Larger shark vertebra, 30mm across

Shark vertebrae, scale in mm.

Sharks have no bony skeleton, but only cartilage. As a result they have left very little fossil evidence, except abundant teeth. The only other shark fossil you can find at B.B. are the centra of their vertebrae, which are nice round disks as illustrated on the left and right.

According to the literature you can also find shark coprolites; a nice word for fossilized shark poop. Maybe we don't know how to recognize the stuff, but we have never found any sofar.

Other trace fossils include bite marks left in the bones of unfortunate dolphins/porpoises, whales and seals, as illustrated in the rib fragment below.

Rib of unfortunate porpoise(?). Scale in mm.

Identifying shark teeth

Sharks loose and grow teeth throughout their entire lives. Their teeth are specialized versions of the little "teeth" in their skin, the dermal denticles. Quite recently engineers realized that by reducing the amount of turbulence these denticles greatly reduce the drag on a shark as it glides through the water. This discovery is now used to create rough surfaces on e.g. airplane wings! If you look into a shark's mouth, you can see row after row of teeth. Note that the flatter side of a tooth is the part that faces outwards (towards the lips, the labial side) once it has marched forward to the front row. The rounder side faces inwards (towards the tongue, the lingual side). Once it reaches the front row, a given tooth may only last 10 days. Given that there can be 50 teeth in the front rows of the upper and lower jaws, and they only last 10 days, a single shark sheds around 1800 teeth per year, and tens of thousands in a life time. Which explains why fossil shark teeth are so common. If you ever visit the National Aquarium in Baltimore, look for teeth on the bottom of the shark tank!

Already after you have collected a few dozen teeth you will probably notice that they do not all look the same. Some are thin and pointy, others are triangular. Some are symmetric, some are not. Some have smooth edges, some are serrated.

After you have collected more teeth, try to separate them into groups that look similar. As you collect more and more teeth you will start to notice differences within groups, and you will be able to make a finer distinction between tooth shapes.

For a beautiful overview of shark teeth, though corresponding to slightly younger deposits, checkout Lee Creek's shark pages.

sand tiger shark teeth

mainly grey shark teeth

cowshark teeth

Some sharks have very different teeth in their upper and lower jaws. And in most sharks, teeth from the front (anterior) of the jaw are different from those to the side (lateral) and the back (posterior). Some sharks have unique and often tiny teeth exactly in the middle of their jaw, where left and right meet. If there is only a single tooth in the center, it is called a symphyseal. If there is a tooth on either side of the middle, they are called para-symphyseals. We humans have para-symphyseals, so do e.g. Snaggletooth sharks. Cow sharks have a symphyseal tooth.

At Brownie's Beach there are several types of teeth which are easy to classify, at least down to a species level.

For more details on tooth characteristics:

• Striations
• Partial cutting edges

Snaggletooth shark - Hemipristis serra

Nearly all teeth from the Snaggletooth shark have coarse serrations (like a saw) on both edges, except for the very point (apex) of the tooth, which is smooth, and except for the lateral teeth in the lower jaw. All teeth are a-symmetric, and there is a clear difference between teeth from the upper and lower jaws, and from the front (anterior) and side (lateral). The teeth are relatively large (25-40mm), but you can also find many teeth of juvenile snaggletooth sharks, which are just smaller versions of the adult ones (?).

Labial (left) and lingual view of the upper right para-symphyseal tooth. Remember that the flat side faces outwards, so the left image is the labial view, and the right the lingual view. And because all (?) teeth curve away from the center (mesial side) towards the side and back (distal side), this is the right para-symphyseal. Note the narrower root on the mesial side, and the large lingual protuberance ("the bump") on the root. (height 25mm)

Labial (left) and lingual view of an upper antero-lateral tooth. (height 24mm)

Labial (left) and lingual view of a lower antero-lateral tooth. Note the striking difference between this tooth and the typical serrated ones. With the little secondary cusps (barely visible in the left picture), these teeth look very much like large sand-tiger shark teeth. You can tell them apart by the "partial cutting edge", which is visible in the left picture as the thin line along the upper quarter of the tooth. It may cover as much as half the edge, but never reaches the root. (height: 30mm)

Labial and lingual views of a lower posterior tooth. The otherwise very similar teeth in the upper and lower jaws can be told apart by the pronounced bump on the curved roots of the lower teeth. The upper teeth, with the exception of the para-symphyseals have very straight and flatter roots.

Cow sharks - Notorynchus primigenius

The teeth from the lower jaw of the cow shark consist of up to nine individual cusps, arranged from large to small, with coarse serrations on the leading edge of the largest cusp. These serrations are so unique that even if you find a broken cow shark tooth, with only the first cusplet, you can recognize it by these serrations. The roots are very flat and thin, and are often broken off just below the enamel. See also the picture above. Upper teeth have one or only a few well separated cusps.

Cow shark: labial and lingual view of lower symphyseal tooth.
(Max. width 10mm)
Cow shark: labial and lingual view of lower tooth.
Max. width 18mm.
Because the roots are very thin, and because of the deep furrow you can see in the left picture, most cow shark teeth are broken just below the crown. See the scanner page for a high resolution picture.

