Nectocaridid ecology, diversity, and affinity: early origin of a cephalopod-like body plan
Here, I examine new and existing nectocaridid material, including a large new form that may represent a sexual dimorph of
Nectocaris pteryx
. Differences between existing taxa largely represent taphonomic variation between sites and specimens—which provides further constraint on the organisms' anatomy. I revise the morphology of the tentacles and fins, and describe mouthparts and phosphatized gills for the first time. A mathematical analysis supports the presence of the earliest known camera-type eyes, and fluid mechanical considerations suggest that the funnel is optimized for efficient jet propulsion in a low Reynolds number flow regime.
Nectocaridids closely resemble coleoid cephalopods, but a position deeper within Cephalopoda raises fewer stratigraphic challenges. Whether its coleoid-like construction reflects common ancestry or profound convergence, the
Nectocaris
body plan adds substantially to Cambrian disparity, demonstrating the rapid colonization of nektobenthic niches after the Cambrian explosion.
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A. Yu. Ivantsov
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- Published
- Jan 01, 2013
- Vol/Issue
- 39(2)
- Pages
- 297-321
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