脊椎動物

関: Vertebrata、vertebrate

WordNet

having a backbone or spinal column; "fishes and amphibians and reptiles and birds and mammals are verbetrate animals"
animals having a bony or cartilaginous skeleton with a segmented spinal column and a large brain enclosed in a skull or cranium (同)craniate
fishes; amphibians; reptiles; birds; mammals (同)subphylum Vertebrata, Craniata, subphylum Craniata

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脊椎(せきつい)動物 / 背骨のある;脊椎動物の

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2017/03/29 14:40:38」(JST)

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A craniate is a member of the Craniata (sometimes called the Craniota), a proposed clade of chordate animals with a skull of hard bone or cartilage. Included in the clade are the vertebrates, and non-vertebrate chordates with skulls. Living representatives are the Myxini (hagfishes), Hyperoartia (including lampreys), and the much more numerous Gnathostomata (jawed vertebrates).^[2]^[3]

The clade was conceived largely on the basis of the Hyperoartia (lampreys and kin) being more closely related to the Gnathostomata (jawed vertebrates) than the Myxini (hagfishes); this suggested that the skull is more ancient feature than the vertebral column, and that the Myxini were descended from a more ancient lineage than the vertebrates. However recent studies using molecular phylogenetics has contradicted this view, with evidence that the Cyclostomata (Hyperoartia and Myxini) is monophyletic; this suggests that the Myxini are degenerate vertebrates, and therefore the vertebrates and craniates are cladistically equivalent, at least for the living representatives.

Characteristics

In the simplest sense, craniates are chordates with well defined heads, thus excluding members of the chordate subphyla Tunicata (tunicates) and Cephalochordata (lancelets), but including Myxini, which have cartilaginous skulls and tooth-like structures composed of keratin. Craniata also includes all lampreys and armored jawless fishes, armoured fish, sharks, skates, and rays, and teleostomians: spiny sharks, bony fish, lissamphibians, temnospondyls and protoreptiles, sauropsids and mammals. The craniate head consists of a brain, sense organs, including eyes, and a skull.^[4]^[5]

In addition to distinct crania (sing. cranium), craniates possess many derived characteristics, which have allowed for more complexity to follow. Molecular-genetic analysis of craniates reveals that, compared to less complex animals, they developed duplicate sets of many gene families that are involved in cell signaling, transcription, and morphogenesis (see homeobox).^[2]

In general, craniates are much more active than tunicates and lancelets and, as a result, have greater metabolic demands, as well as several anatomical adaptations. Aquatic craniates have gill slits, which are connected to muscles and nerves that pump water through the slits, engaging in both feeding and gas exchange (as opposed to lancelets, whose pharyngeal slits are used only for suspension feeding). Muscles line the alimentary canal, moving food through the canal, allowing higher craniates such as mammals to develop more complex digestive systems for optimal food processing. Craniates have cardiovascular systems that include a heart with two or more chambers, red blood cells, and oxygen transporting hemoglobin, as well as kidneys.^[2]

Systematics and taxonomy

Linnaeus (1758)^{[verification needed]} used the terms Craniata and Vertebrata interchangeably to include lampreys, jawed fishes, and terrestrial vertebrates (pr tetrapods). Hagfishes were classified as Vermes, possibly representing a transitional form between 'worms' and fishes.

Dumeril (1806) grouped hagfishes and lampreys in the taxon Cyclostomi, characterized by horny teeth borne on a tongue-like apparatus, a large notochord as adults, and pouch-shaped gills (Marspibranchii). Cyclostomes were regarded as either degenerate cartilaginous fishes or primitive vertebrates. Cope (1889) coined the name Agnatha ("jawless") for a group that included the cyclostomes and a number of fossil groups in which jaws could not be observed. Vertebrates were subsequently divided into two major sister-groups: the Agnatha and the Gnathostomata (jawed vertebrates). Stensiö (1927) suggested that the two groups of living agnathans (i.e. the cyclostomes) arose independently from different groups of fossil agnathans.

