it was the Crassigyrinus it was aguatic and had sharp teeth. == ==
The dominant organisms living at the Cretaceous period or time were first primates and flowering plants. This was the time when the extinction of the dinosaurs took place.
dimetrodon was the dominANT SPECIES OF THE permian period
dinosaurs
Metazoans were abundant during the Vendian Period.
The dominant organisms during the carboniferous time period were plants. They were large, vascular, land plants that sometimes grew to be one hundred feet or more.
dimetrodon and edaphosaurus
You may face troubles with the organisms, for the sea life was then dominant... but most likely it would just be the humidity of the time, and the dominant, or dangerous organisms during the time.
hm plop you
The T-Rex and the Spinosaurus.
Late Horizon
dinosaurs among animals on land and gymnosperms among plants
it depends which time period you are talking about...check google or yahooanswers.