Exceptionally Preserved Fossils

Briggs, Deg

doi:10.1002/9780470999295.ch76

Cited by 21 publications

(14 citation statements)

References 8 publications

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“…Konservat-Lagerstätten are extraordinary fossil occurrences characterized by unusual quality of preservation (Briggs, 2001). Most commonly, they preserve the soft parts of animals and provide rare glimpses of the biology and biodiversity of ancient ecosystems.…”

Section: Introductionmentioning

confidence: 99%

A Paleogene calcareous microfossil Konservat-Lagerstatte from the Kilwa Group of coastal Tanzania

Bown

Jones

Lees

et al. 2008

Geological Society of America Bulletin

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Microfossil assemblages and their shell geochemistry are widely used in paleoceanography, but they can be signifi cantly altered by subtle variations in preservation state. Clay-rich, hemipelagic sediments of the Paleogene Kilwa Group of coastal Tanzania host calcareous microfossils that are exceptionally preserved, as evidenced by morphological, taxonomic, and geochemical data. The planktonic foraminifera are preserved as glassy, translucent tests with original microgranular wall textures that resemble well-preserved modern specimens, and they arguably yield geochemical values that are relatively unaffected by recrystallization. The calcareous nannofossils are extraordinarily diverse and represented by unique assemblage compositions that include dissolution-susceptible taxa, especially holococcoliths and rhabdoliths, and fragile and very small (<3-µm) heterococcoliths, many of which are new taxa. Notably, the extant, deep-photic-zone taxon Gladiolithus is documented for the fi rst time in the pre-Quaternary fossil record. The Kilwa Group calcareous nannofossil diversities are consistently higher than all coeval assemblages and provide a benchmark against which to compare other Paleogene biodiversity data. Highest diversities are preserved in hemipelagic, clay-rich lithologies and the greatest losses occur in lithifi ed, carbonate-rich sediments. Most of the lost diversity, however, is confi ned to distinct taxonomic groups (holococcoliths and Syracosphaerales), and in general the preservational potential of Paleogene coccolithophores was greater than in the modern oceans because a larger proportion of the biodiversity fell within the larger size fractions. For both foraminifera and coccolithophores, incorporation into impermeable clay-rich sediments that have never been deeply buried appears to have been critical in producing this Konservat-Lagerstätte preservation.

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Section: Introductionmentioning

confidence: 99%

A Paleogene calcareous microfossil Konservat-Lagerstatte from the Kilwa Group of coastal Tanzania

Bown

Jones

Lees

et al. 2008

Geological Society of America Bulletin

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“…The first ones, named Konzentrat‐Lagerstätten (or concentration deposits), can be associated with condensation or placer deposits and catastrophic events (e.g. rapid burial: Briggs ), and contain dense concentrations of disarticulated organic hard parts, such as a bonebed sensu Rogers et al . ().…”

Section: Discussionmentioning

confidence: 99%

“…The first ones, named Konzentrat-Lagerstätten (or concentration deposits), can be associated with condensation or placer deposits and catastrophic events (e.g. rapid burial : Briggs 2001), and contain dense concentrations of disarticulated organic hard parts, such as a bonebed sensu Rogers et al (2007). The second ones, named Konservat-Lagerstätten (or conservation deposits), correspond to those deposits in which preservation retains complete organism information.…”

Section: Discussionmentioning

confidence: 99%

Exceptionally well-preserved vegetal remains from the Upper Cretaceous of ‘Lo Hueco’, Cuenca, Spain

