Monday, January 16, 2012

New Jersey Fossil Hunting

While visiting relatives in New York over the summer, my family and I took a day trip to Monmouth County, New Jersey to search for fossils.  We prepared ahead of time by making two sift trays and bringing hand trowels.  Strolling through the streams was the perfect activity for such a hot summer day.  It was a little hard on the back, but the rewards were worth it.  The majority of fossils collected are from the Cretaceous Mount Laurel formation and are more than 75 million years old.

This is the top portion of Exogyra, an oyster that formed vast beds across the shallow sea floors.  This is a very common fossil found in this area.  Below is the bottom portion of the shell.  Exogyra are also known as "devil's toenails."

These next fossils are guards of Belemnitella americana, an ancient squid-like creature from the Belemnoid family that went extinct during the mass extinction at the end of the Cretaceous.  The animal reached lengths of up to 18 inches.  The guards, which were found in the end portion of the animal, are sometimes callled "devil's fingers" or "thunderbolts." 

We found several belemnite guards massed together in the soft muddy sides on either side of the stream. It is thought that many belemnites died en masse from mud slides or just after breeding.

This next item is a trace fossil, a portion of fossilized burrow belonging to a type of ghost shrimp (Protocallinassa mortoni). Holding this fossil sideways, one can see the hole excavated by the shrimp millions of years ago.

By far the most excitement was derived from the discovery of sharks' teeth.  This display shows the 
variety of teeth found mainly on gravel bars.  Most are easy to spot because of their polished look.  Identifying whose mouth they came from was a bit tricky.  The first tooth on the left is from a goblin shark.  Tooth #2 is probably from a porbeagle shark.  Teeth #3 and #9 (last) are perhaps from a hybodont shark (best guess from looking at NJ fossil photos). Tooth #4 from left appears to be from a crow shark.  Teeth #5, #6 and perhaps #7 possibly came from a sand tiger shark.  The prize tooth find was #8 (2nd from last), which measures 3/4" across and 1" from root to tip.  The jury is still out on that one.  We think it's from a sand tiger shark.  If you know, please comment below. 

No trip to the woods would be complete without scat.  Our hunt uncovered a nice shark coprolite.

We also discovered a bunch of "small stuff" including a snail shell, a fish vertebrae, smaller burrows and bits of coral and shells.

Not really positive what this is. Coral? Burrows?  Concretion?

Lastly, the mystery bone fragment.  If anyone knows what type of bone this is, please let me know.  Here are some different views:

A big thank you to my son for assisting me with this blog entry.

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