Choristodera
From Tokaia
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*'''Lazarusuchidae''' | *'''Lazarusuchidae''' | ||
*'''Pelagochampsosauridae'''† | *'''Pelagochampsosauridae'''† | ||
| + | *'''Monjurosuchidae'''† | ||
| + | *'''Ctenogenidae'''† | ||
| + | *'''Simoedosauridae'''† | ||
| + | *'''Hyphalosauridae'''† | ||
</td></tr> | </td></tr> | ||
</table> | </table> | ||
Revision as of 18:36, 2 October 2008
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Choristoderes, also known as champsosaurs, are a linage of crocodile like aquatic reptiles (however, unlike crocodiles they lack scutes and their nostrils are located at the tip of the skull), which became extinct in our world. Their exact relationships within class Sauropsida aren't very well understood; they have been classified both as archosaurs and as lepidosaurs.
In Terra Alternativa
The evolution of choristoderes in Terra Alternativa parallels that of Earth's; however, those in this parallel Earth remained alive, occupying the niches of gharials (which either became extinct or evolved into terrestrial, ant-eater like forms). An extinct linage, Pelagochampsosauridae, gave rise to marine forms in the Eocene period, successfully outcompeting the last marine crocodiles; however, changes in the oceanic currents, plus the evolution of the first marine cynodonts, eventually caused their demise at the Oligocene period (although some remaining species managed to survive until the Piocene).
Nowdays, most species either belong to the family Champsosauridae, or to the family Lazarusuchidae. The first occur naturally in the Americas, while the later in Asia and Australia. While they both diverged from each other presumably as far back as the Triassic (when the first choristoderes evolved), and while their last common ancestor was probably lizard like, both are now gharial like forms that are very similar to each other except for some internal features; an interesting case of parallel evolution.
In What if Dinosaurs
In What if Dinosaurs the evolutionary history of choristoderes was similar to the previous ones; like in Terra Alternativa, some marine champsosaurids have also evolved.
See also
Choristoderes on Wikipedia
