WORLD OF SCIENCE
Digging up dinos
DR. T. V. PADMA
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Palaeontologists thought most landmasses did not have the right sort of rocks for fossils to form in.
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Which continent contains the fewest dinosaur bones? If you had asked that question 75 years or so ago, the answer would have been different from the answer I'd give you today. Why? Because until the early 1970's only one dinosaur bone had been unearthed in the Australian state of Victoria, and very little elsewhere in the Southern Hemisphere.
Palaeontologists just weren't interested in looking for fossils in Australia, New Zealand and Antarctica, in the early part of the last century.
Topography
In their opinion, these landmasses did not have a lot of the right sort of rocks for fossils to form in: large tracts of fossil bearing rocks such as limestone. Even if such rocks were present, the argument went, Australia was the flattest of all continents. Why does a palaeontologist care about a continent's topography? Because it's easiest to dig out dinosaur bones in areas where continental uplift has left these rocks well exposed and easy to get at; places where rocks are exposed, such as cliffs or hillsides, where the surrounding, softer earth has worn away, for example. In flat areas, it's harder to dig fossils out — sometimes, palaeontologists had to dig tunnels into rocks where they thought fossils might exist. There was another consideration: in cold places like Antarctica, fossils are hidden under permafrost or even under layers of snow and ice. Palaeontologists would have to work under very difficult conditions, after guessing where fossils might exist. If the guess were wrong, all that hard work would be for nothing. It was much easier to work on warmer continents.
Palaeontologists had ignored the Southern hemisphere for another reason: its climate. Why did climate count? The answer, next week.
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