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Thus far, work on the Chuar Group has focused on exceptionally
well preserved and abundant populations of vase-shaped
microfossils (VSMs). This work has shown that VSMs have affinities with
the testate amoebae (or ‘thecamoebae’), amoebae that make their
own shells, or tests, and today are important components of freshwater and
terrestrial ecosystems. Recent phylogenetic trees indicate that some testate
amoeban clades are closely related to the animals and fungi. Thus, these
fossils provide an important calibration for branching events in the eukaryotic
crown group. They also provide the earliest evidence for heterotrophic protists,
indicating ecosystem expansion by ~750 Ma. Several VSMs exhibit unusual,
semicircular holes in their tests, which may reflect the activity of
scavengers or predators, suggesting even broader expansion of food web complexity
by this time. |
