凯里生物群腕足动物与游泳动物 共存现象研究

腕足动物是贵州凯里生物群中重要的化石门类,不仅化石数量丰富,分异度高,还具有丰富的生态现象。在寒武系的化石记录上,腕足动物常与海绵、藻类、棘皮动物、水母状生物、软舌螺、威瓦西亚虫、其他腕足动物等保存在一起,凯里生物群中的腕足动物也有类似的共存现象。本文就凯里生物群中腕足动物与游泳动物的共存现象进行了初步研究,认为腕足动物与贵州拟轮盘水母Pararotadiscus guizhouensis存在共栖、共埋两种关系,讨论了这两种关系的不同之处;分析了腕足动物与大型双瓣壳节肢动物加拿大虫Canadaspis的共存现象,推测一只腕足动物与Canadaspis共同保存的化石记录表明这两种生物存在共栖关系。本文的研究丰富了凯里生物群物种之间的生态关系,为凯里生物群的生态多样性提供了更多的证据。     

贵州剑河中寒武世中期甲劳组水母状化石的发现

贵州剑河革东镇八郎村南甲劳组中部钙质白云岩中新近发现的具有粗强放射状辐管的水母状化石和其下凯里组中具细辐管及同心环的拟轮盘水母(Pararotadiscus)有明显区别,属于伊尔东钵科(Eldoniidae)。其层位晚于中寒武世早期凯里生物群中拟轮盘水母(Pararotadiscus)层位1个化石带,属中寒武世中期,是该类化石在中国的最高层位,相当于北美布尔吉斯页岩生物群中Eldonia化石层位。     

贵州台江凯里动物群中的水母状化石

贵州台江中寒武世凯里动物群中的水母状化石Ｒｏｔａｄｉｓｃｕｓｇｕｉｚｈｏｕｅｎｓｉｓｓｐ．ｎｏｖ．，是云南早寒武世澄江动物群中修正涵义后的Ｒａｔｏｄｉｓｃｕｓ属的一个新种。与模式种Ｂ．ｇａｎｄｉｓ相比，新种个体较小，辐管数减少，内环网格状构造更为明显。新种与早寒武世澄江动物群和中寒武世布尔吉斯页岩中的Ｅｌｄｏｎｉａ相似，两者之间均具有相近的消化腔、触手和外形，但Ｅｌｄｏｎｉａ辐管系统更加复杂。根据“Ｕ”形消化腔和环绕口端的触手，新种应归入触手动物类。     

贵州安顺上二叠统的真菌化石

本文记述了贵州安顺上二叠统龙潭组的四种寄生和钻孔真菌,即寄生团菌孢(新属、新种)Sorosporonitesparasiticus(gen.et sp.nov.)内孢贵州丝菌(新属、新种)Guizhounema endosporicum(gen.et sp.nov.)和两种未定名称的菌丝化石。它们保存在钙藻——裸海松藻类的体内和(竹蜓)、腕足类(?)的钙质骨骼内。有些标本保存得相当精美,是寄生在海藻体内真菌化石的首次记录。这一发现的重要意义在于,它为研究古代的寄生现象提供了新的古生物证据。它表明,真菌寄生在藻体内的生态现象的发展历史至少可以追溯到二叠纪。     

闽南-粤东近海上升流区花水母亚纲一新属二新种记述(丝螅水母目,原帽水母科;头螅水母目,棒状水母科)

记述了闽南-粤东近海上升流区花水母亚纲原帽水母科Protiaridae Haeckel,1879裸球拟海帽水母1新种Halitiarella nudibulbus Xu,Huang et Guo,sp.nov.与棒状水母科Corymorphidae Allman,1872张氏八辐端粗水母1新属1新种Octovannuccia zhangjinbiaoi Xu,Huang et Lin,gen.nov.,sp.nov.。模式标本保存在国家海洋局第三海洋研究所。裸球拟海帽水母,新种Halitiarella nudibulbus Xu,Huang et Guo,sp.nov.(图1～2)鉴别特征水母伞无顶突,外伞有分散刺胞;伞缘有4条主辐位触手和4个间辐位缘基球,所有触手和缘基球有背轴眼点;主辐位触手与间辐位缘基球间具2～3条短的实心缘丝。正模(TS045)和副模(TS046-049),闽南-粤东上升流区A25站(22.8°N,118.1°E),水深32m,2009-06-11,项鹏采(第三海洋研究所)。词源:新种以拉丁词nudibulbus为种名,意为裸球,指该种间辐位缘基球无触手。八辐端粗水母,新属Octova...     

