New research study carried out by scientists at The University of Texas at Austin and their collaborators has actually revealed a new fact about the fossils from Germanys Posidonia shale. The source of their golden gleam actually lies in a mix of minerals, which offers ideas about the environment where these fossils came into existence.
“But remarkably, we had a hard time to discover pyrite in the fossils. Even the fossils that looked golden, are preserved as phosphate minerals with yellow calcite. This drastically alters our view of this famous fossil deposit.”
“But remarkably, we struggled to discover pyrite in the fossils. Even the fossils that looked golden, are protected as phosphate minerals with yellow calcite.
The research was published in Earth Science Reviews. Drew Muscente, a former assistant teacher at Cornell College and previous Jackson School postdoctoral scientist, led the research study.
Ammonite fossil From the Ohmden quarry, Posidonia shale lagerstatte. Credit: Sinjini Sinha/ The University of Texas at Austin Jackson School of Geosciences.
The fossils of the Posidonia Shale date back to 183 million years ago, and consist of unusual soft-bodied specimens such as ichthyosaur embryos, squids with ink-sacs, and lobsters. To get more information about the fossilization conditions that caused such beautiful preservation, the scientists put lots of samples under scanning electron microscopes to study their chemical composition.
” I could not wait to get them in my microscope and help inform their preservational story,” stated co-author Jim Schiffbauer, an associate professor at the University of Missouri Department of Geological Sciences, who handled a few of the larger samples.
The scientists found that in every instance, the fossils were mainly made up of phosphate minerals despite the fact that the surrounding black shale rock was dotted with microscopic clusters of pyrite crystals, called framboids.
” I spent days trying to find the framboids on the fossil,” stated co-author Sinjini Sinha, a doctoral student at the Jackson School. “For a few of the specimens, I counted 800 framboids on the matrix while there was perhaps three or four on the fossils.”
Geosciences students from The University of Texas at Austin with ichthyosaur specimens from the Posidonia shale. Credit: Rowan Martindale
Since it exposes key details about the fossilization environment, the truth that pyrite and phosphate are discovered in various places on the specimens is essential. Pyrite forms in anoxic (without oxygen) environments, but phosphate minerals need oxygen. The research study recommends that although an anoxic seafloor sets the stage for fossilization– keeping decay and predators at bay– it took a pulse of oxygen to drive the chemical responses required for fossilization.
These findings complement earlier research performed by the team on the geochemical conditions of websites known for their caches of extremely preserved fossils, called konservat-lagerstätten. Nevertheless, the results of these research studies contradict long-standing theories about the conditions needed for exceptional fossil conservation in the Posidonia.
” Its been thought for a long time that the anoxia triggers the exceptional preservation, however it does not straight help,” stated Sinha. “It assists with making the environment conducive to faster fossilization, which results in the preservation, however its oxygenation thats boosting preservation.”
It turns out, the oxygenation– and the phosphate and accompanying minerals– likewise enhanced the fossils shine.
Recommendation: “What role does anoxia play in exceptional fossil preservation? Lessons from the taphonomy of the Posidonia Shale (Germany)” by A.D. Muscente, Olivia Vinnes, Sinjini Sinha, James D. Schiffbauer, Erin E. Maxwell, Günter Schweigert and Rowan C. Martindale, 23 January 2023, Earth-Science Reviews.DOI: 10.1016/ j.earscirev.2023.104323.
The research was moneyed by Cornell College and the National Science Foundation. The Posidonia fossil specimens utilized in this research study are now part of the collections at the Jackson Schools Non-Vertebrate Paleontology Laboratory.
Golden ammonite fossils at Ohmden quarry. Credit: Rowan Martindale/ The University of Texas at Austin Jackson School of Geosciences.
All that glitters is not gold, or even fools gold in the case of fossils.
New research study performed by researchers at The University of Texas at Austin and their collaborators has actually exposed a brand-new reality about the fossils from Germanys Posidonia shale. They exposed the enduring belief that their shimmer originated from pyrite, widely called fools gold. The source of their golden gleam in fact depends on a mix of minerals, which provides ideas about the environment where these fossils originated.
The discovery is crucial for understanding how the fossils– which are amongst the worlds best-preserved specimens of sea life from the Early Jurassic– concerned form in the first location, and the role that oxygen in the environment had in their formation.
