Giant Oysters Cross Antarctica!

Friday, the Kent State University Department of Geology hosted a talk by Dr. Silvio Casadio of the Univ. Nacional de La Pampa, Argentina.  Dr. Casadio’s talk,  “West Antarctic Rift system: a possible New Zealand- Patagonia Oligocene paleobiogeographic link”, was, in my opinion, one of the most interesting presentations given this semester.  Normally I lean towards the engineering talks such as Dr. Marinos’ from last week, due to my focus and background in engineering.  This week, however, Dr. Casadio won me over.  It could have been due to his affinity for “he-ant” oysters  (that’s “giant” with a heavy South American accent) or even the occasional comic strip thrown into the power point presentation, but the real attraction was the enthusiasm he exhibited during his presentation.  You could tell that even though Dr. Casadio may have been studying fossils for a long time, the subject continues to fascinate him.  This excitement which fed the audience is what made Dr. Casadio’s presentation my favorite so far.  However, the subject of his talk was exciting all by itself.

Discovery of fossilized giant oyster reefs in Patagonia is nothing new.  These 30 million year old giant oysters, along with other fossilized mollusks, brachiopods, and marine invertebrates have been documented in this region since the days of Charles Darwin.  In fact, Dr. Casadio used much of Darwin’s own comments and observations from his voyage on the H.M.S. Beagle in the 1830’s, including an image of a detailed geologic map of Patagonia that Darwin himself sketched and colored.  The focus of Dr. Casadio’s research was to understand just how these giant oysters, and several of the other fossils in the region, came to be in Tierra del Fuego when the exact same species are also found over 9,000 kilometers away, across Antarctica, in New Zealand.  To say the identical specimens evolved separately in two locations is virtually unthinkable, especially when you consider that this isn’t only one species, but many.  There must, then, be some way that these species traveled from point A to point B.  The real ground-breaking discovery was when Dr. Casadio decided to follow in Darwin’s footsteps and visit Port Desire, a rather misleading name, if I do say so myself.  Due to its isolation and desolate nature, not many people have gone fossil hunting at this location.  However, Darwin had discovered a fossil there which Dr. Casadio felt deserved further study.  Once there, several more fossils were found including the one Casadio set out to find.  As it turns out, this fossil (forgive me for not remembering exactly what it was…a type of brachiopod, I believe) was previously thought to exist exclusively in New Zealand.  Tests are currently being run to confirm that this fossil is, in fact, the same species as the New Zealand fossils.  If proven so, it will provide even more evidence that marine life from New Zealand was able to travel across the ocean to South America.  But how is this possible?

Dr. Casadio has an answer to that question.  During the Oligocene, the West Antarctic Rift system (all along the Trans-Antarctic Mountain Ridge) was tectonically very active.  It is hypothesized that during this time, a shallow sea existed along this rift system.  This would indicate that a direct route from New Zealand to Patagonia, across Antarctica, was available to the marine life at that time.  If tests show that the fossils discovered in Patagonia are the same species found in New Zealand, this theory may be proven and much about our Earth’s past in the Antarctic region may be revealed.

I would like to point out again, that this is a very shortened version of Dr. Casadio’s talk.  Additional research, tests, and hypothesizing was included and further supported this theory.  For more information on the subject, you may contact Dr. Silvio Casadio at his website.  From my impression of him, I am sure he would be more than happy to discuss the subject.

Thank you, Dr. Casadio, for visiting Kent State University!


Friday, February 19, The Kent State University Department of Geology will be hosting Brad Shotwell.  Mr. Shotwell will be giving a presentation on applications of a photographic device for taking stereo photos of surfaces in the field.

February 19, 2010

Room 234 McGilvrey Hall


(Click here for a schedule of upcoming/past colloquium speakers)


3 responses to “Giant Oysters Cross Antarctica!

  1. The oysters migrated across the ocean floor from New Zealand to Patagonia. In a freak act of nature, they were subjected to all of the necessary requirements needed for fossilization, at the same time, in an event that spanned at least 9,000 kilometers of ocean. Interesting. I am sure there would be fossilized migrating oysters from point A to point B that should be very easy to find as well. LOL

    • JW,

      While there are undoubtedly fossilized oysters between their known locations in New Zealand and Patagonia, that path cuts straight across Antarctica and is now covered in a thick sheet of ice. Unfortunately, this means the only way of locating such fossils is to drill through the ice overlying the ancient shallow sea through the West Antarctic Rift System. The odds of the drill core passing through and capturing one of these oyster fossils (or any fossil, for that matter) are not great. However, there is research being conducted to try and prove this hypothesis. I have placed a link in the article to contact Dr. Casadio, who is doing this research, if you would like to request more information straight from the source. I’m sure there has been much progress in the year and a half since I wrote this article.


  2. Sounds like the talk was very informative and fascinating. It’s amazing how much we still need to learn about the earth and it’s development. Thank you for sharing.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.