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Vestigiality. In humans, the vermiform appendix is sometimes called a vestigial structure as it has lost much of its ancestral digestive function. Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. [1]
Human vestigiality. The muscles connected to the ears of a human do not develop enough to have the same mobility allowed to monkeys. Arrows show the vestigial structure called Darwin's tubercle. In the context of human evolution, vestigiality involves those traits occurring in humans that have lost all or most of their original function through ...
Double dewclaws on rear leg of dog. A dewclaw is a digit – vestigial in some animals – on the foot of many mammals, birds, and reptiles (including some extinct orders, like certain theropods). It commonly grows higher on the leg than the rest of the foot, such that in digitigrade or unguligrade species, it does not make contact with the ...
Remnant eyes (and eye structures) in animals that have lost sight such as blind cavefish (e.g. Astyanax mexicanus), [88] mole rats, snakes, spiders, salamanders, shrimp, crayfish, and beetles. [89] [90] Vestigial eye in the extant Rhineura floridana and remnant jugal in the extinct Rhineura hatchery (reclassified as Protorhineura hatcherii ...
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]
The evolution of cetaceans is thought to have begun in the Indian subcontinent from even-toed ungulates (Artiodactyla) 50 million years ago (mya) and to have proceeded over a period of at least 15 million years. [2] Cetaceans are fully aquatic mammals belonging to the order Artiodactyla and branched off from other artiodactyls around 50 mya.
The coccyx (pl.: coccyges or coccyxes), commonly referred to as the tailbone, is the final segment of the vertebral column in all apes, [1] and analogous structures in certain other mammals such as horses. In tailless primates (e.g. humans and other great apes) since Nacholapithecus (a Miocene hominoid), [2][3] the coccyx is the remnant of a ...
Pelvic spur. Pelvic spurs (also known as vestigial legs) are external protrusions found around the cloaca in certain superfamilies of snakes belonging to the greater infraorder Alethinophidia. [1] These spurs are made up of the remnants of the femur bone, which is then covered by a corneal spur, or claw-like structure. [1]