Today
I begin a series of essays about a long trip I recently completed, which took
me from Oklahoma to Idaho and back, stopping at lots of places of ecological
and evolutionary interest. The second day of the trip, July 20, I visited
Ashfall Beds in Nebraska, which is one of the most amazing fossil deposits in
the world.
Ashfall
Beds State Park is in rural Nebraska. It is not on the way to anything, but it
was my principal reason for going to Nebraska. But it is well worth a trip to Nebraska even if for no
other reason.
About
twelve million years ago, life was abundant in the savannas of what is now
Nebraska. There was certainly an abundance of animal life. Reptiles included
the giant Hesperotestudo tortoise,
now extinct. Among the now extinct mammals were horned rodents of the family
Mylagauidae, the “raccoon dog” Cynarctus,
saber-toothed deer (I am not making this up), and three-horned deer. There was
a kind of dog that specialized on eating fruit. There were three kinds of small
camels. The most abundant mammal in this fossil deposit was the now extinct
rhinoceros Teleoceras.
The
nearest relatives of some of these mammals live today in Eurasia and South
America. Mammals such as these and many others were thriving in North America
until about twelve thousand years ago (not twelve million), when they died in
the Pleistocene Extinction. This extinction event probably resulted from the
interaction of climate change and overhunting by newly-arrived humans, neither
one of which by itself would have been sufficient. It was an interaction, with
the effects of climate change amplifying the effects of overhunting, and not a
simple additive effect.
What
was perhaps most interesting about these mammals is that they represented
earlier stages of evolution. The best example is probably the horses. Some of
them, such as Protohippus and Hypohippus, had three toes, while
others, like Pliohippus and Hipparion, had a hoof and two small
stubby toes. Some horses grazed (ate grass), while others browsed (ate broad
leaves). The specimen numbered "2" is one of the horses.
What
happened? One day a volcano over the Yellowstone Hot Spot erupted and sent ash
into the air. The finest ash traveled to what is now Nebraska, where it covered
the leaves and grass. The mammals breathed and ate the ash. Tubercles on their
bones showed that they survived for weeks (but not years) after eating the ash.
One of the symptoms was that they got very thirsty and converged on a water
hole. But drinking water did not save them, and they died, piled up on top of
one another at the water hole. That’s where we find the mass of bones today,
entombed in volcanic ash. It was not like one day in Pompeii; it took a few
weeks, but with the same effect.
Creationists
have a nearly impossible time explaining such a fossil deposit. They make no
attempt at all to explain how Noah’s Flood could have produced this deposit. Instead,
they claim that this deposit was formed after the flood in pretty much the way
scientists have discovered. They just claim that it all happened in the last
four thousand years rather than the twelve million years indicated by
radiometric dating of the ash. Processes such as the formation of the
sedimentary cap over the volcanic ash occur slowly today, but the creationists
simply invoke a more rapid pace, perhaps of miraculous origin. The Bible
indicates no such miracles, but creationists love to just make up miracles
whenever they want to. In one creationist article about Ashfall beds,
the authors do not address why the mammals are similar to but not the same as
modern mammals—for example, the three-toed horses. There were no modern horses of the genus Equus. And no modern camels (even the
South American ones) or dogs or cats or… Are we to suppose that God scooched
the primitive-looking mammals over to North America, and kept the modern ones
out, just to trick us into accepting evolutionary science?
Ashfall
Beds is an amazing place to see fossils which fit in perfectly with
evolutionary processes and the evolutionary timeline.
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