Lets start 390 million years ago… During the Devonian Period, there were many creatures living in the oceans (some on their way to becoming the true bony fish of today!)

Placoderms Name means “plated skin” First seen 390 million years ago Extinct 345 million years ago Had true jaws Many were small bottom dwellers, but many more were bottom dwelling predators Armor plates on their skin

A Placoderm

Next came the Chondrichthyes Kingdom:Animalia Phylum:Chordata Subphylum:Vertebrata Class:Chondrichthyes

First seen 375 million years ago They’re still around today Includes sharks and skates Sharks are sometimes called “living fossils” Developed cartilaginous skeletons

Chondrichthyes of old….

Osteichthyes Modern ‘bony fish’ First appeared 395 million years ago Ray-finned fish of today are still the dominant fish group True bones

Osteichthyes

Osteichthyes branched into… Actinopterygii… Kingdom:AnimaliaAnimalia Phylum:ChordataChordata Superclass:OsteichthyesOsteichthyes Class: Actinopterygii Ray-finned bony fish Fins are webs of skin supported by bony or horny spines. They are the dominant aquatic vertebrates today, making up about half of all vertebrate species known

… and Sarcopterygii Kingdom:Animalia Phylum:Chordata Superclass:Osteichthyes Class:Sarcopterygii

Name means “fleshy finned fishes” First appeared 385 million years ago Ancestors of land vertebrates! Internal nostrils, fleshy fins and cosmoid scales

1. What does this mean that sharks are “living fossils”?

Sea to Land Transition

Scientists think that the major cause for marine life moving on to land was a lack of oxygen in the water. There was also fierce competition for food in the oceans. Also, at this time insects were becoming very plentiful on land. 2. What do you think would be required for this sea to land transition to occur?

Tiktaalik roseae

First seen 375 million years ago Large aquatic predator with a flattened head and body Scientists think that Tiktaalik lived on the bottom of the ocean in shallow water Tiktaalik might have been able to come out of the water for brief periods of time Skull, neck, ribs and limbs are similar to the earliest limbed animals Had fish-like features such as scales and fin rays

Tiktaalik roseae Discovered on Ellesmere Island, Canada in 2004 Name means “large freshwater fish” in Inuktituk

Tiktaalik roseae