Cambra‐Moo

Barroso-Barcenilla

Coruña

et al. 2013

LET

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Vegetal remains are considered labile structures that quickly become decayed in ecosystems. However, certain lignified tissues (woody plants) can largely resist decomposition, becoming sometimes exceptionally well preserved. At the Upper Cretaceous site of ‘Lo Hueco’ (Cuenca, Spain), those woody remains (trunks and branches) with resinous material in the inner tracheids and parenchyma cells that were buried rapidly under anoxic conditions experienced a low degree of maturation, becoming exceptionally well preserved. Those woody remains deposited under oxic conditions (sub‐aerial or sub‐aquatic exposure) were more intensely biodegraded and subsequently carbonified, partially or completely mineralized in gypsum and covered by a ferruginous crust. These two modes of preservation are scarce, with silicification or carbonification processes much more common, and both can be considered as ‘exceptional preservation’. Other vegetal remains, such as carbonified leaves, stems and roots, were collected in the site. The different modes of preservation depend directly on: depositional micro‐environment (sandy distributary channel, muddy flood plain); and type (trunk, branch, stem, leave, root) and state (presence or absence of resinous material) of the material. The great abundance and diversity of fossils in ‘Lo Hueco’ identify it as Konzentrat‐Lagerstätten, sequentially formed by alternated events of flooding and drying depositional events, but the exceptional quality and rarity of determinate vegetal macroremains preservation suggest that certain deposits of this site can be considered as conservation deposits.

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“…Microbial biofilms are regarded in retaining optimal conditions for phosphatization (Seilacher et al 1985;Lamboy and Monty 1987;Martill 1989;Abed and Fakhouri 1990;Lamboy 1990Lamboy , 1993Reimers et al 1990;Wilby and Martill 1992;Briggs et al 1993;Wilby et al 1996;Ogihara 1999;Soudry 2000;Rivadeneyra et al 2006;Trela 2008) and they are related to well-preserved phosphatic fossils (Seilacher et al 1985;Soudry and Lewy 1988;Toporski et al 2002;Wilby et al 2004;Arena 2008). According to Briggs (2001), phosphates precipitate very rapidly as tiny crystallites (often \30 nm) and preserve morphological details of the highest fidelity. In the case of phosphatic wood remains, Sweeney et al (2009) proposed that phosphatization resulted from the metabolic activities of microbes exploiting wood tissues.…”

Section: Fossil Wood Preservationmentioning

confidence: 97%

Preservation of phosphatic wood remains in marine deposits of the Brentskardhaugen Bed (Middle Jurassic) from Svalbard (Boreal Realm)

Reolid

Philippe

Nagy

et al. 2010

Facies

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International audienceThe exceptional record of well-preserved wood remains from the Middle Jurassic of Svalbard is studied from the taphonomic point of view. These remains were recovered from the Brentskardhaugen Bed, a conglomerate with phosphatic nodules, which constitutes the record of the eroded deposits corresponding to the Toarcian-Early Bathonian gap. The wood remains occur in the cores of these nodules. These wood fragments are preserved as phosphate (francolite) and as charcoals. The well preservation allows us to identify xenoxyloid cross-field pits and xenoxylean pitting on the radial wall of tracheid, characterizing the species Xenoxylon phyllocladoides. Phosphatic nodules originated as the result of early phosphate precipitation filling the inter-particle pore space of the sandy quartz sediment around the wood fragments (and other organic-rich nucleation centers) below the sediment-water interface. This phosphatization involved a sudden burial of the wood remains in the sea-bottom, the subsequent decay of the lignin, and a fast growth of carbonate fluorapatite forming phosphatic inner moulds. Fossil microbial biofilms induced the phosphatization. The dissolution/decay of the lignin is not possible in charcoal, and phosphatic casts did not develop in charcoalified parts. Some remains were not totally charred, with the lignin preserved only in reduced relicts that were later replaced by phosphate. The phosphate precipitation occurred in recurrent episodes during the Toarcian-Callovian as a result of distinct sea-level rises and the associated nutrification of the shelf. The phosphatic nodules were developed and reworked during the transgressive-regressive cycle of the Toarcian-Early Bathonian, as well as during the final transgression of the Late Bathonian-Earliest Callovian, which resulted in the Brentskardhaugen Be

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Exceptionally Preserved Fossils

Cited by 21 publications

References 8 publications

A Paleogene calcareous microfossil Konservat-Lagerstatte from the Kilwa Group of coastal Tanzania

A Paleogene calcareous microfossil Konservat-Lagerstatte from the Kilwa Group of coastal Tanzania

Exceptionally well-preserved vegetal remains from the Upper Cretaceous of ‘Lo Hueco’, Cuenca, Spain

Preservation of phosphatic wood remains in marine deposits of the Brentskardhaugen Bed (Middle Jurassic) from Svalbard (Boreal Realm)

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