Friday Headlines, February 14, 2014
THE LATEST IN THE GEOSCIENCES
The Corvette-eating sinkhole
A new fossil locality that may be one of the world’s most important
And all this time we thought sponges were the most primitive animals
In Bowling Green, Kentucky in the early morning hours of last Wednesday, a sinkhole opened up within the National Corvette Museum. Eight cars fell in. (I hope they were insured.)
Sinkholes are geological phenomena. They are common in regions of karst.
Karst occurs where there are thick layers of limestone rock at or below the Earth’s surface. Water moving through the rock slowly dissolves the limestone, resulting in elaborate cave systems. Occasionally the roof of these cave systems collapses, resulting in a sinkhole.
If this process continues, a dramatic landscape forms, like this one in China:
One of the most important fossil localities in the world is the famous Burgess Shale. It’s important for two reasons.
1) It dates back to when the modern groups of organisms were first becoming distinct, such as arthropods, segmented worms, vertebrates, etc.
2) The fossils are the preserved remains of the soft parts of the animals. Very rarely are soft tissues fossilized, because they tend to rot so quickly.
The Burgess Shale provides us a window into the early evolution of multicellular organisms that otherwise we’d only be guessing at.
Now, a new fossil locality of the same age (and potentially of the same rock layers) has been discovered in British Columbia about 42 kilometers from the main Burgess Shale locality. This new locality is called the Marble Canyon fossil bed.
In only two weeks of field work, paleontologists from the Royal Ontario Museum were able to collect specimens of over 50 species of animal, including several not previously known.
This, in the world of paleontology, is a really big deal!
So this is old news – from last December – but it was new to me.
You see, all this time I’ve thought of sponges as being the most primitive of animals, then jellyfish and their kin being the next most complex.
But as it happens, a group of jellyfish-like organisms, called ctenophores or comb jellies, are probably the most primitive. It is from the ctenophores that both sponges and jellyfish evolved.
How can we know this?
Scientists at National Human Genome Research Institute used analysis of the DNA of comb jellies, true jellyfish, sponges, and several other organisms to determine their relationships.
After doing the analysis, they determined that both sponges and jellyfish have genetic codes derived from that of the comb jellies, making the comb jellies probably the most primitive animals on the planet.