John Scannella, in a paper presented in Bristol, UK at the conference of the Society of Vertebrate Paleontology (September 25, 2009) reclassified "Torosaurus" as especially mature "Triceratops" individuals, perhaps representing a single sex. Jack Horner, Scannella's mentor at Bozeman Campus, Montana State University, noted that ceratopsian skulls consist of metaplastic bone. A characteristic of metaplastic bone is that it lengthens and shortens over time, extending and resorbing to form new shapes. Significant variety is seen even in those skulls already identified as "Triceratops", Horner said, "where the horn orientation is backwards in juveniles and forward in adults". Approximately 50% of all subadult "Triceratops" skulls have two thin areas in the frill that correspond with the placement of "holes" in "Torosaurus" skulls, suggesting that holes developed to offset the weight that would otherwise have been added as maturing "Triceratops" individuals grew longer frills. A paper describing these findings in detail was published in July 2010 by Scannella and Horner. It formally argues that "Torosaurus" and the similar contemporary "Nedoceratops" are synonymous with "Triceratops".