Re: An even dumber question

["David Marjanovic" <david.marjanovic@gmx.at>]

> What is it about crocodilians that makes them NOT dinosaurs? Ditto
> Komodo Dragons, other monitors, etc...

Their phylogenetic positions. Dinosauria is usually defined as "the most
recent common ancestor of *Megalosaurus bucklandii* and *Iguanodon
bernissartensis*, and all its descendants. This includes birds but excludes
crocs, which are the closest living relatives of dinosaurs:

(strongly shortened; spaces counted so that it lines up in a monospace font)

Archosauria
  |--Crocodylia [sic!]
  `--Dinosauria
       |--Ornithischia
       |    `--*Iguanodon*
       `--Saurischia
            |--*Megalosaurus*
            `--Aves

Monitors are "lizards", far away from dinosaurs:

Amniota
  |--Theropsida
  |    `--Mammalia
  `--Sauropsida
       |--Testudinata (turtles)
       `--Diapsida
            |--Archosauria (see above)
            `--Lepidosauria
                 |--*Sphenodon*
                 `--Squamata
                      |--Iguania (incl. agamas, chamaeleons)
                      `--Scleroglossa
                           |--Nyctisaura (geckos + friends)
                           |--Lacertiformes (true lizards, teyus)
                           `--Diploglossa
                                |--Scincidae (skinks)
                                `--Anguimorpha
                                     |--Anguidae (glass lizards etc.)
                                     `--Varanoidea
                                          |--Helodermatidae (Gila monsters)
                                          `--Thecoglossa
                                               |--Varanidae (monitors)
                                               `--Pythonomorpha
                                                    |--Mosasauroidea
                                                    `--Ophidia (snakes)

Squamata after
Michael S. Y. Lee:
Convergent evolution and character correlation in burrowing reptiles:
towards a resolution of squamate relationships, Biological Journal of the
Linnean Society 65, 369 -- 453 (1998)