This figure is necessary because the entire ocean passes through hydrothermal vents every 10 million years. At this temperature, organic compounds are destroyed. The primordial atmosphere was probably rich in carbon dioxide, implying the absence of the reducing conditions needed for abiotic synthesis of organic compounds, probably requiring an autotrophic beginning. The minimum cellular genome is estimated at about 562,000 nucleotide pairs, close to the 580,000 nucleotide pairs of Mycoplasma genitalium . The limited time for the complex metabolic processes of life to arise contrasts with the conservation of these processes since the origin of life.
Archaeopteryx is a fossil that possesses characteristics of both birds and reptiles.
Its skull was rather poorly preserved in previous specimens, but parts of it are better preserved in the recently discovered seventh specimen. This specimen apparently was buried rapidly, before the brain could disintegrate. The skull shows some distinctly avian features, and some that appear to be uniquely shared with theropod dinosaurs. The authors conclude that Archaeopteryx was a bird rather than a feathered dinosaur. The status of Archaeopteryx has been controversial.