Depth as an overarching environmental variable modulating preservation potential and temporal resolution of shelly taphofacies

Ritter, Matias do Nascimento; Erthal, Fernando; Coimbra, João Carlos

doi:10.1111/let.12289

Cited by 12 publications

(8 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast, the otolith age range at 30 m spans most of the Holocene (6–7961 yr), enabling a clearer signal. The different taphonomic pathways caused by local conditions lead to distinct taphofacies (Brett and Baird 1986; Speyer and Brett 1986; Best and Kidwell 2000a; Tomašových and Zuschin 2009; Petró et al 2018; Ritter et al 2019). Importantly, variation in taphofacies may occur over relatively small spatial and depth scales, as in our case study.…”

Section: Discussionmentioning

confidence: 99%

The taphonomic clock in fish otoliths

Agiadi¹,

Azzarone²,

Hua³

et al. 2021

Paleobiology

View full text Add to dashboard Cite

Paleobiological and paleoecological interpretations rely on constraining the temporal resolution of the fossil record. The taphonomic clock, that is, a correlation between the alteration of skeletal material and its age, is an approach for quantifying time-averaging scales. We test the taphonomic clock hypothesis for marine demersal and pelagic fish otoliths from a 10–40 m depth transect on the Mediterranean siliciclastic Israeli shelf by radiocarbon dating and taphonomic scoring. Otolith ages span the last ~8000 yr, with considerable variation in median and range along the transect. Severely altered otoliths, contrary to pristine otoliths, are likely to be older than 1000 yr. For pelagic fish otoliths, at 30 m depth, taphonomic degradation correlates positively with postmortem age. In contrast, no correlation occurs for demersal fishes at 10 and 30 m depth, mostly because of the paucity of very young pristine (<150 yr) otoliths, possibly due to a drop in production over the last few centuries. Contrary to molluscan and brachiopod shells, young otoliths at these depths are little affected and do not show a broad spectrum of taphonomic damage, because those that derive from predation are excreted in calcium- and phosphate-rich feces forming an insoluble crystallic matrix that increases their preservation potential. At 40 m depth, all dated otoliths are very young but rather damaged because of locally chemically aggressive sediments, thus showing no correlation between taphonomic grade and postmortem age. Our results show that local conditions and the target species population dynamics must be considered when testing the taphonomic clock hypothesis.

show abstract

Section: Discussionmentioning

confidence: 99%

The taphonomic clock in fish otoliths

Agiadi¹,

Azzarone²,

Hua³

et al. 2021

Paleobiology

View full text Add to dashboard Cite

show abstract

“…Erthal (2012) found a correlation between light colors (white, cream) and the presence of mud, and more loosely, between reddish colors and deposits abundant in heavy minerals. Ritter et al (2017) observed the highest color alteration in the shallowest sample of their study, and Ritter et al (2019) noted an increase in the frequency of shells with ocher, yellow, and red colors with depth. As stated above, Tomašových et al (2022) found a relationship between stained bivalves and millennial time averaging, caused by low sedimentary rates and prolonged exposure of shells in a sulfate reduction zone.…”

Section: Introductionmentioning

confidence: 88%

“…The extent of time averaging in modern marine death assemblages varies according to water depth, encompassing a longer period of time in deeper environments, which tend to have low net sedimentation rates but also vary as a function of mixing (bioturbation) and disintegration of shells in the taphonomically active zone (e.g., Fürsich and Aberhan 1990; Olszewski 1999; Petro et al 2018; Ritter et al 2019; Tomašových et al 2022). In coastal and nearshore environments, where the rates of destruction are higher and the production of shells is temporally limited, time averaging has been estimated to reach a maximum of a few thousand years (Kidwell and Bosence 1991; Flessa et al 1993; Kowalewski et al 1998; Kidwell 2013).…”

Section: Introductionmentioning

confidence: 99%

“…They found that discoloration correlated with postmortem age. Erthal (2012) and Ritter et al (2017Ritter et al ( , 2019 incorporated color, among other taphonomic attributes, as evidence of diagenesis on the Brazilian shelf. Erthal (2012) found a correlation between light colors (white, cream) and the presence of mud, and more loosely, between reddish colors and deposits abundant in heavy minerals.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Millenial-Scale Time Averaging Inferred by Discolored Shells in Beach Death Assemblages

