澄江生物群中的卵形川滇虫

近年来在云南昆明附近的海口镇和大板桥地区发现大量的节肢动物卵形川滇虫化石,这些化石隶属于澄江生物群,其所处的地层是下寒武统玉案山组。卵形川滇虫化石的不断发掘使得对该属种化石的研究和认识能在很大程度上取得新的进展。文章基于相当数量化石的信息统计,首先对化石保存的多种方式进行总结并分析其埋藏时的环境条件,其次分析卵形川滇虫一些有趣的生活习性并初步划分卵形川滇虫生长中历经3次蜕皮的发育阶段;对雌雄性个体特征（包括外部形态和内部器官的解剖）进行对照性描述。文中揭示卵形川滇虫的生活环境及运动方式,并将卵形川滇虫与中寒武世瓦普塔虾进行较为详尽的比较,列举两者不可归为一属的可靠证据。     

四川盆地井研—犍为地区寒武系第二统九老洞组古生物化石及其地层划分对比

井研—犍为地区麦地坪组—九老洞组是四川盆地寒武系页岩气重要的勘探目的层,但至今区内缺乏比较可靠的古生物化石资料,严重制约着勘探区地层的精确划分与对比。通过对该地区相关资料的收集和金石1井和金页1井岩心样品的采集分析,在本区九老洞组建立了尖头遵义盘虫(Tsunyidiscus acutus)-阎家寨遵义盘虫(Tsun-yidiscus yanjiazhaiensis)和始莱得利基虫(Eoredlichia)-武定虫属(Wutingaspis)两个三叶虫组合,以及梁山虫(Liangshanella)-小遵义虫(Tsunyiella),朵氏昆明虫(Kunmingella douvillei)-卵形川滇虫(Chuandianella ovata(Lee))-简单虫(Mononotella)和峨眉虫(Emeiella)-粗脊昆明虫(Kunmingella(Validocostatella)fusulus)等三个高肌虫组合,为研究区建立了较为详细的化石对比标准;通过典型化石的分析,对比金石1井和金页1井的地层层位,认为金页1井(3 403 m以下)和金石1井(3 503 m以下)属于深水陆棚相沉积,金页1井(3 403m以上)和金石1井(3 503 m以上)为海水较浅的陆棚沉积带,推测研究区在寒武纪幸运世早期存在局部断陷,造成了沉积环境的重大变化,反映海平面快速下降及随后原断陷盆地的快速充填。     

寒武纪早期宽川铺生物群中圆管螺化石显微结构及显微谱学分析

陕南寒武系底部宽川铺组不仅保存了大量的小壳化石,还以磷酸盐化的方式立体保存了多种软躯体动物的胚胎和成体化石,为研究早期动物矿化模式、个体发育方式以及动物躯体构型的早期辐射过程提供了非常关键的信息。然而宽川铺生物群的研究大多聚焦于化石系统分类及亲缘关系探索,对生物群的沉积背景、埋藏过程和保存模式的分析甚少。本文以宽川铺生物群的核心产出层位——陕西省西乡县大河镇宽川铺组下部磷质碎屑灰岩为研究对象,对其中的一类管状化石圆管螺及其围岩进行了显微结构学和显微谱学综合分析,获得了化石显微结构和关键结构对应的元素、矿物成分等信息,讨论了管状化石圆管螺的埋藏过程和保存模式,并在此基础上对其生物学特征进行了初步探讨。该研究对理解宽川铺生物群的埋藏机制提供了新的线索。     

寒武纪早期锥管状化石Anabarites trisulcatus群居行为的计算流体力学分析

Anabarites trisulcatus是寒武纪早期一类三辐射对称的管栖生物,推测营群居的方式生活在浅海。本文对来自陕南宁强石钟沟剖面寒武系底部宽川铺组的Anabarites trisulcatus进行了计算机流体力学分析。根据化石形态构建3D模型,依据推测的生活环境设计流域参数,进行了单体与群居两种不同生活方式下的流体动力学模拟,结果表明:(1)水动力条件对于底栖Anabarites trisulcatus而言是重要的影响因素;(2)Anabarites trisulcatus以群居的方式生活阻力系数更小,更有利于生存。本文使用计算流体力学的方法对长期存在的功能和生态假说进行定量检验,是微体化石研究新思路的一次有益尝试。     

