placodont

(redirected from Placodonts)

placodont

a fossil reptile from the Triassic period, which possessed flat crushing teeth and probably fed on molluscs.
References in periodicals archive ?
The study of most of these fragmentary sauropterygian remains only provided a poorly-detailed systematic determination, allowing the identification of indeterminate pachypleurosaurs, nothosauroids and pistosauroids, as well as cyamodontoid and no cyamodontoid placodonts. However, some findings were determined at generic or specific level: the placodont Paraplacodus Peyer 1931a (Pinna, 1990); the nothosauroid Simosaurus Meyer 1842 (Miguel Chaves et al, 2015); and the nothosaurs Lariosaurus balsami Curioni 1847 (Sanz, 1976), "Ceresiosaurus" sp.
(2013): Marine flooding in continental Triassic facies identified by a nothosaur and placodont bonebed (South Iberian Paleomargin).
Placodonts are represented by a single small specimen.
A durophagous dentition has been described for several clades of Middle Triassic marine reptiles: placodonts (but see Diedrich, 2010 for an alternative interpretation), some ichthyosaurs (Omphalosaurus, Tholodus, etc.; McGowan and Motani, 2003), claraziids and thalathosaurs.
Moreover, the sediments of the site were deposited in a shallow marine carbonate ramp (Calvet and Tucker, 1988), where we would expect to find placodonts rather than ichthyosaurs, usually found in deposits of open marine settings.
Placodonts occur in the Muschelkalk of Spain and possibly in the Keuper as well (their remains have been reported from about 10 localities, for further details see Sanz et al., 1993 and Bardet et al., 2008 and below).
Placodonts and nothosaurs are known from Riba de Santiuste-Tordelrabano (26) and Rillo de Gallo (27) (Guadalajara) localities (Alafont, 1999).
Several localities in southeastern Iberian Peninsula (Cuenca and Valencia), specially in the Henarejos section, yielded vertebrate remains such as fishes, nothosauroids and placodonts, as in Canete-Boniches, Henarejos, Bugarra, Valdemeca and Royuela sites (28, 29, 30, 31, 32) (Sanz, 1983; Alafont, 1999; Bardet et al., 2008; Botella et al., 2009; Pla et al., 2009).
placodonts Lariosaurus, Nothosaurus), thalattosaurs, and protorosaurians (Cosesaurus), and agrees with the presence of marine environments in this area, as a result of a transgression.