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Evidence for common descent comes from the existence of vestigial structures. [72] These rudimentary structures are often homologous to structures that correspond in related or ancestral species. A wide range of structures exist such as mutated and non-functioning genes, parts of a flower, muscles, organs, and even behaviors.
Vestigial features may take various forms; for example, they may be patterns of behavior, anatomical structures, or biochemical processes. Like most other physical features, however functional, vestigial features in a given species may successively appear, develop, and persist or disappear at various stages within the life cycle of the organism ...
Areoles represent highly specialized branches on cacti. They evolved as abortive branch buds while their spines evolved as vestigial leaves. [2] In branched cacti, such as Opuntioidiae and the saguaro, new branches grow from areoles, because that is where the buds are. The development of the areole seems to have been an important element in the ...
Dried examples of "neotropical anachronisms" from Brazil, Peru, and Nicaragua in the herbarium of the New York Botanical Garden. [1]Evolutionary anachronism, also known as "ecological anachronism", [1] is a term initially referring to attributes of native plant species (primarily fruit, but also thorns) that seemed best explained as having been favorably selected in the past due to their ...
Some stipules are not well understood or may be vestigial. It is known that foliaceous stipules are used like leaves to make energy for the plants. Sometimes stipules protect the next leaf or bud as it grows in then falls off after the leaf unfolds, as with Tulip Poplars. [4] Stipules can be used as climbing tendrils by climbing plants.
The fossil record shows three different types of tracheid cells found in early plants, which were classified as S-type, G-type and P-type. The first two of them were lignified and had pores to facilitate the transportation of water between cells. The P-type tracheid cells had pits similar to extant plant tracheids.
Ileum, caecum and colon of rabbit, showing Appendix vermiformis on fully functional caecum The human vermiform appendix on the vestigial caecum. The appendix was once believed to be a vestige of a redundant organ that in ancestral species had digestive functions, much as it still does in extant species in which intestinal flora hydrolyze cellulose and similar indigestible plant materials. [10]
In social sciences, atavism is the tendency of reversion: for example, people in the modern era reverting to the ways of thinking and acting of a former time. The word atavism is derived from the Latin atavus—a great-great-great-grandfather or, more generally, an ancestor.