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... 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 are marked by a series of biotic crises including the most catastrophic of such events, the end-Permian mass extinction, which eventually led... 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,…
Research Interests: Mass extinctions, Biological Sciences, Osteichthyes, Triassic, Triassic vertebrates, and 14 moreTeleost Evolution, Permian, Body Size, Mass Extinction, Permian vertebrates, Permian-Triassic transition, End-Permian extinction, Holostean Fish, Neopterygii, Biotic Recovery From Extinction Events, Teleosts, Early Triassic, End Permian, and Permian Triassic Boundary
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,... 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 ...
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:... 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., ...
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... 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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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... 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.
A new sampling of Early Triassic (Griesbachian) conodonts is obtained from the microbialite overlying the latest Permian peri-reefal shallow water limestone in Wuzhuan section (Nanpanjiang Basin, Guangxi, South China). High resolution... more
A new sampling of Early Triassic (Griesbachian) conodonts is obtained from the microbialite overlying the latest Permian peri-reefal shallow water limestone in Wuzhuan section (Nanpanjiang Basin, Guangxi, South China). High resolution sam-pling in the lower twelve meters of the Luolou Formation provides rather diversified conodont faunas and allows const-ructing a well resolved conodont distribution for this crucial earliest Triassic interval. In the Wuzhuan section, the nine meters thick microbialite is bracketed by two calcarenite beds and contains several fossiliferous lenses. The co-occurrence of typical Permian foraminifera such as Paraglobivalvulina mira (Reitlinger) and Dagmarita chanakchiensis (Reitlinger) in the calcarenite underlying the microbialite indicates a late Permian age. Our preliminary results indicate the presence of one residual maximal horizon (RMH) based on conodont faunas in the microbialite and of a second one in the overlying calca-renite. The lowest RMH o...
The Lower Triassic sedimentary and carbonate/organic carbon isotope records from the Tulong area (South Tibet) are documented in their integrality for the first time. New age control is provided by ammonoid and conodont biostratigraphy.... more
The Lower Triassic sedimentary and carbonate/organic carbon isotope records from the Tulong area (South Tibet) are documented in their integrality for the first time. New age control is provided by ammonoid and conodont biostratigraphy. The basal Triassic series consists of Griesbachian dolomitic limestones, similar to the Kathwai Member in the Salt Range (Pakistan) and to the Otoceras Beds in Spiti
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The importance of the Early-Middle Triassic boundary (EMTB) lays in the fact that this boundary marks the end of the time interval characterized by the biotic recovery after the end-Permian mass extinction. Therefore, to gain highest... more
The importance of the Early-Middle Triassic boundary (EMTB) lays in the fact that this boundary marks the end of the time interval characterized by the biotic recovery after the end-Permian mass extinction. Therefore, to gain highest possible time accuracy and precision for quantification of biotic processes, we undertook a detailed calibration of the EMTB with high-precision CA-ID-TIMS U-Pb age determinations on zircons from volcanic ash beds interbedded with biostratigraphi-cally well dated marine sedimentary sections. These dates have been used to quantify and calibrate different stratigraphic schemes across the EMTB in the Nanpanjiang basin in South China. Despite an optimal control on the continuity of the studied stratigraphic record and on the accuracy of analytical procedures, we recognized that some single ash-beds yielded ages that are too old and contradict the stratigraphic succession. We therefore try to tackle questions such as: How can we improve the confidence in the...
In contrast to the expectations of many colleagues, fossils from the Muschelkalk (Ani-sian, Ladinian; Middle Triassic) from the Germanic Basin proved to be extraordinarily well preserved in some respects. In the course of examinations of... more
In contrast to the expectations of many colleagues, fossils from the Muschelkalk (Ani-sian, Ladinian; Middle Triassic) from the Germanic Basin proved to be extraordinarily well preserved in some respects. In the course of examinations of fossil molluscs from the Germanic ...
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... The Khuff Fm. yields a rich fauna of brachiopods, conodonts, foraminifers, bivalves, gastropods, ostracods and cephalopods. The brachiopod fauna of the Khuff Fm. ... The Khuff Fm. is given a Wordian age, based on brachiopods and... more
... The Khuff Fm. yields a rich fauna of brachiopods, conodonts, foraminifers, bivalves, gastropods, ostracods and cephalopods. The brachiopod fauna of the Khuff Fm. ... The Khuff Fm. is given a Wordian age, based on brachiopods and conodonts. ...
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With the extinction of approximately 26% of marine animal genera (eg foraminifers, nannoplankton, corals, echinoids, bivalves, ammonoids), the Cenomanian/Turonian boundary (CTB) is one of the ten most severe biotic crisis of life's... more
With the extinction of approximately 26% of marine animal genera (eg foraminifers, nannoplankton, corals, echinoids, bivalves, ammonoids), the Cenomanian/Turonian boundary (CTB) is one of the ten most severe biotic crisis of life's history. The mid-Cretaceous was a ...
The fossil record provides evidence for evolutionary changes and may contribute to our understanding of the tempo and mode of evolution. Marine organisms with a broad paleogeographical distribution, excellent stratigraphic record, high... more
The fossil record provides evidence for evolutionary changes and may contribute to our understanding of the tempo and mode of evolution. Marine organisms with a broad paleogeographical distribution, excellent stratigraphic record, high diversity/disparity, and fast evolutionary ...
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ABSTRACT Here we described a series of ammonoid specimens from the Early Triassic of Chaohu, South China and recognized the occurrence of Procolumbites for the first time in this area. The Procolumbites layer is about one meter above the... more
ABSTRACT Here we described a series of ammonoid specimens from the Early Triassic of Chaohu, South China and recognized the occurrence of Procolumbites for the first time in this area. The Procolumbites layer is about one meter above the first appearance of Chaohusaurus, indicating that the oldest Chaohusaurus is within the Procolumbites Zone of middle Spathian age. This new age constrain is significantly older than the previously suggested Subcolumbites Zone assignment (early late Spathian). To date, Chaohusaurus is the oldest known ichthyopterygian.