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Lars E Holmer - One of the best experts on this subject based on the ideXlab platform.
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The oldest Cambrian trilobite – brachiopod association in South China
Gondwana Research, 2021Co-Authors: Zhiliang Zhang, Lars E Holmer, Glenn A. Brock, Mansoureh Ghobadi Pour, Leonid E. Popov, Feiyang Chen, Yanlong Chen, Zhifei ZhangAbstract:Abstract Limestones of the Xihaoping Member of the Dengying Formation in the Xiaoyangba section, South China, yield the oldest known Cambrian brachiopod–trilobite association. In this member, the trilobite Parabadiella cf. huoi co-occurs with the new brachiopod species Eoobolus incipiens sp. nov. The association provides potential for correlation of lower Cambrian successions and gives novel insights into the origin, palaeobiogeographic distribution and early evolution of linguliform Brachiopods. Parabadiella occurs in shallow marine clastic and carbonate rocks in South China, demonstrating a broad distribution for this taxon. The new discovery indicates an early Chiungchussuan age (Parabadiella trilobite Zone, Cambrian Age 3) for the longstanding problematic Xihaoping Member. Furthermore, this earliest Parabadiella–Eoobolus association helps to establish close links with the oldest known trilobite–brachiopod assemblage from the upper Micrina etheridgei Zone (Parabadiella huoi trilobite Zone) in Australia. Eoobolus incipiens represents one of the earliest known linguliform Brachiopods, with a distinctive mixture of characters shared with both problematic tommotiids, as well as paterinide, lingulide and acrotretide Brachiopods, indicating that these features may be plesiomorphic for the Linguliformea. An age-constrained dispersal mode for early lingulate Brachiopods is proposed, indicating that the Subphylum Linguliformea may have originated in East Gondwana and South China during Cambrian Age 3, and only subsequently dispersed to other major Cambrian palaeocontinents (e.g. Siberia, Laurentia, Antarctica, Baltica, Avalonia, West Gondwana, North China) during the late stage of the Cambrian evolutionary radiation of animals.
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early cambrian organophosphatic Brachiopods from the xinji formation at shuiyu section shanxi province north china
Palaeoworld, 2020Co-Authors: Lars E Holmer, Timothy P Topper, Glenn A. Brock, Bing Pan, Christian B. SkovstedAbstract:Abstract Abundant and diverse small shelly fossils have been reported from Cambrian Series 2 in North China, but the co-occurring Brachiopods are still poorly known. Herein, we describe seven genera, five species and two undetermined species of organophosphatic Brachiopods including one new genus and new species from the lower Cambrian Xinji Formation at Shuiyu section, located on the southern margin of North China Platform. The brachiopod assemblage comprises one mickwitziid (stem group brachiopoda), Paramickwitzia boreussinaensis n. gen. n. sp., a paterinide, Askepasma toddense Laurie, 1986 , an acrotretoid, Eohadrotreta cf. zhenbaensis Li and Holmer, 2004 , a botsfordiid, Schizopholis yorkensis (Holmer and Ushatinskaya in Gravestock et al., 2001 ) and three linguloids, Spinobolus sp., Eodicellomus cf. elkaniiformis Holmer and Ushatinskaya in Gravestock et al., 2001 and Eoobolus sp. This brachiopod assemblage suggests a late Age 3 to early Age 4 for the Xinji Formation and reveals a remarkably strong connection with coeval faunas from East Gondwana, particularly the Hawker Group in South Australia. The high degree of similarity (even at species level) further supports a close palaeogeographic position between the North China Platform and Australian East Gondwana during the early Cambrian as indicated by small shelly fossil data.
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Survival on a soft seafloor: life strategies of Brachiopods from the Cambrian Burgess Shale
Earth-Science Reviews, 2015Co-Authors: Timothy P Topper, Lars E Holmer, Luke C. Strotz, Jeanbernard CaronAbstract:Abstract Understanding the structure of benthic communities in the Cambrian remains a major challenge. Direct evidence for species interrelationships is rare and therefore past ecological interactions typically cannot be reconstructed with great accuracy. Here we reveal the community patterns and modes of life of Brachiopods – one of the most important filter-feeding groups of Cambrian ecosystems – from the Cambrian Burgess Shale Lagerstatte. Burgess Shale Brachiopods attached to a range of hard substrates, including skeletal debris, conspecific Brachiopods and enigmatic tubes, with an overwhelming preference for attachment on the demosponge Pirania muricata . The dominance of P . muricata as a substrate choice – even in bedding assemblages where P . muricata individuals are rare – and similarities to the gregarious attachment strategies of extant brachiopod species suggests that Brachiopods larvae in the Burgess Shale community selected their attachment substrates. The distribution of brachiopod taxa is also intricately linked with the presence of suitable hard substrates, with species declining in bedding assemblages where their preferred hard substrates are absent. In addition, Brachiopods in the Burgess Shale community are predominantly low epifaunal tierers and do not exploit niches high in the water column, despite the presence of suitable attachment sites. Our analysis of tiering height versus host height indicates that there is no selection by brachiopod larvae in regard to the height of attachment and individuals attached at the first point of contact with the selected substrate. Through comparisons with the ‘early’ Cambrian Chengjiang Biota, we confirm that by the ‘middle’ Cambrian (Series 3, Stage 5) Brachiopods had already developed a range of attachment strategies similar to some modern brachiopod populations. Our results provide significant insight into the ecological constraints and adaptability of Brachiopods in the earliest animal communities of the Cambrian.
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Metamorphosis in Craniiformea revisited: Novocrania anomala shows delayed development of the ventral valve
Zoomorphology, 2013Co-Authors: Andreas Altenburger, Andreas Wanninger, Lars E HolmerAbstract:We revisited the brachiopod fold hypothesis and investigated metamorphosis in the craniiform brachiopod Novocrania anomala . Larval development is lecithotrophic and the dorsal (brachial) valve is secreted by dorsal epithelia. We found that the juvenile ventral valve, which consists only of a thin layer that was previously described as periostracal, is not a valve and is not secreted by the same epithelia as the dorsal valve. It is secreted by the attachment area of the larva at the posterior-most tip of the posterior larval lobe. The same attachment area is used by larvae of rhynchonelliform Brachiopods during metamorphosis to cement their pedicle to the substrate. N. anomala is therefore not initially attached by a valve but by material corresponding to pedicle cuticle. This is different to previous descriptions, which had led to speculations about a folding event in the evolution of Brachiopoda. We show that the “brachiopod fold hypothesis,” which argues that Brachiopods are transversely “folded” across the ontogenetic anterior–posterior axis, should be rejected at least with respect to the craniiforms. The data now suggest that the Craniiformea may be a derived group within the Rhynchonelliformea. This interpretation suggests that the last common ancestor of the Craniiformea has lost the pedicle and the ventral valve in early juvenile development. Characters that have previously been considered to be shared between the Craniiformea and the Linguliformea (clade Inarticulata), such as a through-gut and missing hinge articulation, may thus be secondarily derived characters of the Craniiformea within the Rhynchonelliformea.
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Homologous skeletal secretion in tommotiids and Brachiopods
Geology, 2009Co-Authors: Uwe Balthasar, Lars E Holmer, Christian B. Skovsted, Glenn A. BrockAbstract:Tommotiids are distinctive components of the early Cambrian small shelly fauna, almost invariably represented by isolated phosphatic sclerites derived from a multielement protective cover (scleritome). The unusual range of tommotiid sclerite morphologies and unknown construction of the scleritome have severely hampered our understanding of their phylogenetic affinities. However, recent description of rare, articulated scleritome material belonging to the tommotiid genera Eccentrotheca and Paterimitra support the hypothesis that some tommotiids fall within the stem group of the lophophorate phyla Phoronida and Brachiopoda and that at least some tommotiid sclerites are homologous precursors of the shells of organophosphatic Brachiopods. Here we show that the shell microstructure of Eccentrotheca and Paterimitra share substantial similarities with paterinid Brachiopods. While paterinids possess an overall brachiopod morphology, their microstructure appears more similar to Eccentrotheca and Paterimitra than to nonpaterinate lingulids. These findings strongly support the existence of a brachiopod total group that is solidly rooted within tommotiids, and identify the organophosphatic skeletal composition as plesiomorphic with calcareous shells as derived. The microstructural changes of the proposed tommotiid-brachiopod transition probably reflect an adaptation to fluctuating food and phosphorous intake that came with the switch to a sessile life style at the base of the tommotiid clade.
Jisuo Jin - One of the best experts on this subject based on the ideXlab platform.
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the first report of epipunctae in non plaesiomyid Brachiopods from the lowest silurian of southeast china
Palaeoworld, 2020Co-Authors: Bing Huang, Jisuo JinAbstract:Abstract Epipunctae are microscopic perforations that do not penetrate the shell but are confined to the outer layers of the shell. They have been known previously only in the orthidine family Plaesiomyidae. The striated walls of epipunctae are considered unique to Brachiopods and thus of significance for the study of stem-group brachiopod. In this study, we report the first occurrence of epipunctae in a non-plaesiomyid Brachiopods based on a well-preserved external mould of Cathaysiorthis yushanensis from the lower Silurian Shiyang Formation of Jiangxi, southeast China. The species belongs to the Family Cathaysiorthidae which differs from the Family Plaesiomyidae in many aspects especially in dorsal internal structures. The new data implies that epipunctae may be more widespread in orthide Brachiopods than previously thought, strengthening the notion that this is a plesiomorphic character of the brachiopod shell. The discovery of epipunctae, however, depends on excellent preservation of the outer surface of the shells as well as careful cleaning and observation.
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Early–Middle Ordovician brachiopod dispersal patterns in South China
Integrative zoology, 2014Co-Authors: Renbin Zhan, Jisuo JinAbstract:Paleobiogeographic patterns of the brachiopod faunas before and during the first radiation of the Great Ordovician Biodiversification Event (GOBE) in South China at 6 different localities from the upper Jiangnan Slope to the vast area of the Upper Yangtze Platform show several interesting features. First, the initial brachiopod diversity acme was accompanied by both high origination and extinction rates. Second, no significant changes took place in the taxonomic composition and paleobiogeographic pattern of the brachiopod fauna during the radiation at 5 of the 6 localities studied except the near shore locality, where the first brachiopod radiation was much later than at other localities and was marked by a dramatic increase in endemic constituents. Third, orthides were the predominant brachiopod group during the radiation, and regional brachiopod taxa played a significant role in defining the paleobiogeographic pattern of the radiation. Fourth, the first brachiopod radiation was associated with 3 major pulses of onshore migration from the upper Jiangnan Slope through the central Upper Yangtze Platform to the near shore settings of the platform, with the middle pulse being the most significant. Finally, paleogeographic dispersal took place in both onshore and offshore directions, although the onshore expansion was more prominent; several key Brachiopods, such as Paralenorthis, Nocturnellia, Protoskenidioides, Nereidella, Euorthisina and Yangtzeella, first appeared on the upper Jiangnan Slope and later formed distinct, and taxonomically diverse, communities on the Upper Yangtze Platform. The paleogeographic dispersal of Brachiopods is considered to be closely related to the tectonic evolution of the Qianzhong Arch.
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early middle ordovician brachiopod dispersal patterns in south china
Integrative Zoology, 2014Co-Authors: Renbin Zhan, Jisuo JinAbstract:Paleobiogeographic patterns of the brachiopod faunas before and during the first radiation of the Great Ordovician Biodiversification Event (GOBE) in South China at 6 different localities from the upper Jiangnan Slope to the vast area of the Upper Yangtze Platform show several interesting features. First, the initial brachiopod diversity acme was accompanied by both high origination and extinction rates. Second, no significant changes took place in the taxonomic composition and paleobiogeographic pattern of the brachiopod fauna during the radiation at 5 of the 6 localities studied except the near shore locality, where the first brachiopod radiation was much later than at other localities and was marked by a dramatic increase in endemic constituents. Third, orthides were the predominant brachiopod group during the radiation, and regional brachiopod taxa played a significant role in defining the paleobiogeographic pattern of the radiation. Fourth, the first brachiopod radiation was associated with 3 major pulses of onshore migration from the upper Jiangnan Slope through the central Upper Yangtze Platform to the near shore settings of the platform, with the middle pulse being the most significant. Finally, paleogeographic dispersal took place in both onshore and offshore directions, although the onshore expansion was more prominent; several key Brachiopods, such as Paralenorthis, Nocturnellia, Protoskenidioides, Nereidella, Euorthisina and Yangtzeella, first appeared on the upper Jiangnan Slope and later formed distinct, and taxonomically diverse, communities on the Upper Yangtze Platform. The paleogeographic dispersal of Brachiopods is considered to be closely related to the tectonic evolution of the Qianzhong Arch.
