Яндекс.Метрика

N.G. Sozonov, N.I. Bobkov,E.G.Mitchell, A.V. Kolesnikov, D.V. Grazhdankin

Сериальное издание: Estudios Geologicos
Том: 75 , Год издания: 2019

Аннотация

Specimens of Dickinsonia from the Central U rals are characterised by clear bi lateral symmetry. Taking into account observations from Australian specimens, we consider that the so called 'glide reflection symmetry' in these fossils is a taphonomic phenomenon. The size frequency distribution plot shows the predominance of smaller ind ividuals i n the studied population of Dickinsonia from the Central U rals. Assuming that the age of a n individual is manifested i n the body size, there is a significant predominance of juvenile individuals i n the population. Three possible scenarios can be envisaged: (i) the population has a large n u m ber of juvenile i n dividuals as the result of high survivorship rate in the intertidal zone; (ii) the population teems with juvenile forms because it is buried immediately after hatching; (iii) assuming that Oickinsonia was a n actively motile organisms, that abundance of juvenile individuals could be explained by their i nability to escape burial (although it is d ifficult to i magine that some of the mature ind ividuals are buried with signs of escape behaviour); and (iv) the population could be interpreted as a fossilised 'nesting ground' for Dickinsonia in the i ntertidal zone where juvenile forms u nderwent maturation before migrating back to the subtidal zone. The study population can be characterised as expanding or stable; therefore, the intertidal setting can be described as favourable for these organisms.
индекс в базе ИАЦ: 044101