Paleoecology of commensal epizoans fouling Flexicalymene (Trilobita) from the Upper Ordovician, Cincinnati Arch region, USA

2010 ◽  
Vol 84 (6) ◽  
pp. 1121-1134 ◽  
Author(s):  
Marcus M. Key ◽  
Gregory A. Schumacher ◽  
Loren E. Babcock ◽  
Robert C. Frey ◽  
William P. Heimbrock ◽  
...  
Keyword(s):  
Water Column ◽  
Life Style ◽  
Late Ordovician ◽  
Hard Substrate ◽  
Upper Ordovician ◽  
Sea Floor ◽  
Life Habits ◽  
Observational Bias ◽  
Fouling Organisms ◽  
Insight Into

Commensal epizoozoans and episkeletozoans are rarely preserved attached to the external exoskeleton of the Late Ordovician trilobite Flexicalymene. Of nearly 15,000 Flexicalymene specimens examined, 0.1% show epizoozoans or episkeletozoans. Factors limiting Flexicalymene fouling include a shallow burrowing life style, frequent molting of the host, larval preference for other substrates, observational bias caused by overlooking small fouling organisms, and the loss of the non-calcified, outermost cuticle prior to fossilization or as the trilobite weathers from the encasing sediment. Trepostome bryozoans, articulate and inarticulate brachiopods, cornulitids, and a tube-dwelling/boring nonbiomineralized organism represent the preserved members of the Late Ordovician marine hard substrate community fouling Flexicalymene. This assemblage of organisms is less diverse than the hard substrate community fouling Late Ordovician sessile epibenthic organisms. Fouling is not restricted to only large Flexicalymene specimens as observed in previous studies but occurs in medium to large individuals interpreted as early to late holaspid specimens.Epizoozoans fouling the carcasses or molt ensembles of 16 Flexicalymene specimens provide insight into the life habits of the host and these fouling organisms. Trepostome bryozoans, articulate and inarticulate brachiopods, and cornulitids preferentially attached to elevated portions of the dorsal exoskeleton, and preferentially aligned in either the direct line or lee side of currents generated by Flexicalymene walking on the sea floor or swimming through the water column.

Eustatic and local tectonic impact on the Late Ordovician – early Silurian facies evolution on the SW margin of peri-Baltica (the southern Holy Cross Mountains, Poland)

2021 ◽  
pp. 1-15
Author(s):  
Wiesław Trela
Keyword(s):  
Late Ordovician ◽  
Coarse Grained ◽  
Upper Ordovician ◽  
Sedimentary Record ◽  
Trade Winds ◽  
Sedimentary Environments ◽  
Holy Cross Mountains ◽  
Se Poland ◽  
Clastic Sediments ◽  
Insight Into

Abstract This paper provides insight into the Late Ordovician to earliest Silurian evolution of sedimentary environments in the southern Holy Cross Mountains (SE Poland), which at that time were a part of the SW periphery of Baltica. The facies layout in this area was influenced by the basement block faulting, which differentiated the basin bathymetry into submarine horst and grabens, controlling facies distribution. However, the local tectonism was insufficient to fully mask the global eustatic events. Therefore, it is possible to correlate some facies changes in the Upper Ordovician and lower Llandovery sedimentary record of the southern Holy Cross Mountains with eustatic and palaeoceanographic changes reported worldwide. The most noticeable influence of eustasy on the sedimentary record in the studied area occurs at the Ordovician/Silurian boundary. It is manifested by Hirnantian regressive coarse-grained clastic sediments overlain by a post-glacial anoxic/dysoxic interval represented by the Rhuddanian transgressive black cherts and shales. It is noteworthy that the pre- and post-Hirnantian sedimentary environments in the southern Holy Cross Mountains were affected by upwelling induced by the SE trade winds.