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Late Ordovician brachiopod communities of southeast China
Canadian Journal of Earth Sciences, 2002Co-Authors: Renbin Zhan, Jia-yu Rong, Jisuo Jin, L. R. M. CocksAbstract:The Upper Ordovician (mid-Ashgill) Xiazhen and Changwu formations in the Zhejiang-Jiangxi border region of southeastern China contain an abundant and diverse suite of Brachiopods. A cluster analysis of 59 key samples from 180 collections (over 23 000 specimens) allowed delineation of eight distinct brachiopod communities, herein named the Ectenoglossa minor Community, the Eospirifer praecursor Community, the Ovalospira dichotoma Community, the Antizygospira liquanensis Sowerbyella sinensis Community, the Kassinella shiyangensis Community, the Altaethyrella zhejiangensis Community, the Tcherskidium jiangshanensis Community and the Foliomena folium Community. These communities occur predominantly in limey, clayey, to silty mudstone facies, similar to Ziegler's Early Silurian brachiopod communities in the Welsh Borderland. On the basis of lithological, faunal, and paleogeographical evidence, the eight communities are interpreted to have distributed along an onshoreoffshore gradient from BA1 to BA6 settings on the northeastern margin of the Zhe-Gan Platform. In a broad paleo-embayment and mixed carbonatesiliciclastic shelf setting, the distribution of the eight brachiopod communities appears to have been controlled primarily by water depth because a given brachiopod community can be found in different lithofacies. Substrate types, however, must have played an important role, as some of the communities show preferred lithofacies. This study shows that the ecological zonation and community organization of the Late Ordovician pre-extinction Brachiopods were similar to those of Early Silurian post-extinction Brachiopods, although pronounced brachiopod provincialism during the Ashgill makes it difficult to directly correlate these communities with coeval brachiopod communities reported from other paleo-plates.
Matthew E. Clapham - One of the best experts on this subject based on the ideXlab platform.
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The role of bioturbation-driven substrate disturbance in the Mesozoic brachiopod decline
Paleobiology, 2020Co-Authors: Marko Manojlovic, Matthew E. ClaphamAbstract:AbstractBrachiopods dominated the seafloor as a primary member of the Paleozoic fauna. Despite the devastating effects of the end-Permian extinction, the group recovered during the early Mesozoic only to gradually decline from the Jurassic to today. This decline likely had multiple causes, including increased predation and bioturbation-driven substrate disruption, but the role of changing substrate is not well understood. Given the importance of substrate for extant brachiopod habitat, we documented Mesozoic–Cenozoic lithologic preferences and morphological changes to assess how decreasing firm-substrate habitat may have contributed to the brachiopod decline. Compared with bivalves, Mesozoic Brachiopods occurred more frequently and were disproportionately abundant in carbonate lithologies. Although patterns in glauconitic or ferruginous sediments are equivocal, Brachiopods became more abundant in coarser-grained carbonates and less abundant in fine-grained siliciclastics. During the Jurassic, brachiopod species rarely had abraded beaks but tended to be more convex with a high beak, potentially consistent with a non-analogue lifestyle resting on the seafloor. However, those highly convex morphotypes largely disappeared by the Cenozoic, when more terebratulides had abraded beaks, suggesting closer attachment to hard substrates. Rhynchonellides disproportionately declined to become a minor component of Cenozoic faunas, perhaps because of less pronounced morphological shifts. Trends in lithologic preferences and morphology are consistent with bioturbation-driven substrate disruption, with Brachiopods initially using firmer carbonate sediments as refugia before adapting to live primarily attached to hard surfaces. This progressive habitat restriction likely played a role in the final brachiopod decline, as bioturbating ecosystem engineers transformed benthic habitats in the Mesozoic and Cenozoic.