一种类别不明的化石—三瓣石

１９７８年笔者首次发现一种类别不明的微体古动物壳体化石，其长度一不足１ｍｍ，横切面呈三瓣状，命名为三瓣石。现有的标本获自湖中下石炭统，同一层位还产珊瑚、腕足类化石。经过十多年的反复观察，切片研究等，三瓣石的原始壳质，结构构造，形态特征已基本弄清。按初步制定的形态分类方案，现有的上千个标本至少可分为２组３属约３０个种，本文暂描述其中的１３个种。     

贵州台江中寒武世凯里动物群

贵州中寒武世凯里动物群由１０个以上门类化石组成，包括棘皮动物、水母状化石、蠕虫、海绵、软舌螺、三叶虫、腕足类、单板类、菌藻类、疑源类、一些分类不明的化石及遗迹化石。这一动物群形成于浅海陆棚环境，它是继我国已发现的、世界闻名的澄江动物群之后，在我国寒武系发现的另一个布尔吉斯页岩型动物群。     

贵州寒武纪棘皮动物始海百合类的固着器北大核心

固着器(holdfast)或附着盘(attached disc)是寒武系棘皮动物始海百合类固着器的两个称谓,用于吸附固着在泥砂质海底或其他动物体上。寒武系棘皮动物始海百合类固着器与茎连在一起,但其形态构造,特别是功能作用和茎不一样,应作区别于茎的独立器官。贵州寒武系棘皮动物始海百合类化石十分丰富,大部分属种具有固着器。可分为长茎小固着器及短茎大固着器两种类型。前者包括凯里生物群中的卢氏中国始海百合(Sinoeoc-rinus lui)及杷榔动物群中俞氏贵州始海百合(Guizhoueocrinus yui),后者以球形球状始海百合(Globoeocrinus glob-ulus)为代表。少数球形球状始海百合固着器与围岩之间存在过渡带,证实寒武纪早期始海百通过固着器分泌胶质固着在基质上的推论。贵州寒武纪始海百合类固着器幼年期大,可能是为了固着器帮助其稳定,成年期相对变小。固着的基质为软泥沙和生物化石腕足类、三叶虫、软舌螺的骨骼碎屑。贵州寒武系始海百合类固着器是棘皮动物海百合亚门的最原始的固着器官,它的特征及固着基质为棘皮动物海百合亚门的固着器及固着方式、固着基质的变化的深入研究提供了重要的材料。     

一种类别不明的化石──三瓣石（Tripetita）

１９７８年笔者首次发现一种类别不明的微体古动物壳体化石,其长度一般不足１ｍｍ;横切面呈三瓣状,命名为三瓣石（Ｔｒｉｐｅｔｉｔａ）。现有的标本获自湘中下石炭统,同一层位还产珊瑚、腕足类化石。经过十多年的反复观察、切片研究等,三瓣石的原始壳质、结构构造、形态特征已基本弄清。按初步制定的形态分类方案,现有的上千个标本至少可分为２组３属约３０个种。本文暂描述其中的１３个种。     

贵州寒武纪棘皮动物始海百合类的固着器

固着器(holdfast)或附着盘(attached disc)是寒武系棘皮动物始海百合类固着器的两个称谓,用于吸附固着在泥砂质海底或其他动物体上。寒武系棘皮动物始海百合类固着器与茎连在一起,但其形态构造,特别是功能作用和茎不一样,应作区别于茎的独立器官。贵州寒武系棘皮动物始海百合类化石十分丰富,大部分属种具有固着器。可分为长茎小固着器及短茎大固着器两种类型。前者包括凯里生物群中的卢氏中国始海百合(Sinoeoc-rinus lui)及杷榔动物群中俞氏贵州始海百合(Guizhoueocrinus yui),后者以球形球状始海百合(Globoeocrinus glob-ulus)为代表。少数球形球状始海百合固着器与围岩之间存在过渡带,证实寒武纪早期始海百通过固着器分泌胶质固着在基质上的推论。贵州寒武纪始海百合类固着器幼年期大,可能是为了固着器帮助其稳定,成年期相对变小。固着的基质为软泥沙和生物化石腕足类、三叶虫、软舌螺的骨骼碎屑。贵州寒武系始海百合类固着器是棘皮动物海百合亚门的最原始的固着器官,它的特征及固着基质为棘皮动物海百合亚门的固着器及固着方式、固着基质的变化的深入研究提供了重要的材料。     

