scholarly journals Experimental neoichnology of post-autotomy arm movements of sea lilies and possible evidence of thrashing behaviour in Triassic holocrinids

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Przemysław Gorzelak ◽  
Mariusz A. Salamon ◽  
Krzysztof Brom ◽  
Tatsuo Oji ◽  
Kazumasa Oguri ◽  
...  
Keyword(s):  
Arm Movements ◽  
Sediment Surface ◽  
Early Triassic ◽  
Stem Group ◽  
Wide Range ◽  
Mesozoic Marine Revolution ◽  
Water Species

Abstract Echinoderms exhibit remarkable powers of autotomy. For instance, crinoids can shed arm and stalk portions when attacked by predators. In some species, it has been reported that the autotomized arms display vigorous movements, which are thought to divert the attention of predators. This phenomenon, however, has not been well explored. Here we present results of experiments using the shallowest water species of living stalked crinoid (Metacrinus rotundus) collected at 140 m depth. A wide range of movements of detached arms, from sluggish writhing to violent flicks, was observed. Interestingly, autotomized arms produce distinct traces on the sediment surface. They are composed of straight or arched grooves usually arranged in radiating groups and shallow furrows. Similar traces were found associated with detached arms of the oldest (Early Triassic) stem-group isocrinid (Holocrinus). This finding may suggest that the origins of autotomy-related thrashing behaviour in crinoids could be traced back to at least the Early Triassic, underscoring the magnitude of anti-predatory traits that occurred during the Mesozoic Marine Revolution. A new ethological category, autotomichnia, is proposed for the traces produced by thrashing movements of shed appendages.

When bivalves took over the world

Paleobiology ◽  
2007 ◽  
Vol 33 (3) ◽  
pp. 397-413 ◽  
Author(s):  
Margaret L. Fraiser ◽  
David J. Bottjer
Keyword(s):  
Mass Extinction ◽  
Arms Race ◽  
Steady Increase ◽  
Early Triassic ◽  
Environmental Distribution ◽  
Biodiversity Crisis ◽  
Marine Communities ◽  
The World ◽  
Mesozoic Marine Revolution ◽  
Permian Mass Extinction

AbstractThe end-Permian mass extinction is commonly portrayed not only as a massive biodiversity crisis but also as the time when marine benthic faunas changed from the Paleozoic Fauna, dominated by rhynchonelliform brachiopod taxa, to the Modern Fauna, dominated by gastropod and bivalve taxa. After the end-Permian mass extinction, scenarios involving the Mesozoic Marine Revolution portray a steady increase in numerical dominance by these benthic molluscs as largely due to the evolutionary effects of an “arms race.” We report here a new global paleoecological database from study of shell beds that shows a dramatic geologically sudden earliest Triassic takeover by bivalves as numerical dominants in level-bottom benthic marine communities, which continued through the Early Triassic. Three bivalve genera were responsible for this switch, none of which has any particular morphological features to distinguish it from many typical Paleozoic bivalve genera. The numerical success of these Early Triassic bivalves cannot be attributed to any of the well-known morphological evolutionary innovations of post-Paleozoic bivalves that characterize the Mesozoic Marine Revolution. Rather, their ability to mount this takeover most likely was due to the large extinction of rhynchonelliform brachiopods during the end-Permian mass extinction and aided by their environmental distribution and physiological characteristics that enabled them to thrive during periods of oceanic and atmospheric stress during the Permian/Triassic transition.

scholarly journals Final-Stage Magmatic Record of Paleo-Asian Oceanic Subduction? Insights from Late Permian to Early Triassic Intrusive Rocks in the Yanbian Area, Easternmost Central Asian Orogenic Belt

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 799
Author(s):  
Chao Zhang ◽  
Franz Neubauer ◽  
Zheng-Hong Liu ◽  
Fang-Hua Cui ◽  
Qing-Bin Guan
Keyword(s):  
Partial Melting ◽  
Granitic Rocks ◽  
Early Triassic ◽  
Crustal Material ◽  
Late Permian ◽  
The North ◽  
Wide Range ◽  
Intrusive Rocks ◽  
Subduction Setting ◽  
T Values

