Mats Eriksson
Professor
Moulting, ontogeny and sexual dimorphism in the Cambrian ptychopariid trilobite Strenuaeva inflata from the northern Swedish Caledonides
Författare
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.
Avdelning/ar
- Berggrundsgeologi
Publiceringsår
2011
Språk
Engelska
Sidor
685-703
Publikation/Tidskrift/Serie
Palaeontology
Volym
54
Länkar
Dokumenttyp
Artikel i tidskrift
Förlag
Wiley-Blackwell
Ämne
- Geology
Nyckelord
- ptychopariid trilobite
- Strenuaeva inflata
- dimorphism
- enrolment
- functional morphology
- ontogeny
- lower Cambrian
- Sweden
Status
Published
ISBN/ISSN/Övrigt
- ISSN: 1475-4983