Reptile Evolution
 
Tetrapoda
Basal Tetrapoda
Reptilomorpha
Lepospondyli
 
Reptilia/Amniota
Gephyrostegus
 
Archosauromorpha
Basal Archosauromorpha
Protosynapsida
Synapsida
Mammalia
Protodiapsida
Diapsida
Terrestrial Younginiformes
Marine Younginiformes
Enaliosauria
Protorosauria
Archosauriformes
Archosauria
Dinosauria
 
Lepidosauromorpha
Urumqia clade
Cephalerpeton clade
Captorhinidae
Milleretta Limnoscelis clade
Bolosaurus Diadectes clade
Turtle Pareiasaur clade
Lanthanosuchia
Owenettidae
Lepidosauriformes
Lepidosauria
Tritosauria
Fenestrasauria • Pterosauria
Protosquamata
Squamata
 
SMF R 4710
Evolution of the Mesosaurus palate

Above is a selection of palates from Mesosaurus and sister taxa showing the evolution and shifting of the various elments. As a side note, In Carroll 1988 (figure 12-31, taken from Andrews 1910) the palate of Ichthyosaurus was illustrated, labeling the bones lateral to the pterygoids as palatines and the central bones, vomers, all in accord with the palate of archosaurs, etc. Here we can see that the ectopterygoid is actually the bone lateral ot the pterygoid and the palatine has become the medial element in mesosaurs, thalattosaurs and ichthyosaurs.

Carroll RL 1988. Vertebrate paleontology and evolution. New York: W. H. Freeman & Co.

Cope ED 1886. A contribution to the vertebrate paleontology of Brazil. Stereosternum tumidum, gen. et sp. nov. Proceedings of the American Philosophical Society 23 (121):1-21.

Jiang D-Y, Rieppel O, Motani R, Hao W-C, Sun Y-I, Schmitz L and Sun Z-Y. 2008. A new middle Triassic eosauropterygian (Reptilia, Sauropterygia) from southwestern China. Journal of Vertebrate Paleontology 28:1055–1062.

 
Marine Younginiformes
Galesphyrus
Claudiosaurus
 
Enaliosauria
Anarosaurus
 
Mesosauria
PIMUZ-A-III-0192
SMF R 4710
Stereosternum
Mesosaurus
 
Ichthyopterygia
Wumengosaurus
Hupehsuchus
Utatsusaurus
Ichthyosaurs
 
Thalattosauriformes
Serpianosaurus
Askeptosaurus
 
Placodontia
Palatodonta
Paraplacodus
 
Sauropterygia
Pachypleurosaurus
Qianxisaurus

 

 

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