Fish with jaw (Gnathostomata) type placoderma

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Lapray Benoît

The jawed vertebrates appeared more than 445 million years ago and then diversified into several groups. The placoderms, also known as armoured fish, are among the oldest. Their internal skeleton was cartilaginous, but they had heavy bony armour covering the head and the entire front of the body. They were also characterised by their primitive jaws, which had no teeth but sharp plates instead.
Around 410 million years ago, they diversified very widely and adapted to numerous ecological niches. Some large sea predators, such as Dunkleosteus, could exceed 8 metres in length and weigh several tons. However, most placoderms were of moderate size and lived in shallow freshwater and saltwater environments. They all disappeared, leaving no descendants, around 360 million years ago.
The armour of Dunkleosteus was articulated where the head meets the thorax. Because of this, while the mandible opened downwards, the skull could move upwards at the same time. By opening its mouth to the maximum extent in this way, it was able to seize very large prey. In addition, its jaws were among the most powerful known in the animal world until the present day. Its musculature enabled it to open and close its mouth with exceptional speed and force.

Detailed description

Hors tout : H. 60 cm ; l. 90 cm ; P. 50 cm ; Pds 18kg