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2018-04-03 | 编辑: | 【


关键词: 中生代鸟类,牙齿退化,牙齿重量,体重,取食行为 

Negligible effect of tooth reduction on body mass in Mesozoic birds

  ZHOU Ya-Chun, Corwin SULLIVAN, ZHANG Fu-Cheng

Abstract   Tooth reduction and loss was an important evolutionary process in Mesozoic birds. Analysis of evolutionary trends in the total mass of the dentition, a function of tooth size and tooth number, has the potential to shed light on the evolutionary pattern of tooth reduction and loss, and on the causes of this pattern. Because modern birds lack teeth, however, they cannot provide the basis for a model that would allow estimation of tooth masses in their Mesozoic counterparts. We selected the teeth of crocodilians as analogues of those in Mesozoic birds because the former are the closest living relatives of the latter, and the two groups are similar in tooth morphology, tooth implantation, and tooth replacement pattern. To estimate tooth masses in Mesozoic birds, we formulated four regression equations relating tooth mass to various linear dimensions, which were measured in 31 intact isolated teeth from eight individual crocodiles (Crocodylus siamensis). The results for Mesozoic birds show that dental mass as a proportion of body mass was negligible, at least from the perspective of flight performance, suggesting that selection pressure favoring body mass reduction was probably not the primary driver of tooth reduction or loss. Variations in dental mass among Mesozoic birds may reflect the different foods they ate, and the different types of feeding behavior they displayed. 
Key words   Mesozoic birds; dental reduction; tooth mass; body mass, feeding behavior 


Negligible effect of tooth reduction on body mass in Mesozoic birds.pdf
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