Scientists Discover "Inside-Out Monster" That Lived Long Before Dinosaurs

They are trying to determine how it fits into the evolutionary tree of life.

British scientists have discovered a new species of ancient Earth dweller that lived long before the appearance of dinosaurs. Its exceptionally well-preserved fossils were found back in the 2000s, but only now have researchers been able to identify the mysterious creature, affectionately nicknamed Sue. The results of a 25-year study were published in the journal Palaeontology, and briefly summarized by the portal Phys.org.

The creature has been officially named Keurbos susanae. It was a primitive marine arthropod, but its exact evolutionary relationships remain unclear. Establishing these connections is extremely challenging, as today about 85% of all animals on Earth belong to arthropods, including shrimp, lobsters, spiders, mites, and centipedes. However, comparing them is difficult because archaeologists usually find fossilized external parts, while in this case, they have to deal with internal ones.

The remains of Sue were discovered in a layer of mud and clay approximately 400 kilometers north of Cape Town (South Africa). Analysis of marine deposits allowed scientists to determine the time of its existence - 440 million years ago, during a period of global cooling that led to the extinction of about 85% of species on Earth. This event is one of the five largest mass extinctions in the planet's history.

The arthropod lived in extremely toxic conditions - in oxygen-free water with dangerous levels of hydrogen sulfide. Furthermore, the body of water was apparently isolated and somehow protected from severe frosts, which saved it from extinction.

Now scientists want to find out how exactly this creature fits into the evolutionary tree of life.