, 96:789 | Cite as

The armoured dissorophid Cacops from the Early Permian of Oklahoma and the exploitation of the terrestrial realm by amphibians

  • Robert R. ReiszEmail author
  • Rainer R. Schoch
  • Jason S. Anderson
Original Paper


Cacops, one of the most distinctive Paleozoic amphibians, is part of a clade of dissorophoid temnospondyls that diversified in the equatorial region of Pangea during the Late Carboniferous and Early Permian, persisting into the Late Permian in Central Russia and China. Dissorophids were a successful group of fully terrestrial, often spectacularly armoured predators, the only amphibians apparently able to coexist with amniotes when the latter started to dominate terrestrial ecosystems. In this paper, we describe excellent new skulls from the Early Permian of Oklahoma attributed to Cacops, Cacops morrisi sp. nov. and provide for the first time detailed information about this iconic dissorophid. These specimens show anatomical and ontogenetic features that will impact on future studies on the evolution of terrestriality in tetrapods. For example, the large, posteriorly closed tympanic embayment has fine striations on an otherwise smooth surface, documenting the oldest known clear evidence for the presence of a tympanic membrane in the fossil record, a structure that is used for hearing airborne sound in extant tetrapods. The skull of C. morrisi also has several features associated with predatory behaviour, indicating that this dissorophid may have been one of the top terrestrial predators of its time.


Paleozoic tetrapods Dissorophid Tympanic notch Ontogeny Early Permian 



We are indebted to Norbert Adorf and Diane Scott for skilfully preparing the two specimens on which this study is based and to Ms. Scott for photography. Nicola Wong Ken completed the excellent illustrations, including the skull reconstruction. We also thank the staff of the Sam Noble Natural History Museum and especially Richard Cifelli and William May for their continued, enthusiastic assistance and support. Funding support was provided by a NSERC Discovery Grant and the Humbold Foundation (to RRR).


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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Robert R. Reisz
    • 1
    Email author
  • Rainer R. Schoch
    • 2
  • Jason S. Anderson
    • 3
  1. 1.Department of BiologyUniversity of Toronto at MississaugaMississaugaCanada
  2. 2.Staatliches Museum für Naturkunde in StuttgartStuttgartGermany
  3. 3.Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary MedicineUniversity of CalgaryCalgaryCanada

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