Katian (Late Ordovician) conodonts on the northwestern margin of the North China Craton

2021 ◽  
pp. 1-22
Author(s):  
Zhihua Yang ◽  
Xiuchun Jing ◽  
Hongrui Zhou ◽  
Xunlian Wang ◽  
Hui Ren ◽  
...  
Keyword(s):  
North China Craton ◽  
North China ◽  
Late Ordovician ◽  
Carbonate Platforms ◽  
Upper Ordovician ◽  
The North ◽  
Low Latitudes ◽  
Northwestern Margin ◽  
Conodont Fauna ◽  
Stratigraphic Range

Abstract Upper Ordovician strata exposed from the Baiyanhuashan section is the most representative Late Ordovician unit in the northwestern margin of the North China Craton (NCC). In total, 1,215 conodont specimens were obtained from 24 samples through the Wulanhudong and Baiyanhuashan formations at the Baiyanhuashan section. Thirty-six species belonging to 17 genera, including Tasmanognathus coronatus new species, are present. Based on this material, three conodont biozones—the Belodina confluens Biozone, the Yaoxianognathus neimengguensis Biozone, and the Yaoxianognathus yaoxianensis Biozone—have been documented, suggesting that the Baiyanhuashan conodont fauna has a stratigraphic range spanning the early to middle Katian. The Baiyanhuashan conodont fauna includes species both endemic to North China and widespread in tropical zones, allowing a reassessment of the previous correlations of the Katian conodont zonal successions proposed for North China with those established for shallow-water carbonate platforms at low latitudes. UUID: http://zoobank.org/7cedbd4a-4f7a-4be6-912f-a27fd041b586

1.  Toxicity of Fresh and Weathered Sunken Heavy Fuel Oil to the Early Life Stages of Rainbow Trout (Oncorhynchus mykiss) in Simulated Spawning Shoal Environments

2016 ◽  
Author(s):  
Julie Adams
Keyword(s):  
Rainbow Trout ◽  
Water Column ◽  
Aquatic Organisms ◽  
Fuel Oil ◽  
South American ◽  
Benthic Organisms ◽  
Heavy Fuel Oil ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Direct Exposure ◽  
Insight Into

Because the density of heavy fuel oil (HFO) is equal to or greater than that of freshwater, it behaves differently than lighter oils that float. Heavy fuel oil can sink to the bottom or be suspended in the water column and affect aquatic organisms that are not typically exposed to floating oils. Most research on oil spill technologies thus far examines the direct exposure of rainbow trout to floating or submerged oil droplets; there is little knowledge of the impacts of non‐floating heavy fuel oil on the water column and benthic organisms exposed to oil that accumulates in sediments. The toxicity of sunken HFO 6303 and Medium South American (MESA; reference) crude oil, as well as the effects of weathering on toxicity to embryos of rainbow trout were assessed using increasing concentrations of oil on gravel substrate in continuous‐flow desorption columns. Toxicity was assessed by measurement of the rates of mortality and growth, and the prevalence of blue sac disease, a hallmark sign of oil toxicity. The lower median lethal concentration for HFO compared to MESA indicated that HFO is more toxic. Interestingly, the LC50 values for fresh and weathered for both oils were similar, indicating little change in toxicity when the oil weathers naturally. Repetition of this experiment and analysis of PAH content in each treatment will provide more insight into the environmental and health risks associated with sunken heavy fuel oil.   

scholarly journals Effect of Hydrothermal Activity on Organic Matter Enrichment of Shale: A Case Study of the Upper Ordovician and the Lower Silurian in the Lower Yangtze, South China

Minerals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 495 ◽  
Author(s):  
Yizhou Huang ◽  
Zhenxue Jiang ◽  
Kun Zhang ◽  
Yan Song ◽  
Shu Jiang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Oxygen Isotope ◽  
Shale Gas ◽  
Organic Matter Content ◽  
Hydrothermal Activity ◽  
Late Ordovician ◽  
Sedimentary Organic Matter ◽  
Upper Ordovician ◽  
Lower Silurian ◽  
Activity Intensity

