Abstract
The rapid diversification of metazoans and their organisation in modern-style marine ecosystems during the Cambrian profoundly transformed the biosphere. What initially sparked this Cambrian explosion remains passionately debated, but the establishment of a coupling between pelagic and benthic realms, a key characteristic of modern-day oceans, might represent a primary ecological cause. By allowing the transfer of biomass and energy from the euphotic zone—the locus of primary production—to the sea floor, this biological pump would have boosted diversification within the emerging metazoan-dominated benthic communities. However, little is known about Cambrian pelagic organisms and their trophic interactions. Here we describe a filter-feeding Cambrian radiodont exhibiting morphological characters that likely enabled the capture of microplankton-sized particles, including large phytoplankton. This description of a large free-swimming suspension-feeder potentially engaged in primary consumption suggests a more direct involvement of nekton in the establishment of an oceanic pelagic-benthic coupling in the Cambrian.
Highlights
The rapid diversification of metazoans and their organisation in modern-style marine ecosystems during the Cambrian profoundly transformed the biosphere
We show that Pahvantia hastata, an as-yet enigmatic arthropod from the middle Cambrian of Utah, was a suspension-feeding radiodont, a relatively small one
The fourth was originally regarded as the isolated valve of a bivalved carapace belonging to Proboscicaris agnosta; it was recently identified as a lateral element of a radiodont cephalic carapace and re-assigned to the genus Hurdia[22,23]
Summary
The rapid diversification of metazoans and their organisation in modern-style marine ecosystems during the Cambrian profoundly transformed the biosphere. Phytoplankton radically changed at that time with the radiation of small, rapidly evolving ornamented acritarchs (acanthomorphs) This has been interpreted as indirect evidence of the introduction of a key component of modern pelagic ecosystems— herbivorous zooplankton[13]. We show that Pahvantia hastata, an as-yet enigmatic arthropod from the middle Cambrian of Utah, was a suspension-feeding radiodont, a relatively small one This taxon illustrates that shortly after the Cambrian explosion, some nektonic animals were likely capable of feeding on microplankton, including large phytoplankton, and of contributing to primary consumption and the establishment of the biological pump in the oceans
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
