Paris, Ser. doi:10.1671/0272-4634(2008)28[904:froprs]2.0.co;2, Fossil Focus: Stepping through time with tetrapod trace fossils, Patterns In Palaeontology: Digitally Peering Inside Fossil Skulls, Patterns in Palaeontology: The Real Jurassic Park. The placodonts can be divided into two morphotypes: the unarmoured ‘placodontoids’, which resembled reptilian sea cows and lacked a carapace but often had a series of osteoderms (bony deposits in the skin) on their torso (in Placodus and Pararcus); and the heavily armoured, superficially turtle-like cyamodontoids, which are more commonly found in the fossil record (Figs 1 and 2). In contrast to the marine iguana, which feeds on algae, the placodonts ate molluscs and so their teeth were flat and tough to crush their shells. It has been shown that placodonts evolved from a non-durophagous ancestor called Palatodonta which, like placodonts, had a row of teeth on the palatine (Figs 1A and 2). They were specialized for a durophagous diet of shellfish, such as bivalves. The Triassic was a very special time for marine-reptile evolution, with their greatest morphological diversity being known from this period. Zanon, R. T. 1991. Unique method of tooth replacement in durophagous placodont marine reptiles, with new data on the dentition of Chinese taxa. Suggestions that placodonts may have fed on animals other than bivalves have been made from time to time. Emile Kuhn-Schnyder (1965) suggested that crustaceans may have been eaten. Implications phylogénétiques.

The elements identified as quadrates by previous descriptions of the basal taxa Palatodonta bleekeri and Paraplacodus broilii are re-interpreted to represent entirely or in part the quadratojugal. All these adaptations can be counted as perfect examples of convergent evolution, as placodonts were not related to any of these animals. Some of the more derived placodonts, such as Psephoderma and Psephochelys, had toothless, elongate ‘beaks’ that would have been used to probe the sandy sea floor to root out hidden food items. Henodus, however, differs from other placodonts in having developed unique baleen-like denticles, which alongside features of the hyoid and jaw musculature suggest that it was a filter feeder. Henodus, however, developed unique baleen-like denticles, which alongside features of the hyoid and jaw musculature suggest that it was a filter feeder.

The genus Placodus: systematics, morphology, paleobiogeography and paleobiology. Placodus (meaning 'flat tooth') was a genus of marine reptiles, belonging to the order Placodontia, which swam in the shallow seas of the middle Triassic period (c. 240 million years ago). Geology Today 20, 153–158. 1995. It was therefore most likely a terrestrial animal that ventured into the sea in search of food. (ed) Traite de Paleontologie, Vol. Die Placodontier. However, it is now thought that Helveticosaurus was not a placodont but possibly an unusual member of the Archosauromorpha.

For as long as we've read about placodonts, one thing is always agreed upon. Feeding mechanisms in Triassic stem-group sauropterygians: the anatomy of a successful invasion of Mesozoic seas Zoological Journal of the Linnean Society, 135, 33-63. (2002).

Placodontia. Take your favorite fandoms with you and never miss a beat. [1] Before the animals' anatomy was known, they were regarded as fishes' teeth. Diet Chisel-like incisors protruded from the anterior margin of the snout, and were probably used to pluck hard-shelled benthic prey from the substrate. 4). 2008. The first specimen was discovered in 1830. The palate teeth were adapted for this durophagous diet, being extremely thick and large enough to crush thick shell. They have been found throughout central Europe, North Africa, the Middle East and China. Placodonts ("Tablet teeth") is an extinct order of marine reptiles that lived during the Triassic period, becoming extinct at the end of the period. 4. 2002. Placodus had a stocky body with a long tail, and reached a total length of up to 2 metres (6.6 ft). Placodus, meaning flat toothed, was the largest of the placodonts, an extinct group of marine reptiles related to turtles.. Their diet consisted of marine bivalves, brachiopods, and other invertebrates. The placodonts were a group of marine reptiles that lived in shallow coastal waters, and mostly ate hard-shelled prey such as mussels and other bivalves (that is, they were durophagous). Naish, D. 2004. Palaeoecology of the armoured placodonts. All placodonts appear to be specialized for a durophagous diet, with the exception of the very unusual Henodus from the Carnian (Late Triassic) of southern Germany. Academic Press (London). 130, #4, pp. The first specimen was discovered in 1830. Outside of Lagerstätten, the most common remains are shed teeth, lower-jaw fragments, skull material and armour plates.

Ecosystems that had been dominated by amphibians became dominated by reptiles, many of which — including the ichthyosaurs, thalattosaurs, protorosaurs, saurosphargids and first turtles — evolved to become secondarily aquatic during the Early and Middle Triassic. This article needs expanding. (eds) Morphology and Biology of Reptiles.

Unlike more derived sauropterygians, placodonts did not have fins or particularly streamlined bodies; they retained relatively unmodified limbs with fingers and toes, similar to those of terrestrial reptiles.

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