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Vestigial features may take various forms; for example, they may be patterns of behavior, anatomical structures, or biochemical processes. Like most other physical features, however functional, vestigial features in a given species may successively appear, develop, and persist or disappear at various stages within the life cycle of the organism ...
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]
Comparative study of the anatomy of groups of animals or plants reveals that certain structural features are basically similar. For example, the basic structure of all flowers consists of sepals, petals, stigma, style and ovary; yet the size, colour, number of parts and specific structure are different for each individual species. The neural ...
A relict (or relic) plant or animal is a taxon that persists as a remnant of what was once a diverse and widespread population. Relictualism occurs when a widespread habitat or range changes and a small area becomes cut off from the whole.
Tetrapod footprints found in Poland and reported in Nature in January 2010 were "securely dated" at 10 million years older than the oldest known elpistostegids [33] (of which Tiktaalik is an example), implying that animals like Tiktaalik, possessing features that evolved around 400 million years ago, were "late-surviving relics rather than ...
Clutch size in a small sample from Nizhny Novgorod Russia was found to average 3.6. [189] The clutch size average in nest boxes of Samara Oblast was 2.4. [ 171 ] Egg sizes are usually between 46.5 and 52.3 mm (1.83 and 2.06 in) in height by 39 to 44 mm (1.5 to 1.7 in) in diameter, and the eggs weighing on average about 47 g (1.7 oz) when fresh.
Fossils have been found in marine strata. The nares are retracted and the orbits are raised like in other aquatic mammals. Levels of stable isotopes in their tooth enamel suggest an aquatic diet and environment (carbon and oxygen) and fresh or brackish water (strontium). Their spongy bone structure is similar to that of cetaceans.
Caminalcules are a fictive group of animal-like life forms, which were created as a tool for better understanding phylogenetics in real organisms. They were created by Joseph H. Camin ( University of Kansas ) and consist of 29 living 'species' and 48 fossil forms.