Morphological and ecological disparity in naraoiids (Arthropoda) from the Early Cambrian Chengjiang Fauna, China

Chen, Jun-Yuan; Edgecombe, Gregory D.; Ramsköld, Lars

doi:10.3853/j.0067-1975.49.1997.249

Cited by 74 publications

(98 citation statements)

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“…The appendage morphology of Naraoia is well-known (Whittington 1977; see also refinements in Ramsköld and Edgecombe 1996), and its massive, spiny basal endites ('gnathobases') leave little room for doubt that the habits of some species of Naraoia were predatory: 'Naraoia appears to have been particularly welladapted to capture and to feed on the varied, small, worm-like creatures that abounded in the Burgess Shale' (Whittington 1977, p. 438). Chen et al (1997) have suggested that one Naraoia species from the Lower Cambrian of China may have rather lived by ingesting sediment, indicating a wider diparity of feeding habits within naraoiids as a whole. But the evidence derived from the majority of closest-related sister taxa points to predatory habits for olenelloids also.…”

Section: P R I M I T I V E P R E D a T O R Y F E E D I N G H A B I T mentioning

confidence: 99%

“…Papyriaspis). Such caecal patterns have been attributed to digestive glands (Ö pik 1961;Cisne 1975;Chen et al 1997), and, if so, might be supposed to have yielded secretions which aided digestion of the particulate organic material sorted by the trunk limbs. Such a digestive system might account for the comparatively small volume of the stomach in these trilobites; much of the work would have been done by digestive enzymes.…”

Section: Uncalcified Anatomymentioning

confidence: 99%

“…Chen et al (1997) claimed that at least one species of the trilobite sister-taxon Naraoia was a deposit feeder, but the great majority of early arachnomorphs had predator morphology. Natant, particle-or deposit-feeding ptychoparioids had appeared before the end of the Early Cambrian, and were abundant by the Mid Cambrian (e.g.…”

Section: Cheiruroideamentioning

confidence: 99%

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Feeding habits in trilobites

1999

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ABSTRACT. We briefly review the various types of feeding habits in marine arthropods, and suggest that the trilobites adopted a range of different feeding strategies. We show that much of the variety of trilobite exoskeletal development, particularly in the cephalon, can be explained as a response to the adoption of specific feeding modes. We regard the primitive mode as having been predatory/scavenging, both from morphological grounds and by out-group comparison, but this habit had a long subsequent history in the group. Predators/scavengers included those trilobites with rigidly braced and attached conterminant or impendent hypostomes, which often developed posterior forks or rasps used by the animals for manipulating prey after it had been grasped by the 'gnathobases'. Advanced predators often acquired expanded anterior glabellar lobes which are associated with the ingestion of bulky food; concomitantly, the largest trilobites of all had predatory morphology. Associated trace fossils are of the Rusophycus type in which impressions of limb bases and rarely the hypostome can be seen. Detritivors were derived from predators by detachment of the hypostome from the doublure in natant mode; it is significant that the hypostome of such feeders exhibited little change thereafter. The typical detritivor morphology is of the 'generalized' ptychopariid type, common in outer shelf habitats, with rectangular or tapering glabellas and small to moderate overall size. It is suggested that in some species the hypostome may have functioned as a 'scoop' directly to aid ingestion of sediment. Trace fossils of Cruziana semiplicata type have been associated with sediment ploughing in this feeding mode. Filter feeders evolved a vaulted cephalic chamber of trinucleimorph type, and elevated thoraces, often flanked by extended genal spines. Where it is known, the hypostome is curved up inside the cephalic chamber, within which sediment stirred into suspension by the limbs was sorted for edible particles. Filter feeding trilobites are typically small, and are uncommon outside muddy habitats. Bean-like Rusophycus are the associated trace fossils. In trinucleids ingress of the feeding current was alongside the thorax and out through the fringe pits. The combination of different feeding modes with adaptation for different prey and/or particle sizes goes some way to account for the variety of trilobites cohabiting in a single site (alpha diversity). We do not claim that the model accounts for all morphological variation displayed by the group.

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Section: P R I M I T I V E P R E D a T O R Y F E E D I N G H A B I T mentioning

confidence: 99%

Section: Uncalcified Anatomymentioning

confidence: 99%

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Feeding habits in trilobites

1999

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“…Whittington 1975Whittington , 1980. A similar morphology of the exopod has been found in different species of Naraoia Walcott, 1912 (Whittington 1977, Chen et al 1997, Hou & Bergström 1997, a reason why these were often considered to be a kind of soft trilobites (e.g. Whittington 1977).…”

mentioning

confidence: 94%

New insights into the appendage morphology of the Cambrian trilobite-like arthropod Naraoia compacta

Haug¹,

Haug²

2016

Bull. Geosci.

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For understanding the life habits of extinct organisms, functional morphology is of crucial importance. In arthropods, the morphology of the appendages in particular gives insights into the mode of life. Yet, in the fossil record of arthropods mainly dorsal structures are preserved, as they are often more sclerotised or even mineralised. Exceptions are, for example, the species of Naraoia from the Cambrian Burgess Shale (about 508 million years old), of which the appendages are also preserved. We present here new details of the appendages of Naraoia compacta, which were made visible with modern imaging methods that were not yet available during former investigations. According to our re-study, the appendage shows a division into basipod, endopod and exopod. The basipod-body joint has not been visible to earlier investigators, and both basipod and endopod are significantly more strongly adorned than previously interpreted. The most important difference to earlier studies regards our interpretation of the exopod morphology. According to our new data, the exopod is composed of a series of similar, small paddles attached to a shaft, and not feather-like in appearance. This morphology has a strong impact on the swimming behaviour of N. compacta, as the paddles can be closed to form a functionally single large paddle during the power stroke, and will be opened during the recovery stroke to reduce the water drag. In this way, our new data provide important insights into the life habits of this long extinct species. •

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“…The medusiform eldoniids (and rotadiscids) are a characteristic component of Burgess Shale-type faunas. In addition to their type occurrence in the Burgess Shale (Walcott, 1911b;Durham, 1974;Friend, 1995), this group is recorded from other Lower (e.g., Chen et al, 1995;Chen and Zhou, 1997) and Middle Cambrian localities in China (Zhao and Zhu, 1994;Dzik et al, 1997), Siberia (Friend et al, 2002), Poland (Masiak and Zylińska, 1994), and Utah (Conway Morris and Robison, 1988) Taxonomic affinities of the eldoniids have remained controversial (e.g., Zhu et al, 2002). One suggestion has been to link them to the lophophorates (e.g., Dzik et al, 1997).…”

Section: Superphylum Ambulacraria Metschnikoff 1881mentioning

confidence: 99%

New records of Burgess Shale-type taxa from the middle Cambrian of Utah

Morris

Selden

Gunther³

et al. 2015

J. Paleontol.

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Abstract.-Cambrian strata of the Laurentian craton contain numerous examples of Burgess Shale-type faunas. Although displaying a more or less concentric distribution around the cratonal margin, most faunal occurrences are in present-day western North America, extending from the Northwest Territories to California. Nevertheless, the soft-bodied and lightly skeletalized fossils in most of these Lagerstätten are highly sporadic. Here, we extend knowledge of such Middle Cambrian occurrences in Utah with reports of four taxa. An arthropod from the Marjum Formation, Dytikosicula desmatae gen. et sp. nov., is a putative megacheiran. It is most similar to Dicranocaris guntherorum, best known from the younger Wheeler Formation, but differs primarily in the arrangement of pleurae and overall size. Along with a specimen of ?Yohoia sp, a new species of Yohoia, Y. utahana sp. nov., is described. It differs from the type and only known species, Y. tenuis, principally in its larger size and shorter exopods; it is the first description of this genus from outside the Burgess Shale. A new species of a stem-group lophotrochozoan from the Spence Shale, Wiwaxia herka sp. nov., possesses a palisade of dorso-lateral spines that are more robust and numerous than the type species of Wiwaxia, W. corrugata. Another notable taxon is Eldonia ludwigi from the Marjum Formation, which is interpreted as a primitive ambulacrarian (assigned to the cambroernids) and a new specimen of the ?cnidarian Cambrorhytium from the Wheeler Shale is illustrated.

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Morphological and ecological disparity in naraoiids (Arthropoda) from the Early Cambrian Chengjiang Fauna, China

Cited by 74 publications

References 0 publications

Feeding habits in trilobites

Feeding habits in trilobites

New insights into the appendage morphology of the Cambrian trilobite-like arthropod Naraoia compacta

New records of Burgess Shale-type taxa from the middle Cambrian of Utah

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