Architecture and function of the lophophore in the problematic brachiopod Heliomedusa orienta (Early Cambrian, South China)

The detailed structure of the lophophore is a key diagnostic character in the definition of higher brachiopod taxa. The problematic Heliomedusa orienta Sun and Hou, from the Lower Cambrian Chengjiang Lagerstätte of Yunnan, southwestern China, has a well-preserved lophophore, which is unlike that of any known extant or extinct brachiopods. Based on a comparative study of lophophore disposition in H. orienta and the extant discinid Pelagodiscus atlanticus, the in- and excurrent pattern and shell orientation of H. orienta are described and discussed. Reconstructions of lophophore shape and function are based on numerous specimens and comparison with P. atlanticus. The lophophore is composed of a pair of lophophoral arms that freely arch posteriorly rather than coiling anteriorly as commonly seen in fossil and recent lingulids. The lophophore is attached to the dorsal lobe of the mantle; it has neither calcareous nor chitinous supporting structures, and is disposed symmetrically on either side of the valve midline. The mouth can be inferred to be located at the base of the two brachial tubes, slightly posterior to the anterodorsal projection of the body wall. The lophophoral arms bear laterofrontal tentacles with a double row of cilia along their lateral edge, as in extant lingulid brachiopods. The main brachial axes are also ciliated, which presumably facilitated transport of mucous-bound nutrient particles to the mouth. The unique organization of the lophophore in Heliomedusa is not like any known fossil and living brachiopods. This clearly demonstrates that H. orienta is not a member of any crown group. It is here considered as a member of the brachiopod stem group, which challenges recent interpretations of a close discinid affinity.     

RHYNCHONELLIFORMEAN BRACHIOPODS WITH SOFT-TISSUE PRESERVATION FROM THE EARLY CAMBRIAN CHENGJIANG LAGERSTÄTTE OF SOUTH CHINA

Abstract:  Cosmopolitan kutorginates, the most abundant Early Cambrian rhynchonelliformean brachiopods, became extinct at the end of the Middle Cambrian. Consequently, any information concerning the anatomy of this peculiar lineage of brachiopods has great phylogenetic significance with regard to their extant relatives for analogies with the stem-group clade. Such data have been supplied from fossils of which the soft parts have been preserved in exceptional detail. A new brachiopod, Kutorgina chengjiangensis sp. nov., from the Early Cambrian Chengjiang Lagerstätte of southern China, is described here. It is the first articulated brachiopod species collected from this deposit. The specimens preserve a set of soft-body parts, i.e. lophophore, digestive tract and pedicle, all previously poorly known in almost all Palaeozoic calcareous brachiopod taxa. The lophophore attains an early spirolophe stage, clearly homologous to that in the coeval lingulids. The digestive tract consists of a mouth, oesophagus, swollen stomach, intestine and a terminal anus. The pedicle protruding between the valves is stout and elongate, with annulated lamellae on the surface, and contains a putative cœlomic cavity. K. chengjiangensis displays the characteristics of the stem group of calcareous brachiopods, and illustrates anatomical similarities between Cambrian phosphatic- and calcareous-shelled brachiopods, thus corroborating that the Brachiopoda are a monophyletic group.     

The phylogenetic position of entoprocta, ectoprocta, phoronida, and brachiopoda

Ectoprocts, phoronids and brachiopods are often dealt with underthe heading Tentaculata or Lophophorata, sometimes with entoproctsdiscussed in the same chapter, for example in Ruppert and Barnes(1994). The Lophophorata is purported to be held together bythe presence of a "lophophore," a mesosomal tentacle crown withan upstream-collecting ciliary band. However, the mesosomaltentacle crown of pterobranchs has upstream-collecting ciliarybands with monociliate cells, similar to those of phoronidsand brachiopods, although its ontogeny is not well documented.On the contrary, the ectoproct tentacle crown carries a ciliarysieving system with multiciliate cells and the body does notshow archimery, neither during ontogeny nor during budding,so the tentacles cannot be characterized as mesosomal. The entoproctshave tentacles without coelomic canals and with a downstream-collectingciliary system like that of trochophore larvae and adult rotifersand serpulid and sabellid annelids. Planktotrophic phoronidand brachiopod larvae develop tentacles at an early stage, buttheir ciliary system resembles those of echinoderm and enteropneustlarvae. Ectoproct larvae are generally non-feeding, but theplanktotrophic cyphonautes larvae of certain gymnolaemates havea ciliary band resembling that of the adult tentacles. The entoproctshave typical trochophore larvae and many feed with downstream-collectingciliary bands. Phoronids and brachiopods are thus morphologicallyon the deuterostome line, probably as the sister group of the"Neorenalia" or Deuterostomia sensu stricto. The entoproctsare clearly spiralians, although their more precise positionhas not been determined. The position of the ectoprocts is uncertain,but nothing in their morphology indicates deuterostome affinities."Lophophorata" is thus a polyphyletic assemblage and the wordshould disappear from the zoological vocabulary, just as "Vermes"disappeared many years ago.     

