Molecular phylogeny of the protochordates: Chordate evolution.

Protochordate Protochordate, any member of either of two invertebrate subphyla of the phylum Chordata: the Tunicata (sea squirts, salps, etc.) and the Cephalochordata (amphioxus).

Essay on the Introduction to Chordata. Essay on the Origin and Ancestry of Chordata. Essay on the General Characters of Chordata. Essay on the Fundamental Chordate Animals. Essay on the Characters Common to Chordates and Higher Non Chordates. Essay on the Subdivisions of Phylum Chordata.

Molecular phylogeny of the protochordates: chordate.

Nevertheless, the classification of the phylum Chordata and its three sub-phylum system has largely remained unchallenged, although recently a few researchers have come to question this taxonomy.From Wikipedia, the free encyclopedia. Not to be confused with cordate. Example of chordates of four subphylum of lower rank: a Siberian Tiger ( Vertebrata) and a Polycarpa aurata ( Tunicata ), two Olfactores, as well as Ooedigera peeli ( Vetulicolia) and a Branchiostoma lanceolatum ( Cephalochordata ).Kingdom animalia: It includes the entire fauna (animal population) of the world. Subkingdom 1-Protozoa: Unicellular, microscopic animals. Phyum 1: Protozoa (First animals) (i) About 50,000 species, solitory or colonial (ii) Single celled body with single or many nuclei. (iii) Nutrition holozoic, holophytic or saprozoic (iv) Free living, commensal, symbiotic or parasitic.


In the scheme of classification, the animals kingdom is divided first into several majore animal groups called phyla. There are approximately 30 animal phyla currently recognized. The last major group of the animal kingdom is known as phylum chordata. It was created by Balfour in 1880.Classification Of Phylum Chordata into three Sub-Phyla The subphylum Urochordata and Cephalochordata are collectively known as protochordates, which are marine animals. They are invertebrates but they share attributes of chordates.

The origin and ancestory of modern chordates is not very clear and remains obscure. Because their early ancestors most liably were soft bodied and left no definite fossils. The earliest known fossils of truly vertebrate animals were, freshwater forms abundant during the late Silurian and middle devonian periods. Their fossils are collectively known as ostracoderms.

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Traditional metazoan phylogeny classifies the Vertebrata as a subphylum of the phylum Chordata, together with two other subphyla, the Urochordata (Tunicata) and the Cephalochordata. The Chordata, together with the phyla Echinodermata and Hemichordata, comprise a major group, the Deuterostomia.

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Jeffries (1986) provides descriptions and comparisons and argues for the placement of calcichordates near the Chordata. Other workers believe that calcichordates are closer to echinoderms. Reconstructions of these fossil organisms include visceral (pharyngeal or gill) slits that would suggest chordate affinities, but the mineralized skeleton was composed of calcite, like echinoderms, not bone.

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ANNELID THEORY-ORIGIN OF CHORDATES: This theory suggests that the chordates have evolved from an annelid stock. The annelids show bilateral symmetry, mesmerism, head, lateral Coelome complete digestive tract, closed circulatory system, hemoglobin, etc., like chordates. The resemblance is enhanced if, an annelid is turned upside down.

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Classification of Protochordata and Cyclostomata; evolution, affinities and phylogeny of protochordates. Structure, function and life histories of Pyrosoma, Doliolum, Salpa and Oikopleura. Evolution and affinities of Cyclostomata. Unit 2 Classification, origin, evolution and deep sea adaptations in fishes, Parental care.

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Start studying Chapter 2 Phylogenetic Relationships of Chordates and Craniates. Learn vocabulary, terms, and more with flashcards, games, and other study tools.

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Origin of chordates Chordates evolved sometime during Cambrian period, 500 million years ago during Cambrian explosion, almost at the same time when invertebrates were beginning to evolve. They may have evolved from some freshwater forms as Chamberlain (1900) pointed out that all modern chordates possess glomerular kidneys that are designed to remove excess water from body.

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Looking for Protochordate? Find out information about Protochordate. any animal of the phylum Chordata, including the vertebrates and protochordates, characterized by a notochord, dorsal tubular nerve cord, and pharyngeal.

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Protochordates are an informal category of animals (i.e.: not a proper taxonomic group), named mainly for convenience to describe invertebrate animals that are closely related to vertebrates. This group is composed of the Phylum Hemichordata and the Subphyla Urochordata and Cephalochordata.

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