Overview

Brief Summary

Taxonomy

Varanus prisca was originally described in a separate genus (Megalania) before being moved to Varanus.Varanus prisca is now recognised as a close relative of the living Komodo dragon (Varanus komodoensis).Varanus prisca can be distinguished from other monitor lizards by various features of the skeleton including
  • subtle features of the brain case
  • low spines on its trunk vertebrae
  • enormous body size.


Morphology
In many respects, Varanus prisca would have looked like a larger version of a Komodo dragon, with a
  • large, flattened head
  • bulky body
  • long powerful tail
  • jaw lined with sharp serrated teeth
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Introduction

Varanus prisca or giant monitor lizard is an extinct member of the monitor lizard family (Varanidae). The giant monitor lizard was the largest lizard ever to live on land. Fossils of Varanus prisca have only been recovered from eastern Australia, from Pleistocene deposits (between 2.6 million years and 10,000 years ago).The giant monitor lizard is thought to have become extinct due to effects of climate change.
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Comprehensive Description

Biology

Body size
No complete skeleton of Varanus prisca has ever been discovered, so estimating its body length and weight has proved difficult. Some scientists have claimed lengths of up to 8 metres, but this has been disputed and maximum body lengths of 4.5 metres have also been proposed.Similarly, weight estimates vary from 100–2000 kg. More complete skeletons will be needed to arrive at a more accurate figure.Nevertheless, Varanus prisca would still represent the largest of all land-living lizards. The only larger lizards would have been the extinct marine mosasaurs, which lived in the oceans during the Cretaceous Period around 90 to 65 million years ago.

Trophic strategy
The curved, sharply serrated teeth show that this gigantic lizard was a carnivore.It was probably one of the top predators in Pleistocene Australia and may have preyed on a variety of marsupial mammals, as well as ground birds and reptiles.Komodo dragons have a venomous bite and it is tempting to speculate that Varanus prisca shared this adaptation.
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Evolution and Systematics

Evolution

Varanus prisca shares numerous features in common with Komodo dragons, especially in the detailed structure of the skull. These two animals are also closely related to the lace monitor (Varanus varius) and the water monitor (Varanus salvator). All of these species are known from Australia or South-East Asia and represent a radiation of large-bodied lizards from this region.Other, more distantly related, large-bodied monitor lizards are known from Africa (e.g., the Nile monitor, Varanus niloticus) and Australia (the perentie, Varanus giganteus).The evolutionary tree of these animals indicates that the evolution of large body size must have occurred on three separate occasions among monitor lizards.Previously, it was argued that the large body size of Komodo dragons might have been related to living on islands, but their close relationship to Varanus prisca suggests that large body size was a feature already in place at the time Komodo was isolated from the rest of Indonesia and that these gigantic lizards may have moved back and forth between Australia and the Indonesian archipelago as sea-levels rose and fell.
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