The Website for Houston Mollusks
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Texas is replete with a rich array of fossilized animals, most of which are mollusks.  Since all of Texas was once underwater, remnants of marine mollusks can be found all over the state.  Limestone deposits, river banks, quarries, and many other sites yield millions of fossilized shells to collectors and scientists year-round.   

                              Exogyra ponderosa collected in Rosebud, Texas.  Gift of Mr. Bill Moore.


                                         Exogyra species                                                                               Fossilized Clam
Exogyrae are large extinct bivalves prevalent in Texas.           Clam fossils are most often found in limestone.

                              Ammonite (split & polished).  Gift of Ahren and Alicia Simmons. 

 Ammonites were an ancient cephalopod similar to the nautilus.  Their round, ruffled, fossilized  shells are found quite commonly in Texas, particularly in river basins.  The specimen above has been cut open and polished to reveal the crystalized air chambers.

                                                Trio:  Ammonite (back), gastropod (left), clam trace fossil (right). 
                                                      Collected from a dried river bed in San Antonio, Texas.


Ancient Aggies:  There is a large deposit of marine fossils in a river bed near College Station, Texas.  Collectors carefully dig at the dirt cliffs, unearthing delicate remnants of the past.  Some findings include cone-shells, whelks, and squid beaks.  Many of the species found here are still extant today.
( No need to be jealous if you're a Longhorn:  UT Austin has its own Mastodon.) 

Not from Texas, but worth a look...

This fossil was collected from a quarry dump near St. Petersburg, Florida.  It measures approximately one inch tall, and is several thousand years old.  It is heavily encrusted with coral.  
Because the aperture is still open, it is evident that the snail was alive when the coral was forming on its shell.  This is an ancient example of biological camouflage, where one animal uses another to disguise itself and blend in with its environment.
It is unclear if the coral benefited from this cooperation. 


                                       Trace Fossil of a Bivalve, collected in South Shields, England

This trace fossil, made from a sedimentary rock of unknown composition, was originally from one of the major rivers in London.  Ships dredged up millions of tons of rock from the river to use as ballast for the trip to South Shields, where there was a large coal industry.  When the ships reached the loading dock, they dumped their rocky ballast at a designated site and replaced it with coal to be taken back to London.  
When coal production stopped, the massive amount of rock that had accumulated over the years was eventually cleared away to make room for the expansion of South Shields.  As it turns out, they found a 1st Century Roman fort buried underneath, and archeological excavations went underway in 1875. 
In 2009, an expedition was working on the far corner of the site, having dug through a 6-foot deep layer of ballast stones.  This trace fossil was discovered lying on the side of the pit.  The imprint is most likely of a Brachiopod, but bears resemblance to a small species of clam.
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