“西施”河豚     

陈万青 《海洋世界》2009,(11):54-57

河豚，学名河鲍。它有着长椭圆形的身体，粗而圆的头胸部，钝圆的吻部，上下颌骨愈合而成的四个大牙板。它的身体光滑无鳞，没有腹鳍，体内有气囊，遇敌袭击或受到刺激时，气囊充气而使腹部膨胀。内脏有巨毒。河豚分布于温热带近海，以虾、蟹、海胆、乌贼和鱼等为食。在生物分类学上，它属于纯形目，纯科。  相似文献   

河北蔚县大南沟晚更新世草原猛犸象(长鼻目|哺乳动物纲)          下载免费PDF全文

同号文 《第四纪研究》2010,30(2):307-318

在泥河湾盆地真象化石十分常见。  近年来,在泥河湾层中新发现了世界上最早的草原猛犸象(Mammuthus trogontherii)化石,过去被归入古菱齿象的部分材料也被转移到该种;  但以往报道的材料都很零碎,并且时代也较早。本研究的发现于蔚县大南沟东陡壁附近的长鼻类下颌骨(完好下颌体带左右m3)亦可归入该种,主要依据如下特征: 喙突(或吻突)不发育、下颌联合部短、下颌体前缘陡直、具有舌侧神经孔、颊齿齿板中间突不发育和釉质环无菱形结构、下第三臼齿有×18个齿板、齿板较薄、齿板频率为6、釉质层较薄但褶皱不强烈等。蔚县大南沟的化石是迄今在我国所发现的材料最完好和地质时代最晚的草原猛犸象化石记录,距今约4.5万年。  相似文献   

Fossils of Macaca mulatta from Tianyuan Cave,with Notes on Some Previously Unpublished Specimens of Macaca from Zhoukoudian Area     

TONG Haowen 《《地质学报》英文版》2014,88(5):1397-1408

The recently discovered macaque fossils, including isolated teeth and mandible fragments, from Tianyuan Cave and the juvenile maxilla from Wanglaopu Cave near Zhoukoudian can be identified as Macaca mulatta; they represent the first recognized occurrence of fossil M. mulatta in the far north of China. Some previously unearthed but still unpublished Macaca specimens were also studied, including a cranium and the associated mandible from CKT Loc.13A, a maxilla and a mandible from Loc.1, a mandible from Loc.4, and a maxilla from Loc.20, as well as a mandible with complete toothrow from Zhoukoudian but without locality details, all of them can be referred to M. robusta. The study shows M. robusta is more closely related to M. mulatta than to M. anderssonL Zhoukoudian is the richest area of Macacina fossils in North China, totally 2 genera and 4 species were once recognized from 9 localities, namely, Procynocephalus wimani, M. cf. anderssoni, M. robusta and M. mulatta. The fossil records of Macacina in Zhoukoudian area were almost continuous through the Quaternary Period, and it＇s reasonable to assume that Zhoukoudian used to be an evolutionary center for macaques in North China. Therefore, the macaque population of M. mulatta once existed decades ago around Beijing probably originated from the Pleistocene ancestors in the local area, rather than being human-introduced as previously thought.  相似文献