The Fossils of Ferry Farm

Archaeologists have one pretty big hang up, and that is when people ask us if we dig for dinosaurs.  We’re so obsessed with making sure that people know we don’t dig dinosaurs that you can find shirts, coffee mugs, keychains, and other merchandise that all say “Archaeologists Don’t Dig Dinosaurs.” But we get it: dinosaurs and other prehistoric animals are super cool- just ask my 4-and-a-half-year-old son or my nine-year-old nephew.  Still, we archaeologists go to great lengths to emphasize that archaeology and paleontology are pretty different.  Archaeologists study historic and pre-historic human cultures by examining the artifacts they left behind.  Basically, we obsess over dead people’s broken stuff. Paleontologists, however, study ancient plants and animals using the fossil record.  Now, that being said, archaeologists do frequently happen to uncover fossils while excavating for artifacts. We’ve made our share of fossil finds while digging at George Washington’s Ferry Farm and we’re going to share some of those finds with you today.

Archaeologists Don’t Dig Dinosaurs T-Shirt. Credit: cafepress

First, it should be noted that what we call Virginia today looked a lot different when the creatures our fossil finds represent were alive.  During the Cretaceous and early Paleogene periods, which lasted from 145 to around 56 million years ago, much of this part of Virginia was at times completely underwater as part of the newly formed Atlantic Ocean, while inland areas were very swampy with high temperatures and humidity (Yes, even more so than today’s notorious Virginia climate. Back then, it got up to around 100 degrees most days).  Hence, most of the fossils we recover are from marine environments or swamps.

Let’s start with one of my favorites: the turritella, a species of spiral-shaped gastropods or mollusks that still exist today. The turritella we find at Ferry Farm, however, are around 50 million years old.  We don’t usually find the shell, but rather the ‘cast’ which forms when sediment fills the inside of a dead mollusk’s shell and then turns to stone, leaving an impression of the inside of the animal.  The resulting fossil cast resembles a corkscrew.  They’re pretty common in this area.  In this picture, you can see a turritella that still has its shell and fragments of the interior case.  Usually they can be found in clusters, representing mass die-off events in which a lot of the turritella met their demise all at once.

Conglomerate of turritella fossils.

Bits of turritella excavated at Ferry Farm.

Turritella casts from the author’s collection.

Other marine fossils we’ve found include pelecypods.  These bivalves resemble modern day scallops and are estimated to be around 60 million years old.  We have two fragments found at Ferry Farm next to a whole example unearthed by my husband Joe Blondino, who is also an archaeologist, while on another excavation.  We believe these to be Chesapecten jeffersonius pelecypods, which is the Virginia state fossil. Tuck that back in your brain for future trivia nights!

Fragments of Chesapecten jeffersonius found at Ferry Farm (foreground) next to whole examples from the author’s collection.
Ray mouth plate fragment excavated at Ferry Farm.

This little guy above is another one of my favorites.  It may not look like much, but this is a ray mouth plate fragment.  Rays, which also still exist today, used these specialized ‘teeth’ plates to crush the shells of their favorite prey.  It may have shared the waters with some of this fossilized coral, of which we’ve excavated only a few tiny pieces that are as yet unidentified with regard to species.

We also uncover quite a bit of petrified wood.  These trees would have lived during the periods of the Cretaceous when Virginia was a hot and humid swamp.  After falling into the waters, they were covered and, over millions of years, petrified as the trees’ organic tissues were slowly replaced by minerals.  This example is our largest specimen.

Petrified wood excavated at Ferry Farm.

Crocodiles also swam where the George Washington’s boyhood home replica now stands when the land was covered in a warm, shallow sea.  We think the tooth pictured below belongs to one of those crocs, although likely a juvenile one.  Unlike a shark tooth, it is conical, with a depression at the top.

Crocodile tooth, like from a juvenile, found at Ferry Farm.

We’ll end with everyone’s favorite: shark teeth!  They’re the most common fossil found at Ferry Farm due in no small part to the fact that sharks continuously shed their teeth throughout their lifetime. Some sharks go through up to 50,000 teeth in their lifetimes!  Most of our shark teeth belong to a species of sand tiger shark, which still exists today (they’re also called the gray nurse shark).  Starting at the beginning of the Cenozoic Era, approximately 66 million years ago, sand tiger sharks swam near the coast in the warm shallow sea waters that covered this part of Virginia.  Their teeth are not large, but quite numerous. They have a distinctive shape with a long very ‘pointy’ crown, small sharp bumps called cusplets on either side, and relatively long root lobes.  The only shark’s tooth we have that doesn’t resemble the sand tiger at all is one we think may be from a species of white shark (related to the great white).

Sand tiger shark teeth excavated at Ferry Farm.
Possible giant white shark’s tooth excavated at Ferry Farm.

Even though archaeologists do not dig for dinosaurs, we certainly do find fossils in our excavations. Since we are obsessively focused on the human cultures of the past, these fossils are not our primary interest. We do not dig for dinosaurs but maybe we actually do sort of DIG them and all fossils from ancient times in a “Wow, fossils are really cool!” sort of way.

Mara Kaktins, Archaeologist
Archaeology Lab Supervisor