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Vestigial structures are often homologous to structures that are functioning normally in other species. Therefore, vestigial structures can be considered evidence for evolution, the process by which beneficial heritable traits arise in populations over an extended period of time. The existence of vestigial traits can be attributed to changes in ...
Species of the infraorder Cetacea A phylogenetic tree showing the relationships among cetacean families. [1]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]
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 ...
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 evolution. Although structures called vestigial often appear functionless, they may retain lesser functions or develop minor new ones.
That this vestigial response occurs even before becoming consciously aware of a startling noise would explain why the function of ear-perking had evolved in animals. The mechanism serves to give a split-second advantage to a startled animal – possibly an animal being stalked and hunted.
This stylised bird skeleton highlights the furcula Wishbone of a chicken. The furcula (Latin for "little fork"; pl.: furculae) [a] or wishbone is a forked bone found in most birds and some species of non-avian dinosaurs, and is formed by the fusion of the two clavicles. [1]
Males also usually have a single median ossicone on the frontal bone that is larger in northern animals and smaller in southern giraffes. [3] Giraffes can also have small additional paired occipital ossicones on the occipital bones, paired orbital ossicones associated with eyes, and azygous ossicones.
A spur is an outgrowth of bone covered in a sheath of horn found in various anatomical locations in some animals. Unlike claws or nails , which grow from the tip of the toes, spurs form from other parts of the foot, usually in connection with joints where the toes meet the foot or the foot meets the long bones. [ 1 ]