Hugo F R Bucher | University of Zurich, Switzerland (original) (raw)
Papers by Hugo F R Bucher
Science, Mar 1, 2013
Sun et al. (Reports, 19 October 2012, p. 366) reconstructed Permian to Middle Triassic equatorial... more Sun et al. (Reports, 19 October 2012, p. 366) reconstructed Permian to Middle Triassic equatorial seawater temperatures. After correct temporal positioning of their data points, their presumed trends of temperature changes, and hence their assumption of a one-to-one relationship between putative "lethally hot" seawater temperatures and a disputable equatorial "eclipse" of some organisms, are no longer supported by their data.
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Examining the geological past of our planet allows us to study periods of severe climatic and bio... more Examining the geological past of our planet allows us to study periods of severe climatic and biological crises and recoveries, biotic and abiotic ecosystem fluctuations, and faunal and floral turnovers through time. Furthermore, the recovery dynamics of large predators provide a key for evaluation of the pattern and tempo of ecosystem recovery because predators are interpreted to react most sensitively to environmental turbulences. The end-Permian mass extinction was the most severe crisis experienced by life on Earth, and the common paradigm persists that the biotic recovery from the extinction event was unusually slow and occurred in a step-wise manner, lasting up to eight to nine million years well into the early Middle Triassic (Anisian) in the oceans, and even longer in the terrestrial realm. Here we survey the global distribution and size spectra of Early Triassic and Anisian marine predatory vertebrates (fishes, amphibians and reptiles) to elucidate the height of trophic pyramids in the aftermath of the end-Permian event. The survey of body size was done by compiling maximum standard lengths for the bony fishes and some cartilaginous fishes, and total size (estimates) for the tetrapods. The distribution and size spectra of the latter are difficult to assess because of preservation artifacts and are thus mostly discussed qualitatively. The data nevertheless demonstrate that no significant size increase of predators is observable from the Early Triassic to the Anisian, as would be expected from the prolonged and stepwise trophic recovery model. The data further indicate that marine ecosystems characterized by multiple trophic levels existed from the earliest Early Triassic onwards. However, a major change in the taxonomic composition of predatory guilds occurred less than two million years after the end-Permian extinction event, in which a transition from fish/amphibian to fish/reptile-dominated higher trophic levels within ecosystems became apparent.
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The Permian and Triassic were key time intervals in the history of life on Earth. Both periods ar... more The Permian and Triassic were key time intervals in the history of life on Earth. Both periods are marked by a series of biotic crises including the most catastrophic of such events, the end-Permian mass extinction, which eventually led to a major turnover from typical Palaeozoic faunas and floras to those that are emblematic for the Mesozoic and Cenozoic. Here we review patterns in Permian–Triassic bony fishes, a group whose evolutionary dynamics are understudied. Based on data from primary literature, we analyse changes in their taxonomic diversity and body size (as a proxy for trophic position) and explore their response to Permian–Triassic events. Diversity and body size are investigated separately for different groups of Osteichthyes (Dipnoi, Actinistia, ‘Palaeopterygii’, ‘Subholostei’, Holostei, Teleosteomorpha), within the marine and freshwater realms and on a global scale (total diversity) as well as across palaeolatitudinal belts. Diversity is also measured for different palaeogeographical provinces. Our results suggest a general trend from low osteichthyan diversity in the Permian to higher levels in the Triassic. Diversity dynamics in the Permian are marked by a decline in freshwater taxa during the Cisuralian. An extinction event during the end-Guadalupian crisis is not evident from our data, but ‘palaeopterygians’ experienced a significant body size increase across the Guadalupian–Lopingian boundary and these fishes upheld their position as large, top predators from the Late Permian to the Late Triassic. Elevated turnover rates are documented at the Permian–Triassic boundary, and two distinct diversification events are noted in the wake of this biotic crisis, a first one during the Early Triassic (dipnoans, actinistians, ‘palaeopterygians’, ‘subholosteans’) and a second one during the Middle Triassic (‘subholosteans’, neopterygians). The origination of new, small taxa predominantly among these groups during the Middle Triassic event caused a significant reduction in osteichthyan body size. Neopterygii, the clade that encompasses the vast majority of extant fishes, underwent another diversification phase in the Late Triassic. The Triassic radiation of Osteichthyes, predominantly of Actinopterygii, which only occurred after severe extinctions among Chondrichthyes during the Middle–Late Permian, resulted in a profound change within global fish communities, from chondrichthyan-rich faunas of the Permo-Carboniferous to typical Mesozoic and Cenozoic associations dominated by actinopterygians. This turnover was not sudden but followed a stepwise pattern, with leaps during extinction events.
