Silurian (Wenlockian) trilobites from Baillie-Hamilton Island, Canadian Arctic Archipelago

Perry, D. G.; Chatterton, Brian D. E.

doi:10.1139/e77-030

Cited by 30 publications

(39 citation statements)

References 13 publications

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“…Otarion huddyi differs from the slightly younger o. brauni Perry and Chatterton, 1979, in the possession of a narrower glabella; narrower fixigenae; larger palpebral lobes; less elongate glabella; longer genal spine; librigenal field not as long (exsag.) relative to height; eye socle less effaced; pygidium with three as opposed to four well-developed axial rings; posterior pygidial axial rings and pleural bands usually lacking prominent rows of tubercles; pygidium with more pronounced median flexure in posterior view; and apparently smaller maximum size.…”

Section: Systematic Paleontologymentioning

confidence: 86%

The aulacopleurid trilobite Otarion, with new species from the Silurian of northwestern Canada

Adrain

Chatterton

1994

J. Paleontol.

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The genus Otarion Zenker, 1833, first appears in the Wenlock simultaneously with Cyphaspis Burmeister, 1843, as the oldest known species of each occur together in the southern Mackenzie Mountains of the Canadian Northwest Territories. The genera are unambiguous sister groups, a relationship supported most compellingly by a uniquely derived and distinctive pattern of juvenile cephalic spines, shared also with the Carboniferous genus Namuropyge Richter and Richter, 1939. This sister group relationship permits the development of a robust and stratigraphically correlated hypothesis of relationship among the adequately known species of Otarion, Otarion, Cyphaspis, and Namuropyge constitute the tribe Otarionini. The Mississippian genus Dixiphopyge Brezinski, 1988, may also belong to Otarionini. Namuropyge is a paedomorph, likely derived from a Degree Six or Seven meraspid of an older species of uncertain position in the Otarion–Cyphaspis clade.Three Wenlock species of Otarion occur in stratigraphic succession in a single section in the Mackenzie Mountains. Analysis of morphological change with time, and of sequential ontogenies, suggests that the Silurian history of the genus was dominated by incidents of peramorphosis.New species are Otarion huddyi, O. beukeboomi, and O. coppinsensis. Otarion brauni Perry and Chatterton, 1979, is revised.

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Section: Systematic Paleontologymentioning

confidence: 86%

The aulacopleurid trilobite Otarion, with new species from the Silurian of northwestern Canada

Adrain

Chatterton

1994

J. Paleontol.

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“…See Adrain (1994) for discussion of Borealarges species. Acanthopygel rohri was restricted to its holotype pygidium (Perry & Chatterton, 1977) by Adrain (1994). Other pygidia illustrated by Perry & Chatterton (1977, pi.…”

Section: Systematic Palaeontologymentioning

confidence: 90%

“…Silicified trilobites from the Cape Phillips Basin of Arctic Canada (Figs 1, 2) have been the subject of studies by Perry & Chatterton (1977), Chatterton & Perry (1979), Adrain (1994) and Adrain & Edgecombe (1995; in press). Adrain & Edgecombe (in press) have given comprehensive locality information, which is followed herein.…”

Section: Associated Fauna and Stratigraphymentioning

confidence: 99%

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The lichid trilobiteRadiolichasin the Silurian of Arctic Canada and Gotland, Sweden

Adrain

Ramsköld²

1996

Geol. Mag.

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Radiolichas has been a poorly known and exclusively Devonian genus of very limited diversity. Radiolichas raydaviesi sp. nov. and R. davedaviesi sp. nov. are the best-known members of the genus, and extend its stratigraphic and geographic range to the Wenlock of the central Canadian Arctic. A further Silurian occurrence is an unnamed species from the Wenlock Slite Beds of Gotland, Sweden. Radiolichas is most similar to Dicranogmus. Together, the genera lack any of the robust trochurine apomorphies (linear pygidial postaxial ridge, prominent pygidial border, prominent cranidial fossula) and appear to fall outside the phylogenetic structure of that subfamily. They are similar to members of the Tetralichinae, particularly in pygidial features, but lack the composite cranidial lobe characteristic of that subfamily. Their systematic position is presently unresolved. J. M. ADRAIN & L. RAMSKOLD 96*00'Dundaa U 94 -00'

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“…Several authors have tried to document the presence of sexual dimorphs in trilobites (e.g. Hu 1971; Jell 1975; Perry and Chatterton 1977; Liñán and Gozalo 1986; Zhang 1989), but according to Ramsköld and Werdelin (1991), Hughes and Fortey (1995) and Whittington in Kaesler (1997, pp. 161–162), it has not yet been satisfactorily demonstrated.…”

Section: Sexual Dimorphismmentioning

confidence: 99%

Moulting, ontogeny and sexual dimorphism in the Cambrian ptychopariid trilobite Strenuaeva inflata from the northern Swedish Caledonides

Cederström¹,

Ahlberg

Nilsson³

et al. 2010

Palaeontology

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Three thousand seven hundred disarticulated remains together with several articulated specimens of the Cambrian Series 2 ptychopariid trilobite Strenuaeva inflata Ahlberg and Bergström, 1978 have been collected from the Torneträsk area, northern Sweden. The material provides significant new data on the morphology, ontogeny, moulting and enrolment of the species. Two distinct morphotypes, possibly an expression of sexual dimorphism, are recognized. The morph with a pair of bulbs in the frontal area, interpreted as brood pouches, is considered to represent females. Statistical treatment of the length ⁄ width ratio in cranidia reveals isometric growth during ontogeny for both morphotypes. The transition from the meraspid to holaspid ontogenetic period has been established through recognition of the successive development of the number of thoracic segments in articulated late meraspides. Throughout its life cycle, S. inflata went through 11 meraspid degrees and at least 17 holaspid growth stages. Inferred moult ensembles and exuviae reveal the successive opening of cephalic sutures and the function of the rostral plate during exuviation. As in other ellipsocephalid trilobites in which enrolment is known, the pygidium and two or three thoracic segments of S. inflata are concealed beneath the cephalon (spiral enrolment) during complete enrolment.

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Silurian (Wenlockian) trilobites from Baillie-Hamilton Island, Canadian Arctic Archipelago

Cited by 30 publications

References 13 publications

The aulacopleurid trilobite Otarion, with new species from the Silurian of northwestern Canada

The aulacopleurid trilobite Otarion, with new species from the Silurian of northwestern Canada

The lichid trilobiteRadiolichasin the Silurian of Arctic Canada and Gotland, Sweden

Moulting, ontogeny and sexual dimorphism in the Cambrian ptychopariid trilobite Strenuaeva inflata from the northern Swedish Caledonides

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