Population structure of the gomphothere Stegomastodon waringi (Mammalia: Proboscidea: Gomphotheriidae) from the Pleistocene of Brazil

Anais da Academia Brasileira de Ciências

Dimila Mothé²  Leonardo S. Avilla²  Gisele R. Winck¹ 

[1] ,Universidade Federal do Estado do Rio de Janeiro Departamento de Zoologia Laboratório de MastozoologiaRio de Janeiro RJ ,Brasil

关键词: Stegoastodon waringi;    age classes;    morphometric wear index;    populational structure;    Stegomastodon waringi;    classes etárias;    índice morfométrico de desgaste;    estruturas populacionais;   

DOI  :  10.1590/S0001-37652010005000001

来源: SciELO

【 摘 要 】

The Quaternary fossil record of Águas de Araxá (Q AA) is represented mainly by an accumulation of skeletal elements of several sizes, which are assigned to a population of Stegomastodon waringi. We analyzed 97 molars according to the ear stages of Sipson and Paula-Couto (1957), and developed a orphoetric ear index. The population structure (proportion of immature, subadult, adult, mature adult and senile adult individuals) was identified, and these five age classes were compared to those of extant elephant populations and defined with social implications. The analysis made possible to establish that the population is largely composed of adults: 14.89% are immature individuals, 23.04% subadults, 27.65% adults, 17.21% mature adults and another 17.21% senile adults. Based on population structure, we do not discard the possibility that the fossil population was stable or in recovery, and/or was experiencing a high-predation period on younger individuals. The number of individuals composing the past population studied here could suggest that the occupied environment was open due to comparisons to populations of extant elephants. We consider this population as an aggregation of family units, which suggests a time of low environmental humidity. Based on literature and our findings, their extinction appears to be regional and probably related to a catastrophic event.

【 授权许可】

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