نتایج جستجو برای: late devonian
تعداد نتایج: 197086 فیلتر نتایج به سال:
Phytoplankton form the base of most marine trophic chains and studying their past diversity at regional global scales can provide valuable insights into evolution ecosystems climate history. Using a new database more than 4000 species acritarchs prasinophytes, comprehensive investigation taxonomic trajectories this (micro)phytoplankton throughout Paleozoic is performed for first time. This data...
In view of the recent recognition of widespread Late Paleozoic remagnetization of Devonian formations across North America, we undertook a reinvestigation of the Upper Devonian Perry Formation of coastal Maine and adjacent New Brunswick. Thermal demagnetization of samples from the redbeds yielded a characteristic direction (D = 166 ° l = 4 ° ) that fails a fold test. Comparison of the correspon...
Edenopteron keithcrooki gen. et sp. nov. is described from the Famennian Worange Point Formation; the holotype is amongst the largest tristichopterids and sarcopterygians documented by semi-articulated remains from the Devonian Period. The new taxon has dentary fangs and premaxillary tusks, features assumed to be derived for large Northern Hemisphere tristichopterids (Eusthenodon, Hyneria, Lang...
Our understanding of early gnathostome evolution has been hampered by a generally scant fossil record beyond the Devonian. Recent discoveries from the late Silurian Xiaoxiang Fauna of Yunnan, China, have yielded significant new information, including the earliest articulated osteichthyan fossils from the Ludlow-aged Kuanti Formation. Here we describe the partial postcranium of a new primitive b...
The closure time of the Shangdan Ocean is critical for understanding tectonic evolution Proto-Tethys Ocean. However, proposed was prolonged from Ordovician to Devonian. In present study, detrital zircon metasedimentary rocks Liba Group in West Qinling Belt analyzed constrain three youngest grains yield a maximum deposition age 418 ± 13 Ma, indicating Middle Devonian deposition. Detrital show tw...
Osteichthyans comprise two divisions, each containing over 32,000 living species [1]: Sarcopterygii (lobe-finned fishes and tetrapods) and Actinopterygii (ray-finned fishes). Recent discoveries from China highlight the morphological disparity of early sarcopterygians and extend their origin into the late Silurian [2-4]. By contrast, the oldest unambiguous actinopterygians are roughly 30 million...
Late Devonian Minostrobus chaohuensis is one of the earliest monosporangiate-strobilate isoetaleans. Based on new material of this plant, the vegetative axis and microsporangiate strobilus are studied in detail, and the whole plant knowledge is summarized. The vegetative axis is isotomously branched. The stem is up to 55 mm in diameter with helically arranged leaf cushions. Stems and thick bran...
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