Megalania

http://australianmuseum.net.au/megalania-prisca

The Megalania or Varanus Priscus was a truly horrifying creature. It grew to be roughly six metres long and had razor sharp recurved teeth. It lived in Australia at the time of the Megafauna and was a predator for many of the animals at the time. It was most likely an ambush predator and is related closely to the Komodo Dragon. Like the Komodo Dragon it has a venom, making it not only the largest venomous lizard, but the largest venomous creature known. This venom like that of the Komodo Dragon leads to an inability of blood clotting and shock in the creature. This means that the Megalania could have more safely killed its prey by biting and letting the prey weaken until unable to defend itself. It is at this point that Megalania came in and devoured its prey. No prey will have been too ferocious for this predator short of Pallimnarchus or Quinkana, and it is still likely it may have taken on those monstrosities.

Australian Megafauna

In response to Jblob.
The term "Australian Megafauna" indicates that the creatures in this category are roughly 40kg. In other countries the term "Megafauna" indicates that the creature weighed over 100kg, but because of Australia's lack of animals weighing over 100kg, the term is more lenient.

Some Australian Megafauna are:

• Diprotodon

The Diprotodon is the largest marsupial to have ever lived. Its name means two forward teeth. It is commonly known as a giant wombat. Fossils of it have been found across most of mainland Australia. It was roughly 3 metres from nose to tail and 2 metres tall. Some Indigenous Australian cave paintings depict an animal similar to the Diprotodon, indicating that Indigenous may have had contact.

• Zaglossus Hackettii

The Zaglossus Hackettii is a species of Echidna that was roughly 1 metre long and weighed 30kg. It was the largest monotreme to exist, and due to scorch marks on some bones, it is likely that it was hunted.

The cause of the Australian Megafauna's extinction is widely debated. Theories range from climate change to human (Indigenous) hunting.

Myllokunmingia

Myllokunmingia

All known vertebrates can trace their ancestry back to Myllokunmingia, which is thought to be the first animal with vertebrae. This creature is a primitive example of a fish. These fish are thought to have an advantage over other life (invertebrates) due to increased mobility and non-brittle armour. They eventually evolved into amphibians, which had the ability to go onto land, but had to stay near water. These amphibians evolved into reptiles, which were not confined to stay near water all the time as the amphibians were. These reptiles evolved into dinosaurs, mammals and birds.

-Darwin