During the early Jurassic, the supercontinent Pangea broke up into North America, Eurasia and Gondwana. Still, the early Atlantic and Tethyan Oceans were relatively narrow. In the Late Jurassic, the southern continent, Gondwana, started to break up and, as the Tethys closed, the Neotethys basin appeared. Climates were warm, with no evidence of glaciation. As in the Triassic, there was apparently no land near either pole and no extensive ice caps existed.During the Jurassic, the 'highest' life forms living in the seas were fish and marine reptiles. The latter include ichthyosaurs, plesiosaurs and marine crocodiles, of the families Teleosauridae and Metriorhynchidae. In the invertebrate world, several new groups appeared, such as: planktonic foraminifera and calpionelids, which are of great stratigraphic relevance; rudists, a reef-forming variety of bivalves; belemnites; and brachiopods of the terebratulid and rinchonelid groups. Ammonites (shelled cephalopods) were particularly common and diverse, forming 62 biozones. The arid conditions that had characterized much of the Triassic steadily eased during the Jurassic period, especially at higher latitudes; the warm, humid climate allowed lush jungles to cover much of the landscape (Haines 2000). Flowering plants had not evolved yet, and conifers dominated the landscape, as they had during the Triassic. In fact they were the most diverse group of trees and constituted the greatest majority of large trees. Source