Stegosaurus. Allosaurus, which accounted for 70 to 75% of all theropod specimens, was at the top trophic level of the Morrison food web. Other vertebrates that shared this paleoenvironment included ray-finned fishes, frogs, salamanders, turtles like Dorsetochelys, sphenodonts, lizards, terrestrial and aquatic crocodylomorphans such as Hoplosuchus, and several species of pterosaurs such as Harpactognathus and Mesadactylus. Shells of bivalves and aquatic snails are also common. The flora of the period has been revealed by fossils of green algae, fungi, mosses, horsetails, cycads, ginkgoes, and several families of conifers. Vegetation varied from river-lining forests of tree ferns and ferns (gallery forests) to fern savannas with occasional trees such as the Araucaria-like conifer Brachyphyllum. A partial Ceratosaurus specimen indicates the presence of the genus in the Portuguese Porto Novo Member of the Lourinhã Formation. Many of the dinosaurs of the Lourinhã Formation are the same genera as those seen in the Morrison Formation, or have a close counterpart. Besides Ceratosaurus, the researchers also noted the presence of Allosaurus and Torvosaurus in the Portuguese rocks are primarily known from the Morrison, while Lourinhanosaurus has so far only been reported from Portugal. Herbivorous dinosaurs from the Porto Novo Member include, among others, the sauropods Dinheirosaurus and Zby, as well as the stegosaur Miragaia. During the Late Jurassic, Europe had just been separated from North America by the still narrow Atlantic Ocean, and Portugal, as part of the Iberian Peninsula, was still separated from other parts of Europe. According to Mateus and colleagues, the similarity between the Portuguese and North American theropod faunas indicates the presence of a temporary land bridge, allowing for faunal interchange. Malafaia and colleagues, however, argued for a more complex scenario, as other groups, such as sauropods, turtles, and crocodiles, show clearly different species compositions in Portugal and North America. Thus, the incipient separation of these faunas could have led to interchange in some but allopatric speciation in other groups. References External links Ceratosaurs Kimmeridgian life Tithonian life Late Jurassic dinosaurs of Africa Fossils of Tanzania Late Jurassic dinosaurs of Europe Fossils of Portugal Lourinhã Formation Late Jurassic dinosaurs of North America Dinosaurs of the Morrison Formation Fossil taxa described in 1884 Taxa named by Othniel Charles Marsh