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Many examples of these are vestigial in other primates and related animals, whereas other examples are still highly developed. The human caecum is vestigial, as often is the case in omnivores, being reduced to a single chamber receiving the content of the ileum into the colon.
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]
X-ray showing the skeleton of Typhlonectes (Typhlonectidae). Caecilians' anatomy is highly adapted for a burrowing lifestyle. In a couple of species belonging to the primitive genus Ichthyophis vestigial traces of limbs have been found, and in Typhlonectes compressicauda the presence of limb buds has been observed during embryonic development, remnants in an otherwise completely limbless body. [7]
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:
Proturans, sometimes referred to as "coneheads", do not have eyes or antennae. They possess a telson and abdominal styli thought to be vestigial legs. Diplurans have a pair of caudal cerci, from which their name, meaning "two-tailed", is derived. They also possess abdominal styli.
The vestigial gene is considered to be one of the most important genes for wing formation, but when it becomes over expressed the issue of ectopic wings begin to form. [71] The vestigial gene acts to regulate the expression of the wing imaginal discs in the embryo and acts with other genes to regulate the development of the wings.
Life on Earth would be so dull without animals. Lucky for us, there are more than 8 million different species of them on the planet, many of which we might never encounter in our lifetime. From ...
Camelids are large, strictly herbivorous animals with slender necks and long legs. They differ from ruminants in a number of ways. [2] Their dentition show traces of vestigial central incisors in the incisive bone, and the third incisors have developed into canine-like tusks.