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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]
Plants also have vestigial parts, including functionless stipules and carpels, leaf reduction of Equisetum, paraphyses of Fungi. [35] Well known examples are the reductions in floral display, leading to smaller and/or paler flowers, in plants that reproduce without outcrossing, for example via selfing or obligate clonal reproduction. [36] [37]
Scientific literature concerning vestigial structures abounds. One study compiled 64 examples of vestigial structures found in the literature across a wide range of disciplines within the 21st century. [73] The following non-exhaustive list summarizes Senter et al. alongside various other examples:
Anatomical structures are typically mixed depending on which cells are prevalent in different body parts. For example, plants can have two different types of flowers. A mosaic is a genetic anomaly similar in nature and effects to a chimera: genetically different populations of cells within one organism, originated from some propagated mutation ...
Here is a list of examples in which unrelated proteins have similar functions with different structure. The convergent orientation of the catalytic triad in the active site of serine and cysteine proteases independently in over 20 enzyme superfamilies. [252] The use of an N-terminal threonine for proteolysis.
The young Robert Ernst Eduard Wiedersheim, probably in early 1874 by Alfredo Noack in Genoa. [1]Robert Ernst Eduard Wiedersheim (21 April 1848 – 12 July 1923) was a German anatomist who is famous for publishing a list of 86 "vestigial organs" in his book The Structure of Man: An Index to His Past History.
Atavism can also be seen in humans who possess large teeth, like those of other primates. [9] In addition, a case of "snake heart", the presence of "coronary circulation and myocardial architecture [that closely] resemble those of the reptilian heart", has also been reported in medical literature. [ 10 ]
The sudden startled arm-jerking response sometimes experienced when on the verge of sleeping is known as the hypnic jerk.. The evolutionary explanation for the existence of the hypnic jerk is unclear, but a possibility is that it is a vestigial reflex humans evolved when they usually slept in trees.