These pictures are of a male Australasian Darter (Anhinga novaehollandiae) taken in its classic drying / thermoregulation posture.
This bird was making the most of the evening sunshine on Yellow Waters, Kakadu National Park, Northern Territory.
The dark front of this bird identifies it as a male bird. You can see from the close-up of the head why they are sometimes called Snake-Birds when they swim through the water with only their neck and head exposed.
I always find birds like this - cormorants and shags etc - to be convincingly reptilian.