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A reduction in body size (Lilliput effect) has been repeatedly proposed for many marine organisms... more A reduction in body size (Lilliput effect) has been repeatedly proposed for many marine organisms in the
aftermath of the Permian–Triassic (PT) mass extinction. Specifically-reduced maximum sizes of benthic marine
invertebrates have been proposed for the entire Early Triassic. This concept was originally based on observations
on Early Triassic gastropods from the western USA basin and the Dolomites (N Italy) and it stimulated
subsequent studies on other taxonomic groups. However, only a few studies have tested the validity of the
Lilliput effect in gastropods to determine whether the paucity of large-sized gastropods is a genuine signal or
the result of a poor fossil record and insufficient sampling. In combination with a review of the literature, we
document numerous new, abundant, large-sized gastropods from the Griesbachian outcrops of Greenland and
from the Smithian–early Spathian interval in the southwestern USA. We show that large-sized (“Gulliver”)
gastropods (i) were present soon after the PT mass extinction, (ii) occurred in various basins, sedimentary facies
and environmental contexts (from shallow to deeper settings), and (iii) belong to diverse higher-rank taxa.
Focusing on thewestern USA basin,we investigate areas fromwhich microgastropod shell-bedswere previously
presented as being typical. However, we show that Gulliver gastropods do occur in the very same areas.
Insufficient sampling effort is probably the main reason for the rarity of reports of large Early Triassic gastropods,
which is supported by preliminary rarefaction-based simulations. Finally, it appears that the recently
documented middle to late Smithian climate shifts and the severe end-Smithian extinction of nekto-pelagic
faunas did not reduce maximum shell sizes of gastropods.
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Geology, 2006
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Based on the quantitative community analysis using species-level identifications, we track the re... more Based on the quantitative community analysis using species-level identifications, we track the restoration of
benthic ecosystems after the end-Permian mass extinction
throughout the Lower Triassic of the western USA. New data
on the palaeoecology of the Thaynes Group and Sinbad
Formation are provided, which fill a gap between the
recently studied palaeoecology of the Griesbachian–Dienerian
Dinwoody Formation and the Spathian Virgin Formation. In
the Sinbad Formation and Thaynes Group, 17 species (12
genera) of bivalves, 7 species and genera of gastropods and 2
species and genera of brachiopods are recognized. The new
bivalve genus Confusionella (Pteriidae) is described. A comprehensive review of the whole Lower Triassic succession of benthic ecosystems of the western USA indicates that midand inner shelf environments show incipient recovery signals around the Griesbachian–Dienerian transition, during the Smithian and, most profound, during the early Spathian.
Ecological data from youngest strata of the Dinwoody
Formation as well as stratigraphic ranges of species suggest
that the late Dienerian was likely a time interval of environmental stress for benthic ecosystems. Despite some evidence for short-term environmental disturbances (e.g. shift of dominant taxa, transient drop in alpha-diversity) during the
Smithian–Spathian transition, benthic ecosystems did not
show any notable taxonomic turnover at that time, in contrast
to the major crisis that affected ammonoids and conodonts.
Whereas alpha-diversity of benthic communities generally increased throughout the Early Triassic, beta-diversity
remained low, which reflects a persistently wide environmental
range of benthic species. This observation is in accordance with a recently proposed model that predicts a time lag between increasing within-habitat diversity (alphadiversity) and the onset of taxonomic differentiation between habitats (beta-diversity) during biotic recoveries from mass extinction events. The observation that beta-diversity had not significantly increased during the Early Triassic might also provide an explanation for the comparably sluggish increase in benthic diversity during that time, which has previously been attributed to persistent environmental stress.
