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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 share these characteristics with other chordates. [4] 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 ...
All chordates except tunicates sport an intricate, closed circulatory system, with highly branched blood vessels. Olfactores , last common ancestor of tunicates and vertebrates in which olfaction (smell) evolved.
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.
This, combined with an apparent lack of vertebral elements within the Myxini, suggested that the Myxini were descended from a more ancient lineage than the vertebrates, and that the skull developed before the vertebral column. The clade was thus composed of the Myxini and the vertebrates, and any extinct chordates with skulls.
The five synapomorphies are pharyngeal slits, a dorsal nerve cord, notochord, endostyle, and the post-anal-tail which is depicted and labeled well on the chordates page. This image is helpful to visualize the regions where the five synapomorphies existed in chordates and what they looked like.
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 ...