Hugo Bucher

University of Zurich

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Nicolas Goudemand

École Normale Supérieure de Lyon

Arnaud Brayard

Centre National de la Recherche Scientifique

Thomas Brühwiler

University of Zurich

Peter A. Hochuli

University of Zurich

Michael Hautmann

Swiss National Museum

Torsten Vennemann

University of Lausanne

Elke Schneebeli‐Hermann

University of Zurich

David Ware

Museum für Naturkunde

Aymon Baud

University of Lausanne

Urs Schaltegger

University of Geneva

Cooperative Institutions

Centre National de la Recherche Scientifique

University of Zurich

University of Lausanne

Université Claude Bernard Lyon 1

Swiss National Museum

University of Geneva

Sorbonne Université

ETH Zurich

École Normale Supérieure de Lyon

University of Milan

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A new paleoecological look at the Dinwoody Formation (Lower Triassic, western USA): intrinsic versus extrinsic controls on ecosystem recovery after the end-Permian mass extinction

Journal of Paleontology (2013)

Richard Hofmann Michael Hautmann Hugo Bucher

The Dinwoody Formation of the western United States represents an important archive of Early Triassic ecosystems in the immediate aftermath of the end-Permian mass extinction. We present a systematic description and a quantitative paleoecological analysis of its benthic faunas in order to reconstruct benthic associations and to explore the temporal and spatial variations of diversity, ecological structure and taxonomic composition throughout the earliest Triassic of the western United States. A total of 15 bivalve species, two gastropod species, and two brachiopod species are recognized in the study area. The paleoecological analysis shows that the oldest Dinwoody communities are characterized by low diversity, low ecological complexity and high dominance of few species. We suggest that this low diversity most likely reflects the consequences of the mass extinction in the first place and not necessarily the persistence of environmental stress. Whereas this diversity pattern persists into younger strata of the Dinwoody Formation in outer shelf environments, an increase in richness, evenness and guild diversity occurred around the Griesbachian–Dienerian boundary in more shallow marine habitats. This incipient recovery towards the end of the Griesbachian is in accordance with observations from other regions and thus probably represents an interregional signal. In contrast to increasing richness within communities (alpha-diversity), beta-diversity remained low during the Griesbachian and Dienerian in the study area. This low beta-diversity reflects a wide environmental and geographical range of taxa during the earliest Triassic, indicating that the increase of within-habitat diversity has not yet led to significant competitive exclusion. We hypothesize that the well-known prevalence of generalized taxa in post-extinction faunas is primarily an effect of reduced competition that allows species to exist through the full range of their fundamental niches, rather than being caused by unusual and uniform environmental stress.

Early Triassic

Extinction (optical mineralogy)

Permian–Triassic extinction event

Guild

Dominance (genetics)

10.1666/12-153

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Citations (62)

A new pistosaurid (Reptilia: Sauropterygia) from the Middle Triassic of Nevada and its implications for the origin of the plesiosaurs

Journal of Vertebrate Paleontology (1997)

P. Martin Sander Olivier Rieppel Hugo Bucher

ABSTRACT ABSTRACT We describe a new pistosaurid sauropterygian, Augustasaurus hagdorni, gen. et sp. nov., from the Middle Triassic of Nevada. The specimen was collected in Muller Canyon, Augusta Mountains, from a late Anisian laminated mudstone unit in the Fossil Hill Member of the Favret Formation. Augustasaurus hagdorni is based on a partial articulated skeleton consisting of the posterior neck, trunk, shoulder girdle, and both forelimbs. In comparison to Pistosaurus from the Muschelkalk Beds of central Europe, the neural spines of the new pistosaurid are lower and longer with autapomorphic saw-cut rugosities and double facets of unfinished bone. Augustasaurus hagdorni has reduced front limbs with relatively short distal elements and a phalangeal formula of 1-1-3-3-1. This condition is very different from that in plesiosaurs, the presumed sister-group of pistosaurids.

Autapomorphy

Postcrania

10.1080/02724634.1997.10010999

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Citations (80)

Palynostratigraphy at the Permian-Triassic boundary of the Amb section, Salt Range, Pakistan

Palynology (2014)

Elke Schneebeli‐Hermann Hugo Bucher

AbstractPalynostratigraphy across the Permian–Triassic of the Salt Range and Surghar Range area remains poorly known because of the predominance of unsuitable facies and preservation (Nammal, Chhidru, Chitta-Landu and Narmia). Dolomite and limestone in the basal Mianwali Formation prevented the establishment of a palynostratigraphic scheme for the basal Early Triassic (Hermann et al. Citation2012). Based on the study of a new Permian–Triassic section in the Amb valley where siltstone layers are intercalated in the basal Mianwali Formation (Kathwai Member), we describe a new record of palynological assemblages from the uppermost Permian Chhidru Formation and the lowermost part of the Early Triassic Mianwali Formation. The latest Permian Chhidru 2 sporomorph association occurs in the uppermost part of the Chhidru Formation, the so-called 'white sandstone unit'. It is marked by the dominance of bisaccate pollen grains (mainly Protohaploxypinus spp.) and cavate trilete spores (mainly Kraeuselisporites spp.). Here, the previously described lowermost Triassic palynozone PTr 1 is subdivided into two subzones. PTr 1a assemblages are described from the Griesbachian Kathwai Member. They are characterized by continued high bisaccate pollen grain abundances and the presence of the lycopod genera Lundbladispora spp. and Densoisporites spp. In these assemblages, typical 'Permian taxa' and typical 'Triassic taxa' are mixed. The composition of the middle Dienerian PTr 1b assemblages corresponds to the previously described PTr 1 assemblage from Nammal and Chitta-Landu. Lundbladispora spp. and Densoisporites spp. account for ca. 80% of the total assemblage in PTr 1b. Although the Griesbachian assemblages record a decrease in diversity, the middle Dienerian assemblages represent the poorest assemblages of the studied Permian–Triassic interval. Reduviasporonites occurs only sporadically throughout the Amb succession.Keywords: PakistanPermian–Triassic boundarypalynostratigraphyextinction AcknowledgementsThis work was supported by the Swiss National Science Foundation under Grant No. PBZHP2-135955. We thank Peter A. Hochuli for discussion and constructive criticism as well as Annette E. Götz, Susanne Feist-Burkhardt and James B. Riding for their careful review and helpful comments that greatly improved the manuscript. David Ware and Nicolas Goudemand are thanked for providing biostratigraphical data (ammonoids and conodonts).Additional informationNotes on contributorsElke Schneebeli-HermannELKE SCHNEEBELI is a research associate at the University of Zurich and lecturer of Palaeobotany at University and Swiss Federal Institute of Technology, Zurich, Switzerland. Her PhD at Zurich and the following postdoc at Utrecht University included research on mainly Permian to Middle Triassic palynology and stable carbon isotopes. Elke is interested in the reconstruction of ancient terrestrial ecosystems and climate using plant fossil and geochemical data.Hugo BucherHUGO BUCHER is professor of Palaeontology at the University of Zurich and Swiss Federal Institute of Technology, Zurich, Switzerland. His research interests range from the morphogenesis of biological shapes (e.g. molluscs) to the role of mass extinctions and recoveries (e.g. the Permian Triassic crisis) in evolution and diversity of marine clades, with emphasis on biotic-abiotic interactions.

Siltstone

Early Triassic

Biochronology

Dominance (genetics)

10.1080/01916122.2014.921648

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Citations (21)

Evolution of Early Triassic outer platform paleoenvironments in the Nanpanjiang Basin (South China) and their significance for the biotic recovery

Sedimentary Geology (2008)

Thomas Galfetti Hugo Bucher Rossana Martini Peter A. Hochuli Helmut Weissert

Early Triassic

Conodont

Siliciclastic

Carbonate platform

Micrite

Ladinian

Concretion

Stromatolite

10.1016/j.sedgeo.2007.12.008

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Citations (112)

Clade-dependent size response of conodonts to environmental changes during the late Smithian extinction

Earth-Science Reviews (2018)

Marc Leu Hugo Bucher Nicolas Goudemand

Conodont

Early Triassic

Nekton

10.1016/j.earscirev.2018.11.003

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Citations (36)

Geologically oldest oysters were epizoans on Early Triassic ammonoids

Journal of Molluscan Studies (2017)

