Shark Tooth Fossils

Description:

Sharks have inhabited the oceans for approximately 450 million years, making them older than the dinosaurs. These miniature teeth are the only remains of sharks that lived millions of years ago. Incredibly, sharks have survived four of the five major extinction events in the history of the Earth.

The teeth come from a wide variety of species and range in size. Some displays come with 4 smaller teeth, and some come with 2 larger teeth, but everyone will be different since no 2 Shark teeth are the same. 

Significance:

Shark teeth from about 110–40 million years ago are significant because they provide some of the best evidence we have for understanding ancient shark evolution, marine ecosystems, and major environmental changes during the late Cretaceous Period and Paleogene Period.

1. Sharks rarely fossilize, but teeth do

A shark's skeleton is made mostly of cartilage, which decomposes easily. Teeth, however, are highly mineralized and fossilize readily. Since sharks continuously shed teeth throughout their lives, fossil deposits can contain thousands of teeth, giving scientists abundant evidence of ancient species.

2. They document shark evolution

Teeth from 110–40 million years ago capture major evolutionary transitions, including the diversification of:

• Early mackerel sharks (order Lamniformes)
• Ancestors of modern tiger, requiem, and hammerhead sharks
• Large predatory sharks that occupied top positions in marine food webs

Researchers can identify species and evolutionary relationships by studying tooth shape, serrations, and size.

3. They reveal ancient marine ecosystems

Different tooth shapes indicate different diets:

• Long, narrow teeth suggest fish-eating sharks.
• Broad, serrated teeth indicate predators that fed on larger prey.
• Crushing teeth suggest sharks that ate shellfish and other hard-shelled animals.

By examining fossil shark teeth, scientists reconstruct food webs and determine what kinds of animals lived in ancient seas.

4. They record major extinction and recovery events

The interval includes the Cretaceous–Paleogene extinction event, which eliminated non-avian dinosaurs and many marine species. Shark teeth show:

• Which shark groups survived the extinction.
• How marine ecosystems recovered afterward.
• Changes in shark diversity before and after the event.

5. They help reconstruct ancient climates

The chemical composition of fossil teeth can preserve information about:

• Ocean temperatures
• Salinity
• Migration patterns

Scientists analyze isotopes in fossil teeth to learn how ancient oceans changed through time.

Notable sharks from this time range

Some important sharks known from teeth dating within or near 110–40 million years ago include:

• Cretoxyrhina — a large predatory shark of the Late Cretaceous.
• Squalicorax — known for serrated teeth and scavenging/predatory behavior.
• Otodus obliquus — an early giant shark that lived after the dinosaur extinction and is related to later giant megatoothed sharks.