Nectocaridid ecology, diversity, and affinity: early origin of a cephalopod-like body plan

Smith, Martin R (2013) Nectocaridid ecology, diversity, and affinity: early origin of a cephalopod-like body plan. Paleobiology, 39 (2). pp. 297-321. ISSN 0094-8373 DOI 10.1666/12029

Full text not available from this repository.
Official URL: http://www.bioone.org/doi/abs/10.1666/12029

Abstract

Nectocaridids are soft-bodied early to middle Cambrian organisms known from Burgess Shale-type deposits in Canada, China, and Australia. Originally described as unrelated species, they have recently been interpreted as a clade; their flexible tentacles, camera-type eyes, lateral fins, internal gills, axial cavity, and funnel point to a relationship with the cephalopods. However, aspects of this reinterpretation, including the relevance of the group to cephalopod evolution, have been called into question. 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.

Item Type: Article
Additional Information: High resolution images may be accessed from the related Author url listed above once the paper has been published
Uncontrolled Keywords: NIL AREP; IA65;
Subjects: 04 - Palaeobiology
Divisions: 04 - Palaeobiology
Journal or Publication Title: Paleobiology
Volume: 39
Page Range: pp. 297-321
Identification Number: 10.1666/12029
Depositing User: Sarah Humbert
Date Deposited: 31 Mar 2013 21:41
Last Modified: 23 Jul 2013 10:05
URI: http://eprints.esc.cam.ac.uk/id/eprint/2732

Actions (login required)

View Item View Item

About cookies