Presentation on theme: "Ediacarans, Small Shells and the Dawn of the Phanerozoic."— Presentation transcript:
Ediacarans, Small Shells and the Dawn of the Phanerozoic
Edicaran Biota First fossils of multicellular organisms Some controversy –Multicellular life? –Colonies of single cells? Definitely not single cells Signs of tissue differentiation Advanced symmetry
Taphonomy of the Edicaran Biota Soft/firm bodied? Molds and casts in coarse sandstone Facies preference? Taphonomic bias?
Radial and Bilateral Symmetry
Bilateral Symmetry and Differentiated Structures
Symmetry and Diversity
Differentiated Structures, But Which End Was Up?
Significant Diversity or Variations on a Single Theme?
Dawn of the Phanerozoic: Small Shelly Fauna and Trilobites
What Do We Choose as the Start of the Cambrian? Extinction of the Ediacarans? First appearance of the ”small shelly fauna”? –Late Proterozoic First trilobites? – Part of “Cambrian Explosion” –Lower, but not lowest Cambrian First trace fossils of trilobites? First evidence of mobility (burrows)? First burrows chosen