue of the online journal PLoS ONE, focuses on one particular specimen  a single skull  that has been the subject of considerable debate.

Some consider it a Triceratops, while others argue that it is a different genus. The new analysis provides evidence that this specimen is in fact a Triceratops, and that much of the confusion has arisen due to significant skeletal changes that are thought to occur during Triceratops development, as well as natural variation within the genus.

These factors result in specimens with some features that are considerably different, but are nonetheless all Triceratops, the authors conclude.

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More information: Scannella JB, Horner JR (2011) 'Nedoceratops': An Example of a Transitional Morphology. PLoS ONE 6(12): e28705. Scannella JB, Horner JR (2011) 'Nedoceratops': An Example of a Transitional Morphology. PLoS ONE 6(12): e28705. doi:10.1371/journal.pone.0028705