Shark evolution has been studied through their fossil record, as shark teeth are mineralogically stable and can provide details about species. The oldest shark fossils date back 455 million years to scales, while the Devonian era saw sharks becoming truly abundant. Ancient sharks such as Cladoselache differed from modern sharks in having rounded snouts, mouths in front, and equally sized tail lobes. Neoselachian sharks expanded 100 million years ago, inhabiting a variety of habitats as nearshore predators. Modern sharks demonstrate a diversity of forms like cow sharks and hammerheads.

1. Shark Evolution
Mathieu Noe

2. Shark Evolution
 Though sharks often only leave teeth behind this has been
enough to have a fairly detailed fossil record
 There are between 2,000 and 3,000 species of fossil sharks

3. Shark Teeth
 Shark teeth are mineralogicaly stable
 Shark teeth provide a number of characteristics with which
to identify a species
 Erosion and malformities

4. Earliest sharks
 The oldest fossils are scales 455 million years ago
 The oldest true shark scales come from 420 million years
ago
 Devonian era was when shark became truly abundant

5. Ancient sharks
 There are important diferences between ancient sharks and
modern sharks (Cladoselache)
 Short rounded snout with mouth in front
 Tail with both lobes the same size
 Naked

6. Early Modern Sharks
 Hybodonts
 Mcmurdodus
 Paleospinax

7. Neoselachians
 100 million years ago
 Expansion of ray fined fishes
 Expansion of higher teleost
 Predominantly near shore predators
 Expanded to a variety of different habitats

8. Modern Sharks
 Cow and frilled sharks
 Batoids
 Filter feeders
 Hammerheads

9. Laminoid sharks
 Heavy built teeth
 Lots of similar teeth

10. Future for sharks
 Future challenges for the survival of sharks
 Adaptations to climate change