Evolution of Life in the Oceans of Mars? Episodes of Global Warming, Flooding, Rivers, Lakes, and Chaotic Orbital Obliquity

Mars has been subject to repeated waxing and waning episodes of extreme chaotic obliquity (axial tilting) for at least four billion years. Obliquity is currently at 25.19 degrees and has exceeded 80o. Each time obliquity exceeds 40o increased Martian atmospheric pressures and global temperatures cause the melting of glaciers and permafrost and subsurface ice, and result in oceans, lakes and rivers of water flooding across the surface then stabilizing and enduring for hundreds of thousands of years or longer. There is evidence that within these seas evolved stromatolite constructing cyanobacteria, green algae, acritarchs, foraminifera, seaweed, and marine metazoan invertebrates including sponges, tube worms, crustaceans, reef-building corals, bivalves, and those resembling Kimberella, Namacalathus and Lophophorates; all of which (with the possible exception of algae, fungi, lichens) may have become extinct. The last episode of extreme obliquity may have begun over a million years in the past and endured until 110,000 years ago. Subsequently, as axial tilting declined, the waters of Mars seeped back beneath the surface forming vast aquifers and glacial deposits of water-ice and the remainder froze at the poles and atop dusty layers of icy-sediment: the remnants of previous obliquity-driven freeze-thaw cycles that may have caused life to evolve and oceans and lakes to repeatedly form, stabilize, endure then freeze.