An Updated Review of the Middle-Late Jurassic Yanliao Biota: Chronology, Taphonomy, Paleontology and Paleoecology

The northeastern Chinese Yanliao Biota (sometimes called the Daohugou Biota) comprises numerous, frequently spectacular fossils of non-marine organisms, occurring in Middle-Upper Jurassic strata in western Liaoning, northern Hebei, and southeastern Inner Mongolia. The biota lasted for about 10 million years, divided into two phases: the Bathonian-Callovian Daohugou phase (about 168-164 million years ago) and the Oxfordian Linglongta phase (164-159 million years ago). The Yanliao fossils are often taphonomically exceptional (many vertebrate skeletons, for example, are complete and accompanied by preserved integumentary features), and not only are taxonomically diverse but also include the oldest known representatives of many groups of plants, invertebrates, and vertebrates. These fossils have provided significant new information regarding the origins and early evolution of such clades as fleas, birds, and mammals, in addition to the evolution of some major biological structures such as feathers, and have demonstrated the existence of a complex terrestrial ecosystem in northeast China around the time of the Middle-Late Jurassic boundary.     

冀北承德盆地早白垩世火山-沉积地层地质年代学研究: 对热河生物群时空演化的制约

热河生物群是世界闻名的陆相生物化石宝库, 保存了大量特异埋藏化石, 为研究早白垩世脊椎动物、昆虫和植物的演化提供了绝佳的素材.依据古生物组合的不同, 将其分为早、中、晚三期, 分别赋存于河北丰宁花吉营组、辽西义县组和九佛堂组及其周边地区相当层位.河北承德—围场地区处于早-中期热河生物群分布地区的过渡地带, 近年来不断的化石发现为研究华北克拉通破坏及其对陆地生态系统的影响提供了关键证据.但由于缺乏准确的年龄约束, 对于含化石层位的准确时代及其与邻区地层对比存在较大争议.本文利用来自于河北北部承德盆地袁家庄剖面的3个安山岩样品的锆石, 进行化学熔蚀-离子探针(CA-SIMS)锆石U-Pb定年, 获得年龄为129.6~128.7 Ma.结合前人发表的磁性地层学结果建立了新的磁性地层学对比方案和新的综合年代框架, 揭示了该剖面火山-沉积序列记录了古地磁极性序列M8n-M7n, 进一步证明了袁家庄剖面的陆相火山-沉积层序属于欧特里夫晚期.结合区域内前人年代学结果, 将该区域热河生物群化石层时代限定为130~127 Ma.年代地层学对比结果显示, 承德盆地早白垩世火山-沉积序列与滦平盆地大店子组和森吉图—四岔口盆地花吉营组上部时代相当, 明显老于辽西义县组时代, 揭示了华北克拉通北缘早白垩世陆相地层的自西向东逐渐年轻的特征.

     

燕辽生物群叶肢介动物群组成和演化*

中国北方著名中、晚侏罗世的燕辽生物群含有丰富的叶肢介动物群。早期燕辽生物群也称为道虎沟生物群,主要产出层位为海房沟组,含有三饰叶肢介动物群,主要分子包括: 海房沟三饰叶肢介(Triglypta haifanggouensis)、滦平三饰叶肢介(T.luanpingensis)和平泉三饰叶肢介(T. pingquanensis)。晚期燕辽生物群又可称为玲珑塔生物群,主要产出层位为髫髻山组,含有丰富的叶肢介化石,主要分子包括: 建昌三饰叶肢介(Triglypta jiancangensis)、玲珑塔辽西叶肢介(Liaoxiestheria linglongtaensis)、大西山玲珑塔叶肢介(Linglongtaestheria daxishanensis)和青龙玲珑塔叶肢介(Linglongtaestheria qinglongensis)。文中总结了北方雕饰叶肢介(Aquilonoglypta)、柴达木叶肢介(Qaidamestheria)和针孔叶肢介(Punctatestheria)的最新研究成果,支持将柴达木叶肢介、辽西叶肢介和玲珑塔叶肢介划归北方雕饰叶肢介科。同时,三饰叶肢介是由针孔叶肢介演化而来,与柴达木叶肢介并无直接演化关系。     

A new lizard (Reptilia: Squamata) from the Lower Cretaceous Yixian Formation of China,with a taxonomic revision of Yabeinosaurus

