A primitive fish from the Cambrian of North America

Conway Morris, Simon and Caron, Jean-Bernard (2014) A primitive fish from the Cambrian of North America. Nature. ISSN 0028-0836 EISSN: 1476-4687 DOI 10.1038/nature13414

[img]
Preview
Text
nature13414.pdf - Published Version

Download (4MB) | Preview
[img]
Preview
Text
nature13414-s1.pdf - Supplemental Material

Download (1MB) | Preview
[img]
Preview
Image
nature13414-sf1.jpg - Published Version

Download (1MB) | Preview
Official URL: http://www.nature.com/nature/journal/vaop/ncurrent...

Abstract

Knowledge of the early evolution of fish largely depends on soft-bodied material from the Lower (Series 2) Cambrian period of South China. Owing to the rarity of some of these forms and a general lack of comparative material from other deposits, interpretations of various features remain controversial, as do their wider relationships amongst post-Cambrian early un-skeletonized jawless vertebrates. Here we redescribe Metaspriggina on the basis of new material from the Burgess Shale and exceptionally preserved material collected near Marble Canyon, British Columbia, and three other Cambrian Burgess Shale-type deposits from Laurentia. This primitive fish displays unambiguous vertebrate features: a notochord, a pair of prominent camera-type eyes, paired nasal sacs, possible cranium and arcualia, W-shaped myomeres, and a post-anal tail. A striking feature is the branchial area with an array of bipartite bars. Apart from the anterior-most bar, which appears to be slightly thicker, each is associated with externally located gills, possibly housed in pouches. Phylogenetic analysis places Metaspriggina as a basal vertebrate, apparently close to the Chengjiang taxa Haikouichthys and Myllokunmingia, demonstrating also that this primitive group of fish was cosmopolitan during Lower–Middle Cambrian times (Series 2–3). However, the arrangement of the branchial region in Metaspriggina has wider implications for reconstructing the morphology of the primitive vertebrate. Each bipartite bar is identified as being respectively equivalent to an epibranchial and ceratobranchial. This configuration suggests that a bipartite arrangement is primitive and reinforces the view that the branchial basket of lampreys is probably derived. Other features of Metaspriggina, including the external position of the gills and possible absence of a gill opposite the more robust anterior-most bar, are characteristic of gnathostomes and so may be primitive within vertebrates.

Item Type: Article
Uncontrolled Keywords: 2014AREP; IA67;
Subjects: 04 - Palaeobiology
Divisions: 04 - Palaeobiology
08 - Green Open Access
Journal or Publication Title: Nature
Identification Number: 10.1038/nature13414
Depositing User: Sarah Humbert
Date Deposited: 27 Jun 2014 16:20
Last Modified: 27 Dec 2014 01:00
URI: http://eprints.esc.cam.ac.uk/id/eprint/3073

Actions (login required)

View Item View Item

About cookies