منابع مشابه
Bite marks in Jurassic and Cretaceous ammonite s
Ammonites are among some of the best fossils to collect. They are relatively easy to find, for example, in the Lower Jurassic Posidonia Shale in Germany and the Jurassic sediments of Dorset in the south of England. The larger, wellpreserved ones will always be sought after and, if of sufficiently high quality, may even be displayed in museum exhibitions. However, while these nicely-preserved, c...
متن کاملEnvironmental drivers of crocodyliform extinction across the Jurassic/Cretaceous transition
Crocodyliforms have a much richer evolutionary history than represented by their extant descendants, including several independent marine and terrestrial radiations during the Mesozoic. However, heterogeneous sampling of their fossil record has obscured their macroevolutionary dynamics, and obfuscated attempts to reconcile external drivers of these patterns. Here, we present a comprehensive ana...
متن کاملMass mutations of insects at the Jurassic/Cretaceous boundary?
Diverse fossil insect assemblages near the Jurassic/Cretaceous transition from the Shar-Teg in Mongolia comprise frequent deformed species. These (first known) mass fossil animal deformities, expressed as fusions of veins changing the wing geometry, probably represent heritable mutations. They accumulated as a result of a changed structure of selective pressure, and are unique in showing how in...
متن کاملProvenance of Triassic and Jurassic Sandstones in the Banda Arc: Petrography, Heavy Minerals and Zircon Geochronology
Quartz-rich sandstones in the Banda Arc Islands are thought to be equivalent of Mesozoic sandstones on the Australian NW Shelf where they are important proven and potential reservoirs. Previous studies suggested that rivers draining Australia provided most of the sediment input and there have been suggestions of a northern provenance for some Timor sediments. We present results from a provenanc...
متن کاملHigh-precision 40Ar/39Ar geochronology and the advent of North America's Late Cretaceous terrestrial fauna.
A densely sampled, diverse new fauna from the uppermost Cedar Mountain Formation, Utah, indicates that the basic pattern of faunal composition for the Late Cretaceous of North America was already established by the Albian-Cenomanian boundary. Multiple, concordant 40Ar/39Ar determinations from a volcanic ash associated with the fauna have an average age of 98.39 +/- 0.07 million years. The fauna...
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ژورنال
عنوان ژورنال: Geological Society of America Bulletin
سال: 1985
ISSN: 0016-7606
DOI: 10.1130/0016-7606(1985)96<1419:acajg>2.0.co;2