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WUCHIAPINGIAN (LOPINGIAN, LATE PERMIAN) Brachiopods FROM THE EPISKOPI FORMATION OF HYDRA ISLAND, GREECE
Palaeontology, 2009Co-Authors: Shuzhong Shen, Matthew E. ClaphamAbstract:Twenty-three species of silicified Brachiopods are described from four samples in the middle and upper parts of the Episkopi Formation from Hydra Island, Greece. These Brachiopods are newly recorded from the region and together with previously described Brachiopods from the same localities constitute the most diverse Lopingian (Late Permian) brachiopod fauna reported in southern Europe. The brachiopod fauna is Wuchiapingian as indicated by the associated conodonts. The fauna from Hydra exhibits strong palaeobiogeographical links with the faunas from South China. In addition, palaeobiogeographical affinities with the faunas of Thailand and the northern peri-Gondwanan region are also present, which implies a peri-Gondwanan origin for Hydra. Palaeoecologically, the brachiopod assemblage from sample EP in the middle part of the Episkopi Formation is dominated by pedically-attached and cementing genera and reflects moderate energy conditions above storm wave base and an abundance of hard substrates provided by sponges in the biohermal habitat. By contrast, the brachiopod assem- blage in the other three samples from the upper part of the Episkopi Formation is dominated by spinose genera with a free-resting life habit, suggesting soft substrates in a quiet water environment below storm wave base on the outer part of the shelf. New taxa are Petinospiriferina gen. nov., Huste- dia episkopiensis sp. nov., Waterhouseiella hydraensis sp. nov. and Xenosaria tenuis sp. nov.
Glenn A. Brock - One of the best experts on this subject based on the ideXlab platform.
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The oldest Cambrian trilobite – brachiopod association in South China
Gondwana Research, 2021Co-Authors: Zhiliang Zhang, Lars E Holmer, Glenn A. Brock, Mansoureh Ghobadi Pour, Leonid E. Popov, Feiyang Chen, Yanlong Chen, Zhifei ZhangAbstract:Abstract Limestones of the Xihaoping Member of the Dengying Formation in the Xiaoyangba section, South China, yield the oldest known Cambrian brachiopod–trilobite association. In this member, the trilobite Parabadiella cf. huoi co-occurs with the new brachiopod species Eoobolus incipiens sp. nov. The association provides potential for correlation of lower Cambrian successions and gives novel insights into the origin, palaeobiogeographic distribution and early evolution of linguliform Brachiopods. Parabadiella occurs in shallow marine clastic and carbonate rocks in South China, demonstrating a broad distribution for this taxon. The new discovery indicates an early Chiungchussuan age (Parabadiella trilobite Zone, Cambrian Age 3) for the longstanding problematic Xihaoping Member. Furthermore, this earliest Parabadiella–Eoobolus association helps to establish close links with the oldest known trilobite–brachiopod assemblage from the upper Micrina etheridgei Zone (Parabadiella huoi trilobite Zone) in Australia. Eoobolus incipiens represents one of the earliest known linguliform Brachiopods, with a distinctive mixture of characters shared with both problematic tommotiids, as well as paterinide, lingulide and acrotretide Brachiopods, indicating that these features may be plesiomorphic for the Linguliformea. An age-constrained dispersal mode for early lingulate Brachiopods is proposed, indicating that the Subphylum Linguliformea may have originated in East Gondwana and South China during Cambrian Age 3, and only subsequently dispersed to other major Cambrian palaeocontinents (e.g. Siberia, Laurentia, Antarctica, Baltica, Avalonia, West Gondwana, North China) during the late stage of the Cambrian evolutionary radiation of animals.
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early cambrian organophosphatic Brachiopods from the xinji formation at shuiyu section shanxi province north china
Palaeoworld, 2020Co-Authors: Lars E Holmer, Timothy P Topper, Glenn A. Brock, Bing Pan, Christian B. SkovstedAbstract:Abstract Abundant and diverse small shelly fossils have been reported from Cambrian Series 2 in North China, but the co-occurring Brachiopods are still poorly known. Herein, we describe seven genera, five species and two undetermined species of organophosphatic Brachiopods including one new genus and new species from the lower Cambrian Xinji Formation at Shuiyu section, located on the southern margin of North China Platform. The brachiopod assemblage comprises one mickwitziid (stem group brachiopoda), Paramickwitzia boreussinaensis n. gen. n. sp., a paterinide, Askepasma toddense Laurie, 1986 , an acrotretoid, Eohadrotreta cf. zhenbaensis Li and Holmer, 2004 , a botsfordiid, Schizopholis yorkensis (Holmer and Ushatinskaya in Gravestock et al., 2001 ) and three linguloids, Spinobolus sp., Eodicellomus cf. elkaniiformis Holmer and Ushatinskaya in Gravestock et al., 2001 and Eoobolus sp. This brachiopod assemblage suggests a late Age 3 to early Age 4 for the Xinji Formation and reveals a remarkably strong connection with coeval faunas from East Gondwana, particularly the Hawker Group in South Australia. The high degree of similarity (even at species level) further supports a close palaeogeographic position between the North China Platform and Australian East Gondwana during the early Cambrian as indicated by small shelly fossil data.
