vestigial structure

Examples of vestigial structure in the following topics:

• Vestigial Structures

  • Vestigial structures have no function but may still be inherited to maintain fitness.
  • These unused structures without function are called vestigial structures.
  • Vestigial structures are often homologous to structures that function normally in other species.
  • The vestigial versions of a structure can be compared to the original version of the structure in other species in order to determine the homology of the structure.
  • Discuss the connection between evolution and the existence of vestigial structures

• Regional Vertebral Characteristics

  • As it’s alternative name suggests the coccyx forms the basis of a tail which has been lost in humans, although it is incorrect to think of it as a vestigial structure as it is a key attachment point for many muscles and ligaments and plays a key role in supporting the body whilst sitting.

• Evidence of Evolution

  • Scientists call these synonymous parts homologous structures.
  • Some structures exist in organisms that have no apparent function at all, appearing to be residual parts from a common ancestor.
  • These unused structures (such as wings on flightless birds, leaves on some cacti, and hind leg bones in whales) are vestigial.
  • Great ape embryos, including humans, have a tail structure during their development that is lost by birth.
  • Like anatomical structures, the structures of the molecules of life reflect descent with modification.

• Characteristics and Evolution of Amphibians

  • Amphibians evolved from fish 400 million years ago and are characterized by four limbs, moist skin, and sensitive inner ear structures.
  • Some species of salamanders and all caecilians are functionally limbless; their limbs are vestigial.
  • Additional characteristics of amphibians include pedicellate teeth (teeth in which the root and crown are calcified, separated by a zone of noncalcified tissue) and a papilla amphibiorum and papilla basilaris (structures of the inner ear that are sensitive to frequencies below and above 10,00 hertz, respectively).
  • However, it also had four limbs, with the skeletal structure of limbs found in present-day tetrapods, including amphibians.

• Characteristics of Chordata

  • The chordates are named for the notochord: a flexible, rod-shaped structure that is found in the embryonic stage of all chordates and also in the adult stage of some chordate species.
  • In humans and other apes, the post-anal tail is present during embryonic development, but is vestigial as an adult.

• The Evolution of Plastids

  • Cyanobacteria are a group of photosynthetic bacteria with all the conventional structures of prokaryotes.
  • The green algal endosymbiont also exhibits a stunted vestigial nucleus.

• Modern Amphibians

  • The only male amphibians that possess copulatory structures are the caecilians, so fertilization among salamanders typically involves an elaborate and often prolonged courtship.
  • They have vestigial limbs which is evidence that they evolved from a legged ancestor.

• Characteristics of Reptiles

  • Limbless reptiles (snakes and other squamates) have vestigial limbs and, as with caecilians, are classified as tetrapods because they are descended from four-limbed ancestors.

• Thyroid Gland Disorders

  • A persistent sinus tract may remain as a vestigial remnant of the tubular development of the thyroid gland.

• Demographic Shifts

  • Vestigial changes from the countercultural revolution of the 1960s and 1970s were apparent throughout the 1990s.