The following is a short reply from Helen Larson regarding M. exquisita
and how old the waterfalls are above which it occurs.
As to how old the escarpment is and how long have the Melanotaenia,
Mogurnda etc been in the creeks on top - there's no quick answer. The sea
levels have gone up and down and the last tectonic uplift around Kakadu
happened 25-10 Mya. I think fish have been around in freshwaters here for
a long time.
Helen Larson
Tootles
Peter Unmack