This paper reports new zircon LA–ICP–MS U–Pb and Hf isotope data, and whole-rock major and trace element data for Late Permian to Early Triassic intrusive rocks in the Yanbian area, NE China. These data provide new insights into the timing of the final subduction of the Paleo-Asian Ocean beneath the North China Craton. The zircon U–Pb age data indicate that a suite of Late Permian to Early Triassic intrusive rocks related to subduction is present within the Yanbian area. The Late Permian intrusive rocks consist of diorites while the Early Triassic granites and hornblende gabbros constitute a geochemically bimodal igneous rock association. Furthermore, the Early Triassic granites show the geochemical characteristics of shoshonitic rocks. All the rocks are characterized by enrichment in LILEs and LREEs, and depletion in HREEs and HFSEs, suggesting they formed in a subduction setting. Zircons from the Early Triassic gabbros have εHf(t) values and TDM2 ages of +7.6 to +10.7 and 735–1022 Ma, respectively, suggesting that they formed from a primary magma generated by the partial melting of lithospheric mantle material that had been previously modified by subduction-related fluids. The Late Permian diorites have εHf(t) values and TDM2 ages of +0.5 to +9.5 and 853 to 1669 Ma, respectively, while they have high contents of Al2O3, Fe2O3, and low contents of SiO2, Cr, and Ni, indicating Late Permian diorites should derive from the mantle and are influenced by some crustal material. Early Triassic granitic rocks have a wide range of εHf(t) values and TDM2 ages of −4.8 to +9.4 and 852 to 2136 Ma, respectively. Their zircons imply that the Early Triassic granites could be mainly derived from partial melting of the crust, with minor contribution of the crustal material of an ancient crust. The Early Triassic bimodal intrusive rocks in Yanbian area, combined with the regional geologic information; therefore, record a final post-subduction extensional environment due to the break-off of the previously subducted slab.

Two new shallow-water species ofHaliclonafrom north-eastern Brazil (Demospongiae: Haplosclerida: Chalinidae)

2014 ◽  
Vol 96 (2) ◽  
pp. 237-249 ◽  
Author(s):  
André Bispo ◽  
Monica Dorigo Correia ◽  
Eduardo Hajdu
Keyword(s):  
Shallow Water ◽  
Ex Situ ◽  
Eastern Brazil ◽  
Wide Range ◽  
North Eastern ◽  
The World ◽  
Dark Green ◽  
Scientific Collections ◽  
Shallow Water Species ◽  
Water Species

Haliclonais an unusually species-rich genus in Porifera, with more than 400 species described. In spite of many subgenera used in the taxonomic housekeeping of these sponges, over half of them remain unassigned to a subgenus, thus encouraging a wide range of redescriptions and taxonomic revisions of materials from all around the world. In this paper, we describe two newHaliclonaspp. collected at Pernambuco, Alagoas and Bahia States (north-eastern Brazil, between 08°46′S and 13°56′S).Haliclona(Reniera)chlorillasp. nov. is a dark green or black coloured, delicately-branched species; andHaliclona(Soestella)peixinhoaesp. nov., a beige-coloured, tubular species, where tubes frequently bear large thorns and possess a conspicuous sub-superficial meandering reticulation. These species highlight the importance of includingex-situcollections in compiling baseline data, as both were already present in scientific collections by the 1980s and 1990s.

scholarly journals Biodiversity, Community Structural Shifts, and Biogeography of Prokaryotes within Antarctic Continental Shelf Sediment

2003 ◽  
Vol 69 (5) ◽  
pp. 2463-2483 ◽  
Author(s):  
John P. Bowman ◽  
Robert D. McCuaig
Keyword(s):  
Species Richness ◽  
Continental Shelf ◽  
Structural Changes ◽  
Sediment Surface ◽  
Small Subset ◽  
Shelf Area ◽  
The Core ◽  
Shelf Sediment ◽  
Antarctic Continental Shelf ◽  
Wide Range

