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Fossil Record A palaeontological open-access journal of the Museum für Naturkunde
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Volume 18, issue 1
Foss. Rec., 18, 17-30, 2015
https://doi.org/10.5194/fr-18-17-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Foss. Rec., 18, 17-30, 2015
https://doi.org/10.5194/fr-18-17-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 06 Oct 2014

Research article | 06 Oct 2014

New information on the cranial and postcranial anatomy of the early synapsid Ianthodon schultzei (Sphenacomorpha: Sphenacodontia), and its evolutionary significance

F. Spindler1, D. Scott2, and R. R. Reisz2 F. Spindler et al.
  • 1TU Bergakademie Freiberg, Institut für Geologie, Bernhard-von-Cotta-Straße 2, 09599 Freiberg, Germany
  • 2Department of Biology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, Ontario, L5L 1C6, Canada

Abstract. Newly identified material belonging to the holotype specimen of Ianthodon schultzei substantially increases our knowledge of this poorly known basal sphenacodont synapsid from the fossil site in Garnett, Kansas (Missourian, Late Pennsylvanian). The original description, based on a partial dermal skull roof, is augmented with information on the palate and braincase, together with data on the mandible and a few postcranial elements. The known skeletal morphology resembles that of Haptodus garnettensis, another synapsid taxon known from this locality, but with fewer marginal, distinctly recurved teeth and smaller teeth on the transverse flange of the pterygoid. Although recognizing that the holotype and only known specimen represents a juvenile individual, Ianthodon appears to reflect a more basal sphenacodontian condition than H. garnettensis. A restricted phylogenetic analysis based on previous work and newly scored characters for Ianthodon, Cutleria and Pantelosaurus supports this hypothesis. The Garnett locality appears to preserve an assemblage of synapsids (Haptodus, Ianthasaurus, Ianthodon) that are close to the base of the large clade that includes Edaphosauridae and Sphenacodontia, suggesting that an initial diversification of this clade occurred well within the Carboniferous Period.

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