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Middle Ordovician Brachiopods from the Stairway Sandstone, Amadeus Basin, central Australia
Alcheringa: An Australasian Journal of Palaeontology, 2013Co-Authors: Kristian G. Jakobsen, Timothy P Topper, Glenn A. Brock, Arne Thorshøj Nielsen, David A. T. HarperAbstract:Jakobsen, K.G., Brock, G.A, Nielsen, A.T., Topper, T.P. & Harper, D.A.T., 2013. Middle Ordovician Brachiopods from the Stairway Sandstone, Amadeus Basin, central Australia. Alcheringa. ISSN 0311–5518.Middle Ordovician brachiopod faunas from the Amadeus Basin, central Australia are poorly known. The Darriwilian Stairway Sandstone was sampled stratigraphically for macrofossils in order to provide new information on marine benthic diversity in this clastic-dominated, shallow-water palaeoenvironment along the margin of northeastern Gondwana. The Brachiopods from the Stairway Sandstone are of low diversity and represent ca 9% of the entire shelly fauna. Five brachiopod taxa are described from the Stairway Sandstone; all are endemic to the Amadeus Basin at species level. Two new species, Amadeuphyla joanae gen. et sp. nov. and Paralenorthis luritjaorum sp. nov., are described. Unweighted cladistic analysis based on 20 characters places the new genus Amadeuphyla within the Taffinae.Kristian G. Jakobsen [kgjakobs...
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Ancestral billingsellides and the evolution and phylogenetic relationships of early rhynchonelliform Brachiopods
Journal of Systematic Palaeontology, 2013Co-Authors: Timothy P Topper, David A. T. Harper, Glenn A. BrockAbstract:The relationship of many Cambrian rhynchonelliform Brachiopods is poorly understood, with many genera displaying a combination of morphological features that are taxonomically confusing. The study of middle Cambrian–early Tremadocian Brachiopods is critical because this interval is sandwiched directly between the two largest radiation phases in the early Palaeozoic and provides raw data for deciphering the events leading up to the explosion of brachiopod genera in the Ordovician. Here we present a parsimony analysis of a wide selection of Cambrian and Ordovician brachiopod genera with a particular focus on the evolution and phylogeny of Billingsellida. The billingselloids were widespread by the late Cambrian and the group was originally thought to represent the ancestral stock of many Ordovician brachiopod lineages. The phylogenetic analyses portray the polytoechioids as derived billingselloids separate from the clitambonitoids that form a sister group. The Gondwanan brachiopod Roanella is interpreted as ...
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Homologous skeletal secretion in tommotiids and Brachiopods
Geology, 2009Co-Authors: Uwe Balthasar, Lars E Holmer, Christian B. Skovsted, Glenn A. BrockAbstract:Tommotiids are distinctive components of the early Cambrian small shelly fauna, almost invariably represented by isolated phosphatic sclerites derived from a multielement protective cover (scleritome). The unusual range of tommotiid sclerite morphologies and unknown construction of the scleritome have severely hampered our understanding of their phylogenetic affinities. However, recent description of rare, articulated scleritome material belonging to the tommotiid genera Eccentrotheca and Paterimitra support the hypothesis that some tommotiids fall within the stem group of the lophophorate phyla Phoronida and Brachiopoda and that at least some tommotiid sclerites are homologous precursors of the shells of organophosphatic Brachiopods. Here we show that the shell microstructure of Eccentrotheca and Paterimitra share substantial similarities with paterinid Brachiopods. While paterinids possess an overall brachiopod morphology, their microstructure appears more similar to Eccentrotheca and Paterimitra than to nonpaterinate lingulids. These findings strongly support the existence of a brachiopod total group that is solidly rooted within tommotiids, and identify the organophosphatic skeletal composition as plesiomorphic with calcareous shells as derived. The microstructural changes of the proposed tommotiid-brachiopod transition probably reflect an adaptation to fluctuating food and phosphorous intake that came with the switch to a sessile life style at the base of the tommotiid clade.
G R Shi - One of the best experts on this subject based on the ideXlab platform.
