Abstract:  A new non-hadrosaurid hadrosauroid dinosaur (Datonglong tianzhenensis gen. et sp. nov.) is reported. The new taxon is recovered from the Upper Cretaceous Huiquanpu Formation of Tianzhen County, Shanxi Province in northern China, and represented by an almost complete right dentary with dentition. Different from all other hadrosauroids, Datonglong possesses two functional teeth in each alveolus, and the pattern of ridge development on the lingual surface of its dentary crown shows a unique combination of character states (for example: distally offset primary ridge; well-developed secondary ridge; no additional ridge(s); slightly distally curved apical half of primary ridge). Comparative studies indicate advanced non-hadrosaurid hadrosauroids experienced a complex pattern in the evolution of their dentary, especially dentary dentition. Derived hadrosaurid features occurred frequently in these taxa, such as high height/width ratio of tooth crown in Bactrosaurus, one primary and one faint ridges inGilmoreosaurus, median placed primary ridge in Zhanghenglong, rostrally inclined coronoid process in Nanningosaurus, and two functional teeth in each alveolus in Datonglong. This implies incredible diversities and attempts close to the origin of Hadrosauridae and difficulties to elucidate their phylogenetic relationships. 

摘要： 记述了山西天镇晚白垩世灰泉堡组发现的一鸭嘴龙超科恐龙新属种：天镇大同龙Datonglong tianzhenensis gen. et sp. nov.。标本为一保存较完好的右侧齿骨并带牙齿。与其他鸭嘴龙超科恐龙不同，大同龙每个齿槽有两个功能齿，而且舌面齿冠上嵴的发育也具有独特的特征组合(主嵴向远中方向偏移；次嵴发育；无其他附嵴；主嵴上半段略后弯)。对比研究发现，在较进步的非鸭嘴龙科鸭嘴龙超科类群中齿骨和牙齿的演化过程复杂，许多鸭嘴龙科的特征在这些类群中时而出现，如：巴克龙Bactrosaurus齿冠具有较大的高/宽比；吉尔摩龙Gilmoreosaurus齿冠上只有一个主嵴和纤弱的附嵴；张衡龙Zhanghenglong齿冠上主嵴中置；南宁龙Nanningosaurus下颌冠状突前倾；大同龙Datonglong每个齿槽有两个功能齿。这表明为了获得更有效的牙齿咀嚼方式，在鸭嘴龙科起源前它的姐妹群们曾进行过多种尝试；这也告诫我们受大量趋同演化的影响要厘清这些类群间的关系并非易事。