Furongian Epoch

What happened during this time?

Geophysical

• Seafloor substrate was beginning to change 

• The start of the Caledonian orogeny which will create new mountain ranges extending from present-day Scandinavia through Britain and into North America

Biological

• Algal mats penetrated the interstices between sediment particles, fixing and stiffening the sea bottom. 

• By the late Cambrian, metazoans had affected this mat. Some parts are beginning to resemble the loose, muddy, and unconsolidated sea floor. 

• The rate of weathering on land also increased 

• Larger, superficially more advanced trilobites of the Middle Cambrian disappeared in this new, muddier world. 

• By contrast, the tiny agnostids trilobites were well equipped to dig into -- and out of -- the loosened substrate 

• Paleobiodiversity curves indicate that the Cambrian Explosion and the Great Ordovician Biodiversity Event (GOBE) are either two clearly distinguishable ‘events’ or that they both belong to a single, continuous radiation (e.g., Alroy et al., 2008)

• The late Cambrian ‘Furongian Gap,’ which is visible between the Cambrian Explosion and the GOBE, is possibly only due to a sampling artifact because upper Cambrian sediments are relatively rare and paleontological investigations on this interval, sporadic (Harper et al., 2019).

• There is currently no evidence of plants macrofossils, but microfossils in the form of cryptospores exist in Cambrian sediments.

Agamachates casearius † 

• Taylor & Strother, 2009

• Cryptospores, spherical to discoidal in shape

• They are simple and thick-walled, enclosed within a packet characterized by a common envelope (synoecosporal wall) 

• Each packet contains 1-8 cells, typically 1 or 2 paired cells (dyads)

• Packets may be solitary or occur in closely connected dyads, tetrads, or larger aggregated clusters

• These fossils exhibit "...an intermediate condition between the algae and the embryophytes"

• It appears that a land-based Coleochaete-like alga (cryptophyte) produced these thick-walled spores for use in an aerial (non-aquatic) environment