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Rhipidistians
- 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.
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Osteolepis
Rhipidistian from Devonian with a heterocercal tail.
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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.
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Walking Catfish
- A present day example of a fish walking on land to get back to water.
- History:
- 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.
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Amphibia
- Now is used for modern groups only:
- frogs
- Salamanders
- Caecilians
- Lissamphibia
- Temnospondyls (extinct in the Mesozoic)
- Lepospondyls are antoher early extinct tetrapod group.
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Labyrinthodonts
- 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:
- Temnospondyli
- Anthracosauria
- Paraphyletic
- Amniotes and modern amphibians arise within this group.
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Acanthostega
- This animal is Devonian in age, and a transitional form from fish to tetrapod.
- Has eight fingers!
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Ichthyostega
- Labyrinthodont amphibian
- Devonian
- One meter long
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Seymouria
Later anthracosaur from early Permian.
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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.
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Lepospondyls
The expanded cranial "horns" from tabular bones may be to allow an expanded lateral line system.
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Lissamphibia
frogs, calamanders and caecilians
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Reptilia
- two major lineages:
- Sauropsida
- Synapsida
- Diverged by Carboniferous or earlier
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Amniota
Eggs which survive on land and nourish embryos with members.
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Sauropsida
- Birds, dinosaurs, modern reptiles and Mesozoic reptiles.
- two groups:
- Parareptilia
- Eureptilia
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Synapsids
- Monophyletic
- Therapsids, modern mammals and extinct forms.
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Amniote skull types
- These used to be used in classification, but no longer. Now they are functional types only.
- Anapsid
- Synapsid
- Diapsid
- Euryapsid
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Diadectomorphs
- Stem amniotes
- Late Carboniferous
- Related to Seymouriomorphs and amphibia
- Perhaps belong with anthracosaurs and other late non-amniotes
- Also called Cotylosauria
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Mesosaurs
- Specialized aquatic forms
- Not closely related to other aquatic sauropsida
- Permian forms
- Skulls lack fenestrae
- Long snouts and thin, sharp teeth indicate feeding habits
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Parareptilia
- 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)
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Pareiasaurus
Late Permian testudine
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Eureptilia
- Lepidosauromorpha and Archosauromorpha
- Diapsid skulls
- Palatine fenestrae in mouth roof
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Lepidosauromorpha
- Marine sauropterygians and lepidosaurs.
- Terrestrial snakes and lizzards
- Sphenodon
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Eosuchians
- Lepidosaurs that gave rise to modern forms.
- Many have reduced temporal bars and therefore have increased jaw mobility.
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Archosauromorpha
- Dinosaurs and birds
- Ichtyopterigia - icthyosaurs
- Asuropterygia
- Anapsids
- Crocodilians
- Pterosaurs
- Dinosaurs - often became bipedal
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Ichtyopterygia
- Icthyosaurs
- Large marine
- Convergent with other marine forms
- Porpoise-like bodies but tail went side to side
- Sleek shaped bodies
- Predators
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Sauropterygia
- Mesozoic aquatic diapsids
- Triassic Nothosaurs
- Jurassic and Cretaceous Plesiosaurs
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Anapsids
- 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
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Pterosaurs
- May have had a wingspan of up to 8 meters such as Pteranodon.
- Rhamphorhynchus
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Pelycosaurs
- arose in mid-Carboniferous
- Descended from cotylosaurs
- Radiated through Permian
- Some herbivores
- Some carnivores
- Gave rise to therapsids
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Dimetrodon
Many theories have been advanced as uses for the sail, including sailing! It was probably a means of temperature regulation.
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Edaphosaurus
a three meter long herbivore
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Moshops
- a therapsid
- a Permian mammal-like reptile.
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Cynognathus
Specialized dentitions were present in these animals.
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Therapsids
- mammal-like reptiles
- Moschops
- Titanophoneus
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