Adult males of both Gowidon temporalis and Lophognathus gilberti appear to have been stroked with a white paint brush that started wet at the snout and dried up partway down the body.

Big lizards that look like this are common around Darwin and the rest of Australia's Top End. However, there are two closely related species that look like this, Gowidon temporalis and Lophognathus gilberti. The only surefire way to tell them apart without testing their DNA is to carefully examine the scales on their backs. On one species, the scales align in such a way as to form lines that are parallel to the spine. On the other species, the scales align in such a way as to form lines that run diagonally away from the spine. I spent a lot of time staring at my computer screen with various photos at maximum magnification in order to choose which lizards I should identify as which species.

I’ve written up an account of this three-week trip to Australia here.

Sleeping on a sapling, this dragon is showing off its ridiculously long tail.

After a midafternoon rainstorm, the dragons were out in force along the Fogg Dam wall. Females and juvenile males typically show some bands across the body, and less of a white paint stripe.

I had originally identified this as the similar-looking Lophognathus gilberti, but Stephen Mahony set me straight on iNaturalist. The easiest way to tell them apart is that T. temporalis always has a nuchal crest with largish, separated chunky spines, whereas L. gilberti has a nuchal crest with small, pointy, close-together spines.

This mature male was hanging out on a palm tree near the reception desk of the Gagudju Lodge Cooinda, keeping a careful eye on the prospective guests to see if there were any worthy of a wave. He did not wave at us, for what that’s worth.