Word: laurasia
(lookup in dictionary)
(lookup stats)
Dates: all
Sort By: most recent first
(reverse)
...supercontinent known as Pangaea. Because land animals could move and mate at will, dinosaurs from that era look pretty similar all over the world. But by the end of the Jurassic period, about 150 million years ago, continental drift had torn Pangaea into a northern and a southern half, Laurasia and Gondwana. At that point, dinosaurs in each hemisphere should have started evolving along divergent paths. The African dinosaurs should thus most closely resemble those found in South America...
Instead, Carcharodontosaurus closely resembles certain North American carnivores. This implies that the species were exchanging genes well into the early Cretaceous period, which ended perhaps 100 million years ago. Did a bridge of land connect Laurasia and Gondwana after the rest of the landmasses had mostly separated? That's what the new evidence suggests. By 90 million years ago, the separation of continents was evidently complete; Deltadromeus and other African dinosaurs from that period are quite distinct...
...week's Science magazine, Dr. Alber Wolfson of Northwestern University advances his explanation: that they are led astray by the earth's fickle geology. According to a fairly well established theory, says Dr. Wolfson, the continents were once bunched together in two main masses: "Laurasia" (North America and Eurasia) and "Gondwana" (South America, Africa, Antarctica, Australia), which were separated only by shallow seas (see map). During the Cretaceous period, 60 million years ago, both masses broke up and drifted slowly apart, their light granitic rocks floating on the heavy, plastic basalt that underlies both the oceans...
First Continents, More than 100,000,000 years ago the hideous, ungainly reptiles which were then the lords of life roamed two vast continents, ''Gondwanaland" in the southern hemisphere, "Laurasia" in the northern. A globe-girdling ocean, the "Tethys Deep," divided them. Mighty Gondwanaland shuddered, cracked and sundered. Its fragments drifted to form South America. Africa. Australia, Peninsular India, Madagascar. Mighty Laurasia similarly broke to form North America and Eurasia...
...much alike are these records at corresponding stages, urged Dr. Du Toit, that they must have been deposited in one undivided land. But the geological record of the southern hemisphere as a whole is utterly different from that of the northern-which would show that mighty Gondwanaland and mighty Laurasia were divided by some such mighty barrier as the "Tethys Deep...
| 1 |