Microscopic analysis offers new understanding of Middle Triassic Biota

A recent study examining microcoprolites from the Luoping biota has shed light on the dietary habits of lophogastrid shrimps, revealing their consumption of cyanobacteria. This finding, according to a study led by Dr. Michael Benton and published by Science Direct, provides valuable insight into primary producers and consumers in Triassic marine ecosystems following the Permian-Triassic mass extinction event. The discovery is instrumental in understanding the full restoration of marine ecosystems after such a catastrophic event.

The research illuminates how modern-type marine ecosystems were established during the Triassic period post the Permian-Triassic mass extinction. While much focus has been given to higher trophic levels, less attention has been paid to the dynamics at primary levels. The study revealed compelling evidence from microcoprolites found in the Luoping biota, dating back to the early Anisian of the Middle Triassic. This evidence suggests that lophogastrid shrimps consumed cyanobacteria, offering insights into primary producers and consumers within these ecosystems.

Researchers used advanced microscopic techniques including Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) elemental analysis, micro-Computed Tomography (micro-CT), Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) scanning, and Raman testing to meticulously examine these microcoprolites. Their findings revealed crescent-shaped canals arranged symmetrically, suggesting an association with Palaxius isp., an ichnospecies commonly produced by crustaceans. Further support for this inference came from comparative analysis with fossilized intestines from lophogastrid shrimps which showed striking similarities in ultrastructure and chemical composition. This detailed investigation confirms the emergence of modern-type zooplankton, including lophogastrids that replaced extinct Palaeozoic marine invertebrate taxa while primitive phytoplankton like cyanobacteria likely persisted.

The importance of this discovery goes beyond mere paleontological interest. It provides a clearer understanding of the energy pyramid and trophic levels within a well-preserved Middle Triassic marine biota. This study serves as a pivotal example of the resilience and full recovery of marine ecosystems following catastrophic events, shedding light on the processes that drive ecosystem re-establishment and evolution over geological time.

ScienceDirect: Yuxuan Chen, et al., Crustacean microcoprolites from the Middle Triassic Luoping Biota, China: Evidence for primary producers in the first Modern-type marine ecosystems, Palaeogeography, Palaeoclimatology, Palaeoecology (2023). DOI: doi.org/10.1016/j.palaeo.2023.111840