Taxonomy of Ptychagnostus atavus: A key trilobite in defining a global Cambrian stage boundary

Ahlberg, Per; Axheimer, Niklas; Robison, Richard A.

doi:10.1016/j.geobios.2007.01.004

Cited by 11 publications

(22 citation statements)

References 11 publications

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“…; Ahlberg et al . ; Babcock & Peng ; Ergaliev & Ergaliev ; Dubinina ; Robison & Babcock ; Ahlberg & Terfelt ; Peng et al . ).…”

Section: Cambrian Biostratigraphyunclassified

“…Upward from Stage 5 agnostoids are among the principal biostratigraphical guides for the Cambrian (e.g. Westerg ard 1946Westerg ard , 1947Westerg ard , 1953Palmer 1962;€ Opik 1963€ Opik , 1966€ Opik , 1967€ Opik , 1979Shergold 1972Shergold , 1975Shergold , 1980Shergold , 1982Shergold , 1997Daily & Jago 1975;Henderson 1976Henderson , 1977Robison et al 1977;Rushton 1979Rushton , 2009Ergaliev 1980;Rowell et al 1982;Robison 1984Robison , 1994Ludvigsen & Westrop 1985;Shergold et al 1990;Peng 1992;Ahlberg & Ahlgren 1996;Pegel 2000;Ahlberg 2003;Peng et al 2004aPeng et al ,b, 2009bPeng et al 2012a,b;Babcock et al 2005Babcock et al , 2011Peng & Babcock 2005a,b, 2008Varlamov et al 2005;Axheimer et al 2006;Ahlberg et al 2007;Ergaliev & Ergaliev 2008;Dubinina 2009;Robison & Babcock 2011;…”

Section: Cambrian Biostratigraphymentioning

confidence: 99%

“…;Shergold et al 1990;Ahlberg 2003;Fatka et al 2004;Peng et al 2004aPeng et al , 2009b Peng et al 2012a,b;Peng & Babcock 2005b;Axheimer et al 2006; Jago et al 2006;Ahlberg et al 2007;Babcock et al , 2011Ergaliev & Ergaliev 2008;Ahlberg & Terfelt 2012;Peng et al 2015; but seeWestrop et al 2011 for a contrasting view).…”

mentioning

confidence: 99%

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Cambrian trilobite biostratigraphy and its role in developing an integrated history of the Earth system

Babcock

Shanchi

Ahlberg

2017

LET

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One of the principal biostratigraphical tools used in the lower Palaeozoic, and especially the Cambrian System, is trilobites. Historically, both polymerids and agnostoids have commonly been included as ‘trilobite’ groups, although currently the question of whether they comprise a monophyletic group or are polyphyletic is unsettled. Beginning in the late 1800s, the base of the Cambrian System was marked by the lowest occurrence of olenelline trilobites. Discovery of a rich pre‐trilobite metazoan record in the mid‐1900s led to significant modification of that concept, but polymerids and especially agnostoids still rank among the leading biostratigraphical and chronostratigraphical guides through much of the Cambrian. Chronostratigraphical sub‐division of the trilobite‐bearing part of the Cambrian System derives largely from biostratigraphical, ecological and evolutionary concepts about agnostoids and polymerids introduced in the 1940s to 1970s by A.H. Westergård, A.R. Palmer and R.A. Robison. Westergård introduced a zonation for Scandinavia that was largely based on agnostoids. Palmer explained the distribution of Cambrian trilobite faunas in terms of restricted and unrestricted access to open oceans. Together, these ideas coalesced in Robison's recognition of separate zonation schemes for restricted‐shelf polymerids, open‐shelf polymerids and open‐shelf (cosmopolitan) agnostoids. Palmer also introduced the concept of biomeres, which placed sharp limits on biostratigraphical intervals recognizable from trilobites. Global correlation in the upper half of the Cambrian today depends to a large extent on the ranges of agnostoids and some polymerids characteristic of open‐shelf to slope areas, ones that facilitate identification of precise intercontinental tie points. Agnostoid and polymerid biostratigraphy is now being integrated with information about coastal onlap and eustatic sea‐level history, geochemical cycling and other data to provide a more complete understanding of the early Palaeozoic biosphere and its complex physico‐chemical context.

