Data from: The palaeobiological significance of clustering in acritarchs: a case study from the early Cambrian of North Greenland

Aggregated clusters of acritarchs are relatively common among assemblages
of organic-walled microfossils, yet such associations have received
relatively little attention. Here we report a new diversity of acritarch
clusters from the early Cambrian Buen Formation of North Greenland. The
aggregation patterns of four genera (Skiagia, Comasphaeridium, Asteridium,
and Synsphaeridium) are described together with their background
population characteristics (presence of openings, inner bodies, and
overall disparity) in order to better understand the palaeobiology of
these acritarchs. The majority of Skiagia clusters were found to be
monospecific despite significant intraspecific variability, a pattern that
is suggestive of a strong environmental influence on Skiagia morphologies
and aggregation habits. Abundant small (< 20 µm) Comasphaeridium
vesicles were recovered in a broad range of chiefly monospecific clusters
that have likely been formed under bloom conditions. A colonial habit is
tentatively inferred from the tightly packed appearance of monogeneric
Asteridium aggregates, and clearly evidenced by the highly conserved
cellular structure of recovered Synsphaeridium clusters. A lack of
excystment structures in Comasphaeridium and Asteridium vesicles suggests
these taxa represent actively growing cells rather than resting cysts.
Altogether, these findings shed new light on the diversity of cellular
structures and lifestyles represented among Cambrian acritarchs, and
illustrate a range of reproduction and defence strategies adopted by
plankton in the face of novel environmental pressures.