The effect of organic matter on hydrocarbon potential, storage space, and gas content of shale is well-known. Additionally, present-day content of sedimentary organic matter in shale is controlled by depositional and preservation processes. Therefore, a study of the enrichment mechanisms of sedimentary organic matter provides a scientific basis for the determination of favorable areas of shale gas. In this study the Upper Ordovician Xinkailing Fm. and the first member of the Lower Silurian Lishuwo Fm. were examined. Stratigraphic sequences were identified through conventional logs and elemental capture spectrum data. Oxygen isotope analysis was applied to recover paleotemperature of seawater in the study area. The excess silicon content was calculated and the origin of the silica was determined by the Fe-Al-Mn ternary plot. The enrichment mechanism of organic matter was analyzed by two aspects: redox conditions and paleoproductivity. As a result, the stratigraphic interval was divided into two 3rd-order sequences. Through oxygen isotope, the paleotemperature of seawater was 62.7–79.2 °C, providing evidence of the development of hydrothermal activity. Analysis of excess siliceous minerals identified two siliceous mineral origins: terrigenous and hydrothermal. It also revealed an upwards decreasing tendency in hydrothermal activity intensity. Strong hydrothermal activity during the Late Ordovician, recognized as TST1, formed a weak-oxidizing to poor-oxygen environment with high paleoproductivity, which promoted organic matter enrichment. During the Late Ordovician to the Early Silurian, identified as RST1, TST2, and RST2, weakening hydrothermal activity caused the decline of paleoproductivity and increased oxidation of bottom waters, leading to a relative decrease of organic matter content in the shale. Therefore, favorable areas of shale gas accumulation in the Upper Ordovician and Lower Silurian are determined stratigraphically as the TST1, with a high total organic carbonate content. Geographically, the hydrothermally-active area near the plate connection of the Yangtze and the Cathaysian is most favorable.

scholarly journals Decoupled evolution of soft and hard substrate communities during the Cambrian Explosion and Great Ordovician Biodiversification Event

2016 ◽  
Vol 113 (25) ◽  
pp. 6945-6948 ◽  
Author(s):  
Luis A. Buatois ◽  
Maria G. Mángano ◽  
Ricardo A. Olea ◽  
Mark A. Wilson
Keyword(s):  
Late Ordovician ◽  
Hard Substrate ◽  
Cambrian Explosion ◽  
Early Cambrian ◽  
Continuous Increase ◽  
Late Cambrian ◽  
Unconsolidated Sediment ◽  
Underlying Causes ◽  
Hard Substrates ◽  
Shed Light

Contrasts between the Cambrian Explosion (CE) and the Great Ordovician Biodiversification Event (GOBE) have long been recognized. Whereas the vast majority of body plans were established as a result of the CE, taxonomic increases during the GOBE were manifested at lower taxonomic levels. Assessing changes of ichnodiversity and ichnodisparity as a result of these two evolutionary events may shed light on the dynamics of both radiations. The early Cambrian (series 1 and 2) displayed a dramatic increase in ichnodiversity and ichnodisparity in softground communities. In contrast to this evolutionary explosion in bioturbation structures, only a few Cambrian bioerosion structures are known. After the middle to late Cambrian diversity plateau, ichnodiversity in softground communities shows a continuous increase during the Ordovician in both shallow- and deep-marine environments. This Ordovician increase in bioturbation diversity was not paralleled by an equally significant increase in ichnodisparity as it was during the CE. However, hard substrate communities were significantly different during the GOBE, with an increase in ichnodiversity and ichnodisparity. Innovations in macrobioerosion clearly lagged behind animal–substrate interactions in unconsolidated sediment. The underlying causes of this evolutionary decoupling are unclear but may have involved three interrelated factors: (i) a Middle to Late Ordovician increase in available hard substrates for bioerosion, (ii) increased predation, and (iii) higher energetic requirements for bioerosion compared with bioturbation.

