origin and evolution of species [1]![click to hear](/images/speaker.jpg)
Since its formation some 4.6 billion years ago, the Earth has witnessed the genesis of continents and oceans and the appearance of animals and vegetation.
Ordovician ![click to hear](/images/speaker.jpg)
Geological period marked by the appearance of the first vertebrates and new marine invertebrates. Corals, sponges and mollusks were especially abundant.
agnathan ![click to hear](/images/speaker.jpg)
Jawless fish with a cartilaginous skeleton. Fish of this type still exist today (lamprey).
orthoceras ![click to hear](/images/speaker.jpg)
Aquatic invertebrate fossil with a shell and arms equipped with suction cups; it was the ancestor of the nautilus, squid and octopus.
brachiopod ![click to hear](/images/speaker.jpg)
Marine invertebrate fossil with a body protected by a bivalve shell.
Cambrian ![click to hear](/images/speaker.jpg)
Geological period marked by the evolution of animals (appearance of mollusks, crustaceans) and the extinction of half of the marine invertebrates.
trilobite ![click to hear](/images/speaker.jpg)
Marine invertebrate fossil with antennae and a carapace divided lengthwise into three lobes; it disappeared in the Permian period.
Precambrian ![click to hear](/images/speaker.jpg)
The oldest and longest geological era, marked by the formation of continents and the appearance of ocean life.
cyanobacteria ![click to hear](/images/speaker.jpg)
Blue-green algae, among the first living microscopic organisms to appear on Earth.
stromatolite ![click to hear](/images/speaker.jpg)
Stratified calcareous concretion formed by microscopic algae (stromatolites), testifying to the existence of the first life-forms more than 3 billion years ago.