Steanos

Steanos is a genus of extinct trilobites that lived during the Cambrian period. The name Steanos is derived from the Greek words "stema" meaning leg or pillar, and "anos" meaning jaw bone. This refers to the distinctive paired spines or limbs attached to the exoskeleton of the trilobite in this genus.

Steanos fossils have been found in various parts of the world, including China, Canada, and Russia. They are known from evidence in sedimentary rocks that date back to around 515 million years ago.

Steanos trilobites were characterized by their small to medium size and egg-like body shape. They had distinctive sculpturing on their exoskeleton, which often featured a series of fine lines and ridges. The paired spines or limbs on the Steanos trilobite are thought to have played a role in locomotion or possibly even sensory perception.

The evolutionary significance of Steanos is not yet fully understood. However, it is believed to belong to the family Ptychopariidae, which is one of the earliest recorded trilobite families. Trilobites like Steanos likely evolved from a monobathrid ancestor, marking one of the earliest transitions between simple and complex body plans.

Steanos has contributed significantly to our understanding of the early evolution of life on Earth. Further fossil discoveries and research are needed to clarify the relationships between Steanos and other ancient arthropods.