我国寒武系底部几种磷酸盐化保存的蓝菌类化石

本文系统描述了产于我国寒武系底部磷矿层中的微型蓝菌类化石4属4种,其中Girvanella sp.和Spirellus columnaris产于新疆阿克苏、乌什玉尔吐斯组和云南会泽、安宁朱家箐组中谊村段,Endoconchia lata产于四川峨眉灯影组麦地坪段,Cambricodium capilloides和一块属种名未定的化石产于陕西宁强灯影组宽川铺段,从而丰富了我国寒武系底部磷块岩层中的蓝菌类化石。本文还讨论了上述微型蓝菌类化石有直接磷酸盐化保存和钻孔磷酸盐铸模保存的两种保存方式。     

安徽潜山盆地早第三纪叶肢介化石

笔者于1981年6月与安徽省地质局327地质队李继超工程师前往江苏六合冶山,观察寒武系剖面时,在冶山东部下寒武统深灰色薄层灰岩中,找到金臂虫、三叶虫(Redlichia,Pa-raprotolenella 等)(图版Ⅰ)、无铰纲腕足类以及软舌螺类等化石。金臂虫化石系在本区寒武系第一次发现,也是江苏省境内首次发现。该标本经笔者研究为一新属——Yeshanella。这不仅丰富了金臂虫类化石资料,而且为研究我国东部金臂虫类化石提供重要线索。     

广东省海南岛崖县中寒武世的高肌虫及其地质意义

本文描述的全部高肌虫化石系笔者与西北大学地质系79级同学郭健、冯望云于1982年采自海南岛崖县大茅,共计4科9属19种,其中包括1新科2新属1新亚属13新种和4未定种。依据这些高肌虫的新资料,本文论述了崖县中寒武世高肌虫动物群的特征及其在地质学上的意义,并初步探讨了崖县与澳大利亚Queensland中寒武统底界附近生物地层的划分和对比。一、剖面介绍崖县大茅剖面位于大茅磷矿矿区,仅为中寒武统大茅组部分地层,相当于葛梅钰等(1983)所划分的大茅组1段上部至3段中部。其层序如下:     

川蔓藻属系统分类和演化评述

川蔓藻属Ruppia为沉水单子叶植物,世界广布,主要为咸水和盐水生境,具有重要的生态价值、环境指示作用以及植物系统学研究意义.长期以来,川蔓藻属内种的数目以及属的系统位置一直存在争议.根据已有研究资料,目前川蔓藻属共有5个种--R.maritima、R cirrhosa、R. tuberosa、R, megacarpa和R.tuberosa、R.megacarpa和R.palycarpa得到多数学者的认可.关于其系统位置,主要有隶属于眼子菜科Potamogetonaceae和独立成川蔓藻科Ruppiaceae两种观点.尽管目前许多被子植物分类系统都承认了川蔓藻科.近年来分子系统学研究显示川蔓藻属与丝粉藻科cymodoceaceae和波喜荡科Posidoniaceae有近的亲缘关系,但对川蔓藻属和眼子菜属Potamogeton区别特征的比较结果倾向于支持将其放在眼子菜科.本文还结合川蔓藻属及相关类群的化石记录和果实特征对其演化进行了初步探讨,化石属Limnocarpus和Midravalva被认为是川蔓藻属较早的祖先类群,并认为该属植物应该是由淡水祖先逐渐演变成现在的咸水生长植物.最后,提出了在川蔓藻属未来研究中有待进一步解决的问题.     

湖南西部中寒武世早期蠕虫化石

本文所报道的蠕虫材料,部分是1978年湖南省地矿局405队在湘西花垣县渔塘中寒武统高台组底部(属扬子区)采集的;部分是笔者于1983年在湘西慈利县丛木坪中寒武统敖溪组(属过渡区)采集的。蠕虫是一种软体动物,因而在地层中多数是呈虫管、虫迹保存,成为痕迹化石的一种类型,而其驱体,一般很难保存成化石。迄今为止,我国仅在震旦系内发现有蠕虫虫体化石。如湖南沅陵凉水井升天坪震旦系灯影组的中华燐沙蚕(唐天福等,1978)。另外,汪贵翔也报道在安徽的震旦系亦产有蠕虫化石(汪贵翔,1982)。至于寒武系,在国内尚未见有报道。     

