Tuesday, April 8, 2014

Heart of antiquity

Reconstruction of Fuxianhuia protensa showing several organ systems,
including the cardiovascular system (red), the central nervous system
(blue), and the digestive system (green).  Credit: Nicholas Stausfeld.
Image source.
One of the greatest drawbacks in paleontology is the general lack of soft tissue to study.  Normally, paleontologists are limited to studying hard structures, such as shells and bones, and must infer the rest based on a mix of modern analogs and imagination.  On rare occasions, however, the soft parts of an ancient animal are preserved, giving new insight into its form and function.

Yesterday, one of these rare finds was reported in Nature Communications.  A fossil of a shrimp-like arthropod named Fuxianhuia protensa was detailed enough for scientists to map out its cardiovascular system, which includes the heart and blood vessels.  Previous finds had already mapped out the nervous and digestive system, so the inner workings of this creature are now quite well-known.  In their report, the scientists emphasized the complexity of the organ systems of Fuxiahuia, likening it to that of modern arthropods despite dating it to 520 million years ago, a mere 20 million years after the major forms of multicellular life are thought to have evolved.

I should clarify that the blood vessels and other organs were not themselves preserved.  Rather, they left behind carbon imprints in very fine sediment that remained undisturbed since its deposition.  The exact conditions of preservation are still somewhat of a mystery to the authors.  According to Nicholas Stausfeld, professor at the University of Arizona, "...the conditions had to be just right.  We believe that these animals were preserved because they were entomed quickly under very fine-grained deposits during some kind of catastrophic event, and were then permeated by certain chemicals in the water while they were squashed flat.  It is an invertebrate version of Pompeii" (source).  Interestingly, this description perfectly matches the beginning stages of Noah's Flood, in which creationists believe almost all such fossils were buried and formed.

Moreover, the level of complexity of the creature's systems are not surprising to creationists either, who say that Fuxianhuia (or its baramin predecessor) was created along with all other seagoing creatures on Day 5 of Creation Week about 6000 years ago.  In this view, there is no reason to expect any correlation between complexity and placement in the fossil record.  God created with complexity as He saw fit.  In the evolutionary view, Fuxianhuia certainly is a curiosity, possibly even an anomaly, but not exactly a difficulty.  Some amount of complexity was already in place by 520 million years ago, so the level of sophistication seen in Fuxianhuia would not necessarily have been unprecedented.  Nevertheless, it is a pebble in the evolutionary shoe while fitting comfortably for the creationists.

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