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'

Confuciusornis: Beast of the Week

This week we will be checking out possibly one of the most well-understood of all the prehistoric dinosaurs.  Check out Conficiusornis sanctus!  Confuciusornis was a prehistoric bird, that lived in what is now China, during the early Cretaceous Period, between 125 and 121 million years ago.  From beak to tail it measured about a foot and a half long, and had a wingspan of a bit over two feet wide.  When alive, Confuciusornis would have eaten meat but also probably ate plant material, possibly seeds, as well.  Its name translates to "Confucius Bird Sage", in reference to Confucius, the famous Chinese philosopher.

Confuciusornis is known from literally thousands of fossilized specimens, which is unheard of when it comes to other dinosaur fossils.  Because of this we know quite a bit about its anatomy and lifestyle.

Confucius fossil pair.  Possibly a male and female. (note the long tail feathers)

First of all, many of the Confuciusornis specimens preserved soft tissue, including feathers.  It had long, narrow primary feathers on the wings and certain individuals had a pair of extremely long, ribbon like feathers growing from their tails.  It has been suggested that Confuciusornis was sexually dimorphic, the males possessing the long ribbon feathers for display.  It is also possible that both sexes had these feathers, and certain individuals were molting (shedding old feathers) at the time of their deaths.  The presence of these feathers also didn't have any correlation with body size, so if it was sex-related, the males and females were the same size as adults.  These tail feathers are interesting in that only the tips demonstrate the classic feather structure with a central shaft, branching off into barbs on either side.

Confuciusornis possessed a large, toothless beak, like modern birds.  However, there were other prehistoric birds that lived after Confusiusornis had gone extinct that still had teeth.  This proves that Confuciusornis evolved its beak independently of those that we see in modern birds.  The beak would have been relatively powerful in life, and many scientists suggest it could have been a seed-eater.  Modern seed-eating birds, like cardinals and sparrows, have similarly shaped beaks.  However, some doubt this since no gastroliths, small rocks swallowed by animals to help digest hard food, like seeds, were ever found in any Confuciusornis specimen. (and we HAVE found them in many other dinosaur fossils) We know Confuciusornis  at least ate small fish, since the remains of one was found in the neck region of one specimen.  This could have been the crop, a pouch in the throat region of birds, used for storing food before swallowing.

The wings of Confuciusornis tell us that this dinosaur probably could fly, but it wouldn't have been as agile in the air as many modern birds are, especially for long periods of time.  We hypothesize this because Confuciusornis doesn't have a very large breastbone, or keel as it's called in birds, for wing muscles to attach.  Keel bones in many modern birds are proportionally huge.  Even the ones on domestic chickens and turkeys are large. (Next time you eat a rotisserie chicken check this out.  It's where the breast meat attaches to the skeleton.)  Confuciusornis also didn't have as wide of a range of motion in its shoulder joints as modern flying birds do, which would have made flapping a bit more difficult for it.  Finally, it's tail lacked the broad steering feathers found in modern birds.  The hands of Confuciusornis had three distinct fingers, tipped with curved claws, which is something else not common in modern birds.

Confuciusornis life reconstruction showing some display behavior by Christopher DiPiazza.

Lastly, scientists may have figured out what color Conficiusornis' feathers were!  Since the fossilized feathers were so well preserved, scientists were able to look at them under a powerful microscope and see the shapes of melanosomes, organelles that give color to a feather.  Even though the color, itself, wasn't visible, the shape of the organelle would reflect the pigment that would have been there in life.  By comparing these shapes to those of modern bird feather melanosomes, they were able to conclude that Confuciusornis likely had a dark gray body, black tail feathers, and possibly white primary feathers.  However, it should be noted that not ALL kinds of melanosomes necessarily preserved, so an overlapping of different kinds of these organelles may have yielded a different coloration in certain areas.

That is all for this week!  As always feel free to comment below or on our facebook page!

References

Chiappe, Luis M., Shu-An, Ji, Qiang, Ji, Norell, Mark A. (1999) "Anatomy and systematics of the Confuciusornithidae (Theropoda:Aves) from the Late Mesozoic of northeastern China" "Bulletin of the American museum of Natural History no.242 89pp.

Elzanowski, A. (2002) "Biology of basal birds and the origin of avian flight". In: Zhou Z., Zhang F. (eds) Proceedings of the 5th Symposium of the Society of Avian Paleontology and Evolution, Beijing, 1–4 June 2000. Science, Beijing, pp 211–226

Wogelius, R.A., Manning, P.L., Barden, H.E., Edwards, N.P., Webb, S.M., Sellers, W.I., Taylor, K.G., Larson, P.L., Dodson, P., You H., Da-qing L., and Bergmann, U. 2011. Trace metals as biomarkers for eumelanin pigment in the fossil record. Science, 333(6049): 1622-1626.

Zhou Z. and Farlow, J.O. (2001) "Flight capability and habits of Confuciusornis". In: Gauthier and Gall (eds). New perspectives on the origin and early evolution of birds: proceedings of the international symposium in honor of John H. Ostrom. Peabody Museum of Natural History. Yale University, New Haven. pp. 237–254