Aside from the crocodiles, very few prehistoric reptiles after the age of dinosaurs achieved enormous sizes—the notable exception being Megalania, the giant monitor lizard. Depending on reconstructions, Megalania measured anywhere from 12 to 25 feet long and weighed in the neighborhood of 500 to 4,000 pounds—a wide discrepancy, to be sure, but one that would still put it in a bigger weight class than the largest lizard alive today, the Komodo Dragon (a relative lightweight at “only” 150 pounds).
Some paleontologists speculate that Megalania was the “apex predator” of Pleistocene Australia, feasting at leisure on mammalian megafauna like Diprotodon (better known as the Giant Wombat) and Procoptodon (the Giant Short-Faced Kangaroo). This giant monitor lizard would have been relatively immune from predation itself, unless it happened to spar with Thylacoleo, the Marsupial Lion. Whatever, the case, Megalania is one of the few recent, giant animals the demise of which can’t be traced directly to early humans; it was probably doomed to extinction by the disappearance of the gentle, herbivorous, oversized mammals that early Australians preferred to hunt instead.
The Perentie, Varanus giganteus (Varanidae) is Australia’s largest lizard reaching over 2.5 metres in length.
It has a long neck and a stout, robust body ending in a long, tapering tail. The colour is yellow or cream with tawny brown rosettes edged in dark brown on their back and they have dark limbs with white spots. The head and neck are pale creamy-white overlaid with a reticulated pattern of black lines and flecks.
Lean, Green, and Rarely Seen: The Prasinoid Tree Monitors
by Darren Naish
I said in the previous Tet Zoo article on monitor lizards that I really wanted to cover the prasinoids; that is, the arboreal tree monitors of New Guinea, Cape York Peninsula and various of the islands surrounding these areas. So, let’s get to it.
Tree monitors or prasinoids, also termed the Varanus prasinus species group, are slender-bodied, gracile monitors with pointed snouts and especially long, prehensile tails. They tend to be green: some are lime green and some are deserving of another common name, ‘Emerald tree monitor’. Some are patterned in ringlets or chevrons; others, however, are virtually black while others are yellowish. They have brown-orange eyes and pink tongues. Total length can be 110 cm or so but 60-80 cm is more common. [Image below by Greg Hume.] Incidentally, the quote used in the title for this article comes from an article about these amazing lizards by Sprackland (1994).
It is, essentially, universally assumed that tree monitors are specialised for arboreal life, and that they spend much (though not necessarily all) of their time foraging high up in trees. Note that, across many animal groups, assumptions like this are sometimes based on anecdotal impressions and are not really backed up by detailed ecological studies or by the discovery of anatomical features linked with any specific lifestyle or behavioural preference…
Obscure and attractive monitor lizards to know and love
by Darren Naish
Everybody loves monitor lizards, or varanids. And there is so much to learn about, and to appreciate, in these remarkable, charismatic, complex, sophisticated lizards that scientists across many disciplines are being encouraged to study them and – lo – to make remarkable discoveries.
In recent months we’ve seen the discovery of a mammal-like rate of blood flow to varanid limb bones, further documentation of ‘tail-assisted foraging’, the demonstration of rapid, sophisticated coordination between jaw gaping and neck and forelimb movement during prey-grabbing, and the recognition that varanids possess a unidirectional system of breathing. What seems to be the first documented human death caused by varanid oral toxins – the death was that of a 55 year old woman, bitten by a Bengalese monitor Varanus bengalensis – was also published just a few weeks ago.Yet more amazing stuff on varanids is due to hit the presses soon…
A team including staff from BirdLife Partner Burung Indonesia has confirmed the presence of the Komodo Dragon, the world’s largest lizard, in the west of Flores Island, Indonesia. The discovery adds further urgency to the BirdLife Partnership’s campaign to gain formal protection for the Mbeliling Important Bird and Biodiversity Area (IBA), which includes the forests where the giant lizards were found.
Komodo Dragon Varanus komodoensis is classed as Vulnerable on The IUCN Red List. Camera traps recorded at least 12 individuals in the Mbeliling forest in the extreme west of Flores, opposite the small islands of Komodo and Rinca, which are the known strongholds of the Komodo Dragon. The Komodo National Park, a UNESCO World Heritage site, includes these islands and a section of the Flores coast, but the Mbeliling IBA lies outside its boundaries.
As recently as 2004, Komodo Dragons were found at sites on the north and south coasts of Flores, but the survey work by Burung Indonesia and others provides the first confirmation that they also survive in the west…
Unidirectional airflow in the lungs of birds, crocs…and now monitor lizards!?
by Matt Wedel
Today (12/11/13) sees the publication of a new paper by Emma Schachner and colleagues in Nature, documenting for the first time that unidirectional, flow-through breathing–previously only known in birds and crocodilians–happens in freakin’ monitor lizards. The image above, which is most of Figure 1, pretty much tells the tale.
Some quick background: until the early 1970s, no-one was quite sure how birds breathed. Everyone knew that birds breathe, and that the air sacs had something to do with it, and that the bird lungs are set up as a series of tubes instead of a big array of little sacs, like ours, but the airflow patterns had not been worked out.
Then in a series of nifty experiments, Knut Schmidt-Nielsen and his students and colleagues showed that birds have unidirectional airflow through their lungs on both inspiration and expiration. Amazingly, there are no anatomical valves in the lungs or air sacs, and the complex flow patterns are all generated by aerodynamic valving. For loads more information on this, including some cool animations, please see this page (the diagram below is modified from versions on that page).
For a short, eminently readable summary of how undirectional airflow in birds was first discovered (among many other fascinating things), I recommend Schmidt-Nielsen’s wonderful little book, How Animals Work…
This medium sized monitor is native to Indonesia and was only discovered in 2001. They are agile climbers and can grow up to about 40 inches from nose to tail.
Individuals’ color patterns can vary from grey to bright blue, and the black blotches can be spots or stripes. Their irises can also range from brown to orange to red. The tail is prehensile, and is often curled at rest.
Populations are unknown and very unstable. Because they are so beautiful, demands for pet trade and skins are skyrocketing. Since their discovery, illegal poaching and dealing has been taking advantage of the lack of information on this new reptile. Their range is very small, and this over exploitation could wipe them out.
‘Krakatoa, a 75-pound, 7.5-foot long Komodo Dragon, celebrates his eighth birthday with fellow eight-year-olds from R.B. Hunt Elementary School at his enclosure at the St. Augustine Alligator Farm and Zoological Park in St. Augustine, Fla. The children sang Happy Birthday to the large lizard as he was presented with a meat cake topped with mice.’
Komodo dragon in a party hat is basically the best thing that has happened to me today.