Digitale Bibliotheek
Sluiten Bladeren door artikelen uit een tijdschrift
 
<< vorige    volgende >>
     Tijdschrift beschrijving
       Alle jaargangen van het bijbehorende tijdschrift
         Alle afleveringen van het bijbehorende jaargang
           Alle artikelen van de bijbehorende aflevering
                                       Details van artikel 5 van 15 gevonden artikelen
 
 
  Functional significance of bone ballastin in the evolution of buoyancy control strategies by aquatic tetrapods
 
 
Titel: Functional significance of bone ballastin in the evolution of buoyancy control strategies by aquatic tetrapods
Auteur: Taylor, Michael A.
Verschenen in: Historical biology
Paginering: Jaargang 14 (2000) nr. 1-2 pagina's 15-31
Jaar: 2000
Inhoud: The primary function of pachyostosis, pachyosteo-sclerosis, and osteosclerosis may be to act as ballast, not so much (as previously suggested) to neutralise the buoyancy of existing lungs, but to allow enlargement of the lungs. Enlarged lungs cause an animal to lose buoyancy more rapidly with depth. They also provide a larger oxygen store. These features are useful for slow swimmers and shallow divers, such as feeders on benthic plants and invertebrates. Examples are sirenians, primitive sauropterygians ("not-hosaurs"), placodonts, and the sea otter Enhydra. These last two show convergent evolution of adaptations to feeding on hard-shelled invertebrate prey in shallow water. Mesosaurids are problematical. Bone ballast uses body mass and volume less efficiently than other buoyancy control strategies. Theoretical analysis predicts that bone ballast should not occur in semiaquatic forms, fast swimmers or deep divers. It does not usually occur in such organisms. Marine iguanas of the Galapagos, desmostylians, and the aquatic sloth Thalassocnus are all littoral feeders and all lack bone ballast as predicted. Plesiosaurs adopted varied strategies: some used bone ballast, and others used gastroliths. Biomechanical considerations lead to the prediction that a new marine tetrapod clade will typically evolve bone ballast as part of its adaptation to life in water. Slow swimmers and grazers on sessile food, like sirenians and placodonts, develop it more strongly, but active predators like ichthyosaurs and cetaceans secondarily lose this character.
Uitgever: Taylor & Francis
Bronbestand: Elektronische Wetenschappelijke Tijdschriften
 
 

                             Details van artikel 5 van 15 gevonden artikelen
 
<< vorige    volgende >>
 
 Koninklijke Bibliotheek - Nationale Bibliotheek van Nederland