Goanna Dreamtime

Komodo dragonMonitor lizards, otherwise known as varanids (genus Varanus) or goannas (in Australia), are carnivorous lizards found in Africa, Asia, Australia, and many archipelagos and island chains. Until recently some species were thought to possess toxic bacteria, but now we know they have amounts of weak venom, used to help down large prey. Monitor lizards have existed for millions of years, closely related to the extinct mosasaurs and the venomous goanna-like Estesia mongoliensis (Norell, McKenna & Novacek, 1992). Their modern-day relatives include the beaded lizard, Gila monster, and earless monitor. The largest species is the “infamous” Komodo dragon (Komodo Island Monitor, Ora), a 6.5 to 10-foot lizard first discovered in 1910 (by Western scientists).

Nile monitorBeginning with African monitors: I could see large wandering land monitors like Megalania or similar to terrestrial crocodiles. They would likely be scavengers or opportunistic feeders, snatching what they can for themselves or from other predators. Specialized forms may develop, like burrowing monitors feeding on insects such as crickets, ants, and termites. Or maybe, instead of a burrower, a semi-aquatic swimmer that hunts fish and insect larva. The burrower would be a descendant of the savannah monitor (Varanus exanthematicus) and the swimmer would be a descendant of the Nile monitor (Varanus niloticus). In my opinion, Australasian monitors will be much more diverse.

The “goannas” or Australasian monitors have a much more interesting future ahead of them. I don’t see an ant-monitor, simply because there will be mammalian ant-eater equivalents such as echidnas or numbats, although their numbers have declined quite a bit. I’d like to see large 14-foot terrestrial monitors charging around after flightless birds and kangaroos except they have re-refined their venom glands to be able to kill effectively. In the Australasian forests, arboreal monitors will find haven, perhaps even semi-gliding monitors chasing after birds (bats and other birds will probably prevent this). In mountainous regions, the more derived circulatory system of monitors might allow them to become fishers if mammals do not take advantage of the niche.

My final idea is the development of semi-aquatic marine monitors along the coasts of Australia, New Guinea, and nearby islands. They will resemble long-necked monitors will adaptations of crocodiles and the prehistoric nothosaurs. They will not be fully marine, having to return to land to lay eggs. The best prey item will be fish and seabirds and maybe invertebrates.

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2 Responses

  1. Hi there, this is a great blog indeed, I hope you’ll keep posting regularly on it. It seems to me that large, predatory reptiles will always thrive in low-energy ecosystems where not much food is running around. Venom is a very exciting possibility, perhaps there will be brightly-colored but small “viper-monitors” on trees somewhere.

  2. Certainly something I had not thought of. Arboreal or aquatic brightly-colored monitors would be a most interesting change. I don’t know if bright colors would help them in catching prey, though.

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