Lower Cambrian phosphatized Punctatus from southern Shaanxi and their ontogeny sequence

Phosphatized and three-dimensionally preserved embryos and spherical fossils of metazoan recovered from the Kuanchuanpu Member, Dengying Formation in southern Shaanxi, China provide nice devel- opmental sequence for the studies of origination, taxonomy, phylogenic evolution and developmental biology of early animals. Ontogeny of these larva fossils has not been systemically studied mainly due to their poor preservation and limited identification. The Kuanchuanpu Member, predominated by phosphorites and cherts, yields phosphatized animal embryos, particularly those of Olivooides and Punctatus which have high resolution in fine structures and different ontogeny developmental stages. An ontogenetic sequence of the Punctatus is established mainly base on its developmental transitions from body part to oral one, which is perfectly consistent with the embryonic ontogeny sequence pro- posed by Bengtson and Yue (1997). Furthermore, a new genus Quadrapyrgites gen. nov is erected to receive a larva with tetraradial body plan.     

陕西镇巴早寒武世的牙形刺形化石

记述了陕西镇巴小洋坝下寒武统筇竹寺阶灯影组西蒿坪段及水井沱组内的一些牙形刺形化石,共计4个属7个种,其中新属及新种各一个,我国首次发现的有2属4种。它们中的许多分子具有地理分布广泛、演化迅速的特点,已成为早寒武世洲际地层对比的重要依据。     

Sponge fossil assemblage from the Early Cambrian Hetang Formation in southern Anhui

Abundant well-preserved large articulated sponge fossils and isolated spicules have been reported from the Early Cambrian Hetang Formation, southern Anhui Province. This unique epifaunal fossil assemblage dominated by articulated sponge fossils is called the Xidi Sponge Fauna. The sponge fauna lived in a quiet oxygenic environment below the storm wave base. Bloom of phytoplankton and rapid sedimentation rate resulted in the deposition of the black shales. Sufficient food supply, lack of other competitors, abundant ecological niches, and demand for oxygen during early Cambrian were in favor of the diversification and evolution of large sponges in the Early Cambrian.     

Early Cambrian protoconodonts and conodont-like fossils from China: Taxonomic revisions and stratigraphic implications

Tooth likephosphaticprotoconodontsand“con odont likefossils”arecharacteristiccomponentsoftheEarlyCambriansmallshellyfossils (SSF )withaworldwidedistribution .Theyarerepresentedexclu sivelybyisolatedscleritesandareoften presentinaceticacid etchedresiduesfromLowerCambriancar bonates .SincethefirstreportofProtohertzinaMis sarzhevsky 1973fromthebasalCambrianoftheYangtzePlatformin 1977[1] ,andalongwithenthusi asticresearchactivitiesonthesmallshellyfossilsandcandidatesectionsforaglobalPrecamb…     

Pyritization in the Gaojiashan Biota

The Late Sinian (Ediacaran) Gaojiashan Biota was a soft-bodied fossil-Lagersttte dominated by sub-stantial pyritized, three-dimensionally preserved tubular and conotubular fossils. Soft-tissue pyritiza-tion is extremely scarce in the fossil records, especially in the Precambrian, therefore it has very im-portant and unique significance for the study of pyritization in the Gaojiashan Biota. Early pyritization played a pivotal role in the fossil preservation and two main factors ensured the successful pyritization of the fossils, namely rapid burial and permineralization. The former was controlled by secular storm deposition, and the latter was achieved by sufficient supply of available iron from sediments. SEM data of Conotubus demonstrate two types of preservation of the tubes (defined as type A and type B, re-spectively). In type A, pyritization took place relatively earlier and completely preserved both tube wall and coelom, but no detailed structure. While in type B, pyritization took place somewhat later and pre-served the integrated tube wall, but partially the coelom. The size frequency distribution of the pyrite framboids suggests that pyritization took place in two different environments with entire different oxygen content.     

A Chengjiang-type fossil assemblage from the Hongjingshao Formation （Cambrian Stage 3） at Chenggong,Kunming, Yunnan

A new Chengjiang-type fossil assemblage is reported herein from the lower part of the Hongjingshao Formation at Xiazhuang village of Chenggong,Kunming,Yunnan.The fossil assemblage,named as Xiazhuang fossil assemblage,yields predominantly soft-bodied fossils,including arthropods,brachiopods,priapulids,lobopods and some problematic taxa,with arthropods being the most dominant group.Preservation and composition of the fossil assemblage are very similar to the typical Chengjiang biota,which is preserved in the middle Yu’anshan Formation in the large area of eastern Yunnan.The associated trilobites demonstrate that the soft-bodied fossil assemblage belongs to the late Qiongzhusian in age(Stage 3,Cambrian),suggesting that the Hongjingshao Formation is probably a diachronous lithostratigraphic unit ranging from the upper Qiongzhusian to the lower Canglangpuan stages in eastern Yunnan.The fossil assemblage from the Xiazhuang area fills up the missing link between the typical older Chengjiang biota and the younger Malong and Guanshan biotas,making eastern Yunnan a unique area in the world to reveal the early evolutionary history of animals and palaeocommunity dynamics during the‘‘Cambrian explosion’’.     

