Friday Headlines, June 13, 2014
THE LATEST IN THE GEOSCIENCES
It’s Friday the 13th! (Whatever.)
The origin of jaws in vertebrates
Earthquake in Salt Lake City
Embryonic studies, along with evidence from the fossil record, show that vertebrate jaws are derived from what were originally gill supports. These supports were modified to open an close and then later supported teeth.
All vertebrates begin as embryos with several paired arches in the throat region, typically seven. These arches are called pharyngeal arches, branchial arches, and sometimes gill arches. Whatever the term, it’s the same thing.
In vertebrates with jaws, the forward-most pair develops into the jaw. The remaining arches either support gills (in fish), or become part of the throat and neck structure.
One question that has been difficult to answer, however, is when did these gill supports first evolve.
A new fossil dating back about 505 million years clearly shows the arches at the front of the animal. This fish, named Metaspriggina, is the oldest fossil to clearly show these arches, meaning that jaws could have evolved any time after that.
A 3.3 magnitude earthquake doesn’t sound like much, and it really isn’t. What might surprize many of you is that there would be an earthquake in Salt Lake City, there in the middle of Utah.
When people think of earthquakes, they think of California, or Chile, or Japan. Not Utah. What these people are often shocked to learn is that Utah, the Wasatch Front specifically, is primed and ready for a ‘big one.’
By big, I mean 30 foot fault scarps, liquefaction and sinking of homes, and massive landslides. I mean, Salt Lake City could be leveled.
I’m so glad I don’t live there any more.
The entire Basin and Range region of North America is marked by huge faults. These faults lie where the floors of valleys meet the towering mountains.
And unlike the San Andreas Fault in California, the Wasatch Fault that runs through Salt Lake City only moves every 2000 years or so.
And by the way, it’s been more than 2000 years.
There’s a lot of strain built up along that fault, and it will be released catastrophically. Little earthquakes like this 3.3 temblor do happen from time to time, reminding us that the Wasatch Front is a tectonically active area.
This little earthquake will have done little to reduce the strain in the rocks. It just reminds me that the ‘big one’ is coming. We don’t know when, so get ready.