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“…; Ahlberg et al . ; Babcock & Peng ; Ergaliev & Ergaliev ; Dubinina ; Robison & Babcock ; Ahlberg & Terfelt ; Peng et al . ).…”

Section: Cambrian Biostratigraphyunclassified

Section: Cambrian Biostratigraphymentioning

confidence: 99%

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Cambrian trilobite biostratigraphy and its role in developing an integrated history of the Earth system

Babcock

Shanchi

Ahlberg

2017

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“…The first appearance datum of P . atavus defines the base of the Drumian Stage of Cambrian Series 3 (Babcock et al, 2007), and this species has been thoroughly treated by Peng and Robison (2000) and Ahlberg et al (2007).…”

Section: Systematic Paleontologymentioning

confidence: 99%

“…However, it has been difficult to differentiate the two species, because P . atavus has been known to display a wide range of variation in morphological characters such as scrobiculation of the genal region, whether arcuate scrobicules are present opposite anteroglabella, position of the median node on glabellar M2, and relative width of the pygidial border (Robison, 1982; Ahlberg et al, 2007).…”

Section: Systematic Paleontologymentioning

confidence: 99%

Cambrian series 3 agnostoid trilobitesPtychagnostus sinicusandPtychagnostus atavusfrom the Machari Formation, Yeongwol Group, Taebaeksan Basin, Korea

Hong¹,

Choi²

2015

J. Paleontol.

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This paper reports the successive occurrence of Ptychagnostus sinicus Lu, 1957 and Ptychagnostus atavus (Tullberg, 1880) from the lower part of the Machari Formation, Yeongwol Group, Korea. Morphometric approaches of using the landmark and principal component analyses make it possible to differentiate P. sinicus from P. atavus with clarity: pygidia of P. sinicus have a relatively narrow M1, a transverse F2, and a weakly developed M2 tubercle, whereas those of P. atavus are characterized by a broadly arching M1, a chevron-shaped F2, and a prominent M2 tubercle. Recognition of P. atavus, for the first time in Korea, allows the determination of the base of the Drumian Stage in Korea and aids correlation with other parts of the world.

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Biostratigraphy and taxonomy of Drumian (middle Cambrian) agnostid trilobites of the Manuels River Formation, Avalonian Newfoundland, Canada

Hildenbrand

Austermann

Ifrim

et al. 2021

Papers in Palaeontology

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New, accurately located and well-preserved agnostid trilobite material has been collected from the type locality of the Drumian (middle Cambrian, Miaolingian) Manuels River Formation, Newfoundland, Canada. The wellexposed grey to black shales containing the fauna were deposited on the former microcontinent Avalonia. Four interval zones for the succession are proposed, namely, the Tomagnostus fissus, Hypagnostus parvifrons, Ptychagnostus atavus and Ptychagnostus punctuosus zones. The Tomagnostus fissus and Ptychagnostus atavus zones are distinct from each other, which leads to a significantly shorter and stratigraphically higher Ptychagnostus atavus Zone compared with other sections (Scandinavia, South China, Utah and Nevada, Greenland). Specimens of Ptychagnostus atavus, however, occur abundantly, with 107 specimens identified in a short interval of the succession. The Ptychagnostus punctuosus Zone can be correlated globally. The faunal assemblage is comparable to that of Scandinavia, Greenland and England. Ptychagnostus affinis is recorded for the first time from Avalonia. The 1408 collected specimens were assigned to the suborders Agnostina and Eodiscina and to the families Peronopsidae and Ptychagnostidae, and Condylopygidae and Eodiscidae, respectively, with the following species: Peronopsis fallax (Linnarsson), Peronopsis scutalis (Hicks), Hypagnostus parvifrons (Linnarsson), Ptychagnostus punctuosus (Angelin), Ptychagnostus affinis (Brøgger), Ptychagnostus atavus (Tullberg), Tomagnostus fissus (Lundgren), Tomagnostus perrugatus (Gr€ onwall), Pleuroctenium granulatum (Barrande) and Eodiscus punctatus (Salter).

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Taxonomy of Ptychagnostus atavus: A key trilobite in defining a global Cambrian stage boundary

Cited by 11 publications

References 11 publications

Cambrian trilobite biostratigraphy and its role in developing an integrated history of the Earth system

Cambrian trilobite biostratigraphy and its role in developing an integrated history of the Earth system

Cambrian series 3 agnostoid trilobitesPtychagnostus sinicusandPtychagnostus atavusfrom the Machari Formation, Yeongwol Group, Taebaeksan Basin, Korea

Biostratigraphy and taxonomy of Drumian (middle Cambrian) agnostid trilobites of the Manuels River Formation, Avalonian Newfoundland, Canada

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