After much debate over the last 150 years, paleontologists have finally identified the mysterious creature that lived hundreds of millions of years ago. The oddly shaped creature, which is flat-looking with a long arm coming out of its side, is known as a stylophoran which is an ancient relative of starfish, sea urchins, sea lilies, brittle stars, sea cucumbers, and feather stars.
The fossils – which included around 450 specimens of the stylophoran – were discovered during a 2014 excavation at the Fezouata Formation which is along the edge of the Sahara Desert in the southern part of Morocco. These fossils date back approximately 478 million years.
Researchers were able to find out exactly what type of creature it was because their fossils had “unequivocal evidence for exceptionally preserved soft parts, both in the appendage and in the body of stylophorans,” explained Bertrand Lefebvre, who is a researcher at the National Center for Scientific Research (CNRS) at the Laboratory of Geology of Lyon which is located in France.
After analyzing the fossils using a binocular microscope, they noticed that there were also soft parts. Since soft tissues hardly ever fossilize, the stylophorans were only recognized for their hard skeletal parts and not for their soft insides. According to Lefebvre, “Their internal anatomy was not only entirely unknown, but also – and mostly – highly controversial.”
Stylophoran fossils have been discovered around the world since the 1850s which led researchers to confirm that they lived from the middle Cambrian to the late Carboniferous periods, which date back from around 510 million to 310 million years ago.
These creatures had two main parts: a core body and an appendage that were both around 1.2 inches long. From the 1850s to the 1950s, it was believed that stylophorans were “normal” echinoderms with its appendage being compared to the stem of sea lilies. However, in the early 1960s, Georges Ubaghs, who was a Belgian paleontologist, discovered that the creature’s appendage was quite a bit different than a stem and more like an arm for feeding – similar to a starfish.
A few years later, in the late 1960s, Richard Jefferies, who was a British paleontologist, suggested that the main body of the stylophoran was instead a head containing a brain and a pharynx, while its appendage consisted of muscles and a notochord which is a type of primitive backbone. He also believed that stylophorans were the missing link between echinoderms (invertebrates) and chordates (vertebrates).
Much later, in the 2000s, another British paleontologist named Andrew Smith gave his own interpretation of the creature. He believed that stylophorans were not the missing link between echinoderms and chordates and instead they were primitive deuterostomes which put them right in the middle of the gap between acorn worms and echinoderms.
With this new discovery, researchers can perform testing on the creature’s soft tissue and find out which of the theories best explains the creature. Ubaghs’ theory, however, does seem to be the most plausible. The creature’s flat body consisted of intestines and its appendage was more like an arm since it had a water vascular system which would have aided the creature to eat and move the same way that the arms of starfish do.
With their new study (which can be read here), we finally know the origins of the mysterious creature that has baffled scientists for over a hundred years. Lefebvre explained it best when he said, “This discovery is of particular importance, because it brings to an end a 150-year-old debate about the position of these bizarre-looking fossils in the tree of life.”