Scientists have discovered the fossil remains of an unusually large "naked" sea creature that lived in the world's oceans half a billion years ago. This creature belongs to a mysterious and incomprehensible group of animals known under the Latin name Chancelloriidae, and scientists do not even know where to write them on the tree of life. The creatures themselves represent a lineage of spiny tube-shaped animals that appeared during the evolutionary Cambrian "explosion", but very soon became extinct. In some ways, they resemble a sponge, a group of simple filtration animals, but many scientists dismiss this similarity as superficial.
The new species, named Allonnia nuda, was discovered by scientists from the University of Leicester, Oxford and Yunnan (China). The work was published in Proceedings of the Royal Society B. Allonnia nuda found in the Chengjiang fields of Yunnan province in China. During life, the animal was surprisingly large (half a meter or more), but it had no thorns at all. The unusual "nudity" of the fossil species suggests that other species may lurk in the fossil record, and indicates that this group was more diverse than previously thought.
In addition, the new species contains information about the structure of body growth, with clear links to modern sponges. It's too early to say anything in the affirmative, but the discovery highlights the central role of spongy fossils in the debate over early animal evolution. Perhaps Chancelloriidae will find their place on the tree of life somewhere near the sponges.
It turns out that amazing creatures appeared during the Cambrian "explosion".
Ilya Khel