Scientists have discovered an ancient animal that carried its young in capsules tethered to the parent’s body like tiny, swirling kites.
The miniscule creature, Aquilonifer spinosus, was an arthropod that lived about 430 million years ago and grew to less than half an inch long. The only known fossil of the animal was found in Herefordshire, England. Its name comes from “aquila,” which means eagle or kite, and the suffix “fer,” which means carry.
“Modern crustaceans employ a variety of strategies to protect their eggs and embryos from predators—attaching them to the limbs, holding them under the carapace, or enclosing them within a special pouch until they are old enough to be released—but this example is unique,” says lead author Derek Briggs, professor of geology and geophysics at Yale University and curator of invertebrate paleontology at the Peabody Museum of Natural History.
“Nothing is known today that attaches the young by threads to its upper surface.”
Nicknamed “The Kite Runner,” after the 2013 book, the fossil shows 10 juveniles at different stages of development connected to the adult. This probably means the adult postponed molting until the juveniles were old enough to hatch; otherwise, they would have been cast aside with the shed exoskeleton.
The adult specimen’s head is eyeless and covered by a shield-like structure. It lived on the sea floor during the Silurian period with a variety of other animals including sponges, brachiopods, worms, snails, and other mollusks, a sea spider, a horseshoe crab, various shrimp-like creatures, and a sea star. The juvenile pouches, attached to the adult by slender, flexible threads, look like flattened lemons.
The researchers considered the possibility that the juveniles were parasites feeding off a host, but decided it was unlikely because the attachment position would not be favorable for accessing nutrients.
“We have named it after the novel by Khalid Hosseini due to the fancied resemblance of the juveniles to kites,” Briggs says. “As the parent moved around, the juveniles would have looked like decorations or kites attached to it. It shows that arthropods evolved a variety of brooding strategies beyond those around today—perhaps this strategy was less successful and became extinct.”
The researchers were able to describe Aquilonifer spinosus in detail thanks to a virtual reconstruction. They reconstructed the animal and the attached juveniles by stacking digital images of fossil surfaces revealed by grinding away the fossil in tiny increments.
Researchers from the University of Oxford, the University of Leicester, Imperial College London, and Oxford University Museum of Natural History are coauthors of the study in the Proceedings of the National Academy of Sciences.
The Yale Peabody Museum of Natural History, the Natural Environmental Research Council, the John Fell Oxford University Press Fund, and the Leverhulme Trust funded the work.
Source: Yale University