贵州中寒武世凯里生物群双刺吐卓虫(Tuzoia bispinosa)个体发育的研究

大型双瓣壳节肢动物是凯里生物群中重要组成部分,其中吐卓虫属（Tuzoia）最为常见,化石标本达200多件。吐卓虫常见于全球早、中寒武世地层,地理分布广泛,在地层对比和古环境研究中具有重要意义。文章运用数理统计和对比研究的方法,详细检测130多块双刺吐卓虫（Tuzoia bispinosa Yuan and Zhao,1999）化石标本,发现明显可分为幼年期、青年期和成年期3个不同的生长发育阶段。文中探讨双刺吐卓虫的个体发育,确认先前建立的凯里生物群中Tuzoia的2个种：Tuzoia bispinosa和T．magna,应为Tuzoia bispinosa一种。     

Prehistoric Introduction of Domestic Pigs onto the Okinawa Islands: Ancient Mitochondrial DNA Evidence

Ancient DNAs of Sus scrofa specimens excavated from archaeological sites on the Okinawa islands were examined to clarify the genetic relationships among prehistoric Sus scrofa, modern wild boars and domestic pigs inhabiting the Ryukyu archipelago, the Japanese islands, and the Asian continent. We extracted remain DNA from 161 bone specimens excavated from 12 archaeological sites on the Okinawa islands and successfully amplified mitochondrial DNA control region fragments from 33 of 161 specimens. Pairwise difference between prehistoric and modern S. scrofa nucleotide sequences showed that haplotypes of the East Asian domestic pig lineage were found from archaeological specimens together with Ryukyu wild boars native to the Ryukyu archipelago. Phylogenetic analysis of 14 ancient sequences (11 haplotypes; 574 bp) indicated that S. scrofa specimens from two Yayoi-Heian sites (Kitahara and Ara shellmiddens) and two Recent Times sites (Wakuta Kiln and Kiyuna sites) are grouped with modern East Asian domestic pigs. Sus scrofa specimens from Shimizu shellmidden (Yayoi-Heian Period) were very closely related to modern Sus scrofa riukiuanus but had a unique nucleotide insertion, indicating that the population is genetically distinct from the lineage of modern Ryukyu wild boars. This genetic evidence suggests that domestic pigs from the Asian continent were introduced to the Okinawa islands in the early Yayoi-Heian period (1700–2000 BP), or earlier.     

An improved method for estimating original mineral contents in excavated bone using sulfur

Trace element analysis in excavated bones is complicated by the lack of a reliable index for estimating the original amount of bone material. In this study, we subjected modern human bones to alkali treatment to simulate aging. Alkali treatment of vertebrae with attached muscle did not affect sulfur (S) content; it increased the magnesium (Mg), phosphorus (P), and zinc (Zn) contents, and tended to decrease iron (Fe) content of the bones. When vertebrae cleaned of muscle were used, alkali treatment did not affect S and Fe contents but increased Mg, P, Ca, and Zn contents Ca and S contents were higher in excavated bones (200–1300 yr old) than in their surrounding soils. In contrast, S, Mg, and Ca contents per dry weight did not differ between the excavated bones and the alkali-treated modern bones. These results indicate that S can provide a more accurate index of excavated bones than the often-used Ca content or dry wt measures, especially for bones excavated from calcium-rich soils.     

Mitochondrial sequence variation in ancient horses from the Carpathian Basin and possible modern relatives

Movements of human populations leave their traces in the genetic makeup of the areas affected; the same applies to the horses that move with their owners This study is concerned with the mitochondrial control region genotypes of 31 archaeological horse remains, excavated from pre-conquest Avar and post-conquest Hungarian burial sites in the Carpathian Basin dating from the sixth to the tenth century. To investigate relationships to other ancient and recent breeds, modern Hucul and Akhal Teke samples were also collected, and mtDNA control region (CR) sequences from 76 breeds representing 921 individual specimens were combined with our sequence data. Phylogenetic relationships among horse mtDNA CR haplotypes were estimated using both genetic distance and the non-dichotomous network method. Both methods indicated a separation between horses of the Avars and the Hungarians. Our results show that the ethnic changes induced by the Hungarian Conquest were accompanied by a corresponding change in the stables of the Carpathian Basin.     

