Otavia

Otavia is an extinct group of ancient sponge-like animals found in the Otavi Group in Etosha National Park, Namibia. It is considered one of the oldest animal fossils, with rocks containing these fossils dating between 760 and 550 million years old. The oldest Otavia fossils come from the Tonian period, before big glaciations, while the youngest are from the Ediacaran period.

Scientists debate exactly what Otavia was related to, along with other early sponge fossils from the Precambrian time. Some researchers believe Otavia may have evolved over 100 million years earlier than we previously thought, supporting ideas that sponges were among the very first animals on Earth.

Otavia might have played a role in increasing oxygen levels in the atmosphere long ago. Its fossils appear both before and after major ice ages, suggesting it could survive extremely cold conditions known as "Snowball Earth."

Discovery and Naming

Some of the earliest clues about how animals first appeared can be found in fossils from a time called the Ediacaran period. These fossils show how early animals started to change and grow in many different ways.

Scientists in Namibia collected pieces of black stone from places called the Otavi and Nama groups. When they carefully dissolved these stones in a special liquid, they found over a thousand tiny fossils that looked like small sponges. In 2012, a group of scientists described these fossils in a paper and named them "Otavia" after the Otavi group where many were found, giving them the species name "antiqua."

Description

The fossils of Otavia are irregularly shaped but rounded, ranging in size from a third of a millimeter to 5 millimeters. They are hollow inside and have many small holes connecting the inside to the outside, similar to the body plan of most sponges.

Otavia antiqua fossils show more complex internal features, such as small pores, layered chambers, and cavities linked to larger openings, supporting the idea that they were sponge-like animals. The outer material of these fossils is mostly calcium phosphate, along with calcite and dolomite.