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!)
PlacodermsName means “plated skin”First seen 390 million years agoExtinct 345 million years agoHad true jawsMany were small bottom dwellers, but many
more were bottom dwelling predatorsArmor plates on their skin
Next came the Chondrichthyes
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Chondrichthyes
ChondrichthyesFirst seen 375 million years agoThey’re still around todayIncludes sharks and skatesSharks are sometimes called “living fossils”Developed cartilaginous skeletons
OsteichthyesModern ‘bony fish’First appeared 395 million years agoRay-finned fish of today are still the dominant
fish groupTrue bones
Osteichthyes branched into… Actinopterygii…Kingdom:Animalia
Phylum:ChordataSuperclass:OsteichthyesClass: 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
SarcopterygiiName means “fleshy finned fishes”First appeared 385 million years agoAncestors of land vertebrates!Internal nostrils, fleshy fins and cosmoid
scales
Sea to Land TransitionScientists 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 roseaeFirst seen 375 million years agoLarge aquatic predator with a flattened head and
bodyScientists think that Tiktaalik lived on the bottom
of the ocean in shallow waterTiktaalik might have been able to come out of the
water for brief periods of timeSkull, neck, ribs and limbs are similar to the
earliest limbed animalsHad fish-like features such as scales and fin rays
Tiktaalik roseaeDiscovered on Ellesmere Island, Canada in
2004Name means “large freshwater fish” in
Inuktituk