Resolving Three-Dimensional and Subsurficial Features of Carbonaceous Compressions and Shelly Fossils Using Backscattered Electron Scanning Electron Microscopy (Bse-Sem)

Muscente, A.D.; Xiao, Shuhai

doi:10.2110/palo.2014.094

Cited by 34 publications

(23 citation statements)

References 45 publications

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“…Nonetheless, a variety of other tools has proven to be useful in this regard. Chief among these is scanning electron microscopy (SEM), especially in backscattered mode (BSE), which can reveal small‐scale morphological features not otherwise evident (Muscente & Xiao, ; Tang, Pang, Yuan, & Xiao, ). For example, detection of fusellae (microstructures of graptolite tubaria) in specimens assigned to Yuknessia from the Burgess Shale Formation and the Cambrian of Utah (Figure a,b) indicates that this taxon, long regarded as a macroalga, is actually a metazoan with a hemichordate affinity (LoDuca, Caron, Schiffbauer, Xiao, & Kramer ; Maletz & Steiner, ).…”

Section: A Synopsis Of Early Paleozoic Non‐calcified Macroalgal Fossilsmentioning

confidence: 99%

Seaweed morphology and ecology during the great animal diversification events of the early Paleozoic: A tale of two floras

LoDuca

Bykova

et al. 2017

Geobiology

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Non-calcified marine macroalgae ("seaweeds") play a variety of key roles in the modern Earth system, and it is likely that they were also important players in the geological past, particularly during critical transitions such as the Cambrian Explosion (CE) and the Great Ordovician Biodiversification Event (GOBE). To investigate the morphology and ecology of seaweeds spanning the time frame from the CE through the GOBE, a carefully vetted database was constructed that includes taxonomic and morphometric information for non-calcified macroalgae from 69 fossil deposits. Analysis of the database shows a pattern of seaweed history that can be explained in terms of two floras: the Cambrian Flora and the Ordovician Flora. The Cambrian Flora was dominated by rather simple morphogroups, whereas the Ordovician Flora, which replaced the Cambrian Flora in the Ordovician and extended through the Silurian, mainly comprised comparatively complex morphogroups. In addition to morphogroup representation, the two floras show marked differences in taxonomic composition, morphospace occupation, functional-form group representation, and life habit, thereby pointing to significant morphological and ecological changes for seaweeds roughly concomitant with the GOBE and the transition from the Cambrian to Paleozoic Evolutionary Faunas. Macroalgal changes of a similar nature and magnitude, however, are not evident in concert with the CE, as the Cambrian Flora consists largely of forms established during the Ediacaran. The cause of such a lag in macroalgal morphological diversification remains unclear, but an intriguing possibility is that it signals a previously unknown difference between the CE and GOBE with regard to the introduction of novel grazing pressures. The consequences of the establishment of the Ordovician Flora for shallow marine ecosystems and Earth system dynamics remain to be explored in detail but could have been multifaceted and potentially include impacts on the global carbon cycle.

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Section: A Synopsis Of Early Paleozoic Non‐calcified Macroalgal Fossilsmentioning

confidence: 99%

Seaweed morphology and ecology during the great animal diversification events of the early Paleozoic: A tale of two floras

LoDuca

Bykova

et al. 2017

Geobiology

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“…Mechanical preparation such as sectioning or serial grinding may be employed 16 17 18 , but ultimately lead to the destruction of the material. This disadvantage is also shared by methods based on electron microscopy, such as focused ion beam electron microscopy 19 and multi-voltage back-scattered electron imaging 20 , which are additionally limited to small sample sizes, and non-intuitive to interpret. Recently, high resolution x-ray imaging became increasingly popular among palaeontologists for the non-destructive examination of fossils 21 22 23 24 25 26 27 28 29 30 .…”

Section: The Study Of Fossilsmentioning

confidence: 99%

Augmented laminography, a correlative 3D imaging method for revealing the inner structure of compressed fossils

Zubér

Laaß

Hamann

et al. 2017

Sci Rep

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Non-destructive imaging techniques can be extremely useful tools for the investigation and the assessment of palaeontological objects, as mechanical preparation of rare and valuable fossils is precluded in most cases. However, palaeontologists are often faced with the problem of choosing a method among a wide range of available techniques. In this case study, we employ x-ray computed tomography (CT) and computed laminography (CL) to study the first fossil xiphosuran from the Muschelkalk (Middle Triassic) of the Netherlands. The fossil is embedded in micritic limestone, with the taxonomically important dorsal shield invisible, and only the outline of its ventral part traceable. We demonstrate the complementarity of CT and CL which offers an excellent option to visualize characteristic diagnostic features. We introduce augmented laminography to correlate complementary information of the two methods in Fourier space, allowing to combine their advantages and finally providing increased anatomical information about the fossil. This method of augmented laminography enabled us to identify the xiphosuran as a representative of the genus Limulitella.

