New specimen of Cacops woehri indicates differences in the ontogenetic trajectories among cacopine dissorophids

Other literature type English OPEN
Fröbisch, N. B. ; Brar, A. ; Reisz, R. R. (2015)

The Lower Permian Dolese locality has produced numerous exquisitely preserved tetrapod fossils representing members of a lower Permian upland fauna. Therein, at least nine taxa of the clade Dissorophoidea, ranging in size from the large predaceous trematopid <i>Acheloma</i> to the miniaturized amphibamid <i>Doleserpeton</i>, highlight the great taxic and ecological diversity of this anamniote clade. Here we describe a large specimen of the dissorophid <i>Cacops woehri</i>, which was previously only known from the juvenile or subadult holotype skull. Another member of the genus <i>Cacops</i> present at the Dolese locality, <i>Cacops morrisi</i>, is also represented by specimens spanning juvenile, subadult, and adult stages, allowing for a comparison of morphological changes taking place in the late phases of the ontogenetic trajectory of cacopine dissorophids. The new find shows that, in contrast to <i>C. morrisi</i> and <i>C. aspidephorus</i>, <i>C. woehri</i> only undergoes relatively subtle changes in skull morphology in late ontogeny and retains the overall more gracile morphology into adult stages. This includes retention of the rather shallow skull shape as well as a pattern of sculpturing consisting of elongate ridges and grooves and a large occipital flange. This suggests somewhat different functional demands in <i>C. woehri</i> than in other known species of <i>Cacops</i>, possibly associated with a different ecology paralleling the great taxic diversity of dissorophoids at the Dolese locality.
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