Yabeinosaurus was the first lizard genus described from the Early Cretaceous Jehol Biota of China. The holotype of the type species, Y. tenuis, is an immature skeleton but it has been lost for decades. A second species, Y. youngi, was erected based on another immature skeleton and is distinguished by its longer, more gracile limbs. In 2001, a juvenile skeleton from the Jingangshan locality of Liaoning was designated as the neotype for Y. tenuis. Subsequently, several further specimens from other localities, juvenile and adult, have been attributed to this species. Here we describe a second lizard specimen from the neotype locality. In anterior tooth shape, finger-like mandibular angular process, cranial sculpture, maxilla shape, and short, robust humerus, the new specimen resembles adult and subadult material currently attributed to Y. tenuis, but it differs in having bicuspid posterior teeth and a straight rather than a hooked angular process of the mandible. We propose a new species (Y. bicuspidens sp. nov.) for this specimen which represents the first occurrence of bicuspid teeth in an Early Cretaceous lizard from China. However, the recognition of a second species at the neotype locality raises a taxonomic problem. Due to the immaturity of the designated holotype and neotype of Y. tenuis, they cannot be coded for the jaw and dental characters that distinguish the two robust-limbed species. This renders Yabeinosaurus tenuis a nomen dubium. Here we propose that Yabeinosaurus tenuis should be treated as a historic taxon, permitting retention of the generic name under ICZN rules, and erect a second new species (Y. robustus sp. nov.) for the principal robust-limbed morphotype in the Jehol Biota with monocuspid posterior teeth and a hooked angular process.     

辽东半岛南部晚先寒武纪宏体生物序列

辽东半岛市部上先寒武系自下而上划分为4群15组,其中细河群的三个组即钓鱼台组、南芬组、桥头组产宏观藻类化石;五行山群的长岭子组、南关岭组产蠕虫和宏观藻类化石;金县群兴民村组产类水母化石,葛屯组产蠕虫、宏观藻类化石,上覆的下寒武统碱厂组产三叶虫和古杯动物化石。上先寒武系7个宏体生物化石层位构成一个连续的、完整的宏体生物序列,可分为4个演化阶段:①细河期宏观藻类发生发展阶段;②五行山期蠕虫发生发展阶段和宏观藻类发展阶段;③兴民村期类水母发生发展阶段;④葛屯期蠕虫和宏观藻类新的发展阶段。据此可以划分为4个生物群,即细河生物群(800Ma前)、五行山生物群(800—700Ma)、金县生物群(677Ma)、满家滩生物群(600Ma)。另外早寒武世三叶虫和古杯动物组成葫芦套生物群,为早寒武世晚期。辽东半岛与苏皖北部晚先寒武纪地层不仅沉积序列相同,而且宏体生物序列也基本相同,两区生物地层完全可以对比。辽东半岛南部晚先寒武纪宏体生物序列的建立及其在同一地层区的延展性,提高了本区晚先寒武纪地层剖面的地位。使其可能成为全球晚先寒武纪生物地层层型剖面。     

中国东北地区二叠纪生物混生机制讨论

生物混生现象是指不同生物古地理区系的生物出现于同一地区的同时代地层中,表明它们曾同时或略为先后地生活或埋藏在一起。中国东北地区早二叠世时期出现明显的北方冷水动物群（归属北方大区准噶尔－兴安生物省）与特提斯暖水动物群（归属特提斯大区内蒙－吉林生物省）的混生现象;晚二叠世出现安加拉植物群（Ａｎ－ｇａｒａｆｌｏｒａ）与华夏植物群（Ｃａｔｈａｙｓｉａｎｆｌｏｒａ）的混生。对于这些生物混生的机制及阻隔生物迁移扩散的障岩的详细研究,对于解决中国北方二叠纪古海盆性状和南北板块最终缝合带的位置等问题具有重大意义。     

Fossil coniferous wood from the Early Cretaceous Jehol Biota in western Liaoning,NE China: New material and palaeoclimate implications

