Ichthyostega
Ichthyostega is considered one of the earliest known amphibians, notable for its ability to inhabit both aquatic and terrestrial environments. Growing to about three feet long and weighing over 200 pounds, this prehistoric creature resembled modern-day crocodiles in some aspects. Ichthyostega possessed strong front legs that supported its weight on land, while its flipper-like back legs and robust tail facilitated movement in water. Its eyes were positioned high on its head, allowing it to see while floating in murky waters, and it had specialized openings that functioned as snorkels to aid in breathing when submerged.
Ichthyostega primarily fed on small fish, amphibians, and invertebrates, preying on creatures it could swallow whole due to its size. However, it faced threats from larger predators, such as Eurypterids, both in aquatic and terrestrial contexts. While little is known about its reproductive habits—no fossils of young Ichthyostega have been discovered—it is believed that like many amphibians, it likely laid eggs in water. This amphibian thrived in a moist, subtropical climate, with fossil evidence found primarily in Greenland. Overall, Ichthyostega serves as a significant example of early vertebrate evolution, bridging the gap between life in water and on land.
Subject Terms
Ichthyostega
Ichthyostega was one of first reptiles to have lived. It could move on land and in the water. It resembled crocodiles we see today.
Kingdom: Animalia
Phylum: Prehistoric
Class: Amphibia
Order: Ornithischia
Family: Ichthyostegidae
Genus: Ichthyostega
Species: Stensioi
Ichthyostega was not a large animal. It only grew to a length of three feet (one meter) and weighed a little over 200 pounds (90 kilograms). With strong front legs that carried much of the animal's weight, Ichthyostega crawled at a slow speed. In the water, the animal used its flipper-like back legs and strong tail to move it. The animal was able to feel small vibrations in the water through special nerves in the animal's head. This helped it see better in its dark and cloudy surroundings. The eyes of Ichthyostega were located high on the animals head, like a crocodiles. This allowed the animal to see as it floated at the surface of a cloudy swamp. At the back of Ichthyostega's head were two small openings that were connected to the animal's throat. These openings acted as snorkels and helped the animal breathe as it swam. The animal also had special nostrils which helped it smell underwater, like fish do today.
Ichthyostega lived on a diet of fish, amphibians, and invertebrates (animals with no back bone). Ichthyostega preyed on animals on land and in the water as crocodiles do today. Because of its small size, it probably only attacked animals that it could swallow in one bite. Some of the fish that swam with Ichthyostega had thick, armored skin and may have been too difficult for it to eat. It probably had better luck preying on some of the smaller fish, fish larvae (eggs), worms, and insects.
Many of the larger fish, like the freshwater shark, would have had an easy time preying on the small Ichthyostega. It was also in danger of being attacked by Eurypterids. These large, crab-like predators were a threat to Ichthyostega both in the water and on the land. They could grow to be seven feet long and had long, strong legs which they used to cut up their prey.
Scientists do not know very much about the breeding habits of Ichthyostega because no fossils of the young have been found. Most female amphibians lay unfertilized eggs in water, where they are fertilized by the male. The eggs then hatch from larvae, or small egg-like creatures. When born, young Ichthyostega had no gills for breathing in water.
Ichthyostega lived in a moist, subtropical climate near the rivers and coastal areas. This gave Ichthyostega plenty of insects to eat and attracted other small amphibians.
Fossil remains of Ichthyostega have been found in Greenland.