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A chordate (/ ˈ k ɔːr d eɪ t / KOR-dayt) is a deuterostomal bilaterian animal belonging to the phylum Chordata (/ k ɔːr ˈ d eɪ t ə / kor-DAY-tə).All chordates possess, at some point during their larval or adult stages, five distinctive physical characteristics (synapomorphies) that distinguish them from other taxa.
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 ...
The Cambrian chordates are an extinct group of animals belonging to the phylum Chordata that lived during the Cambrian, between 538 and 485 million years ago. The first Cambrian chordate known is Pikaia gracilens , a lancelet -like animal from the Burgess Shale in British Columbia , Canada.
The lampreys are a very ancient lineage of vertebrates, though their exact relationship to hagfishes and jawed vertebrates is still a matter of dispute. [7] Molecular analysis since 1992 has suggested that hagfish are most closely related to lampreys, [8] and so also are vertebrates in a monophyletic sense. Others consider them a sister group ...
The snake returns in the Book of Exodus when Moses turns his staff into a snake as a sign of God's power, and later when he makes the Nehushtan, a bronze snake on a pole that when looked at cured the people of bites from the snakes that plagued them in the desert.
Agnatha (/ ˈ æ ɡ n ə θ ə, æ ɡ ˈ n eɪ θ ə /; [3] from Ancient Greek ἀ-(a-) 'without' and γνάθος (gnáthos) 'jaws') is a paraphyletic infraphylum [4] of non-gnathostome vertebrates, or jawless fish, in the phylum Chordata, subphylum Vertebrata, consisting of both living (cyclostomes) and extinct (conodonts, anaspids, and ostracoderms, among others).
The dorsal nerve cord is an anatomical feature found in chordate animals, mainly in the subphyla Vertebrata and Cephalochordata, as well as in some hemichordates.It is one of the five embryonic features unique to all chordates, the other four being a notochord, a post-anal tail, an endostyle, and pharyngeal slits.
Pikaia gracilens is an extinct, primitive chordate marine animal known from the Middle Cambrian Burgess Shale of British Columbia.Described in 1911 by Charles Doolittle Walcott as an annelid, and in 1979 by Harry B. Whittington and Simon Conway Morris as a chordate, it became "the most famous early chordate fossil", [1] or "famously known as the earliest described Cambrian chordate". [2]