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Re: Science News etc




It is hard to be sure if the Lancian fauna was really stable. Edmontonia may have disappeared hundreds of thousands of years before the end, and few large taxa were common. The discovery of very large edmontosaurs and T. rex specimens suggests a continuing "arms race". (UCMP 118742 was found stratigraphically high). At sea the case for gradual extinction within the late Mastrichtian is better.


Some hypsilophodonts -Atlascopcosaurus IIRC -lived at high latitude and were probably capable of hibernating, which meant that shelter was available and they could endure a scarcity of food. I doubt any birds were as well off. Stidham et al wrote that Neornithines were already proliferating at the expense of Enantis in the late Maastrichtian, and diversifying. Under the circumstances, survival of several Neornithine lineages is remarkable considering their disadvantages compared to certain high latitude dinos, under hypothesized impact conditions.

The proliferation of fern species requiring full sun to make spores was already underway within weeks of the impact, according to Arens. Such species were already more abundant in the upper impact layer than they were prior to the impact. Their ability to experience an "ecological release" indicates that there was adaquate sun and generally benign conditions.




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