最近，古脊椎動物學雜志Journal of Vertebrate Paleontology刊登的一項研究"Evidence for sexual dimorphism in the stegosaurian dinosaur Kentrosaurus aethiopicus from the Upper Jurassic of Tanzania"稱,，科學家們找到了分辨恐龍性別的新方法——考察它們后腿上半部分的骨骼,。
“骨骼是受其上附著的肌肉作用而定型的，因此股骨肌肉附著端的形狀和大小能指示其上肌肉的重量,，”研究者之一，來自倫敦自然歷史博物館的S.Maidment說。她和她的同事研究了坦桑尼亞敦達古魯組（Tendaguru Formation）1.5億年前的劍龍化石,。很多時候一個化石點只能出土一具化石，就無法將它與其它家庭成員進行對比了,。但是這次,，他們在同一地點發(fā)現(xiàn)了大量的劍龍化石：埃塞俄比亞釘狀龍（Kentrosaurus aethiopicus）,。包括50段保存完好的股骨。
“我們考察了恐龍股骨形狀上的差異,，發(fā)現(xiàn)股骨的上端,，即臀肌的附著處，有著一定的個體差異,。”Maidment說,。“根據(jù)這種差異我們將成年劍龍分為兩個統(tǒng)計學差異明顯的群體。”
然而,，未成年劍龍的股骨上端形態(tài)和這兩個群體都不同,，因此骨骼形態(tài)的差異是在成年后發(fā)生的，很可能是幼年恐龍性成熟的時期,。
將這些恐龍分成了兩個群體后,，他們面對的另一問題就是判斷它們各自所代表的性別。“除非發(fā)現(xiàn)一只保存完好的釘狀龍化石,，并且它的輸卵管內(nèi)有一枚卵,，否則我們可能無法知道它們究竟哪組是雄性，哪組是雌性,。”Maidment說,。（生物谷Bioon.com）
doi:10.1080/02724634.2011.557112
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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.
