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Title: Three new naraoiid species from the Burgess Shale, with a morphometric and phylogenetic reinvestigation of Naraoiidae
Abstract

Naraoiids are non‐biomineralized euarthropods characterized by the complete fusion of post‐cephalic tergo‐pleurae into a single shield, as well as an extensively ramified digestive tract. Ranging from the early Cambrian to the late Silurian (Pridoli), these arthropods of simple appearance have traditionally been associated with the early diversification of trilobites and their close relatives, but the interrelationships and affinities of naraoiids within Artiopoda remain poorly characterized. Three new species from the Burgess Shale (middle Cambrian, Stage 5) of British Columbia, Canada, are described here:Misszhouia canadensissp. nov., from Marble Canyon (Kootenay National Park), the first species belonging to the genusMisszhouiaoutside of China;Naraoia magnasp. nov., from Marble Canyon and also from the Raymond Quarry (Yoho National Park), the largest species ofNaraoiadescribed thus far, reaching up to 9 cm in length; andNaraoia arcanasp. nov., from two sublocalities on Mount Stephen (Yoho National Park), defined by its unusual combination of spines. This new material shows that gut morphology is no longer a reliable character to distinguishMisszhouiafromNaraoia. We demonstrate thatNaraoiaandMisszhouiacan instead be discriminated morphometrically, based on simple metrics of the dorsal exoskeleton. Our quantitative results also help with inter‐specific discrimination and illustrate possible cases of sexual dimorphism. Phylogenetically, the inclusion of morphometric data adds resolution to our cladogram, although parsimony and likelihood treatments provide somewhat different evolutionary scenarios. In all cases, liwiines are nested within Naraoiidae, resolved as the most derived clade of trilobitomorph arthropods.

 
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NSF-PAR ID:
10063737
Author(s) / Creator(s):
 ;  ;  ;
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
Palaeontology
Volume:
62
Issue:
1
ISSN:
0031-0239
Page Range / eLocation ID:
p. 19-50
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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