Developmental morphological diversity in caecilian amphibians: systematic and evolutionary implications

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Developmental morphological diversity in caecilian amphibians: systematic and evolutionary implications

Type: Doctoral Thesis
Title: Developmental morphological diversity in caecilian amphibians: systematic and evolutionary implications
Author: Müller, H.
Publisher: Leiden University Press
Issue Date: 2007-11-08
Keywords: Amphibia,
Caecilians
Development
Direct development
Gymnophiona
Metamorphosis
Morphology
Myology
Skull
Systematics
Abstract: Caecilians, or Gymnophiona, constitute one of the three extant orders of the Recent Amphibia and are the least known, major living tetrapod clade. Compared to frogs and salamanders, caecilians have an unusual skull morphology. Earlier reports of an unusually high number of individual skull ossifications in Hypogeophis rostratus are addressed and found to be erroneous. Changes in skull morphology and myology at metamorphoses are investigated in representatives of all taxa possessing free-living larvae. It is argued that caecilians are derived from gymno- or zygokrotaphic ancestors and that stegokrotaphy evolved within Recent caecilians. The influence of different life-histories on postembryonic skull development was studied in two direct-developing species. The direct-developing Boulengerula taitanus is characterized by very immature hatchlings, which is correlated with an extended period of post-hatching parental care in this species, during which juveniles feed on the modified skin of their mothers. Direct development in caecilians is characterized by ontogenetic repatterning and heterochronic shifts in certain developmental events. The ontogeny of Scolecomorphus kirkii was studied as a representative of a viviparous form. The emerging picture of available published information, together with observations presented here, suggest a previously unsuspected degree of developmental diversity among caecilians. It is further argued that caecilians are lissamphibians with temnospondyl affinities rather than closely related to lepospondyl microsaurs.
Promotor: Supervisor: Richardson M.K. Co-Supervisors: Wilkinson M. ; Gower G.J.
Faculty: Faculty of Sciences
University: Leiden University
Uri: urn:isbn:9789087280277
Handle: http://hdl.handle.net/1887/12462
 

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application/pdf Chapter 7 Synopsis 184.6Kb View/Open
application/pdf Acknowledgements 89.93Kb View/Open
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