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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 .
Chordate genomics is the study of the evolution of the chordate clade based on a comparison of the genomes of several species within the clade. The field depends on whole genome data (the entire DNA sequence ) of organisms.
The calcichordate family tree in its original incarnation, with all chordates originating from a soft bodied ancestor. Later versions of the theory had each chordate group having a mitrate ancestor each, requiring three episodes of loss of stereom. Mitrates are assumed to have evolved from the cornutes. [6]
Imaginary cladogram. [2] The yellow mask is a plesiomorphy for each living masked species, because it is ancestral. [2] It is also a symplesiomorphy for them. But for the four living species as a whole, it is an apomorphy because it is not ancestral for all of them. The yellow tail is a plesiomorphy and symplesiomorphy for all living species.
The fin-limbs of lobe-finned fish such as the coelacanths show a strong similarity to the expected ancestral form of tetrapod limbs. The lobe-finned fish apparently followed two different lines of development and are accordingly separated into two subclasses, the Rhipidistia (including the lungfish, and the Tetrapodomorpha , which include the ...
Harvard University palaeontologist Stephen Jay Gould popularised Pikaia as an ancestral species of chordates in his 1989 book Wonderful Life: The Burgess Shale and the Nature of History, [13] from which Pikaia became known as the "most famous early chordate fossil," [14] or the earliest chordate, [15] or the oldest ancestor of humans. [16] [17]
Chordata: Subphylum: Cephalochordata Haeckel, ... Family Branchiostomatidae Bonaparte 1846. ... The cladogram presented here illustrates the phylogeny ...
Order Pterocliformes, sandgrouse (this enigmatic group was traditionally treated as a family in any of three different orders: Charadriiformes, Ciconiiformes, and Columbiformes) Order Columbiformes, doves, pigeons and dodos; Order Psittaciformes, parrots and allies; Order Cuculiformes, cuckoos; Order Strigiformes, owls