Thomson Keith S, Sutton Mark, Thomas Bethia
Oxford University Museum of Natural History, Parks Rd, Oxford OX1 3PW, UK.
Nature. 2003 Dec 18;426(6968):833-4. doi: 10.1038/nature02175.
Perhaps the most enduring of puzzles in palaeontology has been the identity of Palaeospondylus gunni Traquair, a tiny (5-60-mm) vertebrate fossil from the Middle Devonian period (approximately 385 Myr ago) of Scotland, first discovered in 1890 (refs 1-3). It is known principally from a single site (Achanarras Quarry, Caithness) where, paradoxically, it is extremely abundant, preserved in varved lacustrine deposits along with 13 other genera of fishes. Here we show that Palaeospondylus is the larval stage of a lungfish, most probably Dipterus valenciennesi Sedgwick and Murchison 1828 (ref. 5), and that development of the adult form requires a distinct metamorphosis. Palaeospondylus is the oldest known true larva of a vertebrate.
古生物学中或许最持久的谜题之一，就是古椎鱼（Palaeospondylus gunni Traquair）的身份。它是一种小型（5 - 60毫米）的脊椎动物化石，来自苏格兰泥盆纪中期（约3.85亿年前），于1890年首次被发现（参考文献1 - 3）。它主要来自一个单一地点（凯斯内斯郡的阿查纳拉斯采石场），矛盾的是，在那里它极为丰富，与其他13个鱼类属一同保存在纹层状湖相沉积物中。我们在此表明，古椎鱼是一种肺鱼的幼体阶段，极有可能是1828年塞奇威克和默奇森命名的瓦氏双翼鱼（Dipterus valenciennesi）（参考文献5），并且成年形态的发育需要明显的变态过程。古椎鱼是已知最古老的脊椎动物真正幼体。