大叶相思体细胞胚胎发生的初步研究

以种子萌发的无菌苗下胚轴为外植体，在Ｂ５＋２，４－Ｄ（１０－４ｍｏｌ／Ｌ）＋ＢＡ（１０－６ｍｏｌ／Ｌ）＋ＣＨ０．５ｇ／Ｌ的固体培养基上培养４周，获得了胚性愈伤组织．该愈伤组织经Ｂ５＋２．４－Ｄ（１０－４ｍｏｌ／Ｌ）的液体培养基７ｄ的诱导在Ｂ５＋Ｌ－谷氨酰胺（２００ｍｇ／Ｌ）＋ＣＨ（０．５ｇ／Ｌ）的液体培养基上培养１４ｄ产生了球形胚．球形胚具有明显的两极，但只是根端发育，苗端并没有发育     

Lower Cambrian yolk-pyramid embryos from Southern Shaanxi, China

TheCambrianexplosioniswidelyacceptedasthesuddenappearanceofnumerousbilateriananimalphylaatornearthebeginningofCambriantime[1,2 ] .The 5 30 million year oldMaotianshanShalefaunacontainstheoldestgoodwhole bodyfossilsofbilateri ans,documentinganincreasingnumberofpresent dayanimalphyla[3,4 ] orsubphyla[5] (evenincludingvertebrates[6～ 8] aswell)knownfromLowerCambri an .ThebeginningoftheCambrianperiodisdatedat5 43millionyearsago ,whenthefirstlargeandelabo ratefossilburrowstogetherwiththemicrosco…     

疑源类的早期辐射及其意义

通过对元古宙至寒武纪早期疑源类的分析研究表明 :新元古代早期和晚期疑源类的辐射分别与全球范围内超级大陆 （rodinia）形成及海洋中锶同位素 87Sr/86Sr值显著上升 ,陆源物质增加 ,δ13 C值由负值转为正值的时期相吻合 ;早寒武世疑源类的辐射与超级大陆 （pannotia）的形成、裂解对全球环境的影响有关。认为疑源类在早寒武世的适应辐射 ,改变了全球生物的营养结构 ,“中型浮游动物”对小个体棘刺疑源类的有效利用 ,可能是引发“寒武爆发”的原因之一     

寒武纪叶足动物与现生有爪类的亲缘关系再讨论

目的 对位于中国云南省东部的早寒武世澄江化石库保存的软躯体构造的叶足动物化石进行系统研究,探究叶足动物这一灭绝类群与现生有爪类的亲缘关系.方法 将叶足动物化石与现生有爪类进行形态对比分析,详细讨论它们之间可能的近裔特征,从生物演化角度系统探究两者之间的亲缘关系.结果 叶足动物与现生有爪类亲缘关系相对较远.结论 现生有爪类极有可能是叶足动物演化过程中的一个侧支.     

贵州台江早寒武世台江动物群的发现及意义

贵州台江八郎凯里组剖面中下部中、下寒武统界线之下厚达１５米左右的粉砂质泥岩、页岩中存在着一个类似凯里动物群的台江动物群,由８个门类３９个属组成,核心为蠕形动物,三叶虫数量很多。形成于内陆棚浅海环境。时代为早寒武世末期,介于著名的早寒武世早期澄江动物群和中寒武世早期凯里动物群之间,对于早期后生动物的演化研究具有重要的意义。     

早寒武世疑源类的古生物地理学意义

根据早寒武世疑源类在全球的古地理分布 ,并参考古地磁和动物化石等方面的资料 ,进行了早寒武世疑源类的古地理分区。结果表明 :早寒武世在全球范围内可分为 2个疑源类古地理大区 ,即波罗的海 -北美 -亚、澳大区和地中海大区 ;我国西南地区早寒武世筇竹寺期 ,可根据疑源类分为两个生态区 ,即扬子区和江南区。这一研究结果为今后各区生态结构分析 ,提供了重要基础资料     

陕南城镇体系结构的分形研究

对陕南城镇体系的分形研究发现:等级规模结构的分形特征不太典型,区域中心城市作用不强;在空间结构方面,聚集维数显示空间集聚分形特征明显,区域性中心城市外围形成由中心向四周密度递减的城镇体系,具备成为区域增长极的条件;关联维数显示城镇体系内交通网络通达性较好,各城镇之间具备开展经济协作的基础设施条件。基于上述结论,应大力加强区域性中心城市建设,增强辐射带动能力,同时各城镇之间应开展经济合作,进一步促进经济活动的空间集聚。     

The earliest-known ancestors of Recent Priapulomorpha from the Early Cambrian Chengjiang Lagersttte

It was suggested and eventually has been profferedthat the representatives of all extant phyla, including someminor group, occurred during the Cambrian radia-tions[1—10]. Many priapulid-like fossil worms have beenreported from Cambrian Lagerst?tten, such as the EarlyCambrian Chengjiang Lagerst?tte[11—16], the Middle Cam-brian Burgess Shale[17], and the Middle Cambrian Kailifauna[18]. The palaeoscolecidan worms from these Lager-st?tten have been regarded as either a stem group of thepri…     

陕南镇巴早寒武世高肌虫新属种

本文记述了陕南镇已早寒武世高肌虫,计有18个属29个种及3个未定种,其中包括9个新属、1个新亚属及22个新种。这些化石均产于该地区下寒武统水井沱组下部,相当于三叶虫Eoredlichia带至Zhenbaspis带下部。