It was a good thing that Glenn remembered to pack extra gear; there would have been no way to get him to help before hyperthermia set in if we had to hike out. THE FINDS
For the next couple of hours, everything went according to plan. The green sand was plentiful and up to eight inches deep. It wasn’t long before the glitter of shark tooth enamel began to shine from our sieve bottoms. The most common of these teeth are from Sand Tiger sharks (Carcharias Taurus). These constitute 70% of the finds. Most specimens are dark grey to jet black in hue. Color is caused by metallic type minerals leaching into the teeth from ground water, with higher levels of iron causing the darker palette. Sand Tiger sharks’ teeth reach unusually large sizes along the Shark River. The average Potomac River, middle Miocene Sand Tiger tooth gets to lengths of perhaps an inch. In Neptune it is not unusual for these teeth to reach two plus inches in length. Perhaps this epoch was when these shark types achieved their zenith (just as the mega sharks were moving from smaller sizes at this time). As far as condition is concerned, our local green sand has done an excellent job at preservation for the last 26 million years. If there’s a problem with condition, it mostly affects specimens found in the roots; there is a mineralogic reason for this, although its origin is unknown to me. Eroded roots come in clusters, so when one of these areas is encountered you must either dig through or avoid it because these specimens are uncollectable. Happily, this is the exception and not the rule. Most fossils that come from the Shark River are beautiful. Other small to medium species found in this basin are Mackerel sharks (Lamna nasus), Thresher sharks (Alopias superciliosus), Tiger sharks (Galeocerdo cuvier) and Lemon sharks (Negaprion brevirostris). Additional small species that are far less common include Snaggletooth sharks, (Hemipristis elongates) and Cow sharks (Hexanchus griseus). When these appear it is cause for celebration indeed. Also rare are the mammal teeth and bones that occasionally crop up. On the other side of the size range are the mega sharks. They are here, too. The three species of Miocene makos are all represented at Shark River. They include the narrow type (Isurus oxyrhinchus), which is the most common, and the broad type (Isurus hastalis). Also found, but very infrequently, is the “false” mako or Parotodus benedeni. The Ariculatus type shark is a direct ancestor of the big boys and is basically a long, narrow Megalodon with
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2011 American Digger Magazine Sampler
cusps. Additionally, the Cubutensis (which is a Megalodon with vestigial cusps) is commonly found. It is very difficult to distinguish these “Chubies” from their large cousins. Then, of course, there are real ‘Meggies’ (Carcharocles megalodon). All these larger teeth run anywhere from 1.5 to 3.5 inches in length although very large samples are hard to find here (this may be because the bigger sharks had not yet evolved to their largest sizes). Condition is similar to smaller types with most examples in good shape and fossilized in typical dark colors. Sometimes the teeth are found mineralized a light blue or brown. Occasionally, an extinct Great White shark (Carcharodon carcharias) tooth will almost magically appear on someone’s screen. These teeth, like Megalodons, are serrated without cusps but are usually smaller and thinner, and shaped much like a Valentine’s heart.
FACING THE DANGER
After several buckets of green sand and a few good finds between us, things started to tighten up. Now, in order to pursue our coveted sand, we had to work underneath an ever-lengthening overhang. The Kirkwood clay looming high above was compromised and the more we advanced horizontally, the dicier our situation became. Soon paranoia set in for the “sand man” as he wondered if his lookout (who he usually could not see) was actually paying attention. Trust plays a large role at any Shark River dig. Fingers and toes were getting chilled in the 30 degree weather. This low temperature also made sieving in the river difficult. Although we had gloves it was still rough going. The only benefit to the cold was that it gave us the proper incentive to keep moving. We scooped up the last of the sand before having to clear up the runway, then headed down to the water. It can be difficult to find a convenient place at the riverside for sieving. Between fallen logs and water that was either too shallow, too deep, or too rough, this part of the operation was indeed a challenge. On one particular screening, Glenn V. was finding it hard to sit with both his bucket and himself in a workable posture. The first real sign of trouble, though, was him shouting a few well chosen words, followed by a sharp grunt and a loud ker-splash! Glenn, my regular bottle digging partner of 17 years, had taken a step too far. Still a bit of a Shark River novice, he’d managed to slip off a moss laden log while trying January-February 2011 American Digger Magazine
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