The Early Cretaceous Jehol Biota, one of the most important Mesozoic lagerstätten in East Asia, is especially well-known for occurrences of fossil feathered dinosaurs and early angiosperms. However, the terrestrial biodiversity, especially the fossil wood record, is poorly known. In this study, several structurally preserved coniferous wood specimens from the Lower Cretaceous Yixian Formation are investigated, based on collections from the Heichengzi Basin in Beipiao of western Liaoning, Northeast China. Four species referred to four genera of fossil wood are described, including Taxodioxylon heichengziense sp. nov., Thujoxylon beipiaoense sp. nov., Sciadopityoxylon liaoningense Ding and Protocedroxylon shengjinbeigouense sp. nov. These new records enlarge the fossil wood diversity of the Yixian Formation up to 10 species in 9 genera, and provide further insights into the forest vegetation composition of the Early Cretaceous Jehol Biota. Systematic analysis of the floral constitution indicates that the petrified forests of the Yixian Formation are dominated by conifers, represented by Araucariaceae, Podocarpaceae, Sciadopityaceae, Pinaceae and Cupressaceae in the western Liaoning region. Palaeoclimatical analysis of the fossil wood assemblage implies that the western Liaoning region was dominated by a cool temperate, wet and seasonal climate with variable interannual water supply in the western Liaoning region during the Early Cretaceous.     

First record of fossil comb-clawed beetles of the tribe Cteniopodini (Insecta: Coleoptera: Tenebrionidae) from the Jehol Biota (Yixian formation of China), Lower Cretaceous

A new genus and species Platycteniopus diversoculatus is described from the Lower Cretaceous (Yixian Formation, Laoning, China). The new genus belongs to the tribe Cteniopodini as shown by six visible abdominal ventrites (ventrite 6 is sternite VIII), in comparison with other Alleculinae which have five abdominal ventrites; epistomal canthus of eyes not emarginate; anterior margin of first abdominal ventrite not bordered. On the other hand, Platycteniopus diversoculatus has some characters not typical for Cteniopodini: bifid mandibles and serrate antennae. The oldest representative of the tribe has combination of characters of tribes Alleculini and Cteniopodini. Recent representatives of Cteniopodini are associated with flowers of angiosperms, while other groups of Alleculinae, especially Gonoderini and Alleculini are mainly saprophagous and lichenophagous. Age of Platycteniopus finding coincides with the beginning of the angiosperms heyday.     

寒武系底部宽川铺生物群中的卵裂胚胎过程:来自化石薄片的证据

陕南寒武纪早期宽川铺生物群中保存的大量磷酸盐化动物胚胎化石为古生物研究开辟了一个新领域。目前已报道了囊胚期之后不同发育阶段的胚胎化石标本,并且初步建立了从光滑球形胚胎化石Olivooides到带有瘤刺的锥体化石Punctatus的发育序列,而对卵裂期的胚胎化石却鲜有报道。基于通过醋酸浸泡获得的多枚卵裂期、囊胚期及原肠胚期的三维化石标本,加上应用岩石切片技术获得的卵裂期胚胎化石的切片标本,共同见证了从单个卵细胞(Olivooides)经卵裂到囊胚、原肠胚的完整胚胎发育序列。新化石材料的发现,不仅填补了宽川铺生物群中卵裂期胚胎化石的空白,完善了从单个卵细胞(Olivooides)经卵裂到囊胚、原肠胚,再到孵化的锥形幼体(Punctatus)的完整胚胎发育序列,而且通过与贵州瓮安生物群中卵裂期细胞胚胎化石及一些现生的低等动物卵裂期胚胎的对比,对揭示Olivooides胚胎的卵裂过程和特点,探讨其亲缘关系,以及后生动物的早期演化提供了新的化石证据。     

中华弓鳍鱼科的古生物地理及地层对比意义

中华弓鳍鱼科(Sinamiidae)是全骨鱼类弓鳍鱼目中已经绝灭的一个支系,目前只在亚洲东部的早白垩世陆相沉积中有发现,是热河生物群的重要成员。该科现有3属8种,分布范围最北可达中国东北最北部,最南至东南亚的泰国,向西可至甘肃省的酒泉盆地,向东可及日本中部。其中中华弓鳍鱼属Sinamia是热河脊椎动物群属级分类单元中地理分布最广阔的。中华弓鳍鱼科在多个地方性鱼群中也都有出现,这些鱼群分别为:中国华北、东北及西北部分地区的Lycoptera-Peipiaosteus鱼群(包括酒泉盆地的Jiuquanichthy鱼群),中国华南、日本、朝鲜的Mesoclupea-Paraclupea鱼群(包括日本的石?白鱼群、胁野鱼群和韩国的洛东鱼群),以及泰国东部的早白垩世鱼群。中华弓鳍鱼科的分布特征是早白垩世东亚地区自成一个古生物地理区系的证据之一,化石已知时代延限为早白垩世Barremian-Albian期,在Aptian期达到最大分布范围。广泛的分布、集中的时代延限、鲜明的鉴定特征使得此类化石非常有助于提高地层对比的精度,或者提供很好的验证。