主题:動物/精選條目/9

禽龍屬（学名：Iguanodon，意為“鬣蜥的牙齒”），屬於蜥形綱鳥臀目鳥腳下目的禽龍類，是大型草食性動物，身長約10公尺，高3到4公尺，前手拇指有一尖爪，可能用來抵抗掠食動物，或是協助進食。

禽龍的化石多數發現於歐洲的比利時、英國、德國。牠們主要生存於白堊紀早期的巴列姆階到早阿普第階，約1億2600萬年前到1億2500萬年前。禽龍的演化位置大約位於行動敏捷的稜齒龍類首次出現，演化至鳥腳下目中最繁盛的鴨嘴龍類，這段演化過程的中間位置。禽龍與年代更晚的鴨嘴龍類，共同屬於禽龍類演化支。

禽龍的化石在1822年首次發現，並在1825年由英國地理學家吉迪恩·曼特爾進行描述與命名。在過去的研究歷史中，有許多化石被歸類於禽龍，年代橫跨侏罗纪啟莫里階到白堊紀森諾曼階，範圍廣達歐洲、北美洲、亞洲內蒙古、以及北非。但根據近年研究，這些化石多被歸類於其他屬，或是建立為新屬。目前的唯一有效種是貝尼薩爾禽龍（I. bernissartensis）。

禽龍是繼斑龍之後，世界上第二種正式命名的恐龍。斑龍、禽龍、以及林龍是最初用來定義恐龍總目的三個屬。古生物學界對於禽龍的了解，因為新發現的化石而隨著時間不斷改變。禽龍的大量標本，包括從兩個著名屍骨層發現的接近完整骨骸，使得研究人員可提出許多禽龍生活方面的假設，包括進食、移動方式、以及社會行為。禽龍的重建圖也隨著標本的新發現而改變。

Iguanodon (/ɪˈɡwɑːnədɒn/ i-GWAH-nə-don; meaning "iguana-tooth") is a genus of ornithopod dinosaur that existed roughly halfway between the first of the swift bipedal hypsilophodontids of the mid-Jurassic and the duck-billed dinosaurs of the late Cretaceous. While many species have been classified in the genus Iguanodon, dating from the late Jurassic Period to the early Cretaceous Period of Asia, Europe, and North America, research in the first decade of the 21st century suggests that there is only one well-substantiated species: I. bernissartensis, which lived from the late Barremian to the earliest Aptian ages (Early Cretaceous) in Belgium, Spain, and possibly elsewhere in Europe, between about 126 and 125 million years ago. Iguanodon were large, bulky herbivores. Distinctive features include large thumb spikes, which were possibly used for defense against predators, combined with long prehensile fifth fingers able to forage for food.

The genus was named in 1825 by English geologist Gideon Mantell, based on fossil specimens that are now assigned to Therosaurus and Mantellodon. Iguanodon was the second type of dinosaur formally named based on fossil specimens, after Megalosaurus. Together with Megalosaurus and Hylaeosaurus, it was one of the three genera originally used to define Dinosauria. The genus Iguanodon belongs to the larger group Iguanodontia, along with the duck-billed hadrosaurs. The taxonomy of this genus continues to be a topic of study as new species are named or long-standing ones reassigned to other genera.

Scientific understanding of Iguanodon has evolved over time as new information has been obtained from fossils. The numerous specimens of this genus, including nearly complete skeletons from two well-known bonebeds, have allowed researchers to make informed hypotheses regarding many aspects of the living animal, including feeding, movement, and social behaviour. As one of the first scientifically well-known dinosaurs, Iguanodon has occupied a small but notable place in the public's perception of dinosaurs, its artistic representation changing significantly in response to new interpretations of its remains.