نتایج جستجو برای: lower paleozoic
تعداد نتایج: 693427 فیلتر نتایج به سال:
It has previously been thought that there was a steep Cretaceous and Cenozoic radiation of marine invertebrates. This pattern can be replicated with a new data set of fossil occurrences representing 3.5 million specimens, but only when older analytical protocols are used. Moreover, analyses that employ sampling standardization and more robust counting methods show a modest rise in diversity wit...
First description of rare Teichichnus burrows from carbonate rocks of the Lower Paleozoic of Estonia
The paper presents the results of laboratory studies on strength–strain properties shales representing four siltstone-claystone lithostratigraphic units occurring in Baltic Basin. Laboratory a triaxial stress state were conducted as single failure tests cylindrical samples oriented parallel and perpendicular to lamination within rocks. Mutually cut out from same drill core sections order determ...
Late Cambrian to early Ordovician trilobites, the family Olenidae, were tolerant of oxygen-poor, sulfur-rich sea floor conditions, and a case is made that they were chemoautotrophic symbionts. Olenids were uniquely adapted to this habitat in the Lower Paleozoic, which was widespread in the Late Cambrian over Scandinavia. This life habit explains distinctive aspects of olenid morphology: wide th...
چکیده ندارد.
The symmetrical, flexible teleost fish 'tail' has been a prime example of recapitulation - evolutionary change (phylogeny) mirrored in development (ontogeny). Paleozoic ray-finned fishes (Actinopterygii), relatives of teleosts, exhibited ancestral scale-covered tails curved over their caudal fins. For over 150 years, this arrangement was thought to be retained in teleost larva and overgrown, mi...
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