Thymmothian Period. The name derives from the proto-mollusk Tommotia. The climate is mild, and there are no glaciations. Much of North America was located at tropical and temperate latitudes, which allowed the growth of massive colonies of archaeocyathids in shallow waters. Siberia, also home to colonies of these animals, was a separate continent, located just east of North America. The Baltic region (modern-day Scandinavia), Eastern Europe, and European Russia were much further south than their current positions. Most of the remaining continents were joined together in a supercontinent known as proto-Gondwana. Present-day China and the Far East were then fragmented, as was Western Europe. The Tommothian saw the rise of diverse metazoans with skeletons, the so-called small hard fauna. This age is known for having seen the first major animal radiation. The origin of many types of skeletons during this period was a major evolutionary development; The rapid evolution of such a wide variety of external skeletons was probably due to the evolution of advanced predators.
