56 research outputs found
Aspectos morfológicos e de incubação em três espécies de Corbicula Mühlfeld, no lago GuaÃba, Rio Grande do Sul, Brasil (Bivalvia, Corbiculidae)
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Letter to H.B. Stenzel from C.M. Yonge on 1964-03-01
Jackson School of Geoscience
Recommended from our members
Letter to H.B. Stenzel from C.M. Yonge on 1963-10-22
Jackson School of Geoscience
Activation energy for skeletal aragonite deposited by the hermatypic coral Platygyra spp.
An Early Cambrian problematic fossil: Vetustovermis and its possible affinities
The Early Cambrian problematic fossil Vetustovermis (Glaessner 1979 Alcheringa 3, 21–31) was described as an annelid or arthropod. Anatomical analysis of 17 new specimens from the Lower Cambrian Maotianshan Shale at Anning, Kunming (South China) does not support its affinities with annelids or arthropods. Anatomical features instead resemble other animal groups including modern flatworms, nemertines and molluscs. The presence of a pelagic slug-like form and ventral foot, as well as a head with eyes and tentacles indicates a possible affinity with molluscs, but these characters are not present only in molluscs; some of them are shared with other animal groups, including flatworms and nemertines. For example, a ventral foot-like structure is found in nemertines, ‘turbellarians’, and some polychaete groups. The well differentiated head is seen in separate bilaterian groups, but among molluscs it did not occur before the evolutionary level of the Conchifera. Unlike the ctenia-gills in molluscs, the gills in Vetustovermis are bar-like. All the characters displayed in this 525 million-year old soft-bodied animal fail to demonstrate clear affinity with molluscs or any other known extant or extinct animal groups, but argue for representing an independently evolved animal group, which flourished in Early Cambrian and possibly in Middle Cambrian time
Bivalve distribution on coral carpets in the Northern Bay of Safaga (Red Sea, Egypt) and its relation to environmental parameters
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