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“…D–E, N–O). The green material appears brighter than the underlying shale in BSE‐SEM images, indicating that its minerals backscatter more electrons and therefore have a higher average Z value than the silicates in the shale (Muscente and Xiao ). EDS elemental maps show that the minerals in the fossil have higher concentrations of Fe and Mg and lower concentrations of Si and K than the silicates in the underlying shale (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…All type specimens were photographed using standard reflected‐light photography techniques, and their morphologies, ultrastructures and preservational features were studied using a Hitachi TM3000 tabletop thermionic (tungsten filament source) SEM with polepiece BSE four‐array solid‐state detector and Bruker XFlash compact EDS detector housed in the Virginia Tech (VT) Department of Geosciences. All electron images were acquired at an accelerating voltage of 15 keV and working distance of 12 mm using the compositional (atomic number, or Z) contrast imaging mode (Muscente and Xiao ). Conductive coating was not deposited on the specimens prior to imaging, as this study made use of a low vacuum system in which the specimen chambers are held at pressures (~10 −2 torr) allowing for the ionization and electrical conduction of surface charge by gases (Taylor ; Taylor and Jones ).…”

Section: Methodsmentioning

confidence: 99%

The hydroid fossil record and analytical techniques for assessing the affinities of putative hydrozoans and possible hemichordates

2015

Self Cite

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Hydrozoan cnidarians are widespread in modern environments, but their polyps or hydroids, when not biomineralized, are generally rare in the fossil record. To assess the affinities of four hydrozoan taxa previously described on the basis of supposed fossils of non-biomineralized hydroids, we re-analysed the type specimens of these taxa using a combination of light and electron microscopic tools, including backscattered electron (BSE) scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). New morphological, ultrastructural and taphonomic data were generated for Archaeoantennularia byersi from the Devonian of Michigan, Archaeocryptolaria compacta from the Ordovician of Virginia, and Mazohydra megabertha and Drevotella proteana from the Carboniferous Mazon Creek Lagerst€ atte of Illinois, which are preserved as carbonaceous fossils, aluminosilicate films and iron carbonate minerals in siderite concretions, respectively. In the context of these results, we provide a review of the fossil record of non-biomineralized hydroids, describe possible biases and changes through time in their occurrence and preservation, and evaluate the criteria commonly used to identify and interpret their fossils. Although hydroids have been reported from Phanerozoic (particularly lower Palaeozoic) rocks around the world, many putative hydroids from the Palaeozoic are poorly substantiated and may actually be hemichordates. Indeed, none of the type specimens in this study represent unequivocal hydrozoans. As shown in BSE images, metatype specimens of A. byersi possess autothecae, fusellae, stolons, stolothecae and bithecae, which decisively indicate that they are dendroid graptolites rather than hydroids. The analyses yielded no evidence that A. compacta, Mazohydra and Drevotella are hydrozoans, as their holotypes lack the diagnostic morphological, taphonomic and ecological features characteristic of purported hydroid analogues. Consequently, our results suggest that many Palaeozoic hydroids may be hemichordates and that interpretations of hydroid fossils should be tested and refined using data collected via in situ analytical techniques like BSE-SEM and EDS.

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Resolving Three-Dimensional and Subsurficial Features of Carbonaceous Compressions and Shelly Fossils Using Backscattered Electron Scanning Electron Microscopy (Bse-Sem)

Cited by 34 publications

References 45 publications

Seaweed morphology and ecology during the great animal diversification events of the early Paleozoic: A tale of two floras

Seaweed morphology and ecology during the great animal diversification events of the early Paleozoic: A tale of two floras

Augmented laminography, a correlative 3D imaging method for revealing the inner structure of compressed fossils

The hydroid fossil record and analytical techniques for assessing the affinities of putative hydrozoans and possible hemichordates

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