摘要:

The fossil record provides no evidence supporting a unique common ancestry for frogs, salamanders and apodans. The ancestors of the modern orders may have diverged fromoneanother as recently as 250 million years ago, or as long ago as 400 million years according to current theories of various authors. In order to evaluate the evolutionary patterns of the modern orders it is necessary to determine whether their last common ancestor was a rhipidistian fish, a very primitive amphibian, a labyrimhodom or a ‘lissamphibian’. The broad cranial similarities of frogs and salamanders, especially the dominance of the braincase as a supporting element, can be associated with the small size of the skull in their immediate ancestors. Hynobiids show the most primitive cranial pattern known among the living salamander families and “provide a model for determining the nature of the ancestors of the entire order. Features expected in ancestral salamanders include: (1) Emargination of the cheek; (2) Movable suspensorium formed by the quadrate, squamosal and pterygoid; (3) Occipital condyle posterior to jaw articulation; (4) Distinct prootic and opisthotic; (5) Absence ol otic notch; (6) Stapes forming a structural link between braincase and cheek. In the otic region, cheek and jaw suspension, the primitive salamander pattern (resembles most closely the microsaurs among known Paleozoic amphibians, and shows no significant features in common with either ancestral frogs or the majority of labyrinth odonts. The basic pattern of the adductor jaw musculature is consistent within both frogs and salamanders, but major differences are evident between the two groups. The dominance of the adductor mandibulae externus in salamanders can be associated with the open cheek in all members of that order, and the small size of this muscle in frogs can be associated with the large otic notch. The spread of different muscles over the otic capsule, the longus head ol the adductor mandibulae posterior in frogs and the superficial head of the adductor mandibulae internus in salamanders, indicates that fenestration of the skull posterodorsal to the orbit occurred separately in the ancestors of the two groups. Reconstruction of the probable pattern of the jaw musculature in Paleozoic amphibians indicates that frogs and salamanders might have evolved from a condition hypothesized for primitive labyrinthodonts, but the presence of a large otic notch in dissorophids suggests specialization toward the anuran, not the urodele condition. The presence of either an einarginated cheek or an embayment of the lateral surface of the dentary and the absence of an otic notch in microsaurs indicate a salamander‐like distribution of die adductor jaw muscles. The ancestors of frogs and salamanders probably diverged from one another in the early Carboniferous, Frogs later evolved from small labyrinthodonts and salamanders from microsaurs. Features considered typical of lissamphibians evolved separately in the two groups in the late Permian andT

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1980.tb01916.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Bile salts from 21 fish species caught during the Zaïre River Expedition (1974–5) have received partial or complete chemical analysis. Conclusions from the results are as follow. (1)Polypterusbile salts are biochemically advanced, but with easily detectable features regarded as relicts from ancestral stock. The bile acids include haemulcholic acid, previously found only in a marine teleost and an unidentified acid also found in a mormyrid. (2) This mormyrid has advanced bile salts, consisting almost entirely of taurine conjugates of haemulcholic acid (present inPolypterus), and two other C24acids. (3) ThreeAlestesand threeDistichodusspecies have no more than traces of primitive bile salts; their bile acids suggest a degree of activity of intestinal microorganisms during the enterohepatic circulation not previously noticed in fishes. (4) The predatoryHydrocynushas bile acids of an omnivorous rather than a carnivorous type. (5) TheBarbusspecies have primitive bile salts closely similar to those of Cyprinidae previously examined but containing also (in two species) a newly‐discovered bile alcohol sulphate: in contrast, aVaricorhinusdoes not have this new substance and has a chief bile salt found so far only as a minor constituent in the Cyprinidae. (6) TwoLabeospecies are different from all other cyprinids examined: diey both have a new major bile alcohol sulphate. (7) Four Siluriformes show evidence of enterohepatic changes that might be characteristic of some tropical freshwater fish; three have taurine‐conjugated haemulcholic acid. (8)Synodontisspecies are remarkable in having a high proportion of unconjugated bile acid ions and this finding was confirmed with fresh ma

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1980.tb01917.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Diagnoses and a key to the genera of the Isopoda Paranthuridae are presented with a discussion of their relationships.MetanthuraandKatanthuraare synonymized withAccalathura, Cruranthurais synonymized withColanthura, and a new genusZulanthurais described. The 80 species known from the family are listed with the distribution of each.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1980.tb01918.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Alfred Merle Norman (1831–1918), an active clergyman in rural Co. Durham, England, came from an ancient Somerset family. He began to study marine biology during the early 1850s and during the 1860s was an important participant in John Gwyn Jeffreys' expeditions to the Shetland Islands. Norman's field collecting all over the British Isles was extensive and he made important trips to Norwegian fjords for dredging. His best known discoveries wereRhabdopleuraandSynagoga, but he published major work on Protozoa, Porifera, Coelenterata, Mollusca, Crustacea, Echinodermata and other invertebrates. The publicationMuseum Normanianumsummarized Norman's collection of 11,086 species, which was acquired by the British Museum (Natural History). His library, which incorporated John Gwyn Jeffreys' library on molluscs, is now in the Department of Zoology, Cambridge University. Norman was primarily a taxonomist secondarily interested in zoogeography who avoided Darwinian controversies.A bibliography of Norman's 218 publications is include

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1980.tb01919.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1980.tb01916a.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY