TODAY's MAIL: DAY 5

See today's dig diary

See archived mailbags: Day 1 | Day 2 | Day 3 | Day 4 | Day 5

From: Amelia Filmer-Sankey, Sydney, Australia

Question: Is the yellow duck still there?

Reply: Dear Amelia,
You'll be pleased to know that the yellow duck has been safely catalogued and is now housed in the museum's collection. (A plastic yellow duckie was once skillfully planted next to a big bird Dromornis fossil at Alcoota to fool the scientists!)

From: Jessica Shipley, Koonwarra, Victoria, Australia

Question: Can you please tell me if the birds that lived along time ago looked like any birds that are alive today?

Reply: Dear Jessica,
The Dromornis stirtoni or Mihrung birds that lived about 8 million years ago looked a little bit like emus with big heads although they are really related to geese. We think they are most closely related to the living Australian Magpie Goose and the South American Screamers. In our reconstructions of the Mihrung birds we use many of the characteristics of these two birds to imagine what they would have looked like. They were tall and powerful with a big solid body, a long thin neck and a huge bill, but they had tiny wings and did not fly. They would have had sleek feathers like a duck and a fine hexagonal scale pattern on their legs. They may also have had a crest of feathers on their head and colour on their bills.

From: Basil, Sydney, Australia

Question: What different dating techniques (such as flourine, uranium or nitrogen dating) do the Paleontologists use once the fossils are returned to the museum?

Reply: Dear Basil,
Unfortunately we do not have the right minerals in the Alcoota soil to do the kind of dating techniques you mention, which rely on the presence of radioisotopes like uranium or potassium argon. At Alcoota we use a dating technique called 'stage of evolution' or 'stratographic correlation' which means that we look at other easily dated sites where similarly evolved animals have been found and we estimate the age of our animals based on this comparison. The animals from Hill 1 at Alcoota for example are very similar to a site at Beaumaris in Victoria. The Beaumaris site can be quite accurately dated because of the many layers of marine fossils that have been preserved next to the land site. The main pit at Alcoota is older than Hill 1 but by comparing these animals to the Hill 1 animals and animals from later and earlier periods we are able to get a good idea of about how old they are.

From: John S., Sydney, Australia

Question: Can you make out any wounds on the fossils that the animals might have got in their lifetimes?

Reply: Dear John,
At Alcoota there is some evidence on some of the animals of minor trauma like broken ribs and occasionally a crocodile bite, but the bones are so fragmented that many wounds are probably not visible. We think that the animals at Alcoota died more than anything of starvation and were eventually pushed together in a huge bone jam. At Camfield, another megafauna site close to the Victoria River near the Western Australia and Northern Territory border, there is much better evidence of crocodile bites where you can clearly see the holes through the bones that their teeth have made.

From: Jasmine D, Melbourne, Australia

Question: Have you found any plant fossils to tell you what the habitat at Alcoota was like?

Reply: Dear Jasmine,
We unfortunately haven't found any plant fossils at Alcoota which makes it hard to say exactly what plant species were here when the megafauna were living in the late Miocene period. Most of the large herbivorous marsupials however had teeth suitable for eating dry coarse vegetation, such as the scleromorphic vegetation that is still here today. Scleromorphic vegetation means plants with thick skin on their leaves and dry thick twigs and branches. These include modern day plants such as the hakia and the grevillea and during the time of the megafauna we think the habitat would have been a kind of dry rainforest.

From: Geoff Harding, Alberta, Canada

Question: How do you make your connection with the web work from out in the field? Are you linking up with a satellite phone?

Reply: Dear Geoff,
We are linking up through a small satellite dish that allows us to dial up a connection with the AMOL web site in Sydney. We can send images and text from out here that are uploaded to the web site in Sydney as well as receive all your messages via email.