Australia: The Land Where Time Began

A biography of the Australian continent 

A Suspension-Feeding Anomalocaridid from the Early Cambrian

Through the history of life on Earth large, actively swimming suspension feeders have evolved several times, arising independently in groups such as sharks, rays and stem teleost fish, as well as in mysticete whales, though such animals have not been identified from the Early Palaeozoic Era. In this paper the authors¹ report the finding of new material from Tamisiocaris borealis, and Anomalocarid from the Serius Passet Fauna of North Greenland, Early Cambrian (series 2), and propose that its frontal appendage has been specialised for suspension feeding.  On these appendages there are long, slender ventral spines that are equally spaced and have dense rows of long and dense auxiliary spines. It is suggested by this that T. borealis was a microphagous suspension feeder, the appendages being used for sweep-net capture of food items down to 0.5 mm, which is in the size range of mesozooplankton such as copepods. It is suggested by these observations that the earliest appearance of suspension feeders was in the Cambrian explosion, part of an adaptive radiation of anomalocarids. The existence of a complex pelagic ecosystem supported by high primary productivity and flux of nutrients is indicated by the presence of nektonic feeders in the Early Cambrian, as well as evidence of a diverse pelagic community that contained phytoplankton and mesozooplankton. The authors¹ suggest that pelagic ecosystems of the Cambrian appear to have more modern than previously believed.

Sources & Further reading

Vinther, Jakob, Martin Stein, Nicholas R. Longrich, and David A. T. Harper. "A Suspension-Feeding Anomalocarid from the Early Cambrian." Nature 507, no. 7493 (03/27/print 2014): 496-99.