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> Most Jurassic and all Cretaceous dinosaurs are Lazarus taxa, since the
> Aalenian stage of the Jurassic has yielded very few if any dinosaur remains
> of any kind. Going just by the fossil record, dinos apparently became extinct
> at the onset of the Aalenian and returned from extinction when it closed.
> Approximate during of this stage, basal Middle Jurassic: 173.5-178 Ma.
Not quite. Aalenian dinosaurs are rare, granted, but they aren't non-existent
(don't forget that dinosaurs leave evidence other than skeletal material, err...
ichnites for example!). This is not the case for true Lazarus taxa, which leave
a >**TOTAL**< 100% palaeoabsence (e.g. post early Upper Cret. sphenodonts, post
Campanian-Maastrichtian coelacanths). Also, the 5 Ma-long Aalenian record is not
a scratch on the 65 Ma-or-more-long stunt pulled off by true Lazarus taxa.
The whole idea of Lazarus taxa is that they suddenly show up _long_ after their
lineage has apparently gone extinct.
"Greetings exulted one"