Orodromeus

Artistic live image of Orodromeus

• North America (USA and Canada)

• Orodromeus brokerage,

Orodromeus is a genus of dinosaur and an original representative of the ornithopod. It was a small, bipedal running herbivores. To date, fossils of numerous individuals known - among them are the remains of adult animals and young animals of different ages. The fossils come in particular from the Two Medicine Formation of Montana ( USA); However, the species could also be detected in Alberta ( Canada). Orodromeus lived during the Late Cretaceous ( middle to late Campanian ).

This genus was first described with the single species, Orodromeus makelai, 1988 by the paleontologist Jack Horner and David Weishampel. The name Orodromeus (Greek oros - "mountain", gr Dromeus - "Runner ") means as much as " mountain - runner". This name is intended to alert the one on the occurrence of the holotype specimen, the " Egg Mountain", and the other over the American state of Montana.

Features

Orodromeus reached a length of approximately 2.5 meters. The crowns were shield shaped like a broad and triangular. On each side of the upper jaw were each 10 to 13 teeth, depending on the age of the individual. In the premaxillary bone ( premaxilla ), a bone from the upper jaw, were further periods of five tough on each side, as in some related genera.

The rest of the skeleton was characterized as in the related genera Zephyrosaurus and Oryctodromeus by a bone tip on the shoulder blade from; a feature which is interpreted by some researchers as a possible adaptation to a grave lifestyle. Three skull features such as the excessive postorbital suggest, in a close relationship of Orodromeus and Zephyrosaurus.

System

Traditionally Orodromeus the Hypsilophodontidae family is attributed. Recent research shows, however, that the Hypsilophodontidae paraphyletic, so were not a natural group. Consequently Orodromeus considered as representative of the original ornithopods.

Most analyzes indicate that Orodromeus was most closely related to Zephyrosaurus. In the near relationship of the two genera also Oryctodromeus is provided.

Paleobiology

It is speculated that this species may have inhabited caves, as has been demonstrated with his relative Oryctodromeus. Although no structures were found in association with the Orodromeus - bone; some anatomical features that are also found in Oryctodromeus and Zephyrosaurus, however, could be interpreted as an adaptation to burrowing. In addition, the bones were found close together at least two copies, although they would be more widely distributed in normal situations, which indicates that they might be preserved within a building.

Knochenhistologische studies on the long bones of various Orodromeus copies allow conclusions on growth rates, growth patterns and age of the animals. Thus, the growth of this little dinosaur was relatively slow compared to other dinosaurs. Although the animals grew faster than today's crocodiles, but slower than today's birds. Growth was greatest immediately after hatching, but was still in the youth phase very strongly of - faster than the bigger relatives Tenontosaurus and Dryosaurus. After reaching adulthood, growth was almost complete. Likely growth rings of bone suggest that Orodromeus was fully grown with 4 to 6 years.

Jack Horner discovered in the " Egg Mountain " of the Two Medicine Formation fossil eggs and nests near the remains of newly hatched Orodromeus. Consequently, Horner described the eggs and nests Orodromeus to. However, a subsequent analysis examined embryonic remains inside the eggs and came to the conclusion that the eggs and nests actually belonged to Troodon, a small theropod.