Before the Backbone: Views on the origin of the vertebratesWe cannot catechise our stony ichthyolites, as did the necromantic lady of the Arabian Nights did the coloured fishes of the lake which had once been a city, when she touched their dead bodies with her wand, and they straightaway raised their heads and rephed to her queries. We would have many a question to ask them if we could - questions never to be solved. Hugh Miller, The Old Red Sandstone When I started this book in 1991, the subject of vertebrate origins was fusty and unfashionable. Early drafts for this preface read like an extend ed complaint at the lot of traditional morphologists, cast aside by the march of modern molecular biology. But no longer - this book should reach you at a time of renewed inter est in the origin of the vertebrates, our own particular corner of creation. For although the topic has excited interest for well over a century, molec ular biology has only lately achieved the maturity necessary to test its predictions. As a legitimate field of study, it is fashionable again. |
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Page 7
... derived from any embryonic tissue abut either the inside of the body wall or the outside of the gut , and are excluded from direct contact with the coelom by a sheet of mesoderm called the peri- toneum . Some animals have body cavities ...
... derived from any embryonic tissue abut either the inside of the body wall or the outside of the gut , and are excluded from direct contact with the coelom by a sheet of mesoderm called the peri- toneum . Some animals have body cavities ...
Page 11
... derived features to exclude protostomes . In conclusion , the protostomes do not form a natural group : they are simply those coelomate triploblasts left over once deuteros- tomes are excluded . Such remnant groups are termed ...
... derived features to exclude protostomes . In conclusion , the protostomes do not form a natural group : they are simply those coelomate triploblasts left over once deuteros- tomes are excluded . Such remnant groups are termed ...
Page 14
... derived characters . From this concept the ideas of paraphyletic and monophyletic groups arise quite naturally . Groups defined on the basis of shared , primitive characters can be paraphyletic , whereas those associated on the basis of ...
... derived characters . From this concept the ideas of paraphyletic and monophyletic groups arise quite naturally . Groups defined on the basis of shared , primitive characters can be paraphyletic , whereas those associated on the basis of ...
Page 15
... derived charac- ters , and not on primitive ones ( an important distinction between cladis- tics and traditional ... derived feature . Alternatively , the loss of the feature by the second species could be the derived condition : in ...
... derived charac- ters , and not on primitive ones ( an important distinction between cladis- tics and traditional ... derived feature . Alternatively , the loss of the feature by the second species could be the derived condition : in ...
Page 16
... derived characters that all chordates share , and which can be used to distinguish them from other animals , even other deuterostomes ? • All chordates have , at some point in their life cycle , a stiffening rod of mesodermally derived ...
... derived characters that all chordates share , and which can be used to distinguish them from other animals , even other deuterostomes ? • All chordates have , at some point in their life cycle , a stiffening rod of mesodermally derived ...
Contents
The origins of vertebrates | 84 |
Head to head | 160 |
Jefferies Calcichordate Theory | 201 |
Conclusions | 287 |
References | 305 |
Index | 337 |
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Common terms and phrases
adult amphioxus anatomy ancestor ancestry animal annelids anus appendage arthropods ascidians Berrill Berrill's bilateral body brain branchial brates calcichordate calcichordate theory calcite calcite skeleton Cambrian carpoids cells cephalochordates Cephalodiscus Ceratocystis chordates ciliated cladistics cluster coelom conodont cornutes and mitrates Cothurnocystis craniates creatures crinoids deuterostomes dexiothetism dorsal Drosophila echinoderms embryo endostyle enteropneusts evidence evolution evolutionary evolved expression Figure fossil function Garstang Gaskell Gaskell's genetic gill slits Gislén hagfishes head hemichordates Holland homeobox genes homologous Hox genes hydrocoel ideas interpretation Jefferies Lagynocystis lampreys larva lophophore mesoderm metazoan modern molecular morphological mouth muscles neoteny nerve cord nervous system neural crest notochord ontogeny Ordovician organs origin of vertebrates paedomorphosis pharynx phylogenetic phylogeny plates posterior primitive protostomes pterobranchs recapitulation reconstruction segmentation sessile somatocoel somites species stele stem structures suggests symmetry tadpole larva tail theca tion tissue tunicate tadpole urochordates ventral verte vertebrate origins vertebrates visceral water-vascular system
Popular passages
Page 160 - Fillet of a fenny snake, In the cauldron boil and bake ; Eye of newt and toe of frog, Wool of bat and tongue of dog...
Page 84 - My story being done, She gave me for my pains a world of sighs : She swore, in faith, 'twas strange, 'twas passing strange ; 'Twas pitiful, 'twas wondrous pitiful...
Page 88 - According to my opinion the proboscis of the Nemerteans, which arises as an invaginable structure (entirely derived, both phylo- and ontogenetically, from the epiblast), and which passes through a part of the cerebral ganglion, is homologous with the rudimentary organ which is found in the whole series of Vertebrates without exception — the hypophysis cerebri. The proboscidian sheath of the Nemerteans is comparable in situation (and development?) with the chorda dorsalis of Vertebrates.
Page 336 - PA (1993). Reversal of left-right asymmetry: A situs inversus mutation. Science 260, 679-682.
Page 309 - Peel, JS (1995) Articulated halkieriids from the Lower Cambrian of North Greenland and their role in early protostome evolution. Philosophical Transactions of the Royal Society of London, B, 347, 305-358 Corbin, V, Michelson, AM, Abmayr, SM, Neel, V, Alcamo, E., Maniatis, T.
Page 317 - Graham, A., Heyman, I. and Lumsden, A. (1993). Even-numbered rhombomeres control the apoptotic elimination of neural crest cells from odd-numbered rhombomeres in the chick hindbrain. Development, 119, 233-245.
Page 309 - Molecular nature of Spemann's organizer: The role of the Xenopus homeobox gene goosecoid. Cell 67, 1111-1120.