Tommotian

The Tommotian is a subdivision of the Early Cambrian geological period, representing a significant chapter in Earth's history. It follows the Nemakit-Daldynian age and precedes the Atdabanian age. This period is particularly noted for its exceptional fossil record, especially from sites like the Tommot Gorge in Siberia, which gave the age its name.

The Tommotian is characterized by the widespread proliferation of various life forms, marking a dramatic increase in biodiversity. This era saw the rise of many early animal phyla, including those that would eventually evolve into modern-day mollusks, arthropods, and echinoderms. A key feature of Tommotian faunas is the appearance of small shelly fossils (SSFs), which are the mineralized hard parts of primitive animals. These include cap-like shells, spines, plates, and teeth, providing crucial evidence for the early evolution of complex life.

The geological and paleontological evidence from the Tommotian suggests a period of rapid evolutionary innovation and diversification, often referred to as the Cambrian explosion. Environmental changes, such as rising oxygen levels and the development of new ecological niches, are thought to have played a role in this biological radiation. The study of Tommotian fossils continues to shed light on the fundamental processes that shaped the early animal kingdom.