南丹相泥盆系中的翼口蛤类

滇西晚石炭世 Triticites 带的苔藓虫,产于施甸的10种,内含1新种,群体形状单一,生活于温暖、清洁、高能、面向外海的硬基底浅海区;产于腾冲的只有1种,是低能深水特提斯区分子.早二叠世苔藓虫12种,内含1新种,产耿马永德组 Polydiexodina 带之下,系特提斯区分子,据对其中的3层苔藓虫的硬体类型及标本数量分析,耿马含苔藓虫地层代表一个海侵过程.     

The encrustation of fossil and recent sea-urchin tests: ecological and taphonomic significance

A comparison of fossil ( Echitwlampas sp. from the Lower Miocene Zogelsdorf Formation, Austria) and Recent ( Schizaster canaliferus from the northern Adriatic Sea) irregular sea-urchin tests shows that, upon their death, burrowing echinoids can serve as a substrate for a dense epigrowth. Size, shape, stable orientation, and surface residence-time were identified as key factors governing encrustation. The encrusters on fossil Echinolampas were bryozoans, serpulid polychaetes, barnacles, and coralline algae, while the recent material was initially encrusted by serpulids and hydrozoan colonies, and ultimately covered by the full range of sessile, hemi-sessile, and vagile species characterizing the benthic community in the Adriatic. In Echinolampas , epigrowth was more abundant on the lower (oral) surface; this specific distribution was echoed in S. canaliferus , where epigrowth started on the bottom side and grew upward. This indicates that the tests have a stable orientation and a surface residence-time long enough to allow intense encrustation. A taphonomic model is developed, and the role of encrustation on such special substrates for overall community structure is discussed. The Recent/fossil comparison provides new insights for both fields of study: the recent material indicates the role of soft-bodied faunas as well as the complexity of small-scaled ecological processes; the fossil material reflects many of the above phenomena and adds important taphonomic details on the fate of encrusted biogenic structures and on encruster growth patterns and distributions.     

Symbiosis of cornulitids with the cystoporate bryozoan Fistulipora in the Pridoli of Saaremaa,Estonia

Cornulites sp. and Fistulipora przhidolensis formed a symbiotic association in the Pridoli (latest Silurian) of Saaremaa Island, Estonia. This Cornulites sp.–F. przhidolensis association is the youngest example of cornulitid–bryozoan symbiosis. Symbiosis is indicated by intergrowth of both organisms. The cornulitids are completely embedded within the cystoporate bryozoan colony, leaving only their apertures free on the growth surface of bryozoan. In terms of food competition, this association could have been slightly harmful to F. przhidolensis as Cornulites sp. may have been a kleptoparasite. There may have been a small escalation in the evolution of the endobiotic life mode of cornulitids as the number of such associations increased from the Ordovician to Silurian. It is likely that Palaeozoic bryozoan symbiosis reached its maximum in the Late Ordovician. Most of the symbiotic bryozoans in the Palaeozoic are trepostomes, and the diversity of symbiotic associations was also greatest among trepostomes.     

Particle capture in ciliary filter‐feeding gymnolaemate and phylactolaemate bryozoans – a comparative study

Riisgård, H.U., Okamura, B. and Funch, P. 2009. Particle capture in ciliary filter‐feeding gymnolaemate and phylactolaemate bryozoans – a comparative study. —Acta Zoologica (Stockholm) 91 : 416–425. We studied particle capture using video‐microscopy in two gymnolaemates, the marine cheilostome Electra pilosa and the freshwater ctenostome Paludicella articulata, and three phylactolaemates, Fredericella sultana with a circular funnel‐shaped lophophore, and Cristatella mucedo and Lophophus crystallinus, both with a horseshoe‐shaped lophophore. The video‐microscope observations along with studies of lophophore morphology and ultrastructure indicated that phylactolaemate and gymnolaemate bryozoans with a diversity of lophophore shapes rely on the same basic structures and mechanisms for particle capture. Our study also demonstrates that essential features of the particle capture process resemble one another in bryozoans, brachiopods and phoronids.     

New bryozoans from the Devonian of Afghanistan and the Carboniferous of Iran

A new family, Vidronovellidae, with a new genus, Vidronovella, and its type species V. fastigata sp. nov., and a new species, Europora gerirudensis, are described from the Famennian of Afghanistan, and the new species Primorella iranica, Heloclema magnificum, and Worthenopora elbursensis are described from the Viséan of Iran.     