DNA content and distribution in ancient feathers and potential to reconstruct the plumage of extinct avian taxa

Feathers are known to contain amplifiable DNA at their base (calamus) and have provided an important genetic source from museum specimens. However, feathers in subfossil deposits generally only preserve the upper shaft and feather ‘vane’ which are thought to be unsuitable for DNA analysis. We analyse subfossil moa feathers from Holocene New Zealand rockshelter sites and demonstrate that both ancient DNA and plumage information can be recovered from their upper portion, allowing species identification and a means to reconstruct the appearance of extinct taxa. These ancient DNA sequences indicate that the distal portions of feathers are an untapped resource for studies of museum, palaeontological and modern specimens. We investigate the potential to reconstruct the plumage of pre-historically extinct avian taxa using subfossil remains, rather than assuming morphological uniformity with closely related extant taxa. To test the notion of colour persistence in subfossil feathers, we perform digital comparisons of feathers of the red-crowned parakeet (Cyanoramphus novaezelandiae novaezelandiae) excavated from the same horizons as the moa feathers, with modern samples. The results suggest that the coloration of the moa feathers is authentic, and computer software is used to perform plumage reconstructions of moa based on subfossil remains.     

Room without a view—Den excavation in relation to body size in brown bears

Hibernation is an adaptive strategy to survive harsh winter conditions and food shortage. The use of well‐insulated winter dens helps animals minimize energy loss during hibernation. Brown bears (Ursus arctos) commonly use excavated dens for hibernation. Physical attributes of excavated dens are expected to impact the bear's heat retention and energy conservation. The objective of this study was to examine the determinants of cavity size of excavated dens and the impact of physical attributes of excavated dens on energy conservation in hibernating bears, hypothesizing that bears excavate dens in a way to minimize heat loss and optimize energy conservation during hibernation. We predicted that den cavity size would be determined by the bear's body size and that older bears would excavate better‐fitting cavities to minimize heat loss, due to their previous experience. We further predicted that physical attributes of excavated dens would affect the bears’ posthibernation body condition. Our results revealed that bears excavated a den cavity in relation to their body size, regardless of sex, and that older bears tended to excavate better‐fitting den cavities compared to young bears, as we expected. Older bears excavated better‐fitting den cavities, suggesting a potentially experience‐based shift with age in den‐excavation behavior and an optimum cavity size relative to a bear's body size. Our key finding is that insulation of excavated dens provided by wall/rood thickness and bedding materials had a significant positive effect on bears’ posthibernation body condition. We believe that our study provides new insight into how not only the quality of denning habitat, but also the quality of dens may affect hibernating animals, by presenting a potential adaptive aspect of den preparation (age effect on efficiency in den excavation) and effect of den attributes on the posthibernation body condition of brown bears.     

Historical Photogrammetry: Bird's Paluxy River Dinosaur Chase Sequence Digitally Reconstructed as It Was prior to Excavation 70 Years Ago

It is inevitable that some important specimens will become lost or damaged over time, conservation is therefore of vital importance. The Paluxy River dinosaur tracksite is among the most famous in the world. In 1940, Roland T. Bird described and excavated a portion of the site containing associated theropod and sauropod trackways. This excavated trackway was split up and housed in different institutions, and during the process a portion was lost or destroyed. We applied photogrammetric techniques to photographs taken by Bird over 70 years ago, before the trackway was removed, to digitally reconstruct the site as it was prior to excavation. The 3D digital model offers the opportunity to corroborate maps drawn by R.T. Bird when the tracksite was first described. More broadly, this work demonstrates the exciting potential for digitally recreating palaeontological, geological, or archaeological specimens that have been lost to science, but for which photographic documentation exists.     

贵州盘州中三叠世Mixosaurus panxianensis(盘县混鱼龙)前肢形态差异及种内变化探讨*

混鱼龙科除Mixosaurus cornalianus之外的其他属种由于化石材料稀少、保存破碎, 此前对其形态解剖学特征, 特别是前肢形态结构特征及其生长发育过程和种内差异认识存在局限。经对发掘自贵州省盘州市(原为盘县)新民乡及邻区的多件不同大小的Mixosaurus panxianensis标本的前肢进行观察对比和定量研究, 发现其尺骨、桡腕骨、指骨以及豌豆骨显示了一定的随生长发育而发生的特征变化。此外, 桡骨前缘凹口和中间腕骨近端凹口的发育状态在Mixosaurus cornalianus及M. panxianensis中均存在种内变异。