摘要:

Carnian (Upper Triassic) fishes from Polzberg bei Lunz have been known since 1886 but no comprehensive account has been published. Eleven species are described nine of which,Saurichthys calcaratus, Polzbergia brochatus, Peltopleurus dirumptus, Habroichthys gregarius, Nannolepis elegans, Phaidrosoma lunzensis, Elpistoichthys pectinatus, E. striolatusandPholidophoretes salvusare new, and two others,Thoracopterus niederristiBronn andGigantopterus telleriAbel, previously little‐known.New supraspecific taxa defined are:the order Polzbergiiformes, the family Thoracopteridae and the generaPolzbergia, Nannolepis, Phaidrosoma, ElpistoichthysandPholidophoretes.Habroichthys, Thoracopterus, GigantopterusandNannolepisshow an unusual skull‐roof pattern and are included in the re‐defined order Luganoiiformes.Two new ichthyokentemids considerably extend the known time‐range of this family.The genusPholidophoretesis intermediate between the Archaeomenidae Goodrich 1909, and the Pholidophoridae sensu stricto Nybelin 1966.The Polzberg assemblage was probably mainly marine with a small freshwater contribution; it shows less similarity to the Besano and Raibl assemblages than these do to each other.The Luganoiiformes are probably, but not certainly, monophyletic; relationships within the order are analyzed and a cladogram constructed.The Platysiagiformes, Peltopleuriformes, Luganoiiformes and Cephaloxeniformes could all have been derived from a common ancestor at thePerleiduslevel and are probably offshoots of the perleidid ra

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1977.tb00834.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The functional morphology of deposit feeding relative to proboscideal morphology of the maldanid polychaetesAxiothella rubrocincta(Johnson, 1901),Clymenella californicaBlake&Kudenov, 1974, andPraxillella affinis pacifica(Berkeley, 1929) from central California is presented. The proboscides of these species are externally and internally similar. They consist of a cuticulatized buccal mass, a bucco‐pharyngeal junction and ciliated pharynx. A functional unit of the feeding process is the palpode because its secretions enable the proboscis to be effectively everted. These worms exploit die physical properties of the substratum by changing its dilatancy (and thixotropy) while feeding. The rapidly emerging buccal mass increases the dilatancy of the sediment and provides a penetration anchor. The buccal mass partially deflates and loosens the substratum just prior to the forceful extrusion of the bucco‐pharyngeal junction. Sediment about the latter region becomes dilatant. The proboscis then shortens and widens, causing the substratum about the pharynx to become thixotropic while it becomes dilatant about the region of the proboscis proximal to the pharynx. The worms push their proboscides into the loosened sediment while pharyngeal ciliary currents and the undulating bucco‐pharyngeal margin draw food into the pharynx. Pharyngeal cilia and the buccal mass function in particle selection.The maldanids and arenicolids examined to date share similar and basic proboscideal morphologies and activities. It is suggested that the feeding mechanism described for the maldanids,A. rubrocincta, C. californicaandP. affinis pacifica, will be found in some members of both fam

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1977.tb00835.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The heterogonic development of the three basic divisions of the body (head, thorax and abdomen) ofGryllus domesticus, was studied. The relationships in the linear dimensions of each of these parts with the standard parameter (absolute body length) were established through regression equations and the cephalosomatic, thoraco‐somatic and abdomeno‐somatic ratios. Of the body parts investigated the head was found to be the most heterogonic component followed by the abdomen and the thorax. The heterogonic development in the insect body seemed to be the result of varying intensities of the growth potential of different anatomical locati

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1977.tb00836.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1977.tb00834a.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY