Middle Mesoproterozoic Karelia and Kola, and later the united Baltica were located mostly at the latitudes between 35�NĪnd 35�S.
We review paleomagnetic data and paleoclimatological indicators of Baltica and its subcratons. forming the “branches” These biologically-influenced dendrolitic structures provide insight into the complex interplay of microbial communities and the environment, broadening our understanding of shrub and dendrolite formation throughout the rock record. In these modern examples, thick filaments of Lyngbya aestuarii form the “trunk” of the bush, with finer filaments of Lyngbya fragilis, Phormidium sp.
Dendrolites, known throughout the rock record, refer to macroscopic microbialites with mesostuctures composed of unlaminated arborescent structures called shrubs. Dominated by filamentous cyanobacteria, dendrolitic microbial mats are formed when filaments provide a supporting framework as a result of gliding mobility, to build a shrubby morphology. A recent field-intensive program revealed seasonally ephemeral occurrences of modern dendrolitic microbial mats forming in intertidal, low energy settings. Hamelin Pool, Shark Bay, Western Australia, is home to the largest and most diverse assemblage of living marine stromatolites, with shapes and sizes comparable to ancient structures. Diagenetic and metamorphic overprints may have resulted in recrystallisation of the original mineral assemblages and deformation of the original textural features in the sedimentary rocks, in many cases blurring the biologic signatures and jeopardizing the reliable interpretation of the nature of the lifeform. Most important are the effects of post-depositional alteration of the sedimentary host rocks due to exposure to metamorphic temperatures and pressures and metasomatism during the protracted time before their present exposure. Tracking the nature of ancient life using morphological, mineralogical, chemical and isotopic proxies in the rock record on Earth needs, however, to surmount a number of obstacles. The Earth has thus harboured life throughout most of its geologic history, and biological processes have contributed significantly to shaping the environmental conditions on the surface of the planet. Biochemical fingerprints stored in the ancient rock record indicate the presence of traces of life back to some of the oldest sedimentary rocks on the planet. When and how life on Earth started is still an open question.
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