Ancient Seas #8

Ancient Seas

Pteraspis

Photo from Encyclopeadia Britannica

Kingdom: Animalia 

Class: Pteraspidomorphi

Conservation Status: Extinct (EX)

Era: Pragian epoch of Devonian Era, 398 - 416 million years ago

WHAT WAS IT?

The pteraspis was a heterostracan fish. This means it was a jawless vertebrate. It was a common during this era for fish to be jawless. The pteraspis was also a placoderm, which meant it was armoured. To summarise, this fish has a spine but no jaw, and is half armoured. Fish were weird 400 million years ago! However, it was one of the last species of both heterostracan and placoderm fish suggesting there was no longer a need for these evolutionary advantages. Both types of fish were extinct by the end of the Devonian Era.

WHAT DID IT LOOK LIKE?

Well, it wasn't the prettiest fish. Its front half was armour plated, which would have been used for protection against predation. It was streamlined and finless, but did have protrusions from its armour plating over its gills which could have been used for steering. Different sources state that it was both an effecient and ineffecient swimmer - so who really knows on that! - but it certainly looked like it could glide through the water.

While its front half was armoured, its back half was scaled - making it look a little like two fish stuck together. That's certainly the impression I'm getting from the artists' renderings of these fish. Nevertheless, it still looked like a fish and, despite having no fins, it had a lobed tail like modern fish do. They only grew to between 16cm (6.5inches) and 20 cm (8inches).

The last main feature of the pteraspis are its spikey protrusions. At its front it has a horn-like rostrum, meaning like a beak, and on its back it had spikes in varying sizes along its spine. It is thought these were used for further protection from predators.

From Wikipedia

WHERE DID IT LIVE?

Geographically, these creatures inhabited seas that would someday become land masses across Europe - such as Britain and Belgium. The adaptations in its body suggest that these fish preferred swimming up and in open waters, rather than down on the sea bed.

WHAT DID IT EAT?

It is believed that these fish fed on plankton and other small shellfish near the water's surface. Thanks to their lack of jaw, they would have had to suck their food in so it is unlikely that they would have been chomping down on anything! 

Photo from Life Before Dinosaurs

FUN FACTS

• These fish predate dinosaurs. 
• Pteraspis means "wing shield".
• It shared waters with Dunkleosteus.

Listening to: Final Fantasy Piano