An article published in the journal “Proceedings of the National Academy of Sciences” describes the discovery of an arthropod that lived about 430 million years ago. It was named Aquilonifer spinosus, where the genus name means “kite”, a name inspired by the movie “The Kite Runner” because it was carrying its juveniles attached to its body as if they were tiny kites.
Researchers from Yale, Oxford, the University of Leicester and Imperial College London examined the fossils found in Herefordshire, England. The species Aquilonifer spinosus belong to the arthropod group so was related to modern insects, arachnids and crustaceans. Their ancient cousins were really tiny because as adults they reached a length of around a centimeter (almost half an inch).
Among the arthropods there are different strategies for the protection of eggs and embryos but Aquilonifer spinosus had a unique one. Professor Derek Briggs, the lead author of this study, explained that he and his colleagues considered the possibility that the tiny organisms attached to it were parasites. Eventually, they found that it was unlikely because their attachment position wasn’t favorable to access the nutrients taken by the adult Aquilonifer spinosus.
As often happens more and more in paleontological studies, the researchers used modern technology to make a three-dimensional scanning of Aquilonifer spinosus. In this case, they decided to use a destructive type of process because they had to “slice” the fossil in very thin layers.
According to the researchers, it was worth it because it allowed them to appreciate the details of the adult specimen and ten juveniles connected to their parent, in various stages of development. For example, they were able to see that the little ones have six legs, half of the adult. Perhaps the juveniles were still developing and would’ve developed the other legs over time.
Probably, Aquilonifer spinosus lived on the bottom of an ancient sea filtering nutrients in the water. Its juveniles could possibly have benefits remaining attached to their parent getting food more easily and enjoying some protection.
At the time among arthropods there were various strategies to protect eggs and embryos so it’s difficult to accurately assess the advantages of one of them based on one adult with its juveniles. It’s one of the typical problems with such ancient fossils, which are sometimes unique. Every discovery is a new journey in an environment that was very different from the the ones that exist today.