From:

Three-dimensional preservation of cellular and subcellular structures suggests 1.6 billion-year-old crown-group red algae

Stefan Bengtson , Therese Sallstedt, Veneta Belivanova, Martin Whitehouse Published: March 14, 2017

http://dx.doi.org/10.1371/journal.pbio.2000735

“The last common ancestor of modern eukaryotes is generally believed to have lived during the Mesoproterozoic era, about 1.6 to 1 billion years ago, or possibly somewhat earlier. We studied exquisitely preserved fossil communities from ~1.6 billion-year-old sedimentary rocks in central India representing a shallow-water marine environment characterized by photosynthetic biomats.

We discovered amidst extensive cyanobacterial mats a biota of filamentous and lobate organisms that share significant features with modern eukaryotic algae, more specifically red algae. The rocks mainly consist of calcium and magnesium carbonates, but the microbial mats and the fossils are preserved in calcium phosphate, letting us view the cellular and subcellular structures in three dimensions with the use of synchrotron-radiation X-ray tomographic microscopy.

The most conspicuous internal objects in the cells of the filamentous forms are rhomboidal platelets that we interpret to be part of the photosynthetic machinery of red algae. The lobate forms grew as radiating globular or finger-like protrusions from a common centre. These fossils predate the previously earliest accepted red algae by about 400 million years, suggesting that eukaryotes may have a longer history than commonly assumed.”

That’s just an amazing level of detail.

dv said:

That’s just an amazing level of detail.

Agree.

“cellular and subcellular structures in three dimensions with the use of synchrotron-radiation X-ray tomographic microscopy”

This is the important bit of how they achieved such detail – it’s a relatively new tool, as applied to fossils – less than 12 years old. That, and the preservation is excellent.

I wish the tool had been available when I was trying to precisely date sedimentation in a rapidly sedimented geologic basin using paleopalynology. The preservation was good or better, but internal detail of palynomorphs was unable to be extracted by bleaching them, as the basin had been cooked too much.

Michael V said:

“in three dimensions with the use of synchrotron-radiation X-ray tomographic microscopy”

We can do that in Australia, it’s what the Australia synchrotron was specifically designed to do, high energy X-ray tomography.