Wed . 18 Nov 2018


Sphenacodontia is a stem-based clade of derived synapsids It was defined by Amson and Laurin 2011 as "the largest clade that includes Haptodus baylei, Haptodus garnettensis and Sphenacodon ferox, but not Edaphosaurus pogonias"[1] They first appear during the Late Pennsylvanian epoch

Basal Sphenacodontia constitute a transitional evolutionary series from early pelycosaurs to ancestral therapsids which in turn were the ancestors of more advanced forms and finally the mammals One might say that the Sphenacodontians are proto-therapsids


  • 1 Characteristics
  • 2 Classification
  • 3 See also
  • 4 References
  • 5 External links


The defining characteristics include a thickening of the maxilla visible on its internal surface, above the large front caniniform teeth; and the premaxillary teeth being set in deep sockets All other sister group and more primitive synapsid clades have teeth that are set in shallow sockets


Haptodus, from Latest Carboniferous to Early Permian Secodontosaurus, Early Permian

The following taxonomy follows Fröbisch et al 2011 and Benson in press unless otherwise noted[1][2]

Class Synapsida

  • Eupelycosauria
    • Sphenacodontia
      • †Haptodus
      • †Ianthodon
      • †Palaeohatteria
      • †Pantelosaurus
      • Sphenacodontoidea

See also

  • Evolution of mammals


  1. ^ a b Benson, RJ 2012 "Interrelationships of basal synapsids: cranial and postcranial morphological partitions suggest different topologies" Journal of Systematic Palaeontology in press doi:101080/147720192011631042 
  2. ^ Jörg Fröbisch, Rainer R Schoch, Johannes Müller, Thomas Schindler and Dieter Schweiss 2011 "A new basal sphenacodontid synapsid from the Late Carboniferous of the Saar-Nahe Basin, Germany" PDF Acta Palaeontologica Polonica 56 1: 113–120 doi:104202/app20100039 CS1 maint: Uses authors parameter link
  • Laurin, M and Reisz, R R, 1997, Autapomorphies of the main clades of synapsids - Tree of Life Web Project

External links

  • Synapsida: Sphenacodontia


Sphenacodontia Information about


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Sphenacodontia what, Sphenacodontia who, Sphenacodontia explanation

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