X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Type of Medium
Language
Region
Library
Years
Person/Organisation
Subjects(RVK)
Keywords
Access
  • 1
    Online Resource
    Online Resource
    The Definition of Bioregions in Palaeontological Studies of Diversity and Biogeography Affects Interpretations : Palaeozoic Tetrapods as a Case Study (2018)
    Berlin : Humboldt-Universität zu Berlin
    Details
    UID:
    edochu_18452_21444
    Format: 1 Online-Ressource (14 Seiten)
    Content: Studies of diversity, whether of species richness within regions (alpha diversity) or faunal turnover between regions (beta diversity), will depend heavily on the “bioregions” into which a study area is divided. However, such studies in the palaeontological literature have often been extremely arbitrary in their definition of bioregions and have employed a wide variety of spatial scales, from individual localities to formations/basins to entire continents. Such bioregions will not necessarily be separated by biologically meaningful boundaries, and results obtained at different spatial scales will not be directly comparable. In many neontological studies, however, bioregions are defined more rigorously, usually as areas of endemicity. Here a procedure is proposed whereby this principal may be applied to palaeontological datasets. In each time bin/assemblage localities are subjected to two hierarchical cluster analyses, the first grouping the localities by geographic distance, the second by taxonomic distance. Clusters shared between the two will represent geographically continuous areas of endemicity and so may be used as bioregions. When calculating alpha or beta diversity through time, the spatial scale at which the bioregions are defined needs to be standardized between each time bin. This is done by grouping clusters of localities below a predefined geographic cluster node height. This approach is used to assess changes in beta diversity of Palaeozoic tetrapods and resolve disagreements regarding changes in faunal provinciality across the Carboniferous/Permian boundary. When the bioregions are defined at a smaller spatial scale, splitting the globe into many small regions, beta diversity decreases substantially during the earliest Permian. However, when the bioregions are defined at larger spatial scales, representing areas roughly the size of continents, beta diversity remains high. This result indicates that local environmental barriers to dispersal were decreasing in importance, rejecting previous suggestions that the rainforest collapse caused an “island biogeography” effect. Instead, dispersal at this time is restricted by continental-scale barriers, with the increased orogenic uplift as a possible control.
    Content: Peer Reviewed
    In: Lausanne : Frontiers Media S.A., 6
    Language: English
    DOI: 10.3389/feart.2018.00200
    DOI: 10.18452/20719
    URN: urn:nbn:de:kobv:11-110-18452/21444-4
    URL: Volltext  (kostenfrei)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Fulltext
    HU Berlin
  • 2
    Online Resource
    Online Resource
    Diversity patterns of nonmammalian cynodonts (Synapsida, Therapsida) and the impact of taxonomic practice and research history on diversity estimates (2018)
    Berlin : Humboldt-Universität zu Berlin
    Details
    UID:
    edochu_18452_22404
    Format: 1 Online-Ressource (14 Seiten)
    Content: Nonmammalian cynodonts represent a speciose and ecologically diverse group with a fossil record stretching from the late Permian until the Cretaceous. Because of their role as major components of Triassic terrestrial ecosystems and as the direct ancestors of mammals, cynodonts are an important group for understanding Mesozoic tetrapod diversity. We examine patterns of nonmammalian cynodont species richness and the quality of their fossil record. A supertree of cynodonts is constructed from recently published trees and time calibrated using a Bayesian approach. While this approach pushes the root of Cynodontia back to the earliest Guadalupian, the origins of Cynognathia and Probainognathia are close to their first appearance in the fossil record. Taxic, subsampled, and phylogenetic diversity estimates support a major cynodont radiation following the end-Permian mass extinction, but conflicting signals are observed at the end of the Triassic. The taxic diversity estimate shows high diversity in the Rhaetian and a drop across the Triassic/Jurassic boundary, while the phylogenetic diversity indicates an earlier extinction between the Norian and Rhaetian. The difference is attributed to the prevalence of taxa based solely on teeth in the Rhaetian, which are not included in the phylogenetic diversity estimate. Examining the completeness of cynodont specimens through geological time does not support a decrease in preservation potential; although the median completeness score decreases in the Late Triassic, the range of values remains consistent. Instead, the poor completeness scores are attributed to a shift in sampling and taxonomic practices: an increased prevalence in microvertebrate sampling and the naming of fragmentary material.
    Content: Peer Reviewed
    Note: This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.
    In: Cambridge : Cambridge Univ. Press, 45,1, Seiten 56-69
    Language: English
    DOI: 10.18452/21684
    DOI: 10.1017/pab.2018.38
    URN: urn:nbn:de:kobv:11-110-18452/22404-7
    URL: Volltext  (kostenfrei)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Fulltext
    HU Berlin
  • 3
    Book
    Book
    The early evolution of Synapsida (Vertebrata, Amniota) and the quality of their fossil record : von Neil Brocklehurst. (2015)
    Details
    UID:
    almahu_BV042994221
    Format: 497 S. : , Ill., graph. Darst.
    Note: Berlin, Humboldt-Univ., Diss., 2015
    Additional Edition: Erscheint auch als Online-Ausgabe The early evolution of Synapsida (Vertebrata, Amniota) and the quality of their fossil record / von Neil Brocklehurst
    Language: English
    Subjects: Biology
    RVK:
    WH 9420
    Keywords: Hochschulschrift
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Book
    HU Berlin get availability status
  • 4
    Online Resource
    Online Resource
    The early evolution of Synapsida (Vertebrata, Amniota) and the quality of their fossil record / (2015)
    Details
    UID:
    almahu_BV042994129
    Format: 1 Online-Ressource (497 S.) : , Ill., graph. Darst.
    Edition: Online_Ausgabe Berlin Humboldt-Universität zu Berlin, Universitätsbibliothek 2015 Online-Ausg.
    Edition: Nach einem Exemplar der Humboldt-Universität zu Berlin, Universitätsbibliothek mit der Signatur: 2015 B 425
    Note: Berlin, Humboldt-Univ., Diss., 2015
    Additional Edition: Reproduktion von Brocklehurst, Neil The early evolution of Synapsida (Vertebrata, Amniota) and the quality of their fossil record 2015
    Additional Edition: Erscheint auch als Druck-Ausgabe The early evolution of Synapsida (Vertebrata, Amniota) and the quality of their fossil record / von Neil Brocklehurst
    Language: English
    Subjects: Biology
    RVK:
    WH 9420
    Keywords: Vielfalt ; Synapsida ; Verzerrung ; Paläozoikum ; Hochschulschrift
    URN: urn:nbn:de:kobv:11-100233471
    URL: Volltext  (kostenfrei)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Online Resource
    Fulltext
    HU Berlin
Nothing or not found what you are looking for? Please check your search query or use the Interlibrary Loan Search.
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages