Pangaea, Plate Tectonics and Deep Time

One of the many puzzles I've had difficulty getting information on is the relationship between plate tectonics and paleontology.  We're always hearing stuff like "fossils were found in what is present day Arizona and SE China" but rarely do such reports make any mention of the size and shape and juxtaposition of the continents at the time the fossils were laid down.  With such a confusing mishmash of time periods and geographic distribution it's been very hard to me to visualize what parts of the world formerly touched what other parts -- and how this relates to fossil finds.

That's why I went looking for an iPad app on plate tectonics.  The iPad format is ideal for displaying moving continents with a time scale relating to dinosaurs.  I found one, called Ancient Earth, which has a nice globe map and a scale along the bottom giving the time periods.

It's pretty basic -- could have included some information on flora and fauna of each period, could have allowed zoom to a greater degree.  Could have rolled time forward, based on present day movement of the continents to show where they'll be in a couple hundred million years.  Could have shown the speculation -- because I think there's probably little consensus -- where the continents were before Pangaea. They could have gone all the way back to molten Earth, followed by Vaalbara, Ur, Kenorland, Columbia, Rodinia and Panotta -- so far as they're known.

But for what it is, it's pretty neat.  It's called an "introductory version" so maybe more features will be added over time.  Let's hope I don't have to wait until the continents drift.

Wait, there's a second app called "The Assembly of Pangea" (sounds like a church!) that covers 540 million years ago to 200 million years ago.  It folds right into "The Breakup of Pangea" (200 MYA to present) by the same authors.  Too bad they're not integrated together, and extended forward and backward.

I wrote to the author -- there are contact addresses and online references -- and got a prompt reply:

Quote :

Gentlemen,
I just downloaded and have been playing with "The Assembly of Pangea" and "The Breakup of Pangea" on my iPad and I must say, they're wonderful.

All my life I've been curious about the relationship between plate tectonics and paleontology. We're always hearing stuff like "fossils of such-and-such animal are found in present-day Arizona and SE China" but nobody ever takes the next step and describes how these land masses related at the time. How the geologic distribution of various dinosaurs relates to the shape of the continents at the time. Your apps do an admirable job of starting to address these questions, using the cool movie and touch sensitive capabilities of the iPad. I particularly like the ability to rotate the globe and zoom in.

These apps are described as "introductory versions" which leads me to get excited about all of the possible enhancements that could be added in the future, to wit:

• Ability to spin the globe... and keep it turning
  
• Ability to advance time automatically, either forward or backward, at different rates (can you morph between the different maps so it's a continuous flow?)
  
• Integration of "Before Pangea" and "After Pangea" into a single history
  
• The ability to roll forward in time from present day, based on current continental drift directions (see for instance http://io9.com/5744636/a-geological-history-of-supercontinents-on-planet-earth)
  
• Show the complete history of Earth from molten state to the earliest differentiation between oceans & land to present day (and beyond) -- even if this data is sketchy, it'd be fun to model
  
• Integration of dinosaur and fauna/flora data, showing major species alive at each period and their approximate distributions (this could be in different layers that you can turn on and off) -- this would be VERY HELPFUL in tracking fossil finds
  
• The outline of the present-day continents could be in a layer too, able to show or not show
  
• Magnetic pole reversals, show when they occurred and how this relates to seafloor spreading and magma deposition on dry land (in fact, the various wanderings of the magnetic north and south poles would be a fascinating graphic, if combined with tectonics)
  
• Major events such as: the Chixulub asteroid impact at the end of the Cretaceous; the various big & little ice ages and warming periods in between (maybe show average Earth temps and sea level); the Cambrian "explosion" of biologic diversity... It would be cool to see what the Earth looked like at each event
  
• Ability to click on the different geologic periods at the bottom of the screen and get a text description of the major characteristics of that period
  
• Show the ocean floor and the spreading of the plates, show the plate boundaries and the subduction zones at the edges. Show which parts of the Earth's crust have rolled inside the planet never to be seen again (and what might have been on them!)
  
• Show the supercontinents before Pangea: Vaalbara, Ur, Kenorland, Columbia, Rodinia, Panotta, Novopangaea, Amasia -- so far as they're known anyway...
  
• It'd be fun to take various crank theories like Expanding Earth and Velikovsky and explain what they are and why they're wrong

Just some wild-ass ideas. Your apps have me bubbling with the possibilties!

Sincerely,

Quote :

Thanks for your feedback - it’s very much appreciated!

Some comments below:

ory versions" which leads me to get excited about all of the possible enhancements that could be added in the future, to wit:
Ability to spin the globe... and keep it turning

That’s certainly possible, I’ll add it to my list

Ability to advance time automatically, either forward or backward, at different rates (can you morph between the different maps so it's a continuous flow?)

You can do this with bookmarks and by adjusting the animation speed. I believe there’s a tutorial on the site that will help. If not, let me know.

Integration of "Before Pangea" and "After Pangea" into a single history

We’re considering the best options for this. We have concerns about the ongoing legal issues with in-app purchases that are plaguing the software development world

The ability to roll forward in time from present day, based on current continental drift directions (see for instance http://io9.com/5744636/a-geological-history-of-supercontinents-on-planet-earth)

We have a new app that’s going to be submitted soon

Show the complete history of Earth from molten state to the earliest differentiation between oceans & land to present day (and beyond) -- even if this data is sketchy, it'd be fun to model

beyond about 1 billion years, it’s all guesswork. We could do something like that, but it takes up very precious memory space (and we use A LOT)
Integration of dinosaur and fauna/flora data, showing major species alive at each period and their approximate distributions (this could be in different layers that you can turn on and off) -- this would be VERY HELPFUL in tracking fossil finds

Plans are in the works. We will provide some data, but users will be allowed to plot their own data in future releases.
The outline of the present-day continents could be in a layer too, able to show or not show

We’re considering that.

Magnetic pole reversals, show when they occurred and how this relates to seafloor spreading and magma deposition on dry land (in fact, the various wanderings of the magnetic north and south poles would be a fascinating graphic, if combined with tectonics)

We are also planning material like this

Major events such as: the Chixulub asteroid impact at the end of the Cretaceous; the various big & little ice ages and warming periods in between (maybe show average Earth temps and sea level); the Cambrian "explosion" of biologic diversity... It would be cool to see what the Earth looked like at each event

Some of this would be included in the ability to plot data. Some of this other material would require a different way to show data that we currently haven’t included. I am planning a major back-end interface change (it might not appear that different, to a user, though) in the near future that could accommodate such info.

Ability to click on the different geologic periods at the bottom of the screen and get a text description of the major characteristics of that period

similar to the above

Show the ocean floor and the spreading of the plates, show the plate boundaries and the subduction zones at the edges. Show which parts of the Earth's crust have rolled inside the planet never to be seen again (and what might have been on them!)

This is a combination of the material above and articles/lesson plans. We’ve been considering the possibility of such material.

Show the supercontinents before Pangea: Vaalbara, Ur, Kenorland, Columbia, Rodinia, Panotta, Novopangaea, Amasia -- so far as they're known anyway…

Possible, but going too far back makes the maps somewhat pointless because of the underlying infrastructure. Although the app only allows you to plot your current location, you’d have to have a way to plot data for a fictional world to be consistent.

It'd be fun to take various crank theories like Expanding Earth and Velikovsky and explain what they are and why they're wrong

Those would be interesting, but might require another app to allow for changing the size of the Earth.

Just some wild-ass ideas. Your apps have me bubbling with the possibilties!

Not that wild after all, eh?

Tom Moore

Have they been able to make a connection between the continent of Pangea and the Miles Davis album of the same name? Just wondering.

Yes. Miles Davis changed the face of jazz with his tectonic movements, and many of his former bands became continents unto themselves. Others were subducted into other bands.

Some say his playing could be volcanic.

The band Magma was influenced by him.

One of the "factoids" picked up in my reading is that continental drift occurs at about the same rate as youir fingernails grow.

That gives a really visual dimension to the deep time involved, moving continents halfway across the globe.

Well golly.  I poked around some more in the App Store for iPad -- which is vast -- and found another app called Earth Viewer.  You know that list up above of enhancements I recommended for Ancient Earth?  Earth Viewer has them all.  

And more.