Løvtrup (1977) argued that lampreys are more closely related to gnathostomes based on a number of uniquely derived characters, including:

Arcualia (serially arranged paired cartilages above the notochord)
Extrinsic eyeball muscles
Radial muscles in the fins
A closely set atrium and ventricle of the heart
Nervous regulation of the heart by the vagus nerve
A typhlosole (a spirally coiled valve of the intestinal wall)
True lymphocytes
A differentiated anterior lobe of the pituitary gland (adenohypophysis)
Three inner ear maculae (patches of acceleration sensitive 'hair cells' used in balance) organized into two or three vertical semicircular canals
Neuromast organs (composed of vibration sensitive hair cells) in the laterosensory canals
An electroreceptive lateral line (with voltage sensitive hair cells)
Electrosensory lateral line nerves
A cerebellum, i.e. a the multi-layered roof of the hindbrain with unique structure (characteristic neural architecture including direct inputs from the lateral line and large output Purkinje cells) and function (integrating sensory perception and coordinating motor control)

In other words, the cyclostome characteristics (e.g. horny teeth on a "tongue", gill pouches) are either instances of convergent evolution for feeding and gill ventilation in animals with an eel-like body shape, or represent primitive craniate characteristics subsequently lost or modified in gnathostomes. On this basis Janvier (1978) proposed to use the names Vertebrata and Craniata as two distinct and nested taxa.

Validity

The validity of the taxon "Craniata" was recently examined by Delarbre et al. (2002) using mtDNA sequence data, concluding that Myxini is more closely related to Hyperoartia than to Gnathostomata - i.e., that modern jawless fishes form a clade called Cyclostomata. The argument is that, if Cyclostomata is indeed monophyletic, Vertebrata would return to its old content (Gnathostomata + Cyclostomata) and the name Craniata, being superfluous, would become a junior synonym.

The new evidence removes support for the hypothesis for the evolutionary sequence by which (from among tunicate-like chordates) first the hard cranium arose as it is exhibited by the hagfishes, then the backbone as exhibited by the lampreys, and then finally the hinged jaw that is now ubiquitous. In 2010, Philippe Janvier stated:

Although I was among the early supporters of vertebrate paraphyly, I am impressed by the evidence provided by Heimberg et al. and prepared to admit that cyclostomes are, in fact, monophyletic. The consequence is that they may tell us little, if anything, about the dawn of vertebrate evolution, except that the intuitions of 19th century zoologists were correct in assuming that these odd vertebrates (notably, hagﬁshes) are strongly degenerate and have lost many characters over time.^[6]

Classification

Cladogram of the Chordate phylum. Lines show probable evolutionary relationships, including extinct taxa, which are denoted with a dagger, †. Some are invertebrates. The positions (relationships) of the Lancelet, Tunicate, and Craniata clades are as reported^[7] in the scientific journal Nature. Note that this cladogram, in showing the extant cyclostomes (hagfish and lamprey) as paraphyletic, is contradicted by nearly all recent molecular data, which support the monophyly of the extant cyclostomes (see Ota and Kurakani 2007 and references therein for a review of evidence).^[8]

olfactores

Tunicata

Craniata

Myxini

Vertebrata

†Myllokunmingia fengjiaoa

†Zhongjianichthys rostratus

Conodonta†

Cephalaspidomorphi†

Hyperoartia (Petromyzontida)(Lampreys)

Pteraspidomorphi†

Osteostraci†

Gnathostomata

Placodermi† (?paraphyletic)

Chondrichthyes

Teleostomi

	Actinopterygii

	Sarcopterygii

Notes

^ Nielsen, C. (July 2012). "The authorship of higher chordate taxa". Zoologica Scripta. 41 (4): 435–436. doi:10.1111/j.1463-6409.2012.00536.x.
^ ^a ^b ^c Campbell & Reece 2005 p. 676
^ Cracraft & Donoghue 2004 p. 390
^ Campbell & Reece 2005 pp. 675-7
^ Parker & Haswell 1921
^ "MicroRNAs revive old views about jawless vertebrate divergence and evolution." Proceedings of the National Academy of Sciences (USA) 107:19137-19138. [1]
^ Putnam, N. H.; Butts, T.; Ferrier, D. E. K.; Furlong, R. F.; Hellsten, U.; Kawashima, T.; Robinson-Rechavi, M.; Shoguchi, E.; Terry, A.; Yu, J. K.; Benito-Gutiérrez, E. L.; Dubchak, I.; Garcia-Fernàndez, J.; Gibson-Brown, J. J.; Grigoriev, I. V.; Horton, A. C.; De Jong, P. J.; Jurka, J.; Kapitonov, V. V.; Kohara, Y.; Kuroki, Y.; Lindquist, E.; Lucas, S.; Osoegawa, K.; Pennacchio, L. A.; Salamov, A. A.; Satou, Y.; Sauka-Spengler, T.; Schmutz, J.; Shin-i, T. (19 June 2008). "The amphioxus genome and the evolution of the chordate karyotype". Nature. 453 (7198): 1064–1071. Bibcode:2008Natur.453.1064P. doi:10.1038/nature06967. PMID 18563158.
^ Ota, K. G.; Kuratani, S. (September 2007). "Cyclostome embryology and early evolutionary history of vertebrates". Integrative and Comparative Biology. 47 (3): 329–337. doi:10.1093/icb/icm022. PMID 21672842.