Martínez

Rojas

2023

Palaios

View full text Add to dashboard Cite

Molluscan death assemblages occurring on present-day beaches frequently consist of secondary-colored shells, with yellow to brown and gray to black colors. It is hypothesized that this secondary coloration can be related to postmortem age and to conditions in the taphonomically active zone, altering shells to black and gray tones in reducing conditions, and then becoming yellowish or brownish in oxidizing settings. In this study, we assessed whether the variability in the degree of shell discoloration of two species of the infaunal bivalve Mactra collected in beach death assemblages from a temperate siliciclastic beach in Uruguay is a function of postmortem age, and whether this variability in discoloration can be linked to differences in their elemental composition, microstructure, and provenance. Although we did not detect any differences in mineralogy or elemental composition among shells differing in discoloration, we show that modern (younger than a century) beach shells are not secondary-colored, but have remained white, but some white shells are also old (millennial). In contrast, yellow and gray shells are consistently older than 1,000 years, indicating that this degree of discoloration requires millennial residence times in the taphonomically active zone and suggesting that discoloration can be used as an indicator of time averaging. Discolored shells are derived from subtidal death assemblages.

show abstract

“…Preservation patterns of fossil assemblages are often affected by environmental factors; comparative and quantitative taphonomical analyses of fossil assemblages have, therefore, been useful as a basis for reconstructing paleoenvironments (Speyer and Brett 1988;Smith and Nelson 2003;Best 2008;Darroch et al 2016;Ritter et al 2019). One of the tacit assumptions of taphofacies analyses is that preservation pathways of skeletal remains differing in durability or susceptibility to alteration are similar (Kidwell and Flessa 1996;Behrensmeyer et al 2000;Zuschin et al 2000;Staff et al 2002;Powell et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Unveiling the Consequences of Environmental Variation and Species Abundances on Beach Taphofacies in Bahamas: The Role of Cementation and Exhumation

Bayer

Balseiro

Muñoz

et al. 2019

Palaios

View full text Add to dashboard Cite

Although environmental variability generates differences in the preservation of shell assemblages, intrinsic variations in shell characteristics can confound the effects of environment on preservation. However, several studies proposed that the composition of shell supply only affects the intensity of alteration but not its preservation trend along the environmental gradient and that environmental variability represents a major driver of taphofacies preservation. Here, we examine whether taphonomic differences among four infaunal and aragonitic bivalve species differing in shell thickness affect the definition of beach taphofacies in tropical carbonate environments on San Salvador Island (Bahamas). We show that (1) taphofacies can be discriminated with respect to (a) wave and storm activity as a function of exposure to Trade Winds, and (b) sandy beaches versus beaches with a mixture of sands and beach rock (representing a source of exhumed and cemented shells), and (2) species-specific bivalve assemblages show similar gradients in preservation, documenting that differences in preservation between species have minor effects on taphonomic discrimination of beach environments. Environments with a mixture of sands and beach rock are characterized by higher frequency of external cementation and abrasion than sandy beaches. Shells from low-energy beaches are more fragmented and discolored than shells from high-energy beaches. Previous studies showed that shells from San Salvador sandy beaches are more time-averaged than shells from rocky beaches. Differences in preservation between these two environments indicate two pathways: (1) assemblages on sandy beaches are degraded at higher rate but are enriched by old exhumed and lithified shells, and (2) assemblages on rocky beaches are cemented at higher rate. Old and lithified shells on sandy beaches are probably derived from submerged or exposed beach rock patches, leading to the mixture of young, well-preserved shells with old, poorly preserved shells. Shells on sandy beaches thus experience a complex history of burial and exhumation before their final deposition. Therefore, shell assemblages in lower energy carbonate environments from San Salvador Island are highly time-averaged, with the presence of old, poorly preserved shells. The depositional environment is thus the dominant factor controlling the structure of San Salvador beach taphofacies.

show abstract

Depth as an overarching environmental variable modulating preservation potential and temporal resolution of shelly taphofacies

Cited by 12 publications

References 59 publications

The taphonomic clock in fish otoliths

The taphonomic clock in fish otoliths

Millenial-Scale Time Averaging Inferred by Discolored Shells in Beach Death Assemblages

Unveiling the Consequences of Environmental Variation and Species Abundances on Beach Taphofacies in Bahamas: The Role of Cementation and Exhumation

Contact Info

Product

Resources

About