• Plate Tectonics going back 540 million years
  
• Rotatable zoomable globe
  
• time scale on left with geologic periods
  
• clickable links on each period with description
  
• length of day indicator in upper right corner
  
• display of MYA in upper left
  
• oxygen and CO2 indicators in upper left
  
• compass
  
• overlay for location of major present day cities
  
• overlay for major impact events (craters over 100 meters)
  
• overlay for major fossil finds
  
• overlay for mass extinctions
  
• overlay for biological events
  
• overlay for geological events
  
• big essays on the greenhouse effect, mass extinctions, the effects of changing oxygen levels, carbon cycle, photosynthesis, the origin of life, etc.
  
• charts of historical trends in oxygen, temperature, CO2, day length, luminosity and biodiversity
  
• pinchable (zoom in) on geologic time periods
  

All for $free.  The app is from, of all places, the Howard Hughes Medical Institute.

The book I am reading that has triggered all of this research is called "Remarkable Creatures" by Sean Carroll, the same guy who wrote the best book on evolution I've ever read, "Endless Forms Most Beautiful."  This book is the stories of a half dozen pioneers in the field of evolution.

One factoid reprinted here, which I've not seen before, is the length of time represented by the K-T boundary. Turns out the skies rained molten glassy bits for 60 years, and it took 10,000 years for marine life to recover enough to leave any fossils.

Of course something like 75% of all land dwellers never came back.

Wikipedia wrote:

The extinction was also highly selective. Some groups were relatively unaffected, others were devastated, and some were eliminated entirely. Many species of alligator, turtle, and salamander survived, for example. Mammals, birds, and lizards suffered high rates of extinction. Non-avian dinosaurs and pterosaurs were wiped out entirely.

Even though the boundary event was severe, there was significant variability in the rate of extinction between and within different clades. Species that depended on photosynthesis declined or became extinct as atmospheric particles blocked sunlight and reduced the solar energy reaching the Earth's surface. This plant extinction caused a major reshuffling of the dominant plant groups.[20] Photosynthesizing organisms, including phytoplankton and land plants, formed the foundation of the food chain in the late Cretaceous as they do today. Evidence suggests that herbivorous animals died out when the plants they depended on for food became scarce. Consequently, top predators such as Tyrannosaurus rex also perished.

Coccolithophorids and molluscs (including ammonites, rudists, freshwater snails and mussels), and those organisms whose food chain included these shell builders, became extinct or suffered heavy losses. For example, it is thought that ammonites were the principal food of mosasaurs, a group of giant marine reptiles that became extinct at the boundary.[21]

Omnivores, insectivores and carrion-eaters survived the extinction event, perhaps because of the increased availability of their food sources. At the end of the Cretaceous there seems to have been no purely herbivorous or carnivorous mammals. Mammals and birds that survived the extinction fed on insects, worms, and snails, which in turn fed on dead plant and animal matter. Scientists hypothesize that these organisms survived the collapse of plant-based food chains because they fed on detritus (non-living organic material).[22][23][24]

In stream communities few animal groups became extinct because stream communities rely less directly on food from living plants and more on detritus that washes in from land, buffering them from extinction.[25] Similar, but more complex patterns have been found in the oceans. Extinction was more severe among animals living in the water column than among animals living on or in the sea floor. Animals in the water column are almost entirely dependent on primary production from living phytoplankton while animals living on or in the ocean floor feed on detritus or can switch to detritus feeding.[22]

The largest air-breathing survivors of the event, crocodyliforms and champsosaurs, were semi-aquatic and had access to detritus. Modern crocodilians can live as scavengers and can survive for months without food, and their young are small, grow slowly, and feed largely on invertebrates and dead organisms or fragments of organisms for their first few years. These characteristics have been linked to crocodilian survival at the end of the Cretaceous.[23]

After the K–Pg extinction event, biodiversity required substantial time to recover, despite the existence of abundant vacant ecological niches.

NoCoPilot wrote:

One of the "factoids" picked up in my reading is that continental drift occurs at about the same rate as your fingernails grow.

Interesting. I live on the small slice of California that is on the Pacific Plate, rather than the North American Plate. Should I consider my location as the "hangnail" of North America?

But, seriously folks, plate tectonics is fascinating.