Abstract: Lizards are now relatively well known from the Jehol Group of northeastern China, seven taxa having been named from the group or equivalent horizons. Here we describe a lizard specimen from a fossil horizon at Daohugou of Ningcheng, Nei Mongol, which predates the Yixian Formation of the Jehol Group. This is the second lizard from this locality. Comparisons with ontogenetic series of modern lizards show that the new Daohugou lizard is a juvenile. The specimen is notable in having a slender body and relatively long limbs and extremities. Even allowing for immaturity, its proportions differ markedly from those of previously described Jehol Biota lizards. Comparison with modern lizards suggests the new Daohugou lizard may have been at least partly scansorial. Its phylogenetic placement is problematic given its immaturity and preservation, but skull characters and vertebral number preclude attribution to Iguania and it may be a scleroglossan.

摘要： 道虎沟化石层分布于内蒙古宁城县道虎沟以及毗邻的河北北部和辽宁西部等地,已报道4 种有尾类、1 个无尾类蝌蚪、1 个幼年蜥蜴、3 种带原始羽毛的兽脚类恐龙、2 种翼龙、3 种哺乳动物以及双壳类、叶肢介、昆虫和植物等化石(有学者称之为“前热河生物群”)。该层位比热河群义县组低,但地层划分存在争议:中侏罗统九龙山组、上侏罗统道虎沟组和下白垩统热河群均有报道。本文研究的道虎沟蜥蜴是该地点发现的第2 个蜥蜴化石,其身体细长,为一幼年个体;前颌骨、顶骨和额骨均成对;上颌骨的面突高;后额骨和后眶骨不愈合;后额骨较大,但可能未进入上颞孔;后眶骨具宽的后突;牙齿小而尖锐,结构简单且可能为侧生;头骨的眶前区较长;具27 个荐前椎;虽然未成年但个体较大;未见真皮骨板;手掌和四肢较长。上述特征组合区别于所有现生蜥蜴类,四肢比例也与其他蜥蜴有较大区别。欧美中侏罗世- 早白垩世的小盗蜥(Parviraptor)和蒙古早白垩世的一个幼年个体(可能属于壁虎型类)与道虎沟标本比较相似。头骨特征和较大的荐前椎数目显示道虎沟标本可能属于硬舌蜥类(scleroglossan)。但因标本为幼年个体,本文暂将它归入有鳞类属种未定(Squamata gen. et sp. indet. )。测量数据显示,道虎沟标本的手掌和前肢相对较长;该特征常见于适应攀爬的蜥蜴种类,似可显示攀爬习性。但肢体比例可能会随身体增长而发生变化,所以此生活习性并非定论。