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Invertebrate paleontology (also spelled Invertebrate palaeontology) is sometimes described as Invertebrate paleozoology or Invertebrate paleobiology. Whether it is considered to be a subfield of paleontology, paleozoology, or paleobiology, this discipline is the scientific study of prehistoric invertebrates by analyzing invertebrate fossils in the geologic record. By ''invertebrates'' are meant the ''non-vertebrate'' creatures of the kingdom Animalia (or Metazoa) in the biotic domain of Eukaryota. By phyletic definition, these many-celled, ''sub-vertebrate'' animals lack a vertebral column, spinal column, vertebrae, backbone, or long, full-length notochord -- in contrast, of course, to the vertebrates in the one phylum of Chordata. Relatedly, invertebrates have never had a cartilaginous or boney internal skeleton, with its skeletal supports, gill slits, ribs and jaws. Finally, throughout geologic time, invertebrates have remained non-craniate creatures; that is, they never developed a cranium, nerve-chord brain, skull, or hard protective braincase (unlike many vertebrates). ==Invertebrate terminology in science== In the many decades since Jean-Baptiste de Lamarck, a pioneering biologist and evolutionist, first conceptualized and coined the category "Invertebrata" (between 1793 and 1801) and the term "Biology" (in 1802), zoology has come to recognize that the ''non-vertebrate'' category is not a scientifically valid, monophyletic taxon. Evolutionary biology and developmental biology (a.k.a. "evo-devo") now consider the term "Invertebrata" to be both polyphyletic and paraphyletic. Nevertheless, most earth science departments continue to employ this term; and paleontologists find it both useful and practical in evaluating fossil invertebrates and—consequently -- invertebrate evolution. However, there is one contemporary caveat: Paleobiologists and microbiologists in the 21st century no longer classify one-celled "animal-like" microbes ''either'' as invertebrates ''or'' as animals. For example, the commonly fossilized foraminifera ("forams") and radiolarians -- zooplankton both formerly grouped under either an animal phylum or animal sub-kingdom called Protozoa ("first animals") -- are now placed in the kingdom or super-kingdom Protista or Protoctista (and thus called ''protists'' or ''protoctists''). Thus modern invertebrate paleontologists deal largely with fossils of this more strictly defined Animal Kingdom (excepting Phylum Chordata), Phylum Chordata being the exclusive focus of vertebrate paleontology. Protist fossils are then the main focus of micropaleontology, while plant fossils are the chief focus paleobotany. Together these four represent the traditional taxonomic divisions of paleontologic study. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Invertebrate paleontology」の詳細全文を読む スポンサード リンク
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