Ichthyostega

Ichthyostega was an early tetrapod that existed during the late Devonian. This was the first Devonian tetrapod to be discovered and added to the fossil record. This strange creature has been somewhat of a mystery. The examination of the remains show that it was able to hear better under water rather than land. The ear region seems to point to this claim, which may indicate ichthyostega spent most of its time in water. The vertebral column shows that it was capable of terrestrial locomotion. The evidence for land presence can also be seen in ribs, broad shoulders, and forearms. The hind limbs of this tetrapod were paddlelike in structure. The ichthyostega roamed the Earth 370 million years ago and fossils of this organism have only been found in eastern Greenland. Some paleontologists believe that ichthyostegids  could have been around  to the Carboniferous Period. Ichthyostega was only one meter long. The physical attributes of this Devonian organism contained traits from earlier aquatic vertebrates. It contained both a short snout and a preopercular bone, which can be found in fish. The preoperculer bone serves as a covering for the gills of fish. From this, it can deduced that Ichthyostega  had no trouble being in the water for long periods of time. 

It is believed that ichthyostega did not posses gills. If that is so another question emerges about this organism. There is debate to whether icthyostega was a land hunter or caught prey in water. There is a possibility that it could have done both. Hunting both on land and water would give it an advantage in terms of survival. The mixture of fish like and amphibian attributes makes ichthyostega one of the most fascinating animals of the Devonian. Scientists have attempted to seeing through computer models the transition from swimming to walking through computer modeling. Ichthyostega may not have walked like a salamander as previously thought. The quadrupedal concept for this type of tetrapod  according to scientists at the University of Cambridge, London University, and the Royal Veterinary College . This demonstrates there is still much to be learned about the transition from land to water. 

Further Reading 

The Editors of Encyclopædia Britannica. "Ichthyostega." Encyclopædia Britannica. Encyclopædia Britannica, Inc., 27 July 2006. Web. 01 Apr. 2017. <https://www.britannica.com/animal/Ichthyostega>.

Briggs, Helen. "Ancient Walking Mystery Deepens." BBC News. BBC, 23 May 2012. Web. 01 Apr. 2017. <http://www.bbc.com/news/science-environment-18177493>.