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Fossil Friday: Stuck on the Rocky Shores

So were you able to identify our fossil this week?

arfossil2

This if Figure 5 from the only real publication on Arkansas fossil barnacles. I posted an articles on barnacles once before, but time grew short and I neglected to mention specifically the Arkansas ones, an egregious error on a website devoted to Arkansas fossils. So I am now correcting that with this post.

As I mentioned in the last post, barnacles are crustaceans and have been around since the Cambrian Period. They can be found throughout much of the Northwest half of the state, basically anywhere not carved out by the Mississippi river. However, other than some miscellaneous purported barnacles borings on clam shells and the like in the Ozarks and Ouachitas, there is not really any published literature on the subject.

For published information, if you really want to know about barnacles, you need to talk to Victor Zullo at the University of North Carolina, Ernest E. Russell of Mississippi State University, or Frederic Mellon. Sadly, you will find that difficult as they are all now deceased, leaving the field of Arkansas cirriped studies completely wide open to the prospective student.

In 1987, the trio published a paper detailing two new species of barnacles found in a quarry in Hot Springs County, Arkansas.┬áThe first barnacle was identified as being in the suborder Brachylepadomorpha and was named Brachylepas americana. They listed this as important as being “quite possibly the richest single accumulation of brachylepadomorph material ever encountered.” They also suggest that because of its similarity to other species in Europe that there was “unrestricted communication between these widely separated geographic regions during late Campanian time.”

zulloarbarnacle

Another thing I found interesting about these barnacles is where they were found. Thousands of these fossils were found in a gravel within the Brownstone Formation, dated to the Late Cretaceous, and deposited in a littoral environment. This is a high energy, near shore environment. The living representatives of this group, though, are only found near hydrothermal vents.

The other barnacle they discuss and the one which is shown in Figure 5 above is Virgiscalpellium gabbi and a subspecies V. gabbi apertus. These are only known from nine specimens however, unlike the thousands of B. americana. This seems to be a much less common species throughout its range than other barnacles.

Along with the barnacles, the trio mention the Brownstone Formation is rich in fossils of other types, including, the oyster Exogyra ponderosa, several gastropods, a sponge, brachiopod, serpelid worm, bryozoans, nannoplankton, and the odd vertebrate, such as mosasaurs, sharks, and skates.

Zullo, Victor A., Russell, Ernest E., and Mellen, Frederic F. 1987. Brachylepas Woodward and Virgiscalpellium Withers (Cirripedia) from the Upper Cretaceous of Arkansas. Journal of Paleontology. Vol. 61(1):101-111.