Friday Headlines, November 28, 2014
THE LATEST IN THE GEOSCIENCES
Earthquakes tell us about how faults work
What are turtles related to?
Finding fossils is a lot about luck!
(Apologies if the above link is broken, but you can read the original paper here.)
The massive earthquake that struck Chile in 2010 offered scientists an opportunity to examine the interior of the Earth in areas where earthquakes are common and often devastating.
Earthquakes set up vibrations in the Earth that can be detected by seismometers worldwide. The strength, orientation, and speed of the vibrations are due to the composition and structure of the rocks that they pass through. With some amazing computing power, it is possible to reconstruct the interior of the Earth.
In the case of the 2010 Maule earthquake, the initial 8.8 magnitude quake, and the following numerous aftershocks enables scientists at the University of Liverpool to better understand how the Pacific Plate passes below the South American plate in a structure they call a ‘megathrust.’
What they found, in a nutshell, what that part of the deeper parts of the Earth, relic parts of the mantle, remain attached to the South American plate that’s riding over the Pacific plate. This relict mantle affects how and where the Pacific Plate slides under South America. Knowing where such blocks exist in other similar areas may make it possible to better assess seismic hazards.
It is an interesting topic in biology and paleontology. We colloquially refer to turtles, lizards, snakes, crocodiles, and sometimes dinosaurs as ‘reptiles,’ suggesting some sort of relationship between these organisms. As a practicing paleontologist, I know that one of the great debates is how exactly turtles relate to other animals called reptiles.
Turtles are actually unique in structure and are arguably no more related to snakes, lizards, or crocs than we are.
So, where do they fit?
James Partham, at Cal State Fullerton, has used genetic evidence from modern turtles, crocs, lizards, snakes, and birds (as dinosaurs) to come up with an answer.
It seems turtles are more closely to crocs and dinosaurs (birds) than they are to lizards and snakes. This is exciting news, and in contradiction to what I learned when I was a student.
The fossils of early mammals are notoriously difficult to find. I’ve had a lot of experience with this for Paleocene mammals. It gets worse with older mammals, like Cretaceous or Jurassic.
So when a complete skull of a fossil member of the enigmatic mammal group the Gonwanatheria was discovered in a CT scan of a block of rock from Madagascar, it was a big deal.
Gondwanatheres are a group of mammals that are unlike modern mammals and are probably more closely related to other extinct mammal groups like the multituberculates. Understanding the new fossil, called Vintana, will help us better understand these relationships and will ultimately help us better understand what it is about mammals that makes them most mammalian.