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Charles Darwin is best known for discussing the “flaws” of geological records in his book On the Origin of Species, and stated that “no organism can be perfectly preserved.”
However, after more than a century of fossil hunting since the publication of his book, we now know that the preservation of soft creatures is indeed possible – including some of the most fragile animals, like jellyfish.
But what about the exact anatomy of animals, such as their internal organs? Can he also be petrified?
The study by John Patterson, professor of earth sciences at the University of New England, Greg Edgecombe, merit researcher at the Museum of Natural History, Javier Ortega-Hernandez, assistant professor at Harvard Kennedy School, Robert Gaines, professor of geology and Russell Dean Christopher Bicknell, researcher, shows that Postdoctoral fellow in paleobiology at the University of New England, this week published in the journal Geology, how the complex brains of ancient aquatic arthropods (arthropod invertebrates ) could be preserved in detail.
The discovery of a 310-million-year-old horseshoe crab in the United States with its brain intact adds to a string of recent fossil finds that have uncovered some of the oldest arthropods with a nervous system central preserved.
The horseshoe crab fossil documented in the study sheds new light on how these fragile organs – usually subject to very rapid decomposition – were preserved with such precision.
Most of the knowledge about the brains of prehistoric arthropods comes from two main types of fossil deposits: amber and those from the Burgess Shale.
Fossils preserve an incredible amount of anatomical detail, as well as behavior, primarily because very little decomposition occurs after an organism is quickly trapped in resin.
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Using advanced imaging technology for these amber fossils, paleontologists can study the brains of tiny three-dimensional arthropods at tiny scales. However, the oldest amber arthropods extend only to the Triassic Period (around 230 million years ago).
The sediments of the Burgess Shale are much older, being from the Cambrian period (usually 500-520 million years ago).
These fossils are very important because they are unambiguously representative of some of the oldest animals and can therefore tell us about their origins and the history of their evolution. Its remains are preserved mainly as carbon trails in the clay.
The fossilization process begins with storm mudslides that sweep away sensitive animals, burying them at the bottom of the sea under conditions of low oxygen. Over time, the clay turns to stone and compacts, leaving the animals to crash into the rocks.
Numerous specimens of arthropods from the Burgess Shale preserve internal organs, especially the intestine. But fewer parts appear in the central nervous system, such as the optic nerves, the ventral nerve cord, or the brain.
And the new fossil shows that arthropod brains can be preserved in a completely different way. The horseshoe crab specimen, Eupoops danae, comes from the world famous “Mason Creek” deposit in Illinois, USA. Fossils are preserved from these sediments inside concrete made up of the mineral iron carbonate called siderite.
The researchers showed, for the first time, that the animals of Amazon Creek were not only formed by the rapid formation of the mineral siderite which completely buried their bodies, but also that the sideritis rapidly encapsulated internal soft tissues before to decompose.
It should be noted that Euprops’ brain is cloned by a white clay mineral called kaolinite. This metallic mold could have formed later in the space left by the brain, long after its dissolution. Without this clear white mineral, we might never have discovered the brain.
The discovery of these extraordinary specimens offers paleontologists a rare glimpse into the deep past, advancing our understanding of the biology and evolution of long-extinct animals. Apparently, Charles Darwin wasn’t too pessimistic about the fossil record after all.
Source: Scientific alert
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