Dromornithids, "Mihirungs" or "Thunderbirds"

When I came back to Tasmania after my wonderful time at Riversleigh smashing open limestone to get fossils, I decided that my new subject for the pen and paper would be Dromornis stirtoni. After I had drawn a pair of Thylacoleo carnifex scrapping of course. (They are not anatomically sound I know but I will get better at this.) So I pulled out Tom Rich and Pat Vickers-Rich's Wildlife of Gondwana book from the shelves of the Science Library in the University of Tasmania and sketched these dromornithid legs. I saw the skull on one of Micheal Archer's powerpoint slides as he gave a lecture in the relative cool of the evening on the warm open timber awning where we took our meals. Seeing that skull sparked my interest in Dromornis stirtoni once more. I made a quick sketch in the fleeting seconds he had it on the screen...


Here it is amongst the notes I took from Mike's lecture. I really like the shape of this skull. Look at the deep upper jaw with it's beautiful curves. It has such a good solid chin. Isn't it worth swooning over?! :-D After the lecture and all the questions were asked with the lights switched back on, I did a quick reconstruction which was based more heavily on what I remembered of emus, although these Dromornithids are only distantly related to emus. (We actually don't know how these birds are related to other avian lineages but some believe that they are related to primitive anatids, hence Dromornis stirtoni has been dubbed "The Demon Duck of Doom" because of its possible carnivorous habits; others think that they are distantly related to galliforms and it was really a gigantic mutated chook).

You can see the reconstructed head of Dromornis stirtoni lower lefthand corner above. I can do something more interesting with this animal I believe and that is what my next few posts will focus on. In this picture you can also see how I have drawn Thylacoleo carnifex and Thylacinus cynocephalus. Also, I have drawn the skeletal major structures of what I hoped to be closer to the marsupial form. I had an eye opening discussion with Henk Godthelp who told me that that the shoulder structure of marsupials is unique and the scapula is orientated more vertically. The pelvis is likewise in a more vertical position as opposed to the horizontal orientation that you see in placental mammals. Also there are more vertebrae attached to the pelvis of marsupials than those of placental mammals. The marsupial posture is kind of like a kidney bean with the back arched and the limbs held rather lower than it. This is most prominantly seen in bandicoots and wombats. Actually this posture can also be observed in mustilids like otters and ferrets. Henk told me I ought to dissect a possum, but I haven't been able to lay my paws on one yet and I don't fancy going out there and shooting one like many Tasmanians do here. I haven't had time to comb the road for roadkill so far. Micheal Archer told me that the forequarters of marsupials tend to be more well-built than the hindquarters. This can be observed in the Tasmanian Devil (Sarcophilus harrisii) in particular but also in the recently extinct Thylacinus cynocephalus. This is a carry over from the fact that when a marsupial is born, it is very underdeveloped but it does have strong forearms to pull itself through the mother's fur to the pouch. We are more likely to see this feature in Thylacoleo carnifex.