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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]
They first appeared in the fossil record around 66 million years ago, soon after the Cretaceous–Paleogene extinction event that eliminated about three-quarters of plant and animal species on Earth, including most dinosaurs. [25] [26] One of the last Plesiadapiformes is Carpolestes simpsoni, having grasping digits but not forward-facing eyes.
A white-headed dwarf gecko with tail lost due to autotomy. Autotomy (from the Greek auto-, "self-" and tome, "severing", αὐτοτομία) or 'self-amputation', is the behaviour whereby an animal sheds or discards an appendage, [1] usually as a self-defense mechanism to elude a predator's grasp or to distract the predator and thereby allow escape.
In the rest of the books, Aristotle studies the internal and external parts of the blood and non-blood animals, comparing them with human beings, showing the common and the specific. [ 1 ] For Aristotle, the material causes of an organism could not explain all its aspects.
The Caudata ("urodeles"; salamanders and newts), an order of tailed amphibians, is possibly the most adept vertebrate group at regeneration, given their capability of regenerating limbs, tails, jaws, eyes and a variety of internal structures. [2] The regeneration of organs is a common and widespread adaptive capability among metazoan creatures ...
Anatomy (from Ancient Greek ἀνατομή (anatomḗ) 'dissection') is the branch of morphology concerned with the study of the internal structure of organisms and their parts. [2] Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its beginnings in prehistoric ...
The first fully terrestrial vertebrates were reptilian amniotes — their eggs had internal membranes that allowed the developing embryo to breathe but kept water in. This allowed amniotes to lay eggs on dry land, while amphibians generally need to lay their eggs in water (a few amphibians, such as the common Suriname toad, have evolved other ways of getting around this limitation).
The hominoids are descendants of a common ancestor.. Homo sapiens is a distinct species of the hominid family of primates, which also includes all the great apes. [1] Over their evolutionary history, humans gradually developed traits such as bipedalism, dexterity, and complex language, [2] as well as interbreeding with other hominins (a tribe of the African hominid subfamily), [3] indicating ...