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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.
As a subphylum of chordates, all vertebrates have evolved a vertebral column (backbone) based around the embryonic notochord (which becomes the intervertebral discs), forming the core structural support of an internal skeleton, and also serves to enclose and protect the spinal cord.
Vertebrates are distinguished from all other animals, including other chordates, by multiple synapomorphies, namely the vertebral column; skull of bone or cartilage, large brain divided into 3 or more sections, a muscular heart with multiple chambers; an inner ear with semicircular canals; sense organs including eyes, ears, and nose; and ...
The Cambrian chordates are characterised by the presence of segmented muscle blocks called myomeres and notochord, the two defining features of chordates. Before the full understanding of Cambrian fossils, chordates as members the most advanced phylum were believed to appear on Earth much later than the Cambrian.
On the other hand, fossils of early chordates are very rare, as non-vertebrate chordates have no bone tissue or teeth, and fossils of no Post-Cambrian non-vertebrate chordates are known aside from the Permian-aged Paleobranchiostoma, trace fossils of the Ordovician colonial tunicate Catellocaula, and various Jurassic-aged and Tertiary-aged ...
Vertebrates (12 C, 2 P) Ι. Chordate images (2 C, 15 F) Σ. Chordate stubs (2 C, 10 P) Pages in category "Chordates" The following 5 pages are in this category, out ...
Haeckel's Paleontological Tree of Vertebrates (c. 1879). The evolutionary history of species has been described as a " tree " with many branches arising from a single trunk. While Haeckel's tree is outdated, it illustrates clearly the principles that more complex and accurate modern reconstructions can obscure.
The taxonomy of the vertebrates presented by John Zachary Young in The Life of Vertebrates (1962) [1] is a system of classification with emphasis on this group of animals. Phylum Chordata [ edit ]