Pennsylvanian sea level cycles, nutrient availability and brachiopod paleoecology

As with modern organisms, the spatial and temporal distribution of fossil communities was controlled by both the physical setting in which the organisms lived and by the organisms' physiology and interactions. By studying the sedimentological and geochemical context of fossil communities, it is possible to assess the relative importance of the physical setting and the organisms' physiology. Comparison of Pennsylvanian brachiopod associations with changing sedimentological context (water depth/facies) and nutrient availability indicates that body size is a function of water depth and nutrient availability for most spire-bearing (athyridids and spiriferids) brachiopods but rarely for productid brachiopods. Spire-bearing brachiopods dominate the associations in high-nutrient settings, and productid brachiopods dominate the associations in low-nutrient settings. This difference suggests that physiological differences between brachiopod orders, such as lophophore filtering efficiency, play an important role in controlling their distribution.     

The brachiopod fold: a neglected body plan hypothesis

Attention is drawn to Nielsen's radical body plan concept, here named the 'brachiopod fold hypothesis', under which brachiopods and phoronids are recognized to be transversely folded across the ontogenetic anterior–posterior axis so that, to make useful comparisons with other phyla, these organisms must be conceptually unfolded. Under the hypothesis brachiopod brachial and pedicle shell valves are respectively 'anterior' and 'posterior' rather than 'dorsal' and 'ventral' as traditionally described. The hypothesis makes sense of the symmetry axes of the brachiopod shell, is consistent with various indications from fossil and Recent brachiopods, and gives rise to predicted patterns of axis–determining gene expression that differ from those obtaining under the traditional view of the body plan, whilst the variety of folding movements in different lineages implies that superficially dissimilar morphogenetic folds may be fundamentally homologous. Convergent folding patterns are noted in some other organisms. A previous conjecture that inarticulate linguloid brachiopods were derived from halkieriid–like ancestors is elaborated with proposals that recognize possible functional continuities of coelomic and marginal sclerite functions, and it is noted that an ancestrally facultative fold could have become incorporated by genetic assimilation into the brachiopod developmental program. An experimental approach is outlined to test the possibility that some members of the 'small shelly fauna' may have been members of the halkieriid–like brachiopod stem lineage and it is also suggested that buoyancy modification may have been an important function of mineralization amongst Lower Cambrian floaters and swimmers, since negative buoyancy would facilitate access to the benthic niche.     

Epizoans on late Ordovician brachiopods from Southeastern Indiana

The frequency of epizoans (cornulitids, inarticulate brachiopods, bryozoans, solitary and colonial rugosan corals) on over 8000 specimens of articulate brachiopods (four strophomenids, five orthids, one rhynchonellid) was calculated for four stratigraphic horizons in the Dillsboro Formation of southeastern Indiana. Frequency of shells encrusted correlates significantly with the surface area of the valves. Punctae in brachiopod shells (Onniella meeki) may have deterred larval settlement of epizoans. Coarse ribbing on articulates deterred encrustation by the inarticulate brachiopod. The horn coral shows a preference for attachment to the anterior of Hiscobeccus capax. Bryozoans show a preference for the incurrent lateral margins of inferred living hosts, suggesting rheotropic behavior by settling larvae. Inarticulate brachiopods are concentrated around the sloping commissure of the brachial valve of strophomenids, suggesting geotropic behavior and/or selective survival of settling larvae. Inarticulates deterred overgrowth by bryozoans. High frequencies of encrustations of the medial region of pedicle valves of orthids and strophomenids probably reflect post‐mortem encrustations. Alternating intervals of slow sediment accumulation punctuated by tropical storms and rapid shell burial may account for the high frequency of shells with either their entire surface veneered or only a very small area encrusted by bryozoans.     

湖南零陵晚泥盆世叶虾类一新种——Echinocaris hunanensis sp. nov.

描述了湖南零陵普利桥晚泥盆世锡矿山组叶虾类一新种——Echinocaris hunanensis sp.nov..晚古生代叶虾类化石较为稀少,Echinocaris在亚洲是首次发现.