IGUANODONTIA
CLASSIFICATION
Animalia: Vertebrata: Tetrapoda: Sauropsida: Archosauromorpha:
Ornithodira: Dinosauria: Ornithischia: Ornithopoda
CLADOGRAM:
--Iguanodontia "Iguanodon's taxon" == {Iguanodon > Hypsilophodon}
| INCERTAE SEDIS:
| indeterminate material -- Campanian to Maastrichtian -- New Zealand
| indeterminate material (tooth) -- late Hauterivian to Barremian -- Japan
| unnamed form (ribs, etc.) -- Early Cretaceous -- Mongolia
| unnamed small form -- earliest Cenomanian -- Utah
| Jinzhousaurus
| Lophorhothon
|?-"Mandschurosaurus" laosensis
|?-Muttaburrasaurus
|--+--Tenontosaurus
| `--+ INCERTAE SEDIS:
| | unnamed form -- Maastrichtian -- Romania
| | unnamed form -- Maastrichtian -- Romania
| `--Rhabdodon
`--Euiguanodontia "true iguanodonts" == {Iguanodon + Gasparinisaura}
| INCERTAE SEDIS:
| ?Loncosaurus
|--Gasparinisaura
`--Dryomorpha "Dryosaurus forms" == {Dryosaurus + Iguanodon}
|?-Anabisetia
|--Dryosauridae
| | INCERTAE SEDIS:
| | ?unnamed form -- Antarctica
| | indeterminate tiny material -- Turonian -- Argentina
| |--Dryosaurus
| |?-Kangnasaurus
| `--Valdosaurus
`--Ankylopollexia == {Parasaurolophus + Camptosaurus}
| INCERTAE SEDIS:
| unnamed small form -- Early Cretaceous -- S. Africa
| Bihariosaurus
| Pararhabdodon
|--Camptosauridae
| |--Camptosaurus
| `--Draconyx
`--Styracosterna "spiked sterna" == {Parasaurolophus > Camptosaurus}
| INCERTAE SEDIS:
| indeterminate material -- Albian to early Cenomanian -- Africa
| unnamed form -- Campanian -- Antarctica
| Fukuisaurus
| ?Lurdusaurus
| Planicoxa
| +?-Eolambia
| `--Probactrosaurus
`--Iguanodontoidea == {Iguanodon + Hadrosaurus} =Hadrosauriformes
| INCERTAE SEDIS:
| "Camptosaurus" sp.
| Craspedodon
|--Iguanodon
`---->Hadrosauroidea
ALTERNATE CLADOGRAM:
--Dryomorpha
|--Iguanodontoidea
`--Camptosauridae
|--Dryosaurinae
`--Camptosaurinae
ALTERNATE CLADOGRAM:
—Iguanodontoidea
|–+–Iguanodon
| `–Hadrosauridae sensu Horner
`–+–Ouranosaurus
`–Lambeosauridae
ESSAY
| The major characteristic of these medium- to large-sized herbivores is a spiky thumb, possibly used for defense against predators. When Iguanodon, the first non-neornithean dinosaur to be scientifically described, was first put together, its thumb-spike was incorrectly placed on the nose, giving it the look of a reptilian rhinoceros! EVOLUTION:The animals listed here cover the transition from early, hypsilophodont-like iguanodontians to the medium-sized Camptosaurus to the archetypal Iguanodon to the duck-billed dinosaurs, the end result of ornithopod evolution. The evolution of the iguanodontian thumb can be seen along this line as well: small in Camptosaurus, at its maximum in Iguanodon, then tiny or absent in hadrosauroids. |
