The majestic baleen whales are filter-feeders eating vast amounts of small organisms. They typically seek out a concentration of zooplankton and filter the prey from the water using their baleen. Great, actively swimming filter-feeders evolved among sharks, rays, fishes and well-known whales.
However, that understanding was incomplete.
Recently, the fossilized Tamisiocaris borealis (“Tami”) was found in North Greenland . Its frontal body part clearly is specialized for suspension feeding. “Tami” bears long, thin and evenly spaced spines, which are are fitted out with dense rows of long and fine spines. Evidently, “Tami” was feeding on small plankton. It got its food by sweep-net capture of small food-particle (down to 0.5 mm), thus as small as a copepod.
Why get excited about that?
|Fossilized "Tami" - [2, **]|
The presence of swimming suspension feeders in the early Cambrian, more than 525 Million years ago indicate that a complex deep-water ecosystem supported by high primary productivity and nutrient flux existed already at that time. Thus, these Cambrian deep-water ecosystems seem to have been already quite modern – may be less in terms of species, but certainly in terms of viable ecosystem niches.
 A suspension-feeding anomalocarid from the Early Cambrian; Jakob Vinther, Martin Stein, Nicholas R. Longrich & David A. T. Harper; Nature 507, 496–499 (27 March 2014)
[*] from Wikipedia: Anomalocaridids are a group of very early marine animals known primarily from fossils found in Cambrian deposits in China, United States, Canada, Poland and Australia. Anomalocarids are the largest Cambrian animals known — some Chinese forms may have reached 2 m in length — and most of them were probably active carnivores.[**] Artist's view at "http://paleocreations.com/images/536.jpg" on http://paleocreations.com/index.php