Almost West of Eden. Might the Dinosaurs have survived?
West of Eden, is a counter factual novel by Harry Harrison. I read West of Eden, in High School.
http://en.wikipedia.org/wiki/West_of_Eden Harry Harrison was one of my favourite writers when I was a teenager. Imagine my joy when I discovered he had crossed Dinosaurs with Alternate History.
H/T Walking with Dinosaurs BBC...
If the asteroid hit 10 million years earlier, might dinosaurs have survived?
LAST WEEK I answered a question about the origin of dinosaurs, a topic that fascinates me. But just as interesting is the extinction of the dinosaurs: a mystery that has generated more research (and speculation) than any other issue in dinosaur palaeontology.
This question hints at a view that has emerged over the past three decades, as palaeontologists reassess the dinosaur extinction using a wealth of new data provided by recent fossil discoveries and modern techniques for studying evolution.
First, the basics. Dinosaurs (except for birds, of course) became extinct about 66 million years ago, at the same time that an enormous asteroid, about 10km wide, smacked into the Yucatan Peninsula of Mexico.
We know there was an asteroid because there is a crater in Mexico that is 66 million years old. There is also a thin layer of clay that was formed at this time, all around the world, that is enriched in iridium (an element that is extremely rare on earth but very common in asteroids). In addition, there is clear evidence for global wildfires and huge tsunamis that were caused by the impact.
Furthermore, dinosaur fossils are not found in rocks that were formed after this asteroid impact – we simply never find dinosaurs in rocks deposited above the iridium-rich clay layer.
So it seems clear that the asteroid impact had something to do with the dinosaur extinction, a view that has been widely supported since the father-and-son team of Luis and Walter Alvarez first proposed it in 1980.
But one question has remained: were dinosaurs in decline prior to this asteroid impact? If so, perhaps the asteroid simply delivered a final crushing blow to dinosaurs, which were already heading towards extinction.
Recent studies have shown that certain dinosaur groups were in decline during the final 10 million years of the Cretaceous. A study published by my colleagues and I in 2012 showed that the large-bodied, bulk-feeding, plant-eating dinosaurs (ceratopsids and hadrosauroids) dramatically decreased in diversity during this time.
Another intriguing study, published by my colleague Jonathan Mitchell and his co-workers, asked an important question: what did this decline actually mean for dinosaurs?
They constructed food webs for several dinosaur ecosystems during the final 10 million years of the Cretaceous. These food webs are similar to what I used to draw out in grade school science classes: an interconnected network of species showing who eats who, that links together all members of an ecosystem.
Mitchell et al then used a computer to perform a calculation: what would happen to these food webs if various species became extinct?
They found that the ecosystems that existed when the asteroid hit were far more susceptible to devastating extinctions (where the extinctions of a few species has cascading consequences throughout the food web) than the ecosystems of 10 million years before. The asteroid impacted at a time when ecosystems were particularly vulnerable and weak.
So it does seem as if dinosaurs suffered some pretty bad luck, and would have had a better chance of surviving the asteroid apocalypse if it had occurred 10 million years earlier...
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