References

Campbell, Neil A.; Reece, Jane B. (2005). Biology, Seventh Edition. San Francisco CA: Benjamin Cummings.
Cleveland P. Hickman, J., Roberts, L. S., Keen, S. L., Larson, A. & Eisenhour, D. J. (2007). Animal Diversity, Fourth Edition. New York: McGraw Hill.
Cracraft, Joel; Donoghue, Michael J. (2004). Assembling the Tree of Life. New York: Oxford University Press US. ISBN 978-0-19-517234-8.
Delarbre, Christiane; Gallut, C; Barriel, V; Janvier, P; Gachelin, G; et al. (2002). "Complete Mitochondrial DNA of the Hagfish, Eptatretus burgeri: The Comparative Analysis of Mitochondrial DNA Sequences Strongly Supports the Cyclostome Monophyly". Molecular Phylogenetics and Evolution. 22 (2): 184–192. doi:10.1006/mpev.2001.1045. PMID 11820840.
Parker, T. J.; Haswell, W. A. (1921). A Text-book of Zoology. Macmillan & Co.

English Journal

Genetic lineage labeling in zebrafish uncovers novel neural crest contributions to the head, including gill pillar cells.

Mongera A, Singh AP, Levesque MP, Chen YY, Konstantinidis P, Nüsslein-Volhard C.Author information Max-Planck-Institut für Entwicklungsbiologie, 72076 Tübingen, Germany. alessandro.mongera@tuebingen.mpg.deAbstractAt the protochordate-vertebrate transition, a new predatory lifestyle and increased body size coincided with the appearance of a true head. Characteristic innovations of this head are a skull protecting and accommodating a centralized nervous system, a jaw for prey capture and gills as respiratory organs. The neural crest (NC) is a major ontogenetic source for the 'new head' of vertebrates and its contribution to the cranial skeleton has been intensively studied in different model organisms. However, the role of NC in the expansion of the respiratory surface of the gills has been neglected. Here, we use genetic lineage labeling to address the contribution of NC to specific head structures, in particular to the gills of adult zebrafish. We generated a sox10:ER(T2)-Cre line and labeled NC cells by inducing Cre/loxP recombination with tamoxifen at embryonic stages. In juvenile and adult fish, we identified numerous established NC derivatives and, in the cranium, we precisely defined the crest/mesoderm interface of the skull roof. We show the NC origin of the opercular bones and of multiple cell types contributing to the barbels, chemosensory organs located in the mouth region. In the gills, we observed labeled primary and secondary lamellae. Clonal analysis reveals that pillar cells, a craniate innovation that mechanically supports the filaments and forms gill-specific capillaries, have a NC origin. Our data point to a crucial role for the NC in enabling more efficient gas exchange, thus uncovering a novel, direct involvement of this embryonic tissue in the evolution of respiratory systems at the protochordate-vertebrate transition.
Development (Cambridge, England).Development.2013 Feb;140(4):916-25. doi: 10.1242/dev.091066.
At the protochordate-vertebrate transition, a new predatory lifestyle and increased body size coincided with the appearance of a true head. Characteristic innovations of this head are a skull protecting and accommodating a centralized nervous system, a jaw for prey capture and gills as respiratory o
PMID 23362350

Evolution of the axial system in craniates: morphology and function of the perivertebral musculature.

Schilling N.Author information Institute of Systematic Zoology and Evolutionary Biology, Friedrich-Schiller-University Jena, Germany. nadja.schilling@uni-jena.de.Abstract The axial musculoskeletal system represents the plesiomorphic locomotor engine of the vertebrate body, playing a central role in locomotion. In craniates, the evolution of the postcranial skeleton is characterized by two major transformations. First, the axial skeleton became increasingly functionally and morphologically regionalized. Second, the axial-based locomotion plesiomorphic for craniates became progressively appendage-based with the evolution of extremities in tetrapods. These changes, together with the transition to land, caused increased complexity in the planes in which axial movements occur and moments act on the body and were accompanied by profound changes in axial muscle function. To increase our understanding of the evolutionary transformations of the structure and function of the perivertebral musculature, this review integrates recent anatomical and physiological data (e.g., muscle fiber types, activation patterns) with gross-anatomical and kinematic findings for pivotal craniate taxa. This information is mapped onto a phylogenetic hypothesis to infer the putative character set of the last common ancestor of the respective taxa and to conjecture patterns of locomotor and muscular evolution. The increasing anatomical and functional complexity in the muscular arrangement during craniate evolution is associated with changes in fiber angulation and fiber-type distribution, i.e., increasing obliqueness in fiber orientation and segregation of fatigue-resistant fibers in deeper muscle regions. The loss of superficial fatigue-resistant fibers may be related to the profound gross anatomical reorganization of the axial musculature during the tetrapod evolution. The plesiomorphic function of the axial musculature -mobilization- is retained in all craniates. Along with the evolution of limbs and the subsequent transition to land, axial muscles additionally function to globally stabilize the trunk against inertial and extrinsic limb muscle forces as well as gravitational forces. Associated with the evolution of sagittal mobility and a parasagittal limb posture, axial muscles in mammals also stabilize the trunk against sagittal components of extrinsic limb muscle action as well as the inertia of the body's center of mass. Thus, the axial system is central to the static and dynamic control of the body posture in all craniates and, in gnathostomes, additionally provides the foundation for the mechanical work of the appendicular system.
Frontiers in zoology.Front Zool.2011 Feb 10;8(1):4. doi: 10.1186/1742-9994-8-4.
The axial musculoskeletal system represents the plesiomorphic locomotor engine of the vertebrate body, playing a central role in locomotion. In craniates, the evolution of the postcranial skeleton is characterized by two major transformations. First, the axial skeleton became increasingly functional
PMID 21306656

