World of Science
Down the ages
DR. T. V. PADMA
Were dinosaurs reptiles? Or were they warm-blooded?
When the Mesozoic era began most of the continents were stuck together, forming one super continent called Gondwanaland. During the Triassic (245-208 Mya), Australia was in the low latitudes and had a humid, temperate climate, with marked seasonal variations. New Zealand was stuck to Antarctica and had climates similar to Southern Australia. Between 208 and 144 Mya (Jurassic era), Western Australia was warm, but Eastern Australia was cooler. Cold weather plants grew in abundance. Most of the landmasses broke away from Gondwanaland and drifted up during the Jurassic, but Australia and Antarctica were together till the end of that era.
During the Cretaceous, Australia began rifting away from Antarctica but did not completely separate until just into the tertiary period. Sea levels rose and formed a great inland sea through the centre of Australia. The climate was still temperate. South Eastern Australia was close to the Cretaceous South Pole. Vegetation was still dominated by conifers, pines and ferns, though the first flowering plants had appeared. New Zealand had just separated from Western Antarctica about 82-85 Mya, and was still within the Antarctic Circle at the beginning of the Cretaceous. By the close of the Cretaceous, New Zealand had probably drifted out of the Antarctic Circle.
Dinosaur hunters were concerned about paleoclimate, because dinosaurs were thought to have been reptiles. Reptiles are rare in cold climates. How could reptiles as large as dinosaurs possibly have survived these extremes of temperature? How could they have kept warm? Scientists thought it impossible, and paleozoologists ignored the Southern Hemisphere.
Many scientists now think dinosaurs were more like birds than reptiles. Though it's still quite a radical idea, some palaeontologists think a few dinosaurs may have been warm blooded, too.
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