The dermal armor of the cyamodontoid placodonts (Reptilia, Sauropterygia) : morphology and systematic value

Abstract

The dermal armor of cyamodontoid placodonts is described and discussed in detail. A review of all available data on the ontogeny and phylogeny of the cyamodontoid dermal armor precedes the discussion of its value in placodont systematics. The cyamodontoid dermal armor is known from Middle to Upper Triassic fossil remains found in the Germanic and Alpine Triassic and at various circum-Mediterranean localities, most notably Makhtesh Ramon in the Negev, as well as in southern China. This paper recognizes five, possibly six species of cyamodontoids from the Middle Triassic of Makhtesh Ramon, two of them new. The morphology of the cyamodontoid dermal armor is compared in detail to the morphology of the turtle shell. The similarity is shown to be superficial only. The study concludes with comments on the functional anatomy of the cyamodontoid dermal armor