A new genus of the Arenigian bryozoans, <Emphasis Type="Italic">Lynnopora</Emphasis>, and its systematic position in the family Revalotrypidae Gorjunova, 1988

A new genus Lynnopora gen. nov. with the type species L. lunata sp. nov. and a new species Revalotrypa krestensis Koromyslova sp. nov. from the Arenigian Stage (Latorp and Volkhov horizons) of the Ordovician of the Leningrad Region are described. The positions of the genus Revalotrypa Bassler, 1952 and the family Revalotrypidae Gorjunova, 1988 in the order Cystoporida are substantiated. The problems of biogeography and ecological adaptations of bryozoans of the family Revalotrypidae are discussed.     

Three phyla—Two type specimens—One shell: History of a snail shell revealed by modern imaging technology

In a recent revision of the gastropod genus Bellardiella, it became evident that the neotype of B. crassilabris had numerous borings over its entire shell surface. Superficial and light microscopical observation of the shell showed that the borings were made by a bryozoan belonging to the genus Penetrantia. Conventional techniques such as endocasting with the dissolution of the shell are impossible for type material. The application of non‐destructive micro‐CT‐scanning of the shell revealed the three‐dimensional arrangement of the entire colony within the shell. Careful analysis of the structure of the autozooids of the colony revealed that the species could not be assigned to any known species; we accordingly describe it as Penetrantia bellardiellae Schwaha, n. sp. The application of micro‐CT not only allowed the depiction of the new bryozoan species but also revealed the remains of a hermit crab located within the shell. The shell of Bellardiella crassilabris thus represents the type specimen of two species and contains a member of a third phylum inside. To our knowledge, this is a unique case, which also emphasizes the usefulness of micro‐CT imaging for precious specimens as well as the importance of historical museum collections.     

Intracolonial variability in new bryozoans from the Middle Jurassic of the Bryansk Region (Russia)

Two new species of encrusting bryozoans (Stenolaemata, Tubuliporida) from the Middle Callovian (Middle Jurassic) deposits of the Bryansk Region, Oncousoecia guzhovi sp. nov. and Microeciella fokinensis sp. nov., are described. Their intracolonial variability, which is due to differences in astogenetic stages and to external factors, is discussed.     

Faunal evidence for a late quaternary trans‐Antarctic seaway

Collapse of the West Antarctic Ice Sheet (WAIS) would raise global sea level by ～3.3–5 m. Ice‐sheet models and geological data suggest at least one collapse has happened during the last 1.1 Ma, and some scenarios of future climate change predict a collapse within the next two centuries. A complete WAIS collapse would open shallow seaways across West Antarctica, potentially enabling exchange of animals between West Antarctic seas. We investigated biological evidence for past connectivity between different regions of Antarctica by comparing the composition of modern bryozoan assemblages from the continental margin around Antarctica. Surprisingly, we found most similarity between two areas which are not currently connected – the shelves of the Weddell Sea (WS) and Ross Sea (RS). We evaluated three hypotheses to explain this and conclude that bryozoans most likely dispersed through a trans‐Antarctic seaway that opened in response to a WAIS collapse and connected the WS and RS shelves. These bryozoans must have survived glaciations(s) during subsequent ice ages in refuges, whereas they were wiped out in most other regions of the Antarctic shelf. After the last glacial period, bryozoan assemblages could freely disperse between many of the regions we examined (e.g. Antarctic Peninsula and South Shetland Islands), which has allowed recolonization of areas in which bryozoans had been eradicated during the last ice age. For the bryozoans on the WS and RS shelves to be more similar than those which are in close proximity means the trans‐Antarctic seaway may have been as late as the last few interglacials. Current rates of warming are exceptional compared with the near past glacial cycles so our study, the strongest faunal evidence of WAIS collapse during the recent geological past, thus supports predictions of a near future WAIS collapse (with considerable global sea level implications) and resultant future major faunal exchanges.     

Parent and larval RAPD fingerprints reveal outcrossing in freshwater bryozoans

The occurrence of outcrossing in benthic hermaphroditic colonial invertebrates has received much historical debate and little demonstration. Direct genetic study of this question using routine techniques has been limited by both the amount of material required and the detection of adequate DNA polymorphisms. However, the recent development of molecular techniques that require no a-priori sequence data provides new approaches to the characterization of both tiny and genetically similar individuals. Random amplification of polymorphic DNA (the RAPD assay) was used to amplify fragments of DNA (via the polymerase chain reaction) to obtain fingerprints of parental colonies and larval offspring of the hermaphroditic freshwater bryozoan Cristatella mucedo. Here we report the first positive and direct genetic evidence for outcrossing in bryozoans. However, we find that outcrossing generates only low levels of genetic variation in populations that are highly clonal.