Tiger sharks - Galeocerdo aduncus

Tiger shark teeth have one large crown on the anterior side, and many small serrations on the posterior side. This shark evolved in to the modern day tiger shark, Galeocerdo Cuvier, which has almost identical, but larger teeth.

Contortus - (Physogaleus Contortus)

Contortus shark teeth are somewhat similar to Tiger sharks, but the large crown has a twist to it - it is contorted - and the roots are "fatter". This species, formerly known as Galeocerdo Contortus (see discussion on elasmo.com), is now extinct. Unlike the teeth of most miocene sharks, which are found world-wide, contortus teeth are only known from the east coast of the US. (there are a few isolated finds reported from Belgium).

Sand tiger sharks - Odontaspis, Carcharias

Sand tiger sharks have pointy teeth, with very long and curved roots (See Fig. at top of page). Next to the main crown, there are often 2 or four small cusplets, though these have often broken or worn off. There are many different types of sand tiger shark, but I haven't been able to tell them apart.

Angel sharks - Squatina

Teeth from the Angel shark are very rare (1/500) at Brownie's Beach, but very easy to recognize. The crown sits at a right angle to the triangular root. Angel shark teeth are small; the maximum width of the root of the tooth in the movie is 8mm.
(if you missed it, click on the image to restart the movie)

Thresher sharks - Alopias

Teeth from the Thresher shark are also very rare (1/1000) at Brownie's Beach. Their unique characteristic is that the rootlobes are curved outwards, toward the labial side of the teeth. I hope this is clear from the movie. The crowns are rather wide for the size of the root, and except for the anterior (front) teeth, are curved as well. On the labial side, the enameloid covers a larger part of the root. The tooth in the movie is 14mm wide. (if you missed it, click on the image to restart the movie)

Mako Sharks - Isurus

These are relatively large teeth. The crown is very smooth and either broad or narrow. The root is very flat and squarish.

Meg - Carcharocles megalodon

And you thought megalodon only had huge 15cm teeth? Well, look at the example on the left. It is barely 15mm (millimeter!) wide and 12mm high. The shape corresponds to a posterior megalodon tooth, but it is much smaller than the smallest teeth in an adult meg, so it is probably from a juvenile. The picture is not very clear, but in between the enameloid and the root is a narrow intermediate dark region called the bourlette. The bourlette can be seen very well in larger megalodon teeth, and is a feature in all Carcharocles sharks.

The tooth on the right is more like it, but it is not really a Megalodon. As you can see this 2.5 inch tooth has rudimentary cusplets at the base of the enamel, whereas the tooth of a true Megalodon is straight all the way. This tooth once belonged to a Carcharocles chubutensis, the evolutionary ancestor of Megalodon. And by the way, did you know that Megalodon is NOT the ancestor of the current living great white shark, Carcharodon Carcharias? The great white is in all likelihood a decendant of a Miocene Mako shark, that later developed serrations.

Sharpnose - Rhizoprionodon fischeuri

I am pretty sure that these very small, 4-6mm high teeth once belonged to a sharpnose shark. The crowns are very slender, without serrations and the distal shoulder is slightly convex.

Hammerhead - Sphyrna laevissima

measured at the root, 11, 14 and 16mm wide close-up

Also see the detailed hammerhead page. The teeth of Hammerhead sharks are almost identical to those of grey sharks. I did not realize the difference until recently myself. Hammerhead teeth are quite rare at B.B., about one on every 150 grey shark teeth. So if you have a couple of hundred grey shark teeth, but haven't identified any Hammerheads, take another look. The biggest differences are that Hammerhead teeth have no serrations, a more distinct distal shoulder, with a notch at the base of the crown, and the crown is slightly wider with one straight edge and one angled edge.

Mackerel - Carcharoides catticus

This is the labial side of a small, 11mm high tooth, with very nice cusplets, and a compressed root. I believe it is that of a Mackerel shark. These teeth are very rare at B.B. (1/2000), and their black color - determined by the sediments in which the tooth fossilized - is also very uncommon. This may suggest that these teeth are reworked, or wash in from elsewhere. But other suggestions are welcome.

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Statistics

Here is a breakdown of our collection as of winter 1998/1999 5000-5500 teeth:

Severly damaged fragments	±1500	-
Grey shark?	2600	small, simple teeth, may include lemon, others
Sand tiger	473	-
Tiger	114	-
Contortus	71	-
Snaggle tooth	88	+44 fragments recognizable as such
Cow	48	includes all fragments recognizable as such
Mako	18	broad and narrow
Angel	13	perfect condition
Mackerel	4	heavily worn; reworked?
Peculiar	44	weird, but not yet classified
Extinct Great White	0	4 ~1 inch fragments

The relative frequency of what you find will depend on your search methods. There are many more smaller teeth, which fall through our coarse screens. And if you only pick up the teeth from the beach you can see with your bare eye, you will probably find relatively more larger ones, though you will find less in total. And yes, we have seen people walk away with 3+ inch beauties... but that requires either luck or a lot of hard work.