Mars Rover Curiosity Hits the Alluvial Fan: Watch for News of Rock Varnish and Organic Microfossils

The Mars rover Curiosity has landed in a sweet spot: an alluvial fan. As such, in listening for news concerning the Mars rover Curiosity, my ears will perk up if there is any discussion of rock varnish or palynology (the study of organic microfossils). Here’s phys.org quoting a scientist concerning rock varnish, which is produced on Earth by microorganisms:

Alluvial fans on Earth are known for their outstanding manganese-rich varnish coatings that can be viewed from aircraft and even satellites like LANDSAT. However, on Mars, the alluvial fans will be coated with a thin layer of dust so it will be necessary to remove the dust to expose any manganese-rich rock varnish. The Gale crater alluvial fan region is the perfect landing site to look for evidence of manganese-rich rock varnish. . . . Once ChemCam/LIBS determines whether a rock coating is composed of manganese, the rover could then travel up to the rock, scrape a small sample and place it in the SAM organic analyses instrument to see what organic compounds exist.

As for the study of organic microfossils, Wikipedia includes the following as being under its purview:

  • fossil pollen
  • fossil spores
  • fossil orbicules
  • fossil dinocysts
  • fossil acritarchs
  • fossil chitinozoans
  • fossil scolecodonts

Let’s take each of these subjects of palynology in turn, beginning with fossil pollen. What might we expect the scientific discussion to sound like if fossil pollen is found on Mars? For a hint, here’s how Science Daily reported, in 2008, on a scientific study of fossil pollen:

[A] new study by University of Florida and Indiana University Southeast researchers shows insect pollinators have likely played a key role in the evolution and success of flowering plants [on Earth] for nearly 100 million years. . . . The researchers sampled pollen from three sites in Minnesota’s Dakota Formation, which represents a time period when a shallow seaway covered North America’s interior. Co-author David Jarzen, a Florida Museum pollen scientist, refined existing pollen processing techniques for extracting intact fossil pollen from the calcareous Minnesota limestone and silicate mudstone rock matrix.

As to fossil spores, here’s a sentence from an abstract of a scientific paper from 1971:

A Late Cambrian to Ordovician age is indicated by the microflora for the Upper Vindhyan sequence exposed in the Karauli and Kotah areas of Rajasthan [in India]. Sandstone, limestone and shales were processed and a variety of sphaeromorphs, interpreted as microplankton and possible fungal spores were obtained.

As to fossil orbicules, an abstract from another scientific paper says this:

Electron microscopy of in situ fossil (Pennsylvanian) pollen assignable to the taxon Schopfipollenites indicates the presence of orbicules and tapetal [cell carpet] membranes similar to those associated with the secretory tapetum of extant plants. Orbicules are spheroidal, hollow and associated with a complex tapetal membrane system.

As for dinocysts, “[t]he first fossil forms,” according to the UCL website, “were described by Ehrenberg in the 1830s from flint of Cretaceous age.” A dinocyst is a capsule in which a dinoflagellite lives. A dinoflagellite is a form of protist (one-celled organism). According to Ask.com:

Dinoflagellates are single-celled organisms that live in oceans, estuaries, lakes, and ponds. Some of them are bioluminescent — they cause a sparkling of the sea at night as the waves break. Some of them cause “red tides,” which can kill fish or poison humans who eat the fish or shellfish that have eaten the dinoflagellates. The Red Sea may have gotten its name from dinoflagellate blooms.

As for acritarchs (not easily classifiable micro-organic structures that have been around on Earth for 3.2 billion years), according to Wikipedia these “may represent the remains of any of the three domains of life, the archaea, the bacteria, and the eukaryotes.”

As for chitinozoa, these are “a taxon of flask-shaped, organic walled marine microfossils” (Wikipedia). They look pretty interesting:

As for scolecodonts, these are jaws from segmented worms that go back to the Cambrian (Wikipedia).  They also look interesting:

File:Scolecodont ramphoprion.png

Do the above images of a chitinozoa and scolecodont provide hints as to what our first sight of Martian life will be?

But why imagine small? Maybe Curiosity will find, not just microfossils, but fossils left by multicellular organisms possessing shells, exoskeletons, or even bones.

What a let-down if no evidence of life on Mars is found at all. Here’s a NASA image of what appears to be rock varnish on Mars:

rock varnish 3

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About Santi Tafarella

I teach writing and literature at Antelope Valley College in California.
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One Response to Mars Rover Curiosity Hits the Alluvial Fan: Watch for News of Rock Varnish and Organic Microfossils

  1. Pingback: Rock Varnish, Manganese, and Life on Mars « The Manganese Mission

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