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patterns of brachiopod faunal and body size changes across the permian triassic boundary evidence from the daoduishan section in meishan area south china
Palaeogeography Palaeoclimatology Palaeoecology, 2016Co-Authors: G R Shi, Yifan Xiao, Tinglu Yang, Kexin Zhang, Mingliang Yue, Bing ChenAbstract:Abstract New analysis of Permian–Triassic brachiopod assemblages and body-size changes in South China provides insights into the process of the environmental crisis in the lead up to the end-Permian mass extinction. The recently discovered Daoduishan section of South China can be considered as an important auxiliary section for the study of Brachiopods at the Meishan Section D of South China, the GSSP of the Permian–Triassic Boundary (PTB). This paper studied changes of the brachiopod assemblages and body sizes through the upper part of the Changxing Formation and basal Yinkeng Formation of Daoduishan. The results show that significant changes of brachiopod assemblages took place between Beds 24e and 26. Brachiopods?Prelissorhynchia sp. and Paracruirithyris pygmaea are the dominators in Beds 14–24e, while Tethyochonetes pigmaea and Paryphella spp. are the dominators in Beds 26–29. Body sizes of Brachiopods significantly decreased between Beds 24e and 26 and then maintained smaller means in Beds 27–29. Studies of brachiopod morphological features indicate both Tethyochonetes and Paryphella had advantageous adaptations enabling them to copy with living in an anoxic/dysoxic and/or low-productivity environment during the Permian–Triassic crisis.
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late permian marine ecosystem collapse began in deeper waters evidence from brachiopod diversity and body size changes
Geobiology, 2015Co-Authors: G R Shi, Haijun Song, Richard J Twitchett, Y Zhang, K X Zhang, M L Yue, T L Yang, Yifan XiaoAbstract:Analysis of Permian-Triassic brachiopod diversity and body size changes from different water depths spanning the continental shelf to basinal facies in South China provides insights into the process of environmental deterioration. Comparison of the temporal changes of brachiopod diversity between deepwater and shallow-water facies demonstrates that deepwater Brachiopods disappeared earlier than shallow-water Brachiopods. This indicates that high environmental stress commenced first in deepwater settings and later extended to shallow waters. This environmental stress is attributed to major volcanic eruptions, which first led to formation of a stratified ocean and a chemocline in the outer shelf and deeper water environments, causing the disappearance of deep marine benthos including Brachiopods. The chemocline then rapidly migrated upward and extended to shallow waters, causing widespread mass extinction of shallow marine benthos. We predict that the spatial and temporal patterns of earlier onset of disappearance/extinction and ecological crisis in deeper water ecosystems will be recorded during other episodes of rapid global warming.
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paleobiogeographical extinction patterns of permian Brachiopods in the asian western pacific region
Paleobiology, 2002Co-Authors: Shen Shuzhong, G R ShiAbstract:Spatial and temporal variations in biological diversity are critical in understanding the role of biogeographical regulation (if any) on mass extinctions. An analysis based on a latest da- tabase of the stratigraphic ranges of 89 Permian brachiopod families, 422 genera, and 2059 species within the Boreal, Paleoequatorial, and Gondwanan Realms in the Asian-western Pacific region suggests two discrete mass extinctions, each possibly with different causes. Using species/family rarefaction analysis, we constructed diversity curves for late Artinskian-Kungurian, Roadian-Wor- dian, Capitanian, and Wuchiapingian intervals for filtering out uneven sampling intensities. The end-Changhsingian (latest Permian) extinction eliminated 87-90% of genera and 94-96% of species of Brachiopoda. The timing of the end-Changhsingian extinction of Brachiopods in the carbonate settings of South China and southern Tibet indicates that Brachiopods suffered a rapid extinction within a short interval just below the Permian/Triassic boundary. In comparison, the end-Guadalupian/late Guadalupian extinction is less profound and varies temporally in different realms. Brachiopods in the western Pacific sector of the Boreal Realm nearly disappeared by the end-Guadalupian but experienced a relatively long-term press extinction span- ning the entire Guadalupian in the Gondwanan Realm. The end-Guadalupian brachiopod diversity fall is not well reflected at the timescale used here in the Paleoequatorial Realm because the life- depleted early Wuchiapingian was overlapped by a rapid radiation phase in the late Wuchiapin- gian. The Guadalupian fall appears to be related to the dramatic reduction of habitat area for the Brachiopods, which itself is associated with the withdrawal of seawater from continental Pangea and the closure of the Sino-Mongolian seaway by the end-Guadalupian.