The long adventurous journey of rhombic lip cells in jawed vertebrates: a comparative developmental analysis.

Wullimann MF, Mueller T, Distel M, Babaryka A, Grothe B, Köster RW.Author information Graduate School of Systemic Neurosciences and Department Biology II, Ludwig-Maximilians-Universität Munich Planegg, Germany.AbstractThis review summarizes vertebrate rhombic lip and early cerebellar development covering classic approaches up to modern developmental genetics which identifies the relevant differential gene expression domains and their progeny. Most of this information is derived from amniotes. However, progress in anamniotes, particularly in the zebrafish, has recently been made. The current picture suggests that rhombic lip and cerebellar development in jawed vertebrates (gnathostomes) share many characteristics. Regarding cerebellar development, these include a ptf1a expressing ventral cerebellar proliferation (VCP) giving rise to Purkinje cells and other inhibitory cerebellar cell types, and an atoh1 expressing upper rhombic lip giving rise to an external granular layer (EGL, i.e., excitatory granule cells) and an early ventral migration into the anterior rhombencephalon (cholinergic nuclei). As for the lower rhombic lip (LRL), gnathostome commonalities likely include the formation of precerebellar nuclei (mossy fiber origins) and partially primary auditory nuclei (likely convergently evolved) from the atoh1 expressing dorsal zone. The fate of the ptf1a expressing ventral LRL zone which gives rise to (excitatory cells of) the inferior olive (climbing fiber origin) and (inhibitory cells of ) cochlear nuclei in amniotes, has not been determined in anamniotes. Special for the zebrafish in comparison to amniotes is the predominant origin of anamniote excitatory deep cerebellar nuclei homologs (i.e., eurydendroid cells) from ptf1a expressing VCP cells, the sequential activity of various atoh1 paralogs and the incomplete coverage of the subpial cerebellar plate with proliferative EGL cells. Nevertheless, the conclusion that a rhombic lip and its major derivatives evolved with gnathostome vertebrates only and are thus not an ancestral craniate character complex is supported by the absence of a cerebellum (and likely absence of its afferent and efferent nuclei) in jawless fishes.
Frontiers in neuroanatomy.Front Neuroanat.2011 Apr 21;5:27. doi: 10.3389/fnana.2011.00027. eCollection 2011.
This review summarizes vertebrate rhombic lip and early cerebellar development covering classic approaches up to modern developmental genetics which identifies the relevant differential gene expression domains and their progeny. Most of this information is derived from amniotes. However, progress in
PMID 21559349

Japanese Journal

Hagfish Conservation Needed in Taiwan

黒潮圏科学 5(1), 29-32, 2011-03
NAID 40019151963

Generation of prolactin-like neurons in the dorsal strand of ascidians

Zoological science 27(7), 581-588, 2010-07
NAID 40017358617

An early Cambrian craniate-like chordate

Nature 402, 518-522, 1999
NAID 80010786340

Related Pictures

★リンクテーブル★

リンク元	「Vertebrata」「vertebrate」

「Vertebrata」

Craniata; Temporal range: Early Cambrian - Recent PreЄ Є O S D C P T J K Pg N
	A Pacific hagfish, an example of a craniate
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Craniata; Lankester, 1877
Subphyla
	Myxini (hagfishes); Vertebrata Hyperoartia (lampreys) (disputed vertebrates); Cephalaspidomorphi (disputed vertebrates); ;
Synonyms
	Craniota Haeckel, 1866; Pachycardia Haeckel, 1866;