|Tiger shark - God's amazing creature|
Image Animal Discovery
Scientific sons of Adam have named them Chondricthyes from Greek khondor ikhthys, cartilage fish.
Evolutionary biologists suggest that sharks are relatives of placodermi covered by cartilage instead of protective bony armour plates. Dropping the heavy knights iron turned out to be a great decision - heavily protected placodermi perished at the end of Devonian sharks are doing very well, thank you, except for the threat from the even more successful land dwelling bi-pedals ruling over all life on this planet.
Because sharks body is cartilage and not bony with calcium Devonian fossils are quite rare if existent at all. However, their presence from Middle Devonian on can be deducted from the numerous tooth fossils that have survived.
|Shark tooth from Eocene and Pliocene sediments|
Bolton Museum, Lancashire, UK
Fossil forum has a rare photo of a Devonian shark tooth discovered in 2009 Holy Cross Mountain, Kowala, Poland.