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The Pahvant Range lies near the junction of three major geological provinces in the western USA: ... more The Pahvant Range lies near the junction of three major geological provinces in the western USA: the Basin and Range, the Rocky Mountains, and the Colorado Plateau. The complex geological milieu of central Utah provides both challenges and opportunities. Among these is the ...
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The Permian and Triassic were key time intervals in the history of life on Earth. Both periods ar... more The Permian and Triassic were key time intervals in the history of life on Earth. Both periods are marked by a series of biotic crises including the most catastrophic of such events, the end-Permian mass extinction, which eventually led to a major turnover from typical Palaeozoic faunas and floras to those that are emblematic for the Mesozoic and Cenozoic. Here we review patterns in Permian-Triassic bony fishes, a group whose evolutionary dynamics are understudied. Based on data from primary literature, we analyse changes in their taxonomic diversity and body size (as a proxy for trophic position) and explore their response to Permian-Triassic events. Diversity and body size are investigated separately for different groups of Osteichthyes (Dipnoi, Actinistia, 'Palaeopterygii', 'Subholostei', Holostei, Teleosteomorpha), within the marine and freshwater realms and on a global scale (total diversity) as well as across palaeolatitudinal belts. Diversity is also measured for different palaeogeographical provinces. Our results suggest a general trend from low osteichthyan diversity in the Permian to higher levels in the Triassic. Diversity dynamics in the Permian are marked by a decline in freshwater taxa during the Cisuralian. An extinction event during the end-Guadalupian crisis is not evident from our data, but 'palaeopterygians' experienced a significant body size increase across the Guadalupian-Lopingian boundary and these fishes upheld their position as large, top predators from the Late Permian to the Late Triassic. Elevated turnover rates are documented at the Permian-Triassic boundary, and two distinct diversification events are noted in the wake of this biotic crisis, a first one during the Early Triassic (dipnoans, actinistians,…
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Mesozoic FishesSystematics …, 1996
A new fossil fish fauna from the Middle Triassic of Nevada is presented in a preliminary overview... more A new fossil fish fauna from the Middle Triassic of Nevada is presented in a preliminary overview. A bonebed of lower middle Anisian age yields a rich shark fauna which includes several species of Polyacrodus as well as teeth of Acrodus, Palaeobates ...
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Rivista Italiana di …, 2006
Abstract. Early Triassic (Griesbachian to Spathian) ostracod faunas are here first discovered and... more Abstract. Early Triassic (Griesbachian to Spathian) ostracod faunas are here first discovered and described form the Guangxi Province, South China. Thirty-seven species belonging to fourteen genera are recognized. Seven species are new: Bairdia fengshanensis n. sp., ...
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This study synthesizes and revises the ammonoid zonations as well as their correlation with each ... more This study synthesizes and revises the ammonoid zonations as well as their correlation with each other for western Nevada (USA), British Columbia (Canada), and the Sverdrup Basin (Canada) by utilizing the unitary association method. Based on a standard- ized taxonomy, the Anisian in the studied areas contains 13, 10, and 3 zones and a total of 174, 90, and 7
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Lethaia, 2014
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Topics in Geobiology, 1996
ABSTRACT In this chapter we discuss the mode and rate of growth in ammonoids, focusing primarily ... more ABSTRACT In this chapter we discuss the mode and rate of growth in ammonoids, focusing primarily on postembryonic growth. We first discuss the general mode of growth and then describe the ontogenetic sequence of growth stages. These stages are recognized on the basis of changes in morphology. For example, a gràph of the increase in size of whorl width versus shell diameter in an individual reveals changes through ontogeny that pinpoint the end of one growth stage and the beginning of another. We next discuss the overall rate of growth through ontogeny and establish a generalized growth curve. In this discussion, we refer to other cephalopods whose rate of growth is known. Fluctuations in the rate of growth that are superimposed on this growth curve are indicated in ammonoids by the presence of such shell features as varices and constrictions.
