Dryosauridae
Skeletal reconstruction of Dysalotosaurus in the Berlin Museum of Natural History, a representative from the Upper Jurassic of Africa
- North America
- Africa
- Europe
The Dryosauridae are a group ornithopoder dinosaurs that have been proven fossil from the beginning of the Upper Jurassic to Lower Cretaceous ( Aptian ).
The group consists of medium-sized herbivores, which reached approximately two to four meters in length. They were lightly built, adapted to the running animals with long legs and relatively short arms. They are similar by basal Euornithopoda as Hypsilophodon; later, abgeleitetere ornithopods like the Hadrosauridae ( " duck-billed dinosaur " ), however, were larger and more robust built. From other groups, the Dryosauriden let distinguished among other things by the foot skeleton. The feet were relatively slim, the first toe ( hallux ) is entirely missing.
In 1984, named Angela Milner and David Norman family Dryosauridae; it is still regarded as basalste ( primitive ) family of Iguanodontia.
The first precise definition presented Paul Sereno on in 1998: According to the definition include the Dryosauridae all taxa, which are more closely related than Dryosaurus with Parasaurolophus. Within the Iguandontia they belong to Dryomorpha; within these, they form the sister taxon to the Ankylopollexia.
The oldest species that were clearly associated with the Dryosauridae come from the rocks of the Kimmeridgiums ( about 155 million years ago) of Africa and North America ( Dryosaurus and Dysalotosaurus ). The youngest representatives Elrhazosaurus comes from the African Aptian ( about 112 million years). Perhaps Callovosaurus, as in 2007 by José Ruiz- Omeñaca et al. proposed also a representative of the Dryosauridae; then the oldest member of this family would be about 163 million years old.
A recent example of a Kladogramms by Barrett et al. from the year 2011 is just one of the different relationship hypotheses is ::
Callovosaurus
Kangnasaurus
Dryosaurus
Dysalotosaurus
Valdosaurus
Elrhazosaurus