ABSTRACT 16S ribosomal DNA (rDNA) clone library analysis was conducted to assess prokaryotic diversity and community structural changes within a surficial sediment core obtained from an Antarctic continental shelf area (depth, 761 m) within the Mertz Glacier Polynya (MGP) region. Libraries were created from three separate horizons of the core (0- to 0.4-cm, 1.5- to 2.5-cm, and 20- to 21-cm depth positions). The results indicated that at the oxic sediment surface (depth, 0 to 0.4 cm) the microbial community appeared to be dominated by a small subset of potentially r-strategist (fast-growing, opportunistic) species, resulting in a lower-than-expected species richness of 442 operational taxonomic units (OTUs). At a depth of 1.5 to 2.5 cm, the species richness (1,128 OTUs) was much higher, with the community dominated by numerous gamma and delta proteobacterial phylotypes. At a depth of 20 to 21 cm, a clear decline in species richness (541 OTUs) occurred, accompanied by a larger number of more phylogenetically divergent phylotypes and a decline in the predominance of Proteobacteria. Based on rRNA and clonal abundance as well as sequence comparisons, syntrophic cycling of oxidized and reduced sulfur compounds appeared to be the dominant process in surficial MGP sediment, as phylotype groups putatively linked to these processes made up a large proportion of clones throughout the core. Between 18 and 65% of 16S rDNA phylotypes detected in a wide range of coastal and open ocean sediments possessed high levels of sequence similarity (>95%) with the MGP sediment phylotypes, indicating that many sediment prokaryote phylotype groups defined in this study are ubiquitous in marine sediment.

scholarly journals Echinoids from the Tesero Member (Werfen Formation) of the Dolomites (Italy): implications for extinction and survival of echinoids in the aftermath of the end-Permian mass extinction

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7361
Author(s):  
Jeffrey R. Thompson ◽  
Renato Posenato ◽  
David J. Bottjer ◽  
Elizabeth Petsios
Keyword(s):  
Mass Extinction ◽  
Sea Urchins ◽  
Northern Italy ◽  
Early Triassic ◽  
Crown Group ◽  
Stem Group ◽  
Extinction Event ◽  
Permian Extinction ◽  
Permian Mass Extinction ◽  
A New Species

The end-Permian mass extinction (∼252 Ma) was responsible for high rates of extinction and evolutionary bottlenecks in a number of animal groups. Echinoids, or sea urchins, were no exception, and the Permian to Triassic represents one of the most significant intervals of time in their macroevolutionary history. The extinction event was responsible for significant turnover, with the Permian–Triassic representing the transition from stem group echinoid-dominated faunas in the Palaeozoic to Mesozoic faunas dominated by crown group echinoids. This turnover is well-known, however, the environmental and taxonomic distribution of echinoids during the latest Permian and Early Triassic is not. Here we report on an echinoid fauna from the Tesero Member, Werfen Formation (latest Permian to Early Triassic) of the Dolomites (northern Italy). The fauna is largely known from disarticulated ossicles, but consists of both stem group taxa, and a new species of crown group echinoid,Eotiaris teseroensisn. sp. That these stem group echinoids were present in the Tesero Member indicates that stem group echinoids did not go extinct in the Dolomites coincident with the onset of extinction, further supporting other recent work indicating that stem group echinoids survived the end-Permian extinction. Furthermore, the presence ofEotiarisacross a number of differing palaeoenvironments in the Early Triassic may have had implications for the survival of cidaroid echinoids during the extinction event.

Microbial and Thermochemical Controlled Sulfur Cycle in the Early Triassic Sediments of the Western Canadian Sedimentary Basin

2021 ◽  
pp. jgs2020-175
Author(s):  
Mastaneh H. Liseroudi ◽  
Omid H. Ardakani ◽  
Per K. Pedersen ◽  
Richard A. Stern ◽  
James M. Wood ◽  
...  
Keyword(s):  
Sedimentary Basin ◽  
Isotopic Analysis ◽  
Isotopic Signature ◽  
Sulfur Cycle ◽  
Early Triassic ◽  
Content Type ◽  
Wide Range ◽  
Thermochemical Processes ◽  
Supplementary Material ◽  
Montney Formation

