Sunday, July 31, 2011


Acanthostega (uh-canth-oh-STAY-guh) was a genus of tetrapod from the late Devonian Period. Its name means "spiny roof."

Although Acanthostega had legs, they were probably not used for walking because its feet could not support it.

When scientists first discovered Acanthostega, they only found parts of a skull. Very recently, they found a more complete skeleton.

Acanthostega had a leaf-shaped tail, which could have helped it swim. It was about 2 feet long and was probably a descendant of the Sarcopterygii (lobe-finned) fishes Tiktaalik and Panderichthys, and an ancestor of the land-dwelling tetrapod Ichthyostega.

Acanthostega probably lived in swamps full of plants and debris. It was one of the first animals to catch prey by actually biting it, unlike fish, which simply had to suck food in. Acanthostega probably fed by swimming close to shore and grabbing prey with its mouth, or catching things with its head above the water. It had eight digits on the front feet, and maybe even on the hind feet. 


  1. Nice post! Was this one of the first jawed sea-dwellers (as you noted, other fish at the time were not biters)? I am humbled that I'm asking someone almost 1/4 my age this question. You may find the evolution, or lack there of, of jawed fish in fresh water to be fascinating.

  2. Fish first evolved jaws in the late Ordovician Period, and then lobe-finned fish evolved into tetrapods like Acanthostega. The early Cambrian to middle Ordovician fish did not have jaws, and simply had to suck food through their mouths. Jawed fish also had to do this, but instead they opened their jaws to do it. There were also some arthropods that were part jawed and part jawless, like anomalocarids, which had circular mouths, and could only close them partway, so that the sharp teeth in the "pineapple ring" mouth would crunch the prey.

    Thanks for the link!

  3. My brother once cruised in the Caribbean where he swam with Sting Rays. He said they sucked food (from his hand) through their mouths.

    This is why I will never swim with Sting Rays.