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A tetrapod is a form of wave-dissipating concrete block used to prevent erosion caused by weather and longshore drift, primarily to enforce coastal structures such as seawalls and breakwaters. Tetrapods are made of concrete , and use a tetrahedral shape to dissipate the force of incoming waves by allowing water to flow around rather than ...
The water-based lateral line system was used substantially by these aquatic tetrapods to detect danger from predators. [2] Within the Osteichthyan diversification, there were no changes related to respiration in the transition as can be seen by the nasal region and palatal morphology in elpistostegalid fishes.
Marine tetrapods are tetrapods that returned from land back to the sea again. The first returns to the ocean may have occurred as early as the Carboniferous Period [ 20 ] whereas other returns occurred as recently as the Cenozoic , as in cetaceans, pinnipeds , [ 21 ] and several modern amphibians .
Several groups of tetrapods have undergone secondary aquatic adaptation, an evolutionary transition from being purely terrestrial to living at least part of the time in water. These animals are called "secondarily aquatic" because although their ancestors lived on land for hundreds of millions of years, they all originally descended from ...
Tetrapodomorpha (also known as Choanata [3]) is a clade of vertebrates consisting of tetrapods (four-limbed vertebrates) and their closest sarcopterygian relatives that are more closely related to living tetrapods than to living lungfish.
However, most tetrapod species today are amniotes, most of which are terrestrial tetrapods whose branch evolved from earlier tetrapods early in the Late Carboniferous. The key innovation in amniotes over amphibians is the amnion , which enables the eggs to retain their aqueous contents on land, rather than needing to stay in water.
A tide gauge is a device for measuring the change in sea level relative to a vertical datum. [2] [3] It is also known as a mareograph, [4] marigraph, [5] and sea-level recorder. [6] When applied to freshwater continental water bodies, the instrument may also be called a limnimeter. [7] [8]
The water level at each end of the tube will be at the same elevation, whether the two ends are adjacent or far apart, so a line between them will be horizontal at its midpoint and a shed base, building foundation or similar structure laid out using several such lines will be "horizontal" within building tolerances on any scale over which use ...