Koolasuchus

Koolasuchus was a very large ancient amphibian.

It lived a long time ago in Australia. These fossils date back 125 to 120 million years. This was during the Early Cretaceous period. Scientists call it a temnospondyl. This is a group of ancient amphibians. Koolasuchus is the youngest temnospondyl that we know about. It lived in the rift valleys of southern Australia.

It was a large predator that lived in the water. Its body shape was a bit like a crocodile. This is why its name uses the Greek word for crocodile.

This animal lived a very specific way. It lived in fast-moving streams. We know this because of the coarse-grained rocks where its fossils were found. The weather in southern Australia was quite cool back then. This was because the land was below the Antarctic Circle.

Even though it was cool, Koolasuchus was a big hunter. It had a wide and rounded head. It also had horns on the back of its skull. These horns are called tabular horns. Its teeth were sharp and pointed for catching food. The teeth also had tiny ridges called serrations. There were 40 teeth on its lower jaw. This is a much higher number than other similar animals.

Finding these fossils was a long journey for scientists. In 1978 and 1979, a team explored Victoria, Australia. They found two lower jaws at a place called Rowells Beach. At first, scientists were not sure what the bones were. They called the specimen "GOK." This stood for "God Only Knows."

They thought it might be a dinosaur or a crocodile. Later, in 1986, researchers showed it was not a crocodile. In 1989, Lesley Kool found a bone from a vertebra. Mike Cleeland also found a piece of the skull on a beach. These discoveries helped everyone understand what the animal really was.

In 1997, a group of scientists named the animal. Anne Warren, Thomas Rich, and Patricia Vickers-Rich described it. They named the new species Koolasuchus cleelandi. They named it after Lesley Kool and Mike Cleeland.

The fossils come from the Strzelecki Group in Victoria. This includes the Wonthaggi Formation. The bones include parts of the skull and ribs. They also found vertebrae and pectoral elements. These are bones that help make up the body. These fossils are now kept in the National Museum of Victoria.

Koolasuchus tells us how the world changes over time. For a long time, the area was too cold for crocodiles. This allowed the large amphibian to live there. However, the Earth eventually began to warm up. By 110 million years ago, the climate was different.

Crocodiles moved into the area as it got warmer. These crocodiles likely pushed Koolasuchus out of its home. This caused the animal to disappear from the fossil record. Today, Koolasuchus is a special fossil emblem for Victoria. It was adopted as this symbol on 13 January 2022.