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C4 plants use a different metabolic pathway to capture carbon dioxide but also have differences in leaf anatomy and cell biology compared to most other plants. Trunk, a single woody stem came about in unrelated plants: paleozoic tree forms of club mosses, horsetails, and seed plants.
The tetrapods, including all large- and medium-sized land animals, have been among the best understood animals since earliest times. By Aristotle's time, the basic division between mammals, birds and egg-laying tetrapods (the "herptiles") was well known, and the inclusion of the legless snakes into this group was likewise recognized. [28]
Comparative anatomy studies similarities and differences in organisms. The image shows homologous bones in the upper limb of various vertebrates. Comparative anatomy is the study of similarities and differences in the anatomy of different species. It is closely related to evolutionary biology and phylogeny [1] (the evolution of species).
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups.
An evolutionary tree (of Amniota, for example, the last common ancestor of mammals and reptiles, and all its descendants) illustrates the initial conditions causing evolutionary patterns of similarity (e.g., all Amniotes produce an egg that possesses the amnios) and the patterns of divergence amongst lineages (e.g., mammals and reptiles ...
An affinity between the amphibians and the teleost fish is the multi-folded structure of the teeth and the paired supra-occipital bones at the back of the head, neither of these features being found elsewhere in the animal kingdom. [25] The Permian lepospondyl Diplocaulus was largely aquatic
Amphibians in the biological sense (including the extinct Labyrinthodonts) represent a grade, since they are also the ancestors of the amniotes. [12] Reptiles represent a grade composed of the cold-blooded amniotes; this excludes birds and mammals. [4] Dinosaurs were proposed to be the ancestors of birds as early as the 1860s. [13]
The first amphibians appeared on land in the Carboniferous. During the Triassic , mammals and dinosaurs appeared, the latter giving rise to birds in the Jurassic . Extant species are roughly equally divided between fishes of all kinds, and tetrapods.