The placodonts were a strange group of marine reptiles that appeared during the mid-Triassic period but became extinct at the Triassic/Jurassic boundary. They were heavy-bodied swimmers that mostly fed on shellfish; their teeth were specialised for picking shells from rocks and crushing them between their jaws. It is believed that placodonts were not confined to water, and would have been able to travel on land.
Temporal Range: Middle Triassic (245-228 Mya)
Length: 1.3 metres
- Discovery:Cyamodus was discovered in Germany, and was officially named in 1863 by palaeontologist Christian Erich Hermann von Meyer. Cyamodus is a member of the placodont family, and more specifically belongs to the placodont sub-family; cyamodontid.
- Description: Cyamodus measured around 1.3 metres in length and its most characteristic feature is the two-part shell or carapace found on the upper surface of the body. The main part of the shell covers the body to the hips and spreads out sideways, almost covering the animals forelimb span. The second part of the shell is smaller in size and covers the animals hips and the base of the tail. Both shell parts are covered in hexagonal and circular plates of armour. The skull is heart-shaped, and is particularly strong at the rear.
Temporal Range: Late Triassic (228-220 Mya)
Length: 1 metre
- Discovery:Henodus was also discovered in Germany, although it was found later than the fossils of Cyamodus, and was officially named in 1936. Like Cyamodus, Henodus is a member cyamodontid family of placodonts.
- Description: Henodus is the placodont which most closely resembles a turtle. There is a carapace covering the whole body which stretches out well beyond the span of the limbs. It is believed Henodus would have acted as some kind of reptilian ray; paddling its broad, flat body along the bed of shallow lagoons, foraging in the sand with its broad mouth. The weak limbs of Henodus suggest that this placodont would not have spent much time on land, and the fact that it is the only placodont not to be found in marine sediment suggests that it lived in brackish or freshwater lagoons.
Picture Source: Kahless28 (deviant art)