【作者】 欧阳辉；

【导师】 王成善；

【作者基本信息】 成都理工大学 ， 古生物学及地层学， 2003， 博士

【摘要】 中国最著名的蜥脚类恐龙——马门溪龙,因长期缺乏可靠的头骨及全面的描述,致使分类位置众说纷纭,影响了对整个蜥脚类系统发育历史的讨论。本文选择已知保存最好的马门溪龙标本——杨氏马门溪龙为研究对象,对其较完整的骨架,尤其是完好的头骨进行了详细描述。对比分析查明:马门溪龙具有圆顶龙类型的头骨,头后骨骼具有既不同于圆顶龙—腕龙类,也不同于梁龙—叉龙类的特性,故建议将马门溪龙及其相似的属种——峨眉龙、盘足龙等,作为蜥脚类一个单独的科级分类阶元对待,称马门溪龙科。该科以头骨轻巧、头骨孔发达、鼻孔侧位、牙齿勺状、下颌瘦长为特征;头后骨骼则以颈部特长,颈椎数目多,颈肋细长为主要特征;前部尾椎在早期属种中为平凹形,在后期属种中均为前凹形。 本文对较为罕见的蜥脚类恐龙的皮肤化石和巩膜环做了详细描述和报道,同时对杨氏马门溪龙的脑腔、齿腔还运用计算机辅助断层扫描技术(CT)进行了观察,发现其脑腔甚小,但脑腔中已出现较进步的结构分区。蜥脚类的牙齿替换具有连续性,新牙的生长与老牙的齿根吸收是同时进行的;齿根吸收越多的牙齿,其齿冠的磨蚀迹也越显著。杨氏马门溪龙牙齿的磨蚀迹还揭示,这种植食性恐龙的食料可能较为粗糙。马门溪龙类细长的颈肋使颈部强度增强,可是也限制了颈椎间的相对活动以及整个颈部的柔韧性,使颈部变得僵硬,故其长颈不大可能像长颈鹿一样伸向高处,其觅食的适宜高度估计不会超过肩部高度的2米。 本文提出了新的蜥脚类恐龙系统分类方案,建议以马门溪龙科与火山齿龙科、蜀龙科、圆顶龙科、腕龙科、叉龙科、巨龙科构成蜥脚类分类的基本框架。蜥脚类由进步的原蜥脚类通过早、中侏罗世的原始蜥脚类演化而来,其中马门溪龙类主要分布于东亚地区,在中侏罗世就已从原始蜥脚类中分化出来,并在侏罗纪晚期达到繁盛和演化的高峰,进入白垩纪后则走向衰亡。在众多蜥脚类中,马门溪龙与峨眉龙是最容易混淆的两个属,它们的最大差别在于前部尾椎形态。生活于中侏罗世的峨眉龙的前部尾椎为微弱双凹型或平凹型,生活于晚侏罗世的马门溪龙的前部尾椎为前凹型。按此标准,“长寿峨眉龙”、“釜溪峨眉龙”、“毛氏峨眉龙”均该归入马门溪龙。目前,除“井研马门溪龙”因材料混杂而命名可疑外,马门溪龙属的有效种共5个,即建设马门溪龙、杨氏马门溪龙、合川马门溪龙、安岳马门溪龙和中加马门溪龙。更多还原

【Abstract】 Previous opinions on the phylogenetic position of Mamenchisaurus, the most famous sauropod from China, varied because of the lack of the reliable skull and its complete description. This disadvantage has seriously affected and postponed scientific understanding of the phylogenetic history of the entire Sauropoda. Fortunately, the specimen best preserved known up to date of mamenchisaurs, Mamenchisaurus youngi, turned to be available to this study, so that a detailed description of its complete skeleton framework, specially of its skull, has become feasible. The results indicate that Mamenchisaurus has a camarasaurid-type skull and characteristic postcranials, which are different not only from those of camarasaurids-branchiosaurids, but also from those of diplodocuds-dicraeosaurids. Thus, it is suggested that Mamenchisaurus and some similar long-necked genera, such as Omeisaurus and Euhelopus, should be recognized as a distinct sauropoda branch, Mamenchisauridae. The skull of this family is characterized by its lighter structure with large opening, spatulate crown and thin mandibular. The characteristics of its postcranial skeleton include a very long neck, counting 17-19 cervicls associated with long and striaght cervical ribs. The tail is shorter than the neck and the chevrons in the middle caudals are forked. The posterior cervical and anterior dorsal spines are not bifurcated and the anterior caudals are slightly amphicoelous or platycoelous in primitive forms, while in the advanced forms they have the bifurcated spines both on their posterior cervicals and anterior dorsals, and the precoelous centrum on their proximal caudals.Visual descriptions for the sclerotic ring and the fossilized skin of sauropods, which are rarely discovered, are presented here in this thesis. The computerized tomography (CT) scanning technology was used to investigate the cavity structures of the brain and tooth of the Mamenchisaurus youngi. The result displays that this dinosaur had a relatively small brain cavity (less than 80 ml), but with relatively advanced structural divisions, and that its teeth replacement was continuous in life. The absorption of an old tooth root was accompanied with the growth of a new tooth. The more the absorption amounts of the roots, the more prominent the worn facets on the crown. The developed worn facets of teeth also show that the food of更多还原