Antarctic Blast Made Australia, Room For Dinosaurs

Agent Provocateur writes "Posted on the Science Daily site is a story from Ohio State University about a massive Antarctic blast that may have contributed to the Permian-Triassic extinction." From the article: "Its size and location -- in the Wilkes Land region of East Antarctica, south of Australia -- also suggest that it could have begun the breakup of the Gondwana supercontinent by creating the tectonic rift that pushed Australia northward. Scientists believe that the Permian-Triassic extinction paved the way for the dinosaurs to rise to prominence. The Wilkes Land crater is more than twice the size of the Chicxulub crater in the Yucatan peninsula, which marks the impact that may have ultimately killed the dinosaurs 65 million years ago. The Chicxulub meteor is thought to have been 6 miles wide, while the Wilkes Land meteor could have been up to 30 miles wide -- four or five times wider."

Age of impact

[MichaelSmith]

They are guessing that it was in the last 250 million years because they can still detect a mass concentration. I wonder if it is possible to drill to the bottom of an ice cap and then drill into the underlying crust. Doing that may make it possible to accurately date the impact.

Ice drills in my experience melt a hollow cylinder of ice and then extract the core. Presumably they would have to do this down to the surface and send a traditional drill down.

Ecological niches

[Flying pig]

Conventional wisdom is that species evolve to fit particular ecological niches. It is difficult for another species to arise to fill that niche because the one already in it is well adapted to it, therefore a less well suited species will fail to take over - unless there is a change which leads to extinction of the current niche occupier or its becoming less fit. This applies to all sorts of things, even the population of bacteria in our intestines which will adjust to suit changes in diet, or as a result of antibiotics.

So the answer is "lots of existing species of animals", many of which would have been amphibians, reptiles, crossopterygians. Dinosaurs have more sophisticated circulatory systems than ordinary reptiles, so if the atmospheric oxygen percentage went down (for instance) as a result of vegetation changes, they might be at a selective advantage.

Re:Is gravimetrics really this efficient?

[blackdropbear]

They used the gravity fluctuations to identify the anomoly and then used airborne radar data to define the extent. I would hazard a guess that radar wasn't the only set of electronices that airborne survey was doing and that it would have included high res gravity and magnetics as well