I think sharks are amazing creatures.  How do you feel about them?
Modern sharks are known as clade Selachimorpha.
That's cool - what were non-modern sharks known as?
Sharks are a bunch of fish characterized by cartilaginous skeleton.
And they bite.....what do they eat?
eugenedontidans.
Under this broader definition, the earliest known sharks date back to more than 420 million years ago. Acanthodians are often referred to as "spiny sharks"; though they are not part of Chondrichthyes proper, they are a paraphyletic assemblage leading to cartilaginous fish as a whole. Since then, sharks have diversified into over 500 species. They range in size from the small dwarf lanternshark ("Etmopterus perryi"), a deep sea species of only in length, to the whale shark ("Rhincodon typus"
. It is cited as the first most comprehensive catalogue to Sri Lankan cartilage fishes. On 2016 May, he published Illustrated guide of Sharks of Sri Lanka. According to De Silva, there are 60 sharks species and 30 rays and skates found around the coast of Sri Lanka.
Sharks are a group of fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii