Search results
Results from the WOW.Com Content Network
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).
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.
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.
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 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 ...
The distinction between quadrupeds and tetrapods is important in evolutionary biology, particularly in the context of tetrapods whose limbs have adapted to other roles (e.g., hands in the case of humans, wings in the case of birds and bats, and fins in the case of whales). All of these animals are tetrapods, but not all are quadrupeds.
Both species are relatively small whales, 3–5 m (9.8–16.4 ft) in length, with a forehead melon, and a short or absent snout. Premaxillary teeth are absent. [ 1 ] They do not have a true dorsal fin, but do have a narrow ridge running along the back, which is much more pronounced in the narwhal.