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Acanthostega gunnari

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description Acanthostega gunnari Overview

Acanthostega gunnari was a Late Devonian stem tetrapod known from fossils found in East Greenland. It possessed limbs with eight digits, but its limb proportions, tail fin, and internal gills indicate that it remained primarily aquatic rather than moving effectively on land. The animal provides important evidence that digits and recognizable tetrapod limbs evolved in water before vertebrates acquired the anatomical specializations required for sustained terrestrial locomotion.

help Acanthostega gunnari FAQ

Why is Acanthostega important if it could not walk well on land?

Acanthostega shows that recognizable limbs and digits evolved before vertebrates became effective terrestrial walkers. Its fossils therefore overturned the simple idea that feet first appeared specifically for walking out of water.

How many toes did Acanthostega have?

Each known limb had eight digits rather than the five typical of most later tetrapods. Its contemporary Ichthyostega also departed from the five-digit pattern, showing that early tetrapod hands and feet were more varied.

What evidence shows that Acanthostega was mainly aquatic?

It retained internal gills and a tail with fin-supporting structures, while its limbs were poorly suited to bearing its weight on land. The overall anatomy fits movement through shallow, vegetation-rich water better than regular terrestrial walking.

Where and when did Acanthostega live?

Acanthostega gunnari is known from Late Devonian rocks in East Greenland. It lived roughly 365 million years ago, during the evolutionary transition between fish-like vertebrates and later land-capable tetrapods.

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