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- Dominant paleozoic freshwater predators.
- Jointed braincases with strong bites.
- Labyrinthodont teeth, which are also present in Labyrinthodonts.
- Gave rise to tetrapods during Devonian.
- Then went extinct in the Permian.
- Include: Porolepiformes, Osteolepiformes and panderichthyids.
Rhipidistian from Devonian with a heterocercal tail.
Why did vertebrates move onto land?
- They were probably trying to stay in the water!
- Lungfishes, others and "walking catfishes" today, can survive out of water long enough to leave a drying pond in search of a better water source.
- A present day example of a fish walking on land to get back to water.
- Walking catfish were sold as pets - released accidentally, or intentionally, in Florida - survived and spread.
- Generalist feeding species - adapt to many environs.
- The success of these animals showed how it could have happened.
- Now is used for modern groups only:
- Temnospondyls (extinct in the Mesozoic)
- Lepospondyls are antoher early extinct tetrapod group.
- primitive tetrapods
- Had bony scales across abdomen.
- Large, up to 5 meters long.
- Had lateral lines in skull grooves.
- Ex. Icthyostega - Devonian four-footed fish (really amphibious)
- Other Labyrinthodonts:
- Amniotes and modern amphibians arise within this group.
- This animal is Devonian in age, and a transitional form from fish to tetrapod.
- Has eight fingers!
- Labyrinthodont amphibian
- One meter long
Later anthracosaur from early Permian.
Lobe fin fish and amphibian movement
Dorsal views of body profiles of a lobe-finned fish and a tetrapod to show that both move by lateral unduation of body and use of tail.
The expanded cranial "horns" from tabular bones may be to allow an expanded lateral line system.
frogs, calamanders and caecilians
- two major lineages:
- Diverged by Carboniferous or earlier
Eggs which survive on land and nourish embryos with members.
- Birds, dinosaurs, modern reptiles and Mesozoic reptiles.
- two groups:
- Therapsids, modern mammals and extinct forms.
Amniote skull types
- These used to be used in classification, but no longer. Now they are functional types only.
- Stem amniotes
- Late Carboniferous
- Related to Seymouriomorphs and amphibia
- Perhaps belong with anthracosaurs and other late non-amniotes
- Also called Cotylosauria
- Specialized aquatic forms
- Not closely related to other aquatic sauropsida
- Permian forms
- Skulls lack fenestrae
- Long snouts and thin, sharp teeth indicate feeding habits
- Testudines and extinct groups such as parieosaurs.
- Ear drum supported by squamosal bone and retroarticular process.
- Unique foot-ankle articulation.
- Testudines already had carapaces and plastrons.
- Appeared in the Triassic.
- Two modern orders that differ in neck retraction mechanisms.
- Cryptodire - vertical folding of neck.
- Pleurodire - side-folding neck (South American forms)
Late Permian testudine
- Lepidosauromorpha and Archosauromorpha
- Diapsid skulls
- Palatine fenestrae in mouth roof
- Marine sauropterygians and lepidosaurs.
- Terrestrial snakes and lizzards
- Lepidosaurs that gave rise to modern forms.
- Many have reduced temporal bars and therefore have increased jaw mobility.
- Dinosaurs and birds
- Ichtyopterigia - icthyosaurs
- Dinosaurs - often became bipedal
- Large marine
- Convergent with other marine forms
- Porpoise-like bodies but tail went side to side
- Sleek shaped bodies
- Mesozoic aquatic diapsids
- Triassic Nothosaurs
- Jurassic and Cretaceous Plesiosaurs
- Contains Captorhinids that gave rise to later groups.
- Similar to modern reptiles.
- Well-ossified skeletons
- Small teeth probably ate insects.
- No temporal openings appeared in Carboniferous
- Extinct at end of Triassic
- Left descendants
- May have had a wingspan of up to 8 meters such as Pteranodon.
- arose in mid-Carboniferous
- Descended from cotylosaurs
- Radiated through Permian
- Some herbivores
- Some carnivores
- Gave rise to therapsids
Many theories have been advanced as uses for the sail, including sailing! It was probably a means of temperature regulation.
a three meter long herbivore
- a therapsid
- a Permian mammal-like reptile.
Specialized dentitions were present in these animals.
- mammal-like reptiles