Postembryonic development of Dalmanitina, and the evolution of facial suture fusion in Phacopina

Paleobiology ◽  
2018 ◽  
Vol 44 (4) ◽  
pp. 638-659
Author(s):  
Harriet B. Drage ◽  
Lukáš Laibl ◽  
Petr Budil
Keyword(s):  
Fossil Record ◽  
Postembryonic Development ◽  
Large Sample Size ◽  
Upper Ordovician ◽  
Geological Time ◽  
Fusion Event ◽  
Large Sample ◽  
Prague Basin ◽  
Suture Fusion ◽  
Insight Into

AbstractA large sample of postembryonic specimens of Dalmanitina proaeva elfrida and D. socialis from the Upper Ordovician (Sandbian to Katian) Prague Basin allows for the first reasonably complete ontogenetic sequence of Dalmanitoidea (Phacopina). The material provides an abundance of morphological information, including well-preserved marginal spines in protaspides and meraspides, and hypostome external surfaces throughout. The development of D. proaeva elfrida is unusual due to variability in timing of the first trunk articulation. This broadens our developmental understanding of Phacopina, a diverse group of phacopid trilobites, and also allows us to study the evolution of their specializations in exoskeletal molting behavior. Adult phacopines, unlike most other trilobites, had fused facial sutures. This means that rather than molting through the sutural gape mode, characterized by opening of the facial sutures and separation of the librigenae, they disarticulated the entire cephalon in Salter’s mode of molting. For other phacopine clades (Phacopoidea) the transition to Salter’s mode occurs during the meraspid period or at the onset of holaspis, and its developmental timing is intraspecifically fixed. However, owing to the large sample size, we can see that facial suture fusion likely occurred later in Dalmanitina, usually during the holaspid period, and was intraspecifically variable with holaspides of varying sizes showing unfused sutures. Further, D. proaeva elfrida specimens showed an initial librigenal–rostral plate fusion event, where the librigenae began as separate entities but appear fused with the rostral plate as one structure (the “lower cephalic unit”) from M1, and are discarded as such during molting. Dalmanitoidea is considered to represent the first phacopine divergence, occurring earliest in the fossil record. This material therefore provides insight into how linked morphologies and behaviors evolved, potentially suggesting the timing of facial suture fusion in Phacopina moved earlier during development and became more intraspecifically fixed over geological time.

scholarly journals The specificity of paleocoenosis and a trophic structure of the Upper Ordovician Bol’shaya Kos’yu reef (Northern Urals)

2020 ◽  
Author(s):  
L. A. Shmeleva ◽  
Keyword(s):  
Trophic Structure ◽  
Active Participation ◽  
Late Ordovician ◽  
Close Connection ◽  
Upper Ordovician ◽  
Northern Urals ◽  
Leading Role ◽  
Microbial Organisms

The study of the spatial-temporal and paleoecological structures of the paleocenoses of the Bolshaya Kosyu reef showed that the sphinctozoic sponges Amblysiphonelloides reticulata Rigby & Potter, 1986 and Corymbospongia sp. starting from the late Ordovician could settle in sublittoral environments with active hydrodynamics in close connection with cyanobacteria, which played a leading role in the functioning of the trophic structure of this ecosystem. Fossilized biofilms and glycocalyx, tubular and worm-like bacteriomorphs found on the surface of sponges are evidence of active participation of microbial organisms in the life of sphinctozoal sponges.

scholarly journals Upper Ordovician graptolites from the Cape Phillips Formation, Canadian Arctic Islands

1987 ◽  
Vol 35 ◽  
pp. 191-202
Author(s):  
M. J. Melchin
Keyword(s):  
Great Britain ◽  
Shallow Water ◽  
Depositional Environment ◽  
Canadian Arctic ◽  
Late Ordovician ◽  
Outer Shelf ◽  
Upper Ordovician ◽  
The World ◽  
Cape Phillips Formation ◽  
Varying Length

Ashgill age graptolites have been collected from seven sections of the Cape Phillips Formation across most of its outcrop belt. The earliest graptolite zone recognisable is that of Orthograptus fastigatus. It is correla­ted with the Dicellograptus ornatus · Zone of the northern Canadian Cordilllera and the Dicellograptus complexus Subzone of the Dicel/ograptus anceps Zone of Great Britain although no dicellograptids have been found at any of the present sections. The overlying zone is that of Paraorthograptus pacificus, an ea­sily recognisable zone around much of the world. Graptolites of the C/imacograptus extraordinarius and Glyptograptus persculptus zones appear to be en­tirely absent from this formation. This is attributed to the Late Ordovician glaciation which has induced regression and submarine erosion in many areas worldwide. The earliest recognisable Silurian zone varies from section to section due to buried or barren intervals and/or hiatuses of varying length. The Parakidograptus acuminatus Zone has been recognised at only one section. At the others, the Atavograptus atavus, the Lagarograptus acinaces-Coronograptus gregarius, the Monograptus convolutus or the Monograptus spiralis Zone (s.1.) are the earliest recognisable Silurian fau­nas. Relatively low fauna! diversities in the Ashgill and lowest Llandovery portion of the section and the to­tal lack of dicellograptids are interpreted to be due to relatively shallow water, outer shelf or carbonate ramp depositional environment.

The brachiopods Alwynella and Grorudia: homeomorphic plectambonitoids in the Middle and Upper Ordovician of Baltoscandia

2007 ◽  
Vol 98 (3-4) ◽  
pp. 271-280 ◽  
Author(s):  
Linda Hints ◽  
David A. T. Harper
Keyword(s):  
New Species ◽  
Baltic Sea ◽  
Late Ordovician ◽  
Drill Core ◽  
Upper Ordovician ◽  
The Baltic Sea ◽  
New Material ◽  
The Baltic ◽  
A New Species ◽  
Water Facies

ABSTRACTTwo Ordovician plectambonitoid genera, Alwynella and Grorudia, occur in drill core sections of Latvia in the East Baltic, and in exposures and loose blocks on the Swedish Island of Öland in the Baltic Sea. The new material confirms differences between the two taxa that are assigned herein to separate families, Alwynellidae fam. nov. and Grorudiidae Cocks & Rong, 1989. In particular, the undercut cardinalia separates Alwynella from Grorudia and indicates its proximity to the sowerbyellids. The genus Grorudia, which is externally similar to Alwynella, is more closely related to the palaeostrophomenines. A new species Grorudia morrisoni sp. nov. is established in the East Baltic. The specimens from Öland are included tentatively within the genus Grorudia due to lack of interiors. Both Alwynella and Grorudia were confined to deeper-water facies in the Baltic palaeobasin, within successions ranging in age from latest Mid (late Llanvirn) to earliest Late Ordovician (mid Caradoc).

scholarly journals Missing links in the study of solute and particle exchange between the sea floor and water column

2020 ◽  
Vol 77 (5) ◽  
pp. 1602-1616 ◽  
Author(s):  
Saskia Rühl ◽  
Charlie Thompson ◽  
Ana M Queirós ◽  
Stephen Widdicombe
Keyword(s):  
Water Column ◽  
Current Knowledge ◽  
Anthropogenic Impacts ◽  
Future Research ◽  
Sea Floor ◽  
Marine Habitats ◽  
Exchange Processes ◽  
Ecosystem Level ◽  
Particle Exchange

Abstract Exchanges of solutes and solids between the sea floor and water column are a vital component of ecosystem functioning in marine habitats around the globe. This review explores particle and solute exchange processes, the different mechanisms through which they interact at the ecosystem level, as well as their interdependencies. Solute and particle exchange processes are highly dependent on the characteristics of the environment within which they takes place. Exchange is driven directly by a number of factors, such as currents, granulometry, nutrient, and matter inputs, as well as living organisms. In turn, the occurrence of exchanges can influence adjacent environments and organisms. Major gaps in the present knowledge include the temporal and spatial variation in many of the processes driving benthic/pelagic exchange processes and the variability in the relative importance of individual processes caused by this variation. Furthermore, the accurate assessment of some anthropogenic impacts is deemed questionable due to a lack of baseline data and long-term effects of anthropogenic actions are often unknown. It is suggested that future research should be transdisciplinary and at ecosystem level wherever possible and that baseline surveys should be implemented and long-term observatories established to fill the current knowledge gaps.

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