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JVP:考察后腿骨骼有助分辨恐龙性别

来源:化石网 2012-01-10 12:20

最近,古脊椎动物学杂志Journal of Vertebrate Paleontology刊登的一项研究"Evidence for sexual dimorphism in the stegosaurian dinosaur Kentrosaurus aethiopicus from the Upper Jurassic of Tanzania"称,科学家们找到了分辨恐龙性别的新方法——考察它们后腿上半部分的骨骼。

“骨骼是受其上附着的肌肉作用而定型的,因此股骨肌肉附着端的形状和大小能指示其上肌肉的重量,”研究者之一,来自伦敦自然历史博物馆的S.Maidment说。她和她的同事研究了坦桑尼亚敦达古鲁组(Tendaguru Formation)1.5亿年前的剑龙化石。很多时候一个化石点只能出土一具化石,就无法将它与其它家庭成员进行对比了。但是这次,他们在同一地点发现了大量的剑龙化石:埃塞俄比亚钉状龙(Kentrosaurus aethiopicus)。包括50段保存完好的股骨。

“我们考察了恐龙股骨形状上的差异,发现股骨的上端,即臀肌的附着处,有着一定的个体差异。”Maidment说。“根据这种差异我们将成年剑龙分为两个统计学差异明显的群体。”

然而,未成年剑龙的股骨上端形态和这两个群体都不同,因此骨骼形态的差异是在成年后发生的,很可能是幼年恐龙性成熟的时期。

将这些恐龙分成了两个群体后,他们面对的另一问题就是判断它们各自所代表的性别。“除非发现一只保存完好的钉状龙化石,并且它的输卵管内有一枚卵,否则我们可能无法知道它们究竟哪组是雄性,哪组是雌性。”Maidment说。(生物谷Bioon.com)

Evidence for sexual dimorphism in the stegosaurian dinosaur Kentrosaurus aethiopicus from the Upper Jurassic of Tanzania

Holly E. Bardenab & Susannah C. R. Maidmentc

Sexual dimorphism, the condition whereby males and females differ from one another physically, is one of the most fundamental aspects of the biology of any animal. However, sexually dimorphic characters can be subtle and are mainly related to soft tissue anatomy. They are, therefore, difficult to identify reliably in the fossil record particularly when dealing with small sample sizes and osteology alone. The first geometric morphometric analysis of dimorphism in a thyreophoran (armored) dinosaur shows that the femora of the stegosaurian dinosaur Kentrosaurus aethiopicus (Upper Jurassic, Tanzania) bear a statistically significant shape difference of the proximal end, which is independent of size and is therefore proposed to be a sexual difference. Although the disarticulated nature of the material means that intraspecific variation in other skeletal elements, such as the enigmatic dermal armor, cannot be identified as sexual dimorphism at this time, this study provides a methodology for further work on articulated stegosaurian specimens and has the potential to reveal additional information regarding the palaeobiology and population dynamics of this poorly understood clade.

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