Aquilonifer: Beast of the Week

This week we will be looking at a tiny creature that gives us insight to how some of the earliest mothers raised their young.  Check out Aquilonifer spinosus!  Aquilonifer was a small arthropod (same group of animals that includes insects, arachnids, and crustaceans) that lived in what is now Hertfordshire, England, during the Silurian Period, about 430 million years ago.  It measured only about a centimeter long as an adult and would have scuttled around on the ocean floor. We are unsure as to what it ate but it may have been a scavenger, sifting through the sand, and eating any tiny morsel of organic material it could find.  Judging by its mouthparts it may also have been a predator, subduing and eating smaller animals it came across.  The genus name, Aquilonifer, translates to "Kite Carrier" and the species, name spinosus, translates to "spiny".  It was also referred to as "The Kite Runner" by paleontologists who found and studied it for the fashion in which it cared for its young.

Life reconstruction by Christopher DiPiazza

This little creature was found with ten even tinier arthropod organisms attached to its body via fine threads.  At first it was hypothesized they may have been some sort of parasite, but that doesn't make much sense since all known parasites would need to be much closer to their hosts in order to survive, not floating behind it on a string.  It was then determined, upon looking at them more closely, that they were most likely offspring.  This creature would have dragged its kids around like little parasailers underwater!  Even though no animal known today does anything quite like this, many arthropods do carry their young around with them via other means.  Many spiders carry their eggs and young in a silk pouch attached to the abdomen, and mother scorpions pile their liveborn offspring onto their backs.  Considering how old and distantly related Aquilonifer is to these modern creatures, to say this was indeed a method of parenting isn't really unreasonable.  Parasites, on the other hand, tend to be pretty consistent across the board in wanting to be on or inside their hosts.

Basically this, but with less character-building experience.

Aquilonifer was also interesting in that beyond being an arthropod...scientists can't quite figure out exactly where it belongs on the family tree.  It may have been an extremely early branch of the arthropod phylum, that would eventually radiate into the forms that you see today.  When alive it may have crawled around on the ocean floor similar to a centipede does on land with its 26 legs.  It had a long pair of feelers in the front, what appear to be mandibles in the front, and ...get this....no eyes.  This isn't that crazy if you think about it.  This creature probably relied mostly on feeling in an environment where having a sense of sight wouldn't have benefited it.

High power 3D scanning of the tiny fossil allowed scientists to get a more detailed view of its anatomy.

That's it for this week!  As always feel free to comment below or on our facebook page!

References

Siveter, David J, Siveter, Derek J, Sutton, MD and Legg, D, 2016, Tiny individuals attached to a new Silurian arthropod suggest a unique mode of brood care, PNAS Online 

 Jonathan Webb, BBC News, 4 April 2016, Bizarre fossil hauled its offspring around 'like kites'