Pyrite is one of three main sulfur reservoirs and one of the biggest fluxes in the global sulfur cycle. The sulfur isotopic signature of hydrogen sulfide, pyrite, and their parent sulfate is widely used as a proxy for tracking sulfur cycle variations in diagenetic environments. The Early Triassic Montney Formation in the Western Canadian Sedimentary Basin is characterized by distinct regional variations in pyrite abundance, type, sulfur isotopic signature, and H2S concentrations in natural gas. Two main types of framboidal and crystalline pyrite were identified to have formed during various stages of diagenesis. The wide range of δ34Spyrite values (-34.4 to +57.8‰ V-CDT) demonstrates that the sulfur cycle in the Montney Formation is governed by both microbial and thermochemical processes. The comparison of δ34S of the produced-gas H2S with pyrite, anhydrite, and solid bitumen of the Montney, and underlying and overlying formations suggests a mixture of dominantly in situ and minor migrated H2S with TSR origin in the Montney Formation. The large diagenetic variations in pyrite types and δ34Spyrite values suggest a lack of direct biogeochemical connection to the sulfur cycle and emphasize the importance of careful petrographic observations and micro-scale isotopic analysis of sedimentary units to accurately reconstruct paleoenvironmental conditions.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5272484

Hyolithellus in life position from the Lower Cambrian of North Greenland

2011 ◽  
Vol 85 (1) ◽  
pp. 37-47 ◽  
Author(s):  
Christian B. Skovsted ◽  
John S. Peel
Keyword(s):  
Lower Cambrian ◽  
Tube Wall ◽  
Center Of Mass ◽  
Sediment Surface ◽  
Vertical Orientation ◽  
Stem Group ◽  
First Occurrence ◽  
Tubular Specimens ◽  
North Greenland

Tubular specimens belonging to Hyolithellus from silty dolostones of the basal Aftenstjernesø Formation of North Greenland may represent the first occurrence of this widespread Cambrian fossil in life position. A high proportion of preserved specimens are oriented normal to bedding with the tapering end of the tube down. Occasional undulations in the growth of the tubes indicate that the animal actively adjusted its growth to achieve a vertical orientation in relation to the sediment surface. Increasing thickness of the tube wall towards the tapering end shifted the center of mass downwards and resulted in greater stability in the sediment. The tube remained open at both ends throughout ontogeny; it was most likely secreted by an annelid-grade animal which pumped water into the sediment through the tube. Hyolithellus and similar tubular fossils from the Lower Cambrian probably represent stem group annelids.

scholarly journals Isolation of a Methanogen from Deep Marine Sediments That Contain Methane Hydrates, and Description of Methanoculleus submarinus sp. nov

2003 ◽  
Vol 69 (6) ◽  
pp. 3311-3316 ◽  
Author(s):  
Jill A. Mikucki ◽  
Yitai Liu ◽  
Mark Delwiche ◽  
Frederick S. Colwell ◽  
David R. Boone
Keyword(s):  
Growth Rate ◽  
Nankai Trough ◽  
Sequence Similarity ◽  
Sampling Site ◽  
Average Diameter ◽  
Eastern Coast ◽  
Sediment Surface ◽  
Rrna Gene ◽  
C Cells ◽  
Wide Range

ABSTRACT We isolated a methanogen from deep in the sediments of the Nankai Trough off the eastern coast of Japan. At the sampling site, the water was 950 m deep and the sediment core was collected at 247 m below the sediment surface. The isolated methanogen was named Nankai-1. Cells of Nankai-1 were nonmotile and highly irregular coccoids (average diameter, 0.8 to 2 μm) and grew with hydrogen or formate as a catabolic substrate. Cells required acetate as a carbon source. Yeast extract and peptones were not required but increased the growth rate. The cells were mesophilic, growing most rapidly at 45�C (no growth at ≤10�C or ≥55�C). Cells grew with a maximum specific growth rate of 2.43 day−1 at 45�C. Cells grew at pH values between 5.0 and 8.7 but did not grow at pH 4.7 or 9.0. Strain Nankai-1 grew in a wide range of salinities, from 0.1 to 1.5 M Na+. The described phenotypic characteristics of this novel isolate were consistent with the in situ environment of the Nankai Trough. This is the first report of a methanogenic isolate from methane hydrate-bearing sediments. Phylogenetic analysis of its 16S rRNA gene sequence indicated that it is most closely related to Methanoculleus marisnigri (99.1% sequence similarity), but DNA hybridization experiments indicated a DNA sequence similarity of only 49%. Strain Nankai-1 was also found to be phenotypically similar to M. marisnigri, but two major phenotypic differences were found: strain Nankai-1 does not require peptones, and it grows fastest at a much higher temperature. We propose a new species, Methanoculleus submarinus, with strain Nankai-1 as the type strain.

