Download The remains or traces of once-living organisms. Any animal that has

 The remains or traces of once‐living organisms. Any animal that has a segmented vertebral column; includes fish, amphibians, reptiles, birds, and mammals. A biogenic sedimentary structure, especially in limestone, produced by the entrapment of sediment grains on sticky mats of photosynthesizing bacteria. A cell that lacks a nucleus and organelles such as mitochondria and plastids; the cells of bacteria and cyanobacteria. A cell with an internal membrane‐
bounded nucleus that contains chromosomes and other internal structures; possessed by all organisms except bacteria. A type of land plant that has specialized tissues for transporting fluids and nutrients throughout the body and that reproduces by spores rather than seeds (e.g., ferns and horsetail rushes). A flowerless, seed‐bearing land plant. One of a group of animals including dinosaurs, flying reptiles (pterosaurs), crocodiles, and birds. Any of the Mesozoic reptiles that belong to the groups designated as ornithischians and saurischians. An order of dinosaurs characterized by a lizard‐like pelvis; includes theropods, prosauropods, and sauropods. One of the two orders of dinosaurs, characterized by a birdlike pelvis; includes ornithopods, stegosaurs, ankylosaurs, pachycephalosaurs, and ceratopsians. Walking on two legs as a means of locomotion, as in humans, birds, and some dinosaurs. Walking on four legs as a means of locomotion. Any of the Mesozoic flying reptiles. Any of the porpoiselike, Mesozoic marine reptiles. A type of Mesozoic marine reptile. A type of advanced mammal‐like reptile; the ancestor of mammals was among the cynodonts. Any of the vascular plants that have flowers and seeds; the flowering plants. Any of the egg‐laying mammals; includes only the platypus and spiny anteater of the Australian region. Any of the pouched mammals such as kangaroos and wombats that give birth to their young in a very immature state; most common in Australia. Any of the mammals that have a placenta to nourish the developing embryo; most living and fossil mammals. Any of the mammals that belong to the order Primates; characteristics include large brain, stereoscopic vision, and grasping hands. An abbreviated term for Hominoidea, the superfamily that includes apes and humans. Abbreviated form of Hominidae, the family to which humans belong; bipedal primates include Australophithecus and Homo.