"Guess the Squamate" Roundup

A month and some change back I posted some of my photos from the "Lizards & Snakes: ALIVE!" exhibition at the American Museum of Natural History and asked you all to to do a little homework. Well, fellow blogger Susan stepped up to the challenge and successfully named each one of the squamates I photographed. As promised, now it's time to briefly talk a little about each of them and their relationships with one another. I'll also be including a ton of Wikipedia links so that those who want to find out more about the species or clade I'm talking about can easily do so (I normally take Wikipedia with a grain of salt, but to be fair, they are starting to cite a lot of references so check those out too).

The first squamate pictured was the serpent Corallus caninus, commonly known as the emerald tree boa. This boid is a arboreal native of the rain forests of South America, and as you can see, is a pretty good looking animal. This specimen in particular is seen in a typical Corallus pose, coiled around the branch of a tree, head in center. It will remain like this for most of the daylight hours, as it is a nocturnal hunter. Staying coiled up as it hunts, it extends the head and neck out, waiting patiently for a small mammal, bird, or frog to pass by before it strikes with atypically large teeth for a non-venomous snake. It then pulls it's prey in, and like other boas, constricts it until it suffocates. And for those who already think snakes are creepy enough, here's a fun fact for you: Corallus is ovoviviparous, meaning that the mother never lays eggs, but rather, retains them inside of her body as the young develop and hatch, until she finally gives birth to live young (Mehrtens 1987). Awesome.

Second on the list is Chlamydosaurus kingii, the frilled or frill-neck lizard. This agamin agamid is well known for its distinctive frill of skin and cartilage which it unfolds both as a defense mechanism and a sexual display. Found in Australia and New Zealand, it feeds on insects and small vertebrates. It spends a lot of time in the trees, where it's mottled gray and brown tones help it blend in perfectly. With the frill folded in it looks remarkably like the branch of a tree. It's a bit more conspicuous with its frill out, charging straight at you on two legs (Shine & Lambeck 1989). Fun fact: the dinosaur designers for Jurassic Park were so inspired by this enigmatic lizard that they decided to put a similar frill on their fictional Dilophosaurus. PLEASE NOTE: there is no evidence whatsoever to indicate that Dilophosaurus was neither frilled nor venomous. But that doesn't stop people from adamantly believing it was.

Following is another member of Iguania, Cyclura cornuta, the rhinoceros iguana. This iguanid is found on the island of Hispaniola and the nearby smaller islands. It is primarily herbivorous, and forages for vegetation mostly on rocky outcrops, scrub woodland, and other dry environments. It gets its name from the bony growths on their heads and snouts which resemble those of rhinoceros. They are a sexually dimorphic species, males being larger and having more pronounced growths. Males also have a larger dewlap, and a big fatty pad in the occipital region of of the head. These traits may help this aggressive species defend its territory from rival males. While the species is found abundantly

in captivity, it is considered threatened in its natural habitat. Fun fact: rhinoceros iguanas are commonly captured and eaten on their island homes (Capula 1989). I've never tried it, but I've heard it tastes like chicken.

Next we have another agamin, Physignathus lesueurii lesueurii, the eastern water dragon. This subspecies of Australian water dragon is found in, you guessed it, Australia, in or near water. It is semi-aquatic, and can be distinguished from P. l. howitti (the Gippsland water dragon) by the dark band behind the eye. Seeing one in captivity was a first for me, as this species is less well known then its cousin from the Far East, P. cocincinus, the Chinese water dragon. The males have a red chest which can be seen as they display. The young are gregarious, often being seen in small groups. They are extremely powerful swimmers, and have been known to stay submerged in the water for up to one hour. Fun fact: chances of seeing P. l. lesueurii in the wild may be slim due to its shy nature. But you're very likely to hear one as it plops in the water from a overhanging branch (Wilson & Knowles 1988).

The last three lizards all fell within Iguania, which is a sister group to the rest of the squamates in the suborder Scleroglossa. That means that the final squmate pictured is more closely related to the serpents than it is to any of the other lizards I've talked about today. That might seem strange considering the fact that snakes seem to be so radically different from the rest of the "lizards". But the truth of the matter is, looks can be deceiving. One has to remember that snakes are only limbless now, having evolved from a lizard-like, four limbed ancestor. This fact can be confirmed through both genetics and anatomy. See for yourself. The next time you're in the museum and you see the skeleton of a large constrictor, take a peek towards the posterior end of the animal and take note of the little bones sitting inside the rib cage. Likewise, getting a glimpse of the ventral surface of the snake and you might notice two little spurs sticking out of the animal. Many modern boids and pythonids retain a vestigial pelvic girdle and hind limbs; proof positive of their tetrapod origins.

So now that we have the phylogeny out of the way, I'd like to present the last squamate on the quiz, Varanus prasinus, the emerald tree monitor. This varanid anguimorph is found in the swamps and forests of New Guinea and the surrounding islands. Its body is covered in scales of green to turquoise with dark banding across the dorsal surface. They are arboreal, and have many traits that facilitate life in the trees like a prehensile tail, long claws, enlarged scales on the manus and pedes, and a slender body that is easily supported in the branches. V. prasinus is unique among varanoids in that it is omnivorous, supplementing a diet of insects, small mammals and birds with fruits and berries (King et al. 2004). Fun fact: the largest terrestrial lizard, largest marine lizard, and largest extant lizard are all varanoids. They are Mosasaurus, Megalania, and the Komodo dragon (V. komodensis) respectively.

Phew, and there you have it. Good job to everyone who took a chance at playing "Guess the Squamate". I have plenty of photographs from that exhibit, so there's a good chance there will be another round in the future.

References

Capula, Massimo. 1989. Simon & Schuster's Guide to Reptiles and Amphibians of the World. Simon & Schuster (New York).

King, R. A., Pianka, E. R., & King, D. 2004. Varanoid Lizards of the World. Indiana University Press (Bloomington).

Mehrtens, J. M. 1987. Living Snakes of the World in Color. Sterling Publishers (New York).

Shine, Richard & Lambeck, Robert. 1989. Ecology of Frillneck Lizards in Tropical Australia. Australian Wildlife 16, 491-500.

Wilson, S. K. & Knowles, D. G. 1988. Australia's reptiles a photographic reference to the terrestrial reptiles of Australia. Collins Publishers (Australia).