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In effect, "tetrapod" is a name reserved solely for animals which lie among living tetrapods, so-called crown tetrapods. This is a node-based clade , a group with a common ancestry descended from a single "node" (the node being the nearest common ancestor of living species).
Marine tetrapod (sperm whale) Internal skeletal structures showing the vertebral column running from the head to the tail Marine vertebrates are vertebrates that live in marine environments , which include saltwater fish (including pelagic , coral and deep sea fish ) and marine tetrapods (primarily marine mammals and marine reptiles , as well ...
The evolution of tetrapods began about 400 million years ago in the Devonian Period with the earliest tetrapods evolved from lobe-finned fishes. [1] Tetrapods (under the apomorphy-based definition used on this page) are categorized as animals in the biological superclass Tetrapoda, which includes all living and extinct amphibians, reptiles, birds, and mammals.
In the tetrapod and higher clades from the lower-middle Famennian there are several defining changes on the basis of anatomy of Ichthyostega, Tulerpeton, and Acanthostega. In the cranium, there is a stapes derived from the hyomandibular of fishes; a single bilateral pair of nasal bones, and a fenestra ovalis in the otic capsule of the braincase ...
A humpback whale has stunned scientists with a journey that spanned three oceans and more than 8,000 miles, setting the record for the longest known migration between breeding grounds.
The nearly 50-foot sperm whale is beached on top of a sandbar, officials said. Massive whale that stunned beachgoers in Australia is now stranded, officials say Skip to main content
The pygmy right whale shares several characteristics with the right whales, with the exception of having a dorsal fin. Also, pygmy right whales' heads are no more than one quarter the size of their bodies, whereas the right whales' heads are about one-third the size of their bodies. [11] The pygmy right whale is the only extant member of its ...
Spade-toothed whales are the world’s rarest, with no live sightings ever recorded. No one knows how many there are, what they eat, or even where they live in the vast expanse of the southern ...