A suspension-feeding anomalocarid from the Early Cambrian

TY - JOUR

T1 - A suspension-feeding anomalocarid from the Early Cambrian

AU - Vinther, Jakob

AU - Stein, Martin

AU - Longrich, Nicholas R.

AU - Harper, David A. T.

PY - 2014

Y1 - 2014

N2 - Large, actively swimming suspension feeders evolved several times in Earth's history, arising independently from groups as diverse as sharks, rays and stemteleost fishes1, and in mysticete whales2. However, animals occupying this niche have not been identified fromthe early Palaeozoic era. Anomalocarids, a group of stem arthropods that were the largest nektonic animals of the Cambrian and Ordovician periods, are generally thought to have been apex predators3-5. Here we describe new material from Tamisiocaris borealis6, an anomalocarid fromthe EarlyCambrian (Series 2) Sirius Passet Fauna of North Greenland, and propose that its frontal appendage is specialized for suspension feeding. The appendage bears long, slender and equally spaced ventral spines furnished with dense rows of long and fine auxiliary spines. This suggests that T. borealiswas a microphagous suspension feeder, using its appendages for sweep-net capture of food items down to 0.5mm, within the size range of mesozooplankton such as copepods. Our observations demonstrate that large, nektonic suspension feeders first evolvedduring theCambrian explosion, as part of an adaptive radiation of anomalocarids. The presence of nektonic suspension feeders intheEarlyCambrian, togetherwith evidence for a diverse pelagic community containing phytoplankton7,8 andmesozooplankton7,9,10, indicate the existence of a complex pelagic ecosystem11 supported by high primary productivity and nutrient flux12,13. Cambrian pelagic ecosystems seem to have been more modern than previously believed.

AB - Large, actively swimming suspension feeders evolved several times in Earth's history, arising independently from groups as diverse as sharks, rays and stemteleost fishes1, and in mysticete whales2. However, animals occupying this niche have not been identified fromthe early Palaeozoic era. Anomalocarids, a group of stem arthropods that were the largest nektonic animals of the Cambrian and Ordovician periods, are generally thought to have been apex predators3-5. Here we describe new material from Tamisiocaris borealis6, an anomalocarid fromthe EarlyCambrian (Series 2) Sirius Passet Fauna of North Greenland, and propose that its frontal appendage is specialized for suspension feeding. The appendage bears long, slender and equally spaced ventral spines furnished with dense rows of long and fine auxiliary spines. This suggests that T. borealiswas a microphagous suspension feeder, using its appendages for sweep-net capture of food items down to 0.5mm, within the size range of mesozooplankton such as copepods. Our observations demonstrate that large, nektonic suspension feeders first evolvedduring theCambrian explosion, as part of an adaptive radiation of anomalocarids. The presence of nektonic suspension feeders intheEarlyCambrian, togetherwith evidence for a diverse pelagic community containing phytoplankton7,8 andmesozooplankton7,9,10, indicate the existence of a complex pelagic ecosystem11 supported by high primary productivity and nutrient flux12,13. Cambrian pelagic ecosystems seem to have been more modern than previously believed.

U2 - 10.1038/nature13010

DO - 10.1038/nature13010

M3 - Letter

C2 - 24670770

SN - 1061-4036

VL - 507

SP - 496

EP - 499

JO - Nature: New biology

JF - Nature: New biology

IS - 7493

ER -