Intraspecific variability in paradoxidid trilobites from the Purujosa trilobite assemblage (middle Cambrian, northeast Spain)

Esteve, Jorge

doi:10.4202/app.2012.0006

Cited by 16 publications

(30 citation statements)

References 34 publications

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“…-The bivariate and PCA analyses give consistent results. The most variance occurs in the length of the cranidium and glabella relative to the greatest widths as specimens grow, which is consistent with results from similar studies and a common trait in trilobites (Esteve 2014 and references therein). The relative differences in variance are helpful to explain the components of allometric growth involved, but in this case it mostly did not contribute to the differentiation of the species analysed.…”

Section: Principal Component Analysis (Pca)supporting

confidence: 79%

“…7), the anterior pleurae curve backwards in a wide arc, almost from the axial furrow to the pleural tip; distal of the fulcrum, the pleural furrows fade out and the pleurae form nearly flat blades with a broad doublure (Fig. 10B), as in the above-mentioned species, and also in E. pradoanus (Verneuil & Barrande), well figured by Esteve (2014, fig. 5).…”

Section: A B C D Ementioning

confidence: 85%

“…27D). However, this distinction remains inconclusive because the number of thoracic segments is known to vary within some paradoxidid species (Bergström & Levi-Setti 1978, Esteve 2014, whereas it appears to be constant in others (fide Westergård 1936, p. 33;Westergård 1953, p. 35). One small holaspid (Fig.…”

Section: A B C D E Fmentioning

confidence: 99%

“…The other is that the growth-trajectory in paradoxidids is unusually long, such that a species may grow from a small holaspid to a well grown form that is 10 or even 15 times as long (see Šnajdr 1987, p. 99). To be able to refer specimens of such different sizes with confidence to a single species may require favourable occurrence and preservation; nevertheless, from published accounts over many years (Barrande 1852, Esteve 2014 it is quite evident that small holaspid specimens of a paradoxidid species can be recognised as conspecific with much larger examples in those cases where the holaspid growth is largely isometric, and provided that sufficient specimens are available. The large-scale investigation by Esteve (2014, figs 16, 17) showed several isometric trends in the growth of cranidia of Eccaparadoxides pradoanus and some allometric trends, particularly in the smaller growth stages (Esteve 2014, fig.…”

Section: Problems With the Taxonomy Of Paradoxidesmentioning

confidence: 99%

“…22, figs 9-15), and in several other species it is markedly elongated (Courtessole 1973, pl. 9, figs 4, 6, 7;Esteve 2014, fig. 13).…”

Section: A B C D Ementioning

confidence: 99%

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Paradoxidid trilobites from a mid-Cambrian (Series 3, stage 5) limestone concretion from Jämtland, central Sweden

Rushton¹,

Weidner²,

Ebbestad³

2016

Bull. Geosci.

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This paper describes the morphology and discusses the taxonomy of the paradoxidid trilobites present in the moult ensemble described by Ebbestad et al. (2013) from a huge limestone concretion of the Alum Shale Formation collected at Östnår, Jämtland. Two species, both represented by numerous but small complete holaspid specimens are described as new: Eccaparadoxides? thorslundi sp. nov. is distinctive, but its generic position is considered doubtful; Hydrocephalus spinulosus is similar to H. vikensis (also present as a rarity in the moult ensemble) and is partly distinguished from it by characters of the thorax. Also illustrated are a few specimens that have been collected at various localities between Hackås and Brunflo. They appear to represent individuals of some of the species in the moult ensemble and are about twice the size of their type specimens.•

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Section: Principal Component Analysis (Pca)supporting

confidence: 79%

Section: A B C D Ementioning

confidence: 85%

Section: A B C D E Fmentioning

confidence: 99%

Section: Problems With the Taxonomy Of Paradoxidesmentioning

confidence: 99%

“…22, figs 9-15), and in several other species it is markedly elongated (Courtessole 1973, pl. 9, figs 4, 6, 7;Esteve 2014, fig. 13).…”

Section: A B C D Ementioning

confidence: 99%

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Paradoxidid trilobites from a mid-Cambrian (Series 3, stage 5) limestone concretion from Jämtland, central Sweden

Rushton¹,

Weidner²,

Ebbestad³

2016

Bull. Geosci.

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The post‐embryonic ontogeny of the early Cambrian trilobite Estaingia bilobata from South Australia: trunk development and phylogenetic implications

Holmes

Paterson

García‐Bellido

2020

Papers in Palaeontology

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Trilobites are one of the most diverse and abundant fossil groups from the early Palaeozoic, and as such are useful for answering important questions about early animal evolution, including developmental processes. Ontogenetic information for a large number of trilobite species has been published, but cases where multiple articulated specimens are known across the full range of developmental stages are rare. The early Cambrian (Series 2, Stage 4) Emu Bay Shale biota from Kangaroo Island (South Australia) is numerically dominated by trilobites, particularly articulated specimens of the ellipsocephaloid Estaingia bilobata, which are present in densities of >600 individuals per square metre on certain bedding planes. Here we describe the essentially complete post-embryonic ontogenetic series of E. bilobata from the Emu Bay Shale, and investigate patterns of growth relating to articulation and segmentation in this early Cambrian arthropod. Estaingia bilobata exhibits the hypoprotomeric mode of growth, with the epimorphic phase (the cessation of trunk segment generation) reached prior to the onset of the holaspid period. The meraspid pygidium had an extended equilibrium period in which anterior segment release into the thorax was matched by subterminal segment generation. Previously undocumented morphological features of E. bilobata, including the hypostome and bispinose pleural tips in holaspides, are also described. The growth characteristics and morphological features of E. bilobata documented herein strengthen close phylogenetic relationships between the Estaingiidae, Ellipsocephalidae and Xystriduridae.

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A new look at Eccaparadoxides (Cambrian, Trilobita) and its biostratigraphic significance

Geyer

Landing

Żylińska

2021

PalZ

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Eccaparadoxides is a geographically widely distributed trilobite genus that occurs in the middle part of the Cambrian System. However, the systematically important morphologic characteristics that can be used to differentiate taxa are often problematical in their application. A review of the large number (over 30) of significant species or forms assigned to Eccaparadoxides clearly indicates that only the pygidia offer fairly reliable morphologic criteria that can be used taxonomically and phylogenetically. The pygidia allow for recognition of four different morphological groups (pusillus, lamellatus, pradoanus and asturianus) of which the asturianus group can only be questionably assigned to the genus. Species known only from cranidia cannot be assigned to Eccaparadoxides with certainty. This study refines the biostratigraphy for the interval from the upper Wuliuan to the middle Drumian and shows that this interval brackets the range of most Eccaparadoxides species. The genera or subgenera Baltoparadoxides, Rejkocephalus and Macrocerca are evaluated. Eccaparadoxides zelus, E. epimetheus and Eccaparadoxides? hestia are newly proposed species.

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Intraspecific variability in paradoxidid trilobites from the Purujosa trilobite assemblage (middle Cambrian, northeast Spain)

Cited by 16 publications

References 34 publications

Paradoxidid trilobites from a mid-Cambrian (Series 3, stage 5) limestone concretion from Jämtland, central Sweden

Paradoxidid trilobites from a mid-Cambrian (Series 3, stage 5) limestone concretion from Jämtland, central Sweden

The post‐embryonic ontogeny of the early Cambrian trilobite Estaingia bilobata from South Australia: trunk development and phylogenetic implications

A new look at Eccaparadoxides (Cambrian, Trilobita) and its biostratigraphic significance

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