Ode to the Corsicana Formation

[Uncle Siphuncle]

The Corsicana Formation is a Maastrichtian sequence about 68 MYA that outcrops in a 350 mile long band paralleling the Balcones Fault from north to south Texas.  It has contemporary exposures from the East Coast to Mexico, and I've been fortunate to collect some of these exposures in Mississippi to complement my Texas experience.  Once upon a time I had 8 or 10 producing Corsicana sites in Texas; now I have nothing worth a hoot, so I'm feeling a bit nostalgic. 

 

But I did seize the opportunity during the golden years to amass quite a stockpile of material to prep...only to realize that I had more than I needed for my personal collection.  I tend to have a retention bias for the flashiest fossils; however, not all fossils have to be beautiful ot have scientific significance.  A fossil need not be without blemish to retain diagnostic features and other data.

 

Coupled with the realization that I only have time to prep the stuff I plan to retain, I have been making some pretty significant donations over the last year or so.  It is also worth noting that donating unprepared material may retain micro details and matrix associations that I've potentially been (unwittingly) blowing through with my scribe. 

 

The AMNH was eager to receive a bunch of ammonite and nautiloid specimens.  Wright State accepted about 100 crabs (MMNS serving as repository), and I have about 50 more ready to hand off.  I've donated huge numbers of various inverts to USF, probably over 1000 specimens, with another big box ready to go.  There could be some undescribed species in the latter.  I've made some other donations here and there over the years including Emory, Smithsonian, researchers in Europe, etc.  

 

Let's have a peek at some pics of things I hung onto in no particular order, just as they are stored on my phone.

[Uncle Siphuncle]

Eutrephoceras, Pachydiscus, Sphenodiscus, Dakoticancer.  My wife found the 2 carapaces shown stacked.

[Uncle Siphuncle]

More Dakoticancers.  At one point I realized that if I took more care to excavate matrix chunks surrounding carapaces in the ground, I could reassemble more blown appendages.  Then some of my experience scribing hard concretions from other states taught me to slow down on prep.  Another reason I choose not to prep them all, just the best.  
 

The gastropod is Striaticostatum.

[Uncle Siphuncle]

A few echinoids.  3 examples of a new Codiopsis, plus Proraster, Hemiaster and Diplodetus.

[Uncle Siphuncle]

More from the Dakoticancer and Pachydiscus depts, plus an indet shark vert and Cretalamna tooth.

[Uncle Siphuncle]

More Dakoticancer, Pachydiscus, Sphenodiscus, and Gaudryceras.

[Uncle Siphuncle]

Well, that's everything I had on my phone.  Perhaps some rainy day, I'll do a more comprehensive photo dump from my computer.  

 

For those interested in blazing their own trail, I'd suggest starting in some of the more boreal regions where outcrop aerial extents are broad enough to warrant mapping of the formation divided.  In areas mapped undivided, formations can be difficult to distinguish as there are vast expanses of apparently barren, soft strata that weather and vegetate readily.  If you encounter the oysters Exogyra costata and Pycnodonte mutabilis, you are getting warm.

[Tidgy's Dad]

Beautiful specimens. 

My favourite is perhaps that wonderful nautiloid. 

Thank you for sharing these impressive finds.  

[caterpillar]

Very nice crabs. If you want to trade one, I'm your man

[Ludwigia]

Too bad we don't have a *drool* smiley here....

[sharkdoctor]

Great finds!

[Jeffrey P]

What a collection of crabs, echinoids, and ammonites, Dan! If this was all you had, your fossil collecting career would still impress. Thanks for sharing. Too bad this formation is mostly played out now. 

[Pemphix]

Very nice !