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Mats Eriksson

Mats Eriksson

Professor

Mats Eriksson

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

Author

  • Peter Cederstrom
  • Per Ahlberg
  • Carin H. Nilsson
  • John Ahlgren
  • Mats Eriksson

Summary, in English

Three thousand seven hundred disarticulated remains together with several articulated specimens of the Cambrian Series 2 ptychopariid trilobite Strenuaeva inflata Ahlberg and Bergstrom, 1978 have been collected from the Tornetrask 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.

Department/s

  • Lithosphere and Biosphere Science

Publishing year

2011

Language

English

Pages

685-703

Publication/Series

Palaeontology

Volume

54

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Geology

Keywords

  • ptychopariid trilobite
  • Strenuaeva inflata
  • dimorphism
  • enrolment
  • functional morphology
  • ontogeny
  • lower Cambrian
  • Sweden

Status

Published

ISBN/ISSN/Other

  • ISSN: 1475-4983