When bivalves took over the world

Paleobiology ◽  
2007 ◽  
Vol 33 (3) ◽  
pp. 397-413 ◽  
Author(s):  
Margaret L. Fraiser ◽  
David J. Bottjer
Keyword(s):  
Mass Extinction ◽  
Arms Race ◽  
Steady Increase ◽  
Early Triassic ◽  
Environmental Distribution ◽  
Biodiversity Crisis ◽  
Marine Communities ◽  
The World ◽  
Mesozoic Marine Revolution ◽  
Permian Mass Extinction

AbstractThe end-Permian mass extinction is commonly portrayed not only as a massive biodiversity crisis but also as the time when marine benthic faunas changed from the Paleozoic Fauna, dominated by rhynchonelliform brachiopod taxa, to the Modern Fauna, dominated by gastropod and bivalve taxa. After the end-Permian mass extinction, scenarios involving the Mesozoic Marine Revolution portray a steady increase in numerical dominance by these benthic molluscs as largely due to the evolutionary effects of an “arms race.” We report here a new global paleoecological database from study of shell beds that shows a dramatic geologically sudden earliest Triassic takeover by bivalves as numerical dominants in level-bottom benthic marine communities, which continued through the Early Triassic. Three bivalve genera were responsible for this switch, none of which has any particular morphological features to distinguish it from many typical Paleozoic bivalve genera. The numerical success of these Early Triassic bivalves cannot be attributed to any of the well-known morphological evolutionary innovations of post-Paleozoic bivalves that characterize the Mesozoic Marine Revolution. Rather, their ability to mount this takeover most likely was due to the large extinction of rhynchonelliform brachiopods during the end-Permian mass extinction and aided by their environmental distribution and physiological characteristics that enabled them to thrive during periods of oceanic and atmospheric stress during the Permian/Triassic transition.

scholarly journals A new stem group echinoid from the Triassic of China leads to a revised macroevolutionary history of echinoids during the end-Permian mass extinction

2018 ◽  
Vol 5 (1) ◽  
pp. 171548 ◽  
Author(s):  
Jeffrey R. Thompson ◽  
Shi-xue Hu ◽  
Qi-Yue Zhang ◽  
Elizabeth Petsios ◽  
Laura J. Cotton ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Middle Triassic ◽  
Phylogenetic Analyses ◽  
Early Triassic ◽  
Crown Group ◽  
Stem Group ◽  
History Of ◽  
Permian Mass Extinction ◽  
Lazarus Effect ◽  
A New Species

The Permian–Triassic bottleneck has long been thought to have drastically altered the course of echinoid evolution, with the extinction of the entire echinoid stem group having taken place during the end-Permian mass extinction. The Early Triassic fossil record of echinoids is, however, sparse, and new fossils are paving the way for a revised interpretation of the evolutionary history of echinoids during the Permian–Triassic crisis and Early Mesozoic. A new species of echinoid, Yunnanechinus luopingensis n. sp. recovered from the Middle Triassic (Anisian) Luoping Biota fossil Lagerstätte of South China, displays morphologies that are not characteristic of the echinoid crown group. We have used phylogenetic analyses to further demonstrate that Yunnanechinus is not a member of the echinoid crown group. Thus a clade of stem group echinoids survived into the Middle Triassic, enduring the global crisis that characterized the end-Permian and Early Triassic. Therefore, stem group echinoids did not go extinct during the Palaeozoic, as previously thought, and appear to have coexisted with the echinoid crown group for at least 23 million years. Stem group echinoids thus exhibited the Lazarus effect during the latest Permian and Early Triassic, while crown group echinoids did not.

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