The indigenous peoples of Australia likely encountered Megalania over 40,000 years ago.
Description & Size
Megalania, which means “Giant Romer” in Greek, was a very large Australian lizard that existed at the end of the Pleistocene Epoch. The first Megalania fossil discovery is attributed to English naturalist, Richard Owen, who named the animal Megalania prisca. Paleontologists later recategorized the animal into the Varanus genus, naming it Varanus priscus, although the name “Megalania” remained in popular culture.
We can draw similarities in appearance to the Perentie (Australian monitor lizard) and Komodo dragon which are both thought to be Megalania’s closest living relatives.
Fossils tell us that these animals could have averaged anywhere from 15 feet to 26 feet in length. The debate of Megalania’s length depends on which of the aforementioned lizards it is closer to in the phylogenic tree. If closer to the monitor lizard, Megalania would reach upwards of 26 feet due to a longer tail.
It’s clear that Megalania exists within the Varanidae genus, but there are some uncertainties as to where it exists in the genus. Similarities in skull shape suggest a relation to the Prentie.
Studies have also suggested a sister-taxon relationship to the Komodo dragon. This means that the two species are equally distant from a primary common ancestor, which is the earliest varanus in this case.
These questions also put a gap in the animal’s known weight. On the high (23-26 foot) end, Megalania would way over 4,200 pounds. At the lightest, the lizard could have weighed a little more than 700 pounds.
Megalania is a part of the Toxifera group, which encompasses all reptiles that secrete venom. Based on its phylogenetic relatives, we can assume that Megalania’s venom would increase the blood flow from wound sites, shocking prey and making them more vulnerable.
Equipped with stout limbs, a crested skull, and a full jaw of serrated teeth, estimations tell us that Megalania resembled a monstrously large Komodo dragon.
Key Facts:
- 15 to 23 feet long
- Related to Komodo dragon and monitor lizard
- Venomous
- Largest known terrestrial lizard
- Largest known venomous vertebrate
- 700-4,200 pounds
- Serrated teeth
- Heavy, stout limbs
- Large, crested skull
The cast fossil of Megalania from Queensland Australia in Melbourne Museum. It is an extinct giant goanna or monitor lizard.
©Danny Ye/Shutterstock.com
Megalania Behavior
We can estimate Megalania’s behavior based on the behavior of other members of the Varanidae family.
Most Varanidae spend much of their time near shallow water. They also swim strongly and are capable divers, making their way out to sea in rare instances. You might have also found Megalania basking on water-side rocks or horizontally-extended trees if they were strong enough to hold the lizard’s massive body.
When venturing away from the water, you might see Megalania prowling for other ancient Megafauna to eat or exploring the waterside nests of possible prey. They’d move around at roughly the speed of a freshwater crocodile, reaching speeds of around 5 or 6 miles per hour.
Many members of the Varanus family sleep around half of the day. Notably, Komodo dragons require heating and cooling time proportional to their size. Larger individuals require more time to heat and cool than smaller ones.
If this extends to Megalania, that means they would spend a significant amount of time basking in the sun or shade, respectively, trying to adjust their temperature.
Diet – What Did Megalania Eat?
From what we know about the size of Megalania, it would have been a formidable apex predator in its ancient ecosystem. Mainly feasting on mid-sized to large animals, Megalania would have been a carnivore. Modern monitor lizards are also strict carnivores.
A large part of their diets might have been the various marsupials in Australia at that time. Australia was host to a wide variety of massive marsupials such as Diprotodon and Procoptodon, which were prey to many other formidable hunters like Thylacoleo. Diprotodon would have been roughly Hippopotamus-sized.
Megalania hunted other species as well, including birds (and their eggs), other lizards, and some smaller mammals of various kinds.
While they would have hunted extensively, these individuals wouldn’t have been the primary predators of the area. Other predators of a similar size are known to have been living throughout Australia at that time. Further, there have been very few Megalania fossils discovered, suggesting that the population was relatively small.
Habitat – When and Where It Lived
Megalania existed on the Australian plains, gravitating toward areas with access to streams, rivers, the ocean, or reliable bodies of water. That said, these versatile Megafauna could exist in a variety of environments.
They could probably live all over Australia so long as they had an adequate food source. Forests, grasslands, woodlands, caves, and more were all possibilities. Fossil discoveries are located mostly in eastern and southeastern Australia along rivers or tributary beds.
Threats and Predators
Megalania would have been what’s known as an “apex predator.” This means they sat at the top of the food chain. Occupying a wide distribution of habitats, though, there’s no telling what other kinds of apex predators they would have encountered.
It’s likely that the only threats to Megalania would have been similarly large carnivores that lived at the end of the Pleistocene Epoch in Australia. The aforementioned Thylacoleo carnifex, known as the “marsupial lion,” would have been a potential foe.
Other apex predators with a similar diet would likely gravitate toward the same places as Megalania. This would provide grounds for the two species to fight for the food source. That said, there wouldn’t have been a large number of predators or threats to this, the largest known terrestrial lizard of all time.
Discoveries and Fossils – Where It Was Found
The first discovery of Megalania come in 1859. Sir Richard Owen is credited with the discovery of these bones.
The discovery consisted of only a few vertebrate bones amidst a number of other marsupial bones. All of these remains were sitting at the bottom of a tributary to the Condamine River which flows near the eastern coast of Australia.
Most of the other Megalania fossils discovered have been somewhere near the eastern or southeastern coasts of Australia.
Extinction – When Did It Die Out?
Megalania is believed to have gone extinct somewhere between 40,000 and 50,000 years ago. Humans arrived on the Australian continent roughly 65,000 years ago.
Alongside many other animals that died out at the end of the Pleiocene Epoch, Megalania’s reason for extinction likely had something to do with humans. It wasn’t necessarily that people hunted Megalania (although they could have), but instead that humans hunted Megalania’s prey extensively.
As a result, there would have been fewer species for Megalania to eat. That scarcity would have affected other apex predators as well, reducing the feeding pool and contributing to competition. The presence of a new apex predator (Homo sapiens) did a lot of damage to the existing ecosystem, especially to animals like Megalania which were particularly slow-moving.
Climate Change
The end of the Pleistocene Epoch was a period marked by significant glacial activity and global climate change. It’s very possible that Megalania died out due to drastic changes to its environment.
Temperatures, wildlife, predators, and prey would all have shifted gradually, reaching a crest roughly 11,000 years ago when the epoch ended. It was during that time that sea levels fell, exposing land bridges that ancient humans used to travel to Australia in the first place.
The combination of these elements surely contributed to Megalania’s extinction.
Similar Animals to Megalania
Komodo Dragon – The Komodo dragon is one of the best-known members of the Varanus genus. They live predominantly on Indonesian islands which are relatively close to Megalania’s home, Australia. This lizard is thought to share a general posture with Megania due to its similar bone structure.
Monitor Lizards (Varanus) – The Varanidae are the group of lizards that make up the genus Varanus. Lizards such as Komodo dragons, Grey’s monitor, and various other species share ancestry with Megalania.
Megalania Pictures
View all of our Megalania pictures in the gallery.
Erik Laan/Shutterstock.com
