|Even though this page is not about sharks, but the fossil teeth from sharks, we thought we would give you a little information about sharks. Thanks to the popular movie that we will not mention, a movie that made a lot of people cringe and stay out of the water, how people think and feel about sharks will now take some time to change. Though the sharks of today send fear through most people, they are but toys to what the shark's predecessors were like. Take the image of the Carcharodon megalodon jaw below. Though the jaw is a reproduction, the teeth are real fossilized teeth of the Carcharodon megalodon. To understand just how big this jaw is, an adult could stand inside it.|
|Sharks, skates, rays, and even stranger fish make up the Chondrichthytes, which are cartilaginous fish. First appearing on Earth almost 450 million years ago, cartilaginous fish today, include some who are fearsome predators, while others are rather harmless. The primitive Chondrichthyans were cartilaginous fishes, whereas Neoselachians have skeletons of calcified cartilage. Members of the Chondrichthyes all lack true bone and have a skeleton made of cartilage, which is the flexible material you can feel in your nose and ears. Because their skeletons were formed of cartilage, which is far less durable than bone, preservation of the whole body of a cartilaginous fish only takes place under special conditions. Unfortunately, few fossilized remains of prehistoric sharks exist, and the shark fossil record is fragmentary at best. Most fossils found so far consist of nothing but teeth. In some cases a few vertebra have been found. In the rarest of cases complete fossil sharks have been discovered.|
|Though somewhat rare, the image above is that of the dorsal fine spine for Ctenacanthus, a type of shark. Any further identification is difficult, as such isolated fossils are not found with any related fossils, such as teeth. Fossil sharks are particularly difficult to identify, since their skeletons are rarely preserved, and we usually find only scraps like teeth or fin spines|
|Dinosaurs spark the imagination of a time long past,
especially since they are long gone, and sharks are not. However,
sharks existed in the waters of the earth for millions of years, and the
shark's fossil record is three times as long as that of the dinosaurs.
In the carboniferous period the xenocanths and ctenacanths groups of shark
began to show resemblance to today's sharks, the Neoselachii. The
Neoselachii first appeared in the Triassic period, evolving mostly in the
Jurassic and Cretaceous periods, to the 35 families now in existence.
The xenocanths which appear on the fossil record 450 million years ago,
with a fossil example of one shown above, were exclusively a fresh water
fish. Despite this, they managed to achieve world wide distribution
and flourished until their extinction approximately 220 million years ago.
Another group were the hybodonts, who made their appearance some 320 million
years ago, and were quite common throughout salt water and fresh
water environments. They were probably the closest group to the modern
shark. For reasons unknown, the hybodonts became extinct at about
the same time as the dinosaurs, which died out some 65 million years ago.
|Sharks are polyphyodont, which means they shed their teeth approximately once every month. Even though sharks left very little in the way of fossil reminders, in other aspects, it did provide a form of compensation by shedding teeth so often. There is correspondingly a wealth of shark tooth fossils. Shark tooth fossils thus present a possible study of a vast number of samples, with small evolutionary diversification, for the time period of the last 200 million years. Paleontologists have learned about ancient sharks primarily from their teeth, composed of a bone-like substance coated with hard enamel. Here are several fossil examples for you to see, including some images that show both the lingual (back) view, and the labial (front) view.|
|The largest shark to ever swim the oceans is called
the megalodon. At a size of approximately 40-50 feet in length, it
is safe to say that megalodon is still considered to be the largest predatory
fish to exist. The better known species is Carcharodon megalodon
and was once believed to have been the ancestor to the Great White Shark.
More recent research indicates that Carcharocles megalodon was the
last species to evolve in a separate line. A streamlined predator
like modern sharks, the Carcharodon megalodon lived between 5 million and
1.6 million years ago. Below is an individual fossil tooth
from a Carcharocles megalodon and another image showing a little variety.
Though some teeth of Carcharocles have been found up to 18 cm in length
(just over 7 feet), the length of this individual tooth is about (just
over 2½ inches). It has been determined that the size
of the jaw can be estimated based on the size of the tooth.
For example, every inch of tooth is roughly equal to one foot in jaw height.
At 6.5 cm, or just over 2½ inches, the jaw for this individual
fossil tooth would be just over 2½ feet. At 18 cm, or just
over 7 feet, the jaw for a fossil tooth of this size would be just over
7 feet. Now that is one big mouth and that is the size of the jaw
shown at the top of this page.
|To give you a more unique view of a shark's tooth, just click on the image below to see a 3D view of one, and you can move the image using your mouse|
|To see images of the different shark teeth we have found, just click on the icon below|