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A Redescription of the Anatomy of the Late Devonian Spodichthys Buetleri Jarvik, 1985 (Sarcopterygii, Tetrapodomorpha) from East Greenland
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Physiology and Developmental Biology, Evolutionary Organism Biology.
2008 (English)In: Journal of Vertebrate Paleontology, ISSN 0272-4634, Vol. 28, no 3, 637-655 p.Article in journal (Refereed) Published
Abstract [en]

The tetrapodomorph fish Spodichthys buetleri from the Upper Devonian of East Greenland is redescribed from computed tomography scans of material originally studied by Erik Jarvik. A wealth of new anatomical data was revealed by scanning the nearly perfectly three-dimensional specimens, including detailed information on the shape of the brain cavity and the internal structure of the lower jaws. Spodichthys displays an interesting mix of generalized “osteolepidid,” or primitive tetrapodomorph, and tristichopterid features. Derived characters shared by Spodichthys, tristichopterids and (Panderichthys + Tetrapoda) include the loss of cosmine, a small kite-shaped parasymphysial plate, and a long commissural lamina of the entopterygoid. The presence of an extratemporal lateral to the tabular and a single fang position on the posterior coronoid and ectopterygoid are examples of basal tetrapodomorph characters retained in Spodichthys. Spodichthys is unique in having coronoid fangs positioned lateral to the corresponding replacement pit rather than having an anterior-posterior alternation between developed fang and replacement pit, which is the normal tetrapodomorph condition. Jarvik's original conclusion that Spodichthys is closely related to the tristichopterids is confirmed by a phylogenetic analysis, which places Spodichthys as the sister taxon of the Tristichopteridae.

Place, publisher, year, edition, pages
2008. Vol. 28, no 3, 637-655 p.
National Category
Biological Sciences
URN: urn:nbn:se:uu:diva-97001DOI: 10.1671/0272-4634(2008)28[637:AROTAO]2.0.CO;2ISI: 000259414500006OAI: oai:DiVA.org:uu-97001DiVA: diva2:171764
Available from: 2008-04-03 Created: 2008-04-03 Last updated: 2012-05-10
In thesis
1. Morphology, Taxonomy and Interrelationships of Tristichopterid Fishes (Sarcopterygii, Tetrapodomorpha)
Open this publication in new window or tab >>Morphology, Taxonomy and Interrelationships of Tristichopterid Fishes (Sarcopterygii, Tetrapodomorpha)
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Tristichopterids (Sarcopterygii, Tetrapodomorpha) form a monophyletic group of exclusively Devonian fishes. This thesis consists of descriptions of new material of tristichopterids and closely related taxa, as well as new interpretations and descriptions of previously figured material. Redescribed specimens were originally figured as far back as 1861, and publications as old as this are almost always of limited use as anatomical and systematical references, in addition to being difficult to acquire. The possibility of using new techniques and new theoretical frameworks also provides good justification for taking a second look at such specimens. In the case of this thesis, this includes the use of computed tomography scanning methods, and the cladistic approach to describing the interrelationships of taxa.

The thesis includes a complete taxonomy of valid tristichopterid taxa, in addition to two new phylogenetic analyses incorporating the taxa that were described or redescribed. One of the analyses deals with the interrelationships of taxa along the entire tetrapod stem, and establishes the monophyly of the Tristichopteridae. The other analysis focuses on tristichopterid interrelationships.

An account is given of evolutionary trends within Tristichopteridae, and instances of parallel evolution between tristichopterids and other tetrapodomorph groups are discussed.

The biogeographical implications of tristichopterid occurences world-wide seem to corroborate the picture provided by other vertebrate groups, and give further support to one of two main hypotheses concerning the relative positions of Gondwana and Laurussia, the two major palaeocontinents during the Late Devonian. The supported hypothesis proposes a close proximity between southern Laurussia and northwestern Gondwana, as evidenced by the wide dispersal of derived tristichopterids by the Late Devonian. A Laurussian origin of tristichopterids is proposed.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2008. 54 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 421
Organismic biology, Sarcopterygii, Tetrapodomorpha, Tristichopteridae, biogeography, phylogeny, Computed Tomography, Devonian, Organismbiologi
urn:nbn:se:uu:diva-8625 (URN)978-91-554-7153-8 (ISBN)
Public defence
2008-04-25, Lindahlsalen, Evolutionsbiologiskt Centrum, Norbyvägen 18A, Uppsala, 13:15 (English)
Available from: 2008-04-03 Created: 2008-04-03 Last updated: 2009-04-03Bibliographically approved

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