Chordate

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Chordates Fossil range: Latest Ediacaran - Recent
Image:Tuna.jpg Yellowfin tuna, Thunnus albacares
Scientific classification
Domain: Eukaryota Kingdom: Animalia Subkingdom: Eumetazoa (unranked) Bilateria Superphylum: Deuterostomia Phylum: Chordata Bateson, 1885
Typical Classes
See below

Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates. They are united by having, at some time in their life, a notochord, a hollow dorsal nerve cord, pharyngeal slits, an endostyle, and a muscular tail extending past the anus. Some scientists argue that the true qualifier should be pharyngeal pouches rather than slits.^{[citation needed]}

The phylum Chordata is broken down into three subphyla: Urochordata, Cephalochordata, and Vertebrata. Urochordate larvae have a notochord and a nerve cord but they are lost in adulthood. Cephalochordates have a notochord and a nerve cord but no vertebrae. In all vertebrates except for Hagfish, the dorsal hollow nerve cord has been surrounded with cartilaginous or bony vertebrae and the notochord generally reduced.

The chordates and two sister phyla, the hemichordates and the echinoderms, make up the deuterostomes, a superphylum.

The extant groups of chordates are related as shown in the phylogenetic tree below. Many of the taxa listed do not match traditional classes because several of those classes are paraphyletic. Different attempts to organize the profusion of chordate clades into a small number of groups, some with and some without paraphyletic taxa, have thrown vertebrate classification into a state of flux. Also, the relationships of some chordate groups are not very well understood.

Chordates all have:(1)a notochord atleast at one point in their life(2)a tail that extends farther than their anus(3) and a backbone. The chordata phylum contains vertebrates and invertebrates. The animals you are most familiar with are probably in the Chordata phylum. ( cat, dog, hamster, and monkeys)

Classification

Taxonomy

• Phylum Chordata
  • Subphylum Urochordata - Tunicates
  • Subphylum Cephalochordata - Lancelets
  • Subphylum Vertebrata (Vertebrates - animals with backbones)
    • Infraphylum Agnatha (jawless vertebrates)
      • Class Myxini or Hyperotreti (hagfish)
      • Class Conodonta (Conodonts)
      • Class Hyperoartia (Lampreys)
      • Class Cephalaspidomorphi (Paleozoic jawless fish)
      • Class Pteraspidomorphi (Paleozoic jawless fish)
    • Infraphylum Gnathostomata (jawed vertebrates)
      • Class Placodermi (Paleozoic armoured forms)
      • Class Chondrichthyes (cartilaginous fish)
      • Class Acanthodii (Paleozoic "spiny sharks")
      • Superclass Osteichthyes (bony fishes)
        • Class Actinopterygii (ray-finned fish)
        • Class Sarcopterygii (lobe-finned fish)
      • Superclass Tetrapoda (four-legged vertebrates)
        • Class Amphibia (amphibians)
        • Series Amniota (amniotic egg)
          • Class Sauropsida - (reptiles)
          • Class Aves (birds)
          • Class Synapsida (mammal-like "reptiles")
          • Class Mammalia (mammals)

                          |label2= Amniota 
                          |2={{clade
                             |label1= Synapsida 
                             |1=

void	Mammalia

                             |label2= Sauropsida 
                             |2={{clade
                                |label1=void 
                                |1={{clade
                                   |1= Aves

Note: Lines show probable evolutionary relationships, including extinct taxa which are denoted with a dagger, †.

Wikipedia information about Chordate This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Chordate". It may not have been reviewed by professional editors (see full disclaimer). Help contribute to Americola and edit this article.