19 marzo 2012

Temibili sorrisi. Come funzionavano i denti del T-Rex. Un articolo su "Canadian Journal of Earth Sciences"

Miriam Reichel La ricerca della biologa Miriam Reichel (Università di Alberta, Canada) pubblicata nella rivista "Canadian Journal of Earth Sciences" dimostra che la tipologia e la posizione dei denti del T-Rex è frutto di una particolare evoluzione. In altre parole la specializzazione dentale si è dimostrata un enorme vantaggio per un dinosauro la cui preoccupazione principale era strappare la carne di altri dinosauri. I denti anteriori del T-Rex servivano per trattenere la preda mentre quelli laterali laceravano la carne. Un aspetto sorprendente dei denti del T-Rex, comune a tutti i tirannosauridi era la forma: non a pugnale ma più simile a quella di una banana. Questo perché se troppo taglienti avrebbero potuto spezzare la preda, mentre serviva tenerla bloccata. Determinante, pertanto, era la forza muscolare della bocca di questo enorme predatore.

The variation of angles between anterior and posterior carinae of tyrannosaurid teeth
Miriam Reichel (Department of Biological Sciences, University of Alberta, Canada)
Canadian Journal of Earth Sciences, 2012, 49(3): 477-491, 10.1139/e11-068 (Published on the web 10 February 2012)
Abstract
Tyrannosaurid tooth measurements have been shown to be a powerful tool for systematic analyses, as well as for studies on function and evolution of theropod dentition. In this analysis, a variable not previously addressed in depth is added to the tyrannosaurid data set. The angle between the anterior and posterior carinae can be difficult to measure consistently and a method is hereby proposed through the use of a digitizer. Five tyrannosaurid genera were analyzed: Tyrannosaurus, Tarbosaurus, Albertosaurus, Daspletosaurus, and Gorgosaurus. Only in situ data were used, and therefore some of the taxa had a limited amount of information available for this analysis. The measurements were analyzed through multivariate analyses using Paleontological Statistics (PAST), version 2.06. The analyses included principal component analyses (PCAs), discriminant analyses (DAs), and canonical variates analyses (CVAs). The results of these analyses revealed that the angle between carinae contributes significantly to the variation in the tyrannosaurid tooth data set. Additionally, this variable showed a strong correlation to tooth function (and, consequently, to tooth families), rather than tooth size. The variation observed between taxa at this stage seems insufficient for systematic purposes, however additional in situ data would help improve the effectiveness of this tool.

T. rex’s killer smile revealed (University of Alberta, February 29, 2012)

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