Antiquatonia teres, Composita ambigua 'Camarotoechia' proava Gastropods (most
Porcellanous Limestones (slightly hypersaline)
Sanguinolites roxburghensis, Schizodus Turreted gastropods Modiolus latus
Table VI The order of disappearance of various groups of fossils in the Northumberland Trough (northern England) as the water increased in salinity.
A common feature of all these diversity gradients is that there is usually a large number of individuals of few species in the less favourable environment, but not necessarily an actual decrease in the number of animals living there.
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