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Science, Mar 1, 2013
Sun et al. (Reports, 19 October 2012, p. 366) reconstructed Permian to Middle Triassic equatorial... more Sun et al. (Reports, 19 October 2012, p. 366) reconstructed Permian to Middle Triassic equatorial seawater temperatures. After correct temporal positioning of their data points, their presumed trends of temperature changes, and hence their assumption of a one-to-one relationship between putative "lethally hot" seawater temperatures and a disputable equatorial "eclipse" of some organisms, are no longer supported by their data.
Bookmarks Related papers MentionsView impact
Examining the geological past of our planet allows us to study periods of severe climatic and bio... more Examining the geological past of our planet allows us to study periods of severe climatic and biological crises and recoveries, biotic and abiotic ecosystem fluctuations, and faunal and floral turnovers through time. Furthermore, the recovery dynamics of large predators provide a key for evaluation of the pattern and tempo of ecosystem recovery because predators are interpreted to react most sensitively to environmental turbulences. The end-Permian mass extinction was the most severe crisis experienced by life on Earth, and the common paradigm persists that the biotic recovery from the extinction event was unusually slow and occurred in a step-wise manner, lasting up to eight to nine million years well into the early Middle Triassic (Anisian) in the oceans, and even longer in the terrestrial realm. Here we survey the global distribution and size spectra of Early Triassic and Anisian marine predatory vertebrates (fishes, amphibians and reptiles) to elucidate the height of trophic pyramids in the aftermath of the end-Permian event. The survey of body size was done by compiling maximum standard lengths for the bony fishes and some cartilaginous fishes, and total size (estimates) for the tetrapods. The distribution and size spectra of the latter are difficult to assess because of preservation artifacts and are thus mostly discussed qualitatively. The data nevertheless demonstrate that no significant size increase of predators is observable from the Early Triassic to the Anisian, as would be expected from the prolonged and stepwise trophic recovery model. The data further indicate that marine ecosystems characterized by multiple trophic levels existed from the earliest Early Triassic onwards. However, a major change in the taxonomic composition of predatory guilds occurred less than two million years after the end-Permian extinction event, in which a transition from fish/amphibian to fish/reptile-dominated higher trophic levels within ecosystems became apparent.
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The Permian and Triassic were key time intervals in the history of life on Earth. Both periods ar... more The Permian and Triassic were key time intervals in the history of life on Earth. Both periods are marked by a series of biotic crises including the most catastrophic of such events, the end-Permian mass extinction, which eventually led to a major turnover from typical Palaeozoic faunas and floras to those that are emblematic for the Mesozoic and Cenozoic. Here we review patterns in Permian–Triassic bony fishes, a group whose evolutionary dynamics are understudied. Based on data from primary literature, we analyse changes in their taxonomic diversity and body size (as a proxy for trophic position) and explore their response to Permian–Triassic events. Diversity and body size are investigated separately for different groups of Osteichthyes (Dipnoi, Actinistia, ‘Palaeopterygii’, ‘Subholostei’, Holostei, Teleosteomorpha), within the marine and freshwater realms and on a global scale (total diversity) as well as across palaeolatitudinal belts. Diversity is also measured for different palaeogeographical provinces. Our results suggest a general trend from low osteichthyan diversity in the Permian to higher levels in the Triassic. Diversity dynamics in the Permian are marked by a decline in freshwater taxa during the Cisuralian. An extinction event during the end-Guadalupian crisis is not evident from our data, but ‘palaeopterygians’ experienced a significant body size increase across the Guadalupian–Lopingian boundary and these fishes upheld their position as large, top predators from the Late Permian to the Late Triassic. Elevated turnover rates are documented at the Permian–Triassic boundary, and two distinct diversification events are noted in the wake of this biotic crisis, a first one during the Early Triassic (dipnoans, actinistians, ‘palaeopterygians’, ‘subholosteans’) and a second one during the Middle Triassic (‘subholosteans’, neopterygians). The origination of new, small taxa predominantly among these groups during the Middle Triassic event caused a significant reduction in osteichthyan body size. Neopterygii, the clade that encompasses the vast majority of extant fishes, underwent another diversification phase in the Late Triassic. The Triassic radiation of Osteichthyes, predominantly of Actinopterygii, which only occurred after severe extinctions among Chondrichthyes during the Middle–Late Permian, resulted in a profound change within global fish communities, from chondrichthyan-rich faunas of the Permo-Carboniferous to typical Mesozoic and Cenozoic associations dominated by actinopterygians. This turnover was not sudden but followed a stepwise pattern, with leaps during extinction events.
Bookmarks Related papers MentionsView impact
A reduction in body size (Lilliput effect) has been repeatedly proposed for many marine organisms... more A reduction in body size (Lilliput effect) has been repeatedly proposed for many marine organisms in the
aftermath of the Permian–Triassic (PT) mass extinction. Specifically-reduced maximum sizes of benthic marine
invertebrates have been proposed for the entire Early Triassic. This concept was originally based on observations
on Early Triassic gastropods from the western USA basin and the Dolomites (N Italy) and it stimulated
subsequent studies on other taxonomic groups. However, only a few studies have tested the validity of the
Lilliput effect in gastropods to determine whether the paucity of large-sized gastropods is a genuine signal or
the result of a poor fossil record and insufficient sampling. In combination with a review of the literature, we
document numerous new, abundant, large-sized gastropods from the Griesbachian outcrops of Greenland and
from the Smithian–early Spathian interval in the southwestern USA. We show that large-sized (“Gulliver”)
gastropods (i) were present soon after the PT mass extinction, (ii) occurred in various basins, sedimentary facies
and environmental contexts (from shallow to deeper settings), and (iii) belong to diverse higher-rank taxa.
Focusing on thewestern USA basin,we investigate areas fromwhich microgastropod shell-bedswere previously
presented as being typical. However, we show that Gulliver gastropods do occur in the very same areas.
Insufficient sampling effort is probably the main reason for the rarity of reports of large Early Triassic gastropods,
which is supported by preliminary rarefaction-based simulations. Finally, it appears that the recently
documented middle to late Smithian climate shifts and the severe end-Smithian extinction of nekto-pelagic
faunas did not reduce maximum shell sizes of gastropods.
Bookmarks Related papers MentionsView impact
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Geology, 2006
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Nature Geoscience, 2011
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Geology, 2011
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Based on the quantitative community analysis using species-level identifications, we track the re... more Based on the quantitative community analysis using species-level identifications, we track the restoration of
benthic ecosystems after the end-Permian mass extinction
throughout the Lower Triassic of the western USA. New data
on the palaeoecology of the Thaynes Group and Sinbad
Formation are provided, which fill a gap between the
recently studied palaeoecology of the Griesbachian–Dienerian
Dinwoody Formation and the Spathian Virgin Formation. In
the Sinbad Formation and Thaynes Group, 17 species (12
genera) of bivalves, 7 species and genera of gastropods and 2
species and genera of brachiopods are recognized. The new
bivalve genus Confusionella (Pteriidae) is described. A comprehensive review of the whole Lower Triassic succession of benthic ecosystems of the western USA indicates that midand inner shelf environments show incipient recovery signals around the Griesbachian–Dienerian transition, during the Smithian and, most profound, during the early Spathian.
Ecological data from youngest strata of the Dinwoody
Formation as well as stratigraphic ranges of species suggest
that the late Dienerian was likely a time interval of environmental stress for benthic ecosystems. Despite some evidence for short-term environmental disturbances (e.g. shift of dominant taxa, transient drop in alpha-diversity) during the
Smithian–Spathian transition, benthic ecosystems did not
show any notable taxonomic turnover at that time, in contrast
to the major crisis that affected ammonoids and conodonts.
Whereas alpha-diversity of benthic communities generally increased throughout the Early Triassic, beta-diversity
remained low, which reflects a persistently wide environmental
range of benthic species. This observation is in accordance with a recently proposed model that predicts a time lag between increasing within-habitat diversity (alphadiversity) and the onset of taxonomic differentiation between habitats (beta-diversity) during biotic recoveries from mass extinction events. The observation that beta-diversity had not significantly increased during the Early Triassic might also provide an explanation for the comparably sluggish increase in benthic diversity during that time, which has previously been attributed to persistent environmental stress.