Michael Hautmann David Ware Hugo Bucher

Ammonoids that lived in the wake of the end-Permian mass extinction are frequently encrusted by the shells of cementing bivalves, but the majority of these epizoans are too poorly preserved for a precise taxonomic identification. However, our huge collection of Griesbachian – Dienerian (Early Triassic, c. 252–251 Ma) ammonoids from east Greenland, the Salt Range (Pakistan) and Spiti (India) includes three ammonoid specimens with epizoans that can reliably be identified as oysters, based on their attachment by the left valve and the morphology of their ligament area. Some of these oysters have their right (upper) valve preserved, which shows the characteristic morphology of Liostrea. These finds predate (1) the previously known first occurrence of oysters by c. 5 Myr, (2) that of Gryphaeidae by c. 15 Myr and (3) that of Liostrea by c. 20 Myr. Moreover, the stratigraphic polarity indicates that Liostrea is a candidate ancestor of Gryphaea and not vice versa. The open-marine habitat of the Liostrea epizoans described herein provides an explanation for the unusual ecology of its putative descendent Gryphaea as a fully marine soft-bottom dweller with a preference for relatively deep water environments during the Triassic. The revised timing of the early phylogeny of oysters suggests that this bivalve clade underwent rapid morphological divergence during the initial phase of its evolution.

myr

Early Triassic

Ammonoidea

10.1093/mollus/eyx018

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Citations (19)

On the presence ofMixosaurus(Ichthyopterygia: Reptilia) in the Middle Triassic of Nevada

Journal of Paleontology (1990)

P. Martin Sander Hugo Bucher

The small ichthyosaur Mixosaurus is the most widely distributed ichthyosaur. It is known from Lower Triassic rocks of British Columbia, Canada (Callaway and Brinkman, 1989), and Middle Triassic rocks of northwestern North America (Alaska, British Columbia), China, Timor, the western Tethys (Switzerland, Italy, Turkey), the Germanic Triassic, and the high Arctic (Spitsbergen, Exmouth Island) (Mazin, 1986; Callaway and Brinkman, 1989; Callaway and Massare, 1989). The presence of Mixosaurus in one of the richest ichthyosaur provinces, the Middle Triassic of Nevada (Merriam, 1908), has been difficult to establish. The history of this problem is very colorful and is the topic of this note together with the description of a new specimen from the Nevada Middle Triassic.

Trias

10.1017/s0022336000042396

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Citations (12)

Good Genes and Good Luck: Ammonoid Diversity and the End-Permian Mass Extinction

Science (2009)

Arnaud Brayard Gilles Escarguel Hugo Bucher Claude Monnet Thomas Brühwiler

The end-Permian mass extinction removed more than 80% of marine genera. Ammonoid cephalopods were among the organisms most affected by this crisis. The analysis of a global diversity data set of ammonoid genera covering about 106 million years centered on the Permian-Triassic boundary (PTB) shows that Triassic ammonoids actually reached levels of diversity higher than in the Permian less than 2 million years after the PTB. The data favor a hierarchical rather than logistic model of diversification coupled with a niche incumbency hypothesis. This explosive and nondelayed diversification contrasts with the slow and delayed character of the Triassic biotic recovery as currently illustrated for other, mainly benthic groups such as bivalves and gastropods.

Permian–Triassic extinction event

Ammonoidea

Extinction (optical mineralogy)

10.1126/science.1174638

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Citations (273)

An Early Triassic Pleuromeia strobilus from Nevada, USA

Review of Palaeobotany and Palynology (2022)

Morris Mendelin Elke Schneebeli‐Hermann Evelyn Kustatscher Hendrik Nowak Christian Vérard

A lycopsid reproductive organ from the Koipato Group in the southern Humboldt Range, Nevada, is described. It was found in fine-grained volcanogenic turbitides of mid-Spathian age derived from the Koipato volcanic arc. The strobilus is preserved as an imprint with small amounts of organic material. The shape of the reproductive organ, as well as the sporophylls, resemble those of the genus Pleuromeia, especially Pleuromeia sternbergii. Immature spores extracted from the organic matter are partly covered by authigenic muscovite crystals. This is the first record of this iconic taxon in the Early Triassic of North America. It further strengthens the global distribution of this genus during the Early Triassic by filling up a major paleogeographic gap.

Strobilus

Authigenic

10.1016/j.revpalbo.2022.104663

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Citations (4)

Early Late Permian coupled carbon and strontium isotope chemostratigraphy from South China: Extended Emeishan volcanism?

Gondwana Research (2018)

Borhan Bagherpour Hugo Bucher Elke Schneebeli‐Hermann Torsten Vennemann Massimo Chiaradia

Large igneous province

Chemostratigraphy

Early Triassic

Isotopic signature

Seafloor Spreading

10.1016/j.gr.2018.01.011

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Citations (24)