By Bob And Ashby Gale
FIVE UNIQUE SHARK TEETH
Many adventurous beachgoers spend their time combing sandy shorelines in search of seashells. The ocean holds an incredible diversity of many-colored shells in various shapes and sizes, which were once the protective homes and skeletons of equally unusual creatures. There are other riches among the sands to be discovered by those who love to scour southeastern beaches extending from Texas, to the Florida peninsula, and up through southern New Jersey. These treasures range from ten thousand to millions of years in age and reflect life on earth long before, and soon after, man appeared. They are the fossil remains of mammals, reptiles, birds, and fish species from an earlier era of history.
Some of these were giant versions of animals that are common today. Glyptodonts and giant armadillos were up to nine feet in length and were contemporaries of giant ground sloths, land tortoises, tapirs, and alligators. Other fossilized remains include intricately patterned teeth and mouth parts of the ancestors of manta rays, pufferfish, and drum fish. Finely-toothed sting ray spines and beautifully colored shark teeth can be found, as well as whale vertebrae and inner ear bones, and huge pieces of leg joints, toe bones, tusks, and molars of mammoths and mastodons.
The good news is that these fossils are available on beaches and inlets that are open to the public! You won’t be disturbing any paleontological sites by collecting them, because they have naturally eroded out of ancient soils along coastal plain rivers or churned up from long buried ocean sediments. Then, the fossils are randomly washed up onto beaches by tidal currents and left behind as the tides retreat. Thanks to the gravitational pull of the moon, this happens twice in every 24-hour cycle. And even more fossils appear from the churning wave action brought on by regular offshore storms or occasional hurricanes.
Of all the fossils, shark teeth are undoubtedly the most popular sought out by beachgoers. Many people do not realize that the teeth they find are actually fossils, not teeth recently lost by today’s shark population. Sharks have multiple rows or “files” of teeth. They regularly lose teeth and replace them from these files. Only teeth that rapidly become buried in sediments have a chance to become fossilized, though. Those that don’t, quickly decompose. So, there is only a small chance that a tooth will actually become fossilized. Fortunately, the many millions of years that sharks have reigned in the seas guarantees that there is an abundant supply of these fossils! The following are descriptions of fossil teeth from five unique shark species, both living and extinct.
GREAT WHITE SHARK
The Great White Shark (Carcharodon carcharias), which lives today, has lived in our oceans for the past 5 million years, so many fossilized great white teeth can be currently found. This shark rose to prominence with the best-selling book and movie “Jaws.” This new-found fame also tragically led to the great white’s demise as it became a popular food cuisine that led to overfishing and a crash in the shark’s worldwide population. Protective measures have helped to bring its numbers up, but the shark is still listed internationally as “Vulnerable”—one step away from endangered status. Great white shark teeth are broadly triangular and flat in shape, as well as being large, measuring up to 3" long and 1.5" to 2" wide. Both edges of their enamel crowns have coarse serrations, which allow them to saw easily into their prey of bony fish and sea mammals.
SAND TIGER SHARK
Another commonly found tooth is that of the modern Sand Tiger Shark (Carcharias taurus). These teeth are much narrower and more pointed than the great white shark and have sharply U-shaped roots. When viewed from the side, the teeth show a slight but elegant undulating curve from the root to the crown tip. The overall length of sand tiger teeth is slightly over one inch. The teeth have another feature that makes them readily recognizable. They have what looks like a tiny sharp tooth or “cusplet” protruding from the root on either side of the pointed crown. These teeth are efficiently designed to pierce and grip small to medium sized prey and act as a “cage” preventing their escape! Sand tiger sharks appeared during the late Cretaceous, around 72 million years ago, replacing their predecessor, the Extinct Sand Tiger shark (Carcharias cuspidatus), which appeared more than 45 million years earlier. This species had similar teeth, but contained double, rather than single cusplets. Sand tiger shark teeth have changed very little over the last 70 million years, the only significant differences being in the shapes and sizes of each species’ cusplets.
LONGTOOTH TIGER SHARK
The extinct Longtooth Tiger Shark (Physogaleus contortus) is fascinating in its overall shape, which includes a long twisting crown and a centrally raised root. On some shark species, the upper and lower teeth look quite different, but longtooth tiger sharks are identical in both sets. The twisted, or contorted, crown can be very pronounced on many teeth and this feature gives rise to the shark’s species name. The raised root appears as a noticeable bulge above the crown. Longtooth tiger sharks lived during the Oligocene and Miocene epochs 33 to 5.3 million years ago.
Another extinct shark, but one with easily recognizable teeth, has the wonderfully descriptive name Snaggletooth Shark (Hemipristis serra). This shark has very different upper and lower teeth with the former being slightly broad and more or less triangular, but sharply curved. The lower teeth are long and pointed and at first glance resemble sand tiger shark teeth, especially when viewed from the side. The striking feature that makes this fossil tooth stand out appears in the crowns of both sets of teeth. The enamel edges of the crowns are lined with coarse serrations that cover all but the tips, one edge being coarser than the other. The snaggletooth shark was a contemporary of the longtooth tiger shark, but outlived that species, surviving through the Oligocene and Miocene and well into the Pleistocene before becoming extinct 1.1 million years ago.
GIANT WHITE SHARK
The last shark mentioned here is the granddaddy of all sharks from prehistoric times to the present and was the apex predator from about 16 to 3.6 million years ago. This was the mighty Extinct Giant White Shark (Carcharocles megalodon). Known more commonly as “Megalodon” or “Meg,” this shark’s teeth are the most massive, robust teeth of any shark. Specimens have tall prominent roots, a wide V-shaped dental band, or “bourlette,” between the crown and the root, and medium serrations along both crown edges. The teeth are wide, thick, and dense, and cannot be mistaken for the teeth of any other shark species. The largest tooth specimens are recorded at just over seven inches tall and the body length of this shark was nearly 60 feet!
These teeth and other animal fossils are out there waiting to be found, so get out there and start hunting!
Bob, Pam, and Ashby Gale have just written the first extensive book on beach fossils, A Beachcomber’s Guide to Fossils. The book contains more than 1,200 high-quality color photographs and detailed descriptions of more than three hundred fossil specimens found on beaches from Texas, east to Florida, and north to New Jersey. Learn more at www.fossilsabg.org.
This article appeared in the Beachcombing Magazine November/December 2020 issue.