Hobbins Peter
Department of History, University of Sydney, Sydney, NSW, 2006, Australia.
J Hist Biol. 2015 Nov;48(4):499-537. doi: 10.1007/s10739-015-9409-4.
For over two centuries, the platypus (Ornithorhynchus anatinus) has been constructed and categorized in multiple ways. An unprecedented mélange of anatomical features and physiological functions, it long remained a systematic quandary. Nevertheless, since 1797, naturalists and biologists have pursued two recurring obsessions. Investigations into platypus reproduction and lactation have focused attention largely upon females of the species. Despite its apparent admixture of avian, reptilian and mammalian characters, the platypus was soon placed as a rudimentary mammal--primitive, naïve and harmless. This article pursues a different taxonomic trajectory, concentrating on a specifically male anatomical development: the crural spur and venom gland on the hind legs. Once the defining characteristic of both the platypus and echidna (Tachyglossus aculeatus), by 1830 this sexed spur had been largely dismissed as inactive and irrelevant. For a creature regularly depicted as a biological outlier, the systematic and evolutionary implications of platypus poison have remained largely overlooked. In Australia, however, sporadic cases of 'spiking' led to consistent homologies being remarked between the platypus crural system and the venom glands of snakes. As with its reproductive reliance upon eggs, possession of an endogenous poison suggested significant reptilian affinities, yet the platypus has rarely been classed as an advanced reptile. Indeed, ongoing uncertainty regarding the biological purpose of the male's spur has ostensibly posed a directional puzzle. As with so many of its traits, however, platypus poison has been consistently described as a redundant remnant, rather than an emergent feature indicating evolutionary advance.
两个多世纪以来，鸭嘴兽（Ornithorhynchus anatinus）一直以多种方式被构建和分类。它拥有前所未有的一系列解剖特征和生理功能，长期以来一直是一个系统分类学上的难题。然而，自1797年以来，博物学家和生物学家一直有两个反复出现的关注点。对鸭嘴兽繁殖和泌乳的研究主要集中在该物种的雌性个体上。尽管鸭嘴兽明显混合了鸟类、爬行类和哺乳类的特征，但它很快就被归类为一种原始的哺乳动物——原始、单纯且无害。本文追寻一条不同的分类轨迹，专注于一个特定的雄性解剖学发育特征：后腿上的胫距刺和毒腺。胫距刺曾经是鸭嘴兽和针鼹（Tachyglossus aculeatus）的共同特征，到1830年，这个具有性别差异的刺在很大程度上已被视为不活跃且无关紧要。对于一个经常被描绘为生物学异类的生物来说，鸭嘴兽毒液的系统分类学和进化意义在很大程度上一直被忽视。然而，在澳大利亚，零星的“刺伤”案例导致人们注意到鸭嘴兽的胫距系统与蛇的毒腺之间存在一致的同源性。与其生殖依赖卵一样，拥有内源性毒液表明它与爬行类有显著的亲缘关系，但鸭嘴兽很少被归类为高等爬行类。事实上，关于雄性鸭嘴兽胫距刺的生物学用途一直存在不确定性，这显然构成了一个方向性难题。然而，就像它的许多特征一样，鸭嘴兽毒液一直被一致描述为一种多余的残余物，而不是表明进化进步的新出现特征。
