Temporal Range: Middle Triassic (241.1-235 Mya)
Length: 3 metres
– Discovery: Placodus is one of the best known and most commonly found of all the placodonts. It was named in 1833 by Swiss palaeontologist Louis Agassiz, who indecently thought the teeth he had first discovered belonged to a fish. It was not until 1858 when Richard Owen recognised that the teeth were in fact reptilian that Placodus was identified as a reptile. Since then, numerous fossils have been found in Germany, France, Poland and also China.
– Description: Like Paraplacodus, Placodus had a stocky body with a lengthy tail. It was also the largest of the known placondonts, growing to lengths of around three metres. Also like Paraplacodus, it had three forward-pointing teeth in each premaxilla but, unlike its close relative, these teeth were incredibly robust and the ends of each one were broad and rounded. The skull was particularly strong, developed so as to be able to cope with the stresses of crushing seashells.
The vertebral processes of Placodus dove-tailed into each other and were firmly connected, creating an extremely rigid trunk. It also possessed a row of bony scutes along the top of its neural spines which likely would have given Placodus some form of defence from predators. Like Paraplacodus, Placodus was a negatively buoyant creature. Its large body and heavy bones mean it would have had no trouble staying on the seafloor to feed.