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The Pahvant Range lies near the junction of three major geological provinces in the western USA: ... more The Pahvant Range lies near the junction of three major geological provinces in the western USA: the Basin and Range, the Rocky Mountains, and the Colorado Plateau. The complex geological milieu of central Utah provides both challenges and opportunities. Among these is the ...
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The Permian and Triassic were key time intervals in the history of life on Earth. Both periods ar... more The Permian and Triassic were key time intervals in the history of life on Earth. Both periods are marked by a series of biotic crises including the most catastrophic of such events, the end-Permian mass extinction, which eventually led to a major turnover from typical Palaeozoic faunas and floras to those that are emblematic for the Mesozoic and Cenozoic. Here we review patterns in Permian-Triassic bony fishes, a group whose evolutionary dynamics are understudied. Based on data from primary literature, we analyse changes in their taxonomic diversity and body size (as a proxy for trophic position) and explore their response to Permian-Triassic events. Diversity and body size are investigated separately for different groups of Osteichthyes (Dipnoi, Actinistia, 'Palaeopterygii', 'Subholostei', Holostei, Teleosteomorpha), within the marine and freshwater realms and on a global scale (total diversity) as well as across palaeolatitudinal belts. Diversity is also measured for different palaeogeographical provinces. Our results suggest a general trend from low osteichthyan diversity in the Permian to higher levels in the Triassic. Diversity dynamics in the Permian are marked by a decline in freshwater taxa during the Cisuralian. An extinction event during the end-Guadalupian crisis is not evident from our data, but 'palaeopterygians' experienced a significant body size increase across the Guadalupian-Lopingian boundary and these fishes upheld their position as large, top predators from the Late Permian to the Late Triassic. Elevated turnover rates are documented at the Permian-Triassic boundary, and two distinct diversification events are noted in the wake of this biotic crisis, a first one during the Early Triassic (dipnoans, actinistians,…
Bookmarks Related papers MentionsView impact
Mesozoic FishesSystematics …, 1996
A new fossil fish fauna from the Middle Triassic of Nevada is presented in a preliminary overview... more A new fossil fish fauna from the Middle Triassic of Nevada is presented in a preliminary overview. A bonebed of lower middle Anisian age yields a rich shark fauna which includes several species of Polyacrodus as well as teeth of Acrodus, Palaeobates ...
Bookmarks Related papers MentionsView impact
Rivista Italiana di …, 2006
Abstract. Early Triassic (Griesbachian to Spathian) ostracod faunas are here first discovered and... more Abstract. Early Triassic (Griesbachian to Spathian) ostracod faunas are here first discovered and described form the Guangxi Province, South China. Thirty-seven species belonging to fourteen genera are recognized. Seven species are new: Bairdia fengshanensis n. sp., ...
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This study synthesizes and revises the ammonoid zonations as well as their correlation with each ... more This study synthesizes and revises the ammonoid zonations as well as their correlation with each other for western Nevada (USA), British Columbia (Canada), and the Sverdrup Basin (Canada) by utilizing the unitary association method. Based on a standard- ized taxonomy, the Anisian in the studied areas contains 13, 10, and 3 zones and a total of 174, 90, and 7
Bookmarks Related papers MentionsView impact
Lethaia, 2014
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Topics in Geobiology, 1996
ABSTRACT In this chapter we discuss the mode and rate of growth in ammonoids, focusing primarily ... more ABSTRACT In this chapter we discuss the mode and rate of growth in ammonoids, focusing primarily on postembryonic growth. We first discuss the general mode of growth and then describe the ontogenetic sequence of growth stages. These stages are recognized on the basis of changes in morphology. For example, a gràph of the increase in size of whorl width versus shell diameter in an individual reveals changes through ontogeny that pinpoint the end of one growth stage and the beginning of another. We next discuss the overall rate of growth through ontogeny and establish a generalized growth curve. In this discussion, we refer to other cephalopods whose rate of growth is known. Fluctuations in the rate of growth that are superimposed on this growth curve are indicated in ammonoids by the presence of such shell features as varices and constrictions.
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