During the Devonian period, sea creatures like ichthyologi evolved to move and live on land. This period is also known as the Age of the Fish. Fish ventured out of the water and evolved limbs to move on land. These animals belonged to the first group of tetrapods on Earth.
Quadrupeds are vertebrates with four limbs. These animals include reptiles, mammals, birds and amphibians. Tetrapods can include vertebrate land animals that have evolved to live in water.
Tetrapods The earliest tetrapods evolved from vertebrates known as tetrapod fish. These fish have thick fins that can evolve and turn into limbs. This article will discuss what a tetrapod was, when it existed and how it went extinct.
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description and dimensions
Ichthyostega is a four-limbed fish that lived during the Devonian period. This fish is a quadruped that evolved limbs to stay out of the water. Their gills and fins are fused with the amphibian’s skull and limbs. Ichthyostellus have blowholes on their heads. Four-limbed fishes of this period could breathe air through their blowholes.
Ichthyostega means “fish roof” in Greek. They existed between 370 and 362 million years ago. This period is the Devonian, the Quaternary period of the Paleozoic Era. Their amphibious body structure serves as a bridge between amphibians and fish. They have limbs and lungs to help them swim. Some facts about ichthyolipids include:
- Weight – 50 lbs
- Length – 1.5 meters
- Skin Type – Scaly
- Attributes – Limbs, Frog/Fish Head, Tail Fin and Gills
This animal belongs to and has four known species, which are; Ichthyosis, Ichthylolithia fahrenheit, Ichthyosisand Kochi Ichthyostellum. This species was identified in 1932 by Gunnar Save-Soderbergh. The species differences are even more pronounced in the patterning of the skulls.

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Ichthyologis move on all fours while balancing on their tails. Younger animals would have been better able to move on land due to their smaller size and weight. They also increase their body temperature through exposure to sunlight. This may be one of the reasons why they need to adapt to land movement.
The hindlimbs of ichthyosaurs are smaller. These limbs may not be able to carry them at their adult size. Their skin reduces evaporation and reduces water loss from the body’s surface. Stronger forelimbs help to drag themselves out of the water.

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Diet – What do ichthyosaurs eat?
Ichthyostega has been described as a piscivora. A piscivora is a carnivore that feeds primarily on fish. They have dentate teeth that allow them to chew meat with ease. As carnivores, they also feed on small reptiles that can hunt on land. Most of these prey are small lizards.
Ichthyostelloids are known to rely more on gills than lungs. They drag themselves when moving on land, which makes it slow, unlike their fast movement in water. This fact suggests that it spent most of its time in water and probably ate mainly fish.
Habitat – when and where ichthyostids live
Ichthyologis lived during the early evolution of tetrapods 370 million years ago. This period was the third period of the Paleozoic Era, the Devonian. The animal evolved from waters and lived a restrained amphibious life.
Ichthyostega lived in swamps and shallow waters in what is now Greenland. Their limbs were unable to support movement on land, suggesting that they lived primarily in water. Their ability to live on land is due to the stomata they possess.
Without water habitats, ichthyologi may not survive. They lay 1 or 2 eggs. These eggs are gelatinous and require water to survive. Therefore, fertility can only take place in water.
Ichthylolith Threats and Predators
Ichthyophylls are solitary animals. They spend most of their time alone, which suggests that they do not have herding behavior. Their main defense mechanism is their labyrinth teeth. Ichthyostega was probably the prey of large marine animals at that time.
They also face the inevitable extinction that all species face. These species extinctions were mainly caused by natural disasters. There is evidence that the formation of glaciers threatens and affects their habitat.
Finds and Fossils – Where to Find Ichthyolithian Fossils
The first fossils of ichthyolipids were discovered in the 1920s. These fossils were later identified and described by Gunnar Säve-Söderberg. Gunnar also unearthed four fossils in Devonian Greenland.
Subsequent fossil discoveries were made in 1929 and 1932. These fossils describe four species of ichthyologis. Fossils of ichthyolipids have been found in East Greenland. The fossils were found in sediments from the Upper Famenian. This sector is of the late Devonian period.

© Oleg Tarabanov – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=30408738 – License
Extinct – When did it become extinct?
Ichthyologis lived between 370 and 362 million years ago. Their extinction was due to a mass fish extinction about 360 million years ago. This extinction event caused a reset in the evolution of life on Earth.
The exact cause of this mass extinction is unknown. Evidence of glacier formation was found in the Late Devonian. These glaciers are large enough to lower sea levels. Since ichthyologis were primarily an aquatic animal, this affected them greatly and led to their extinction.
Animals similar to Ichthyostega
Ichthyologids belong to a group of animals called tetrapods. Quadrupeds are not limited to amphibian or marine animal types. They evolved around a time when marine animals were developing limbs that could move on land.
Quadrupeds are vertebrates with four limbs, which covers a long list of animals. Tetrapods are divided into amphibians, birds, mammals, reptiles, and ancient quadrupeds about 397 million years ago.
During the Devonian period, ichthyolipids lived among other tetrapods that also started the evolution of limbed fish. They also have close relatives today, with similar appearance and evolutionary traits.
Animals similar to ichthyologi include:
- Acanthemum – Acanthostega means pointed roof in Greek. This animal existed in the Late Devonian period about 360 million years ago. They weigh between 5 and 10 pounds and can be up to 2 feet long. Acanthostega is one of the famous tetrapods that evolved and lived with ichthyolipids. They also live in swamps and rivers.
- lungfish – The lungfish is a freshwater fish that can breathe both in water and on land. They evolved about 400 million years ago and retain some ancient evolutionary traits. They have an internal lung to expel waste and inhale oxygen. This lung helps provide buoyancy when they are in water.
- Tiktaalik – Tiktaalik was an animal of the late Devonian period, about 375 million years ago. They are often referred to as “ichthyopods” due to their similar characteristics to fish and tetrapods. They have four legs and a flat reptilian head. It has fishy features, such as scales, fins, and gills, and the wide neck and ribs of a quadruped. Tiktaalik fish also live in shallow waters, rivers and swamps. They also have some human features like wrists, elbows and shoulders.
- dolphin – Dolphins are a type of whale. They stand about 32 feet tall and weigh about 13,000 pounds. Their lifespan can reach around 60 years. Dolphins live in oceans all over the world. They are carnivores and prey on other fish and sea animals. They have strong teeth that can tear the skin of their prey.
- frog – Frogs are amphibians related to early quadrupeds. They have four limbs, two long hind limbs for jumping and two small forelimbs. They can live both on land and in water. Frogs are carnivores, preying on insects and small invertebrates. Their leap is a defense mechanism against prey.
in conclusion
Ichthyologis were an early quadruped that started the evolution of animals from water to land. This evolution paved the way for some amphibians and some ornaments of today. Their limbs do not provide a seamless mobility experience on land.
Evidence suggests that the animal lived primarily underwater. Their biological system supports long periods of underwater life because they have gills for breathing. They also have fins and are fast swimmers. They looked like some of today’s four-limbed reptiles, but differed in their biological composition.

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