摘要:

Dimensions of dinosaur bones and of models of dinosaurs have been used as the basis for calculations designed to throw light on the posture and gaits of dinosaurs.Estimates of the masses of some dinosaurs, obtained from the volumes of models, are compared with previous estimates. The positions of dinosaurs' centres of mass, derived from models, show that some large quadrupedal dinosaurs supported most of their weight on their hind legs and were probably capable of rearing up on their hind legs.Distributions of bending moments along the backs of large dinosaurs are derived from measurements on models. The tensions required in epaxial muscles to enableDiplodocusto stand are calculated. It is likely that the long neck of this dinosaur was supported by some structure running through the notches in the neural spines of its cervical and dorsal vertebrae. The nature of this hypothetical structure is discussed.An attempt is made to reconstruct the walking gait of sauropod dinosaurs, from the pattern of footprints in fossil tracks.The dimensions of dinosaur leg bones are compared to predictions for mammals of equal body mass, obtained by extrapolation of allometric equations. Their dimensions are also used to calculate a quantity which is used as an indicator of strength in bending. Comparisons with values for modern animals lead to speculations about the athletic performance of dinosaurs.Estimates of pressures exerted on the ground by the feet of dinosaurs are used in a discussion of the ability of dinosaurs to walk over soft ground.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1985.tb00871.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Relationships within the freeliving marine nematode family Comesomatidae and the systematic position of the Comesomatidae are discussed. Composite pictures representing all valid comesomatid genera are provided as an aid to identification. Of the 73 nominalSabatieriaspecies extant prior to this revision: six were already consideredspecies dubiae, to which is added a further 14 based on insufficient original description; one is transferred to another genus; nine are synonymized with previously described species; seven are consideredspecies inquirendae, to which is added a new species previously described under another name; two possess synapomorphic features warranting recognition as a separate genus,Setosabatieriagen. nov.; 34 are considered validSabatieriaspecies and two previously synonymized species are reinstated. Pictorial keys and tabular information are provided to facilitate species identification. Several other minor taxonomic changes are proposed.

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1985.tb00872.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The defining morphological characters of the family Elapidae are analysed in an attempt to evaluate whether the front‐fanged, proteroglyphous, snakes constitute a natural (monophyletic) group or whether proteroglyphy is more likely to be a condition achieved independently by a number of higher snake lineages. The evidence relating to presumed elapids whose affinities have been questioned, namely a South African genusHomoroselapsand New World proteroglyphs(MicrurusandMicruroides), is examined. It concluded thatHomoroselapsis a genuinely equivocal case, the evidence for its inclusion in the Elapidae is balanced by features which suggest that it is more closely related to the Aparallactinae. However,MicrurusandMicruroidesseem clearly to be more closely related to undisputed elapids than to any other caenophidians. It is suggested that, at least for the present, the family Elapidae be retained in its broad sense to include all proteroglyphous snake

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1985.tb00873.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

ISSN:0024-4082    

DOI:10.1111/j.1096-3642.1985.tb00871a.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY