Sediment effects on the preservation of Burgess Shale–type compression fossils

“At a broader scale, there is a conspicuous correlation between BST preservation and a Cambro–Ordovician spike in the occurrence of anomalously shallow-water glauconite (see Brasier 1980; Chafetz and Reid 2000; Nielsen and Schovsbo 2011; Peters and Gaines 2012).”

“The recognition of secondary, diagenetically induced shifts in preservation potential also has important implications for interpreting the histological and phylogenetic affiliations of problematic BST fossils (Butterfield 2003).”

“…BST preservation invoke mineralspecific diagenesis as an essential factor, either by suppressing normal enzyme–microbial-based decay processes (e.g., Butterfield 1990, 1995; Gaines et al. 2005, 2012) or secondarily by enhancing the recalcitrance of relatively labile substrates (e.g., Orr et al.…”

“…mineralspecific diagenesis as an essential factor, either by suppressing normal enzyme–microbial-based decay processes (e.g., Butterfield 1990, 1995; Gaines et al. 2005, 2012) or secondarily by enhancing the recalcitrance of relatively labile substrates (e.g., Orr et al. 1998; Petrovich 2001).”

“…enhancing the preservation potential of more labile substrates, early diagenetic tanning—like early diagenetic mineralization—undermines assumptions of tapho-anatonomic ordering based on sediment-free degradation experiments (e.g., Allison 1988; Briggs and Kear 1993, 1994a; Sansom et al. 2010).”

“More generally, it has been argued that the rise and fall of BST preservation tracked the weathering flux of Al-rich clays as well as particular biogeochemical conditions that affected the composition of clay in marine sediment (Butterfield, 1995; Wilson & Butterfield 2014).”

“…decay rate versus pre-burial residence time on the seafloor (Zhao et al. 2009; O’Brien et al. 2014), but the relationships between preservational fidelity, original histology and host sediment types (including mineralogy) should also be considered (Gaines et al. 2012b; Wilson & Butterfield 2014).”

“The widespread occurrence of glauconite during the Cambrian and Ordovician, interpreted as a result of the contribution of extensive weathering to the clay content of marine sediments, may have reduced rates of decay at this time (Wilson and Butterfield 2014).”

“…mats, elevated concentrations of silica, redox gradients, and the activity of sulfate reducing microbes that ultimately produce pyrite (Darroch et al., 2012; Gehling, 1999; Laflamme et al., 2011; Naimark, Kalinina, Shokurov, Boeva, et al., 2016; Tarhan et al., 2016; Wilson & Butterfield, 2014).”

“…phosphates, hydroxides, clays) for the morphological (e.g., Briggs and Kear, 1993; Briggs et al., 1993; Grimes et al., 2001; Martin et al., 2003; Wilson and Butterfield, 2014; Iniesto et al., 2015) and chemical (e.g., Li et al., 2013, 2014; Picard et al., 2015a, 2015b) preservation/degradation…”

“…198 BST fossil-bearing localities (e.g., Aitken et al., 1973; Odom, 1976; Rolf et al., 1977; 199 Butterfield, 1994; Butterfield and Harvey, 2012; Wilson and Butterfield, 2014), however 200 the abundance of glauconite is not significantly higher in samples that contain BST 201 fossils (see GSA…”

“Certain fine-grained sediments, in particular clays, have been posited to slow decay due to their chemistry (Butterfield 1995; Wilson and Butterfield 2014).”

“It should be noted that these experiments were carried out in different plastic containers (Wilson & Butterfield 2014).”

“…preservation, if themineralization or stabilization rates remain higher than tissue decomposition rates (Allison, 1988; Briggs, 1995; Carpenter, 2005; Gehling, 1999; McNamara et al., 2009; Naimark et al., 2016a, 2016b, 2018a; Petrovich, 2001; Sagemann et al., 1999; Wilson & Butterfield, 2014).”

“…potential chemical and geologic pathways of preservation (Briggs and Kear 1994; Briggs et al. 1995), including effects of sediment type on rate of decomposition (Wilson and Butterfield 2013) and the preservation-enhancing potential of microbial death masks on organic material (Darroch et al. 2012).”

“fects of aluminosilicate on microorganisms (Liu et al., 2016; Wilson and Butterfield, 2014), but bacterial activity was not inhibited by the interfacial interactions between montmorillonite and bacteria (Wilson and Butterfield, 2014).”

“Evidence is also emerging that kaolinite, in particular, may attach to or precipitate on some tissues early in diagenesis, helping to conserve them by providing a protective coating and/or facilitating polymerization [14,19,20].”

“Our study expands on previous experimental work (e.g., Darroch et al. 2012; Wilson and Butterfield 2014; Naimark et al. 2016a, 2016b, 2018a, 2018b) by enabling a more active transport of ions and solutes and by characterizing the preservation of organisms that lack resistant cuticles.”

“…organic cellular components could play an important role for the morphological preservation of soft- bodied organisms (e.g., Bernard, Benzerara, Beyssac, & Brown, 2010; Briggs, 2003; Li et al., 2014; Orr, Briggs, & Kearns, 1998; Picard et al., 2015; Wacey et al., 2014; Wilson & Butterfield, 2014).”

“a symptom of some other factor important in BST preservational pathways, or a cause (86,87).”

“In the case of the experiments carried out in plastic containers (Wilson and Butterfield, 2014), it is possible that oxygen penetrated through the walls of the containers, as some sorts of plastic are not completely impervious (Birger, 1993), and this may have caused whitening of the darkened…”

“…be said for the formation or taphonomic function of associated clay minerals (e.g., Butterfield 1995; Orr et al. 1998; Petrovich 2001; Powell 2003; Gaines et al. 2008; Page et al. 2008; Anderson et al. 2011; Cai et al. 2012; Forchielli et al. 2012; Wilson and Butterfield 2014; McMahon et al. 2016).”

“Kaolinite is therefore implicated as promoting preservation, supporting previous work that has also suggested that kaolinite aids the spectacular preservation of non-skeletal metazoans of the Cambrian Burgess Shale and similar deposits [50].”

“Burial experiments have shown that secular changes in average clay mineralogy, particularly the kaolinite content, may have been significant factors for the opening and closing of the taphonomic window for exceptional preservation of Burgess Shale type carbonaceous fossils (Wilson and Butterfields, 2014).”

“Unlike other experiments with comparatively large animals (Briggs 157 and Kear 1993; 1994; Wilson and Butterfield 2014), we were able not only to give a descriptive 158 pattern of decay, but also count the specimens in each decay group within the samples (Gostling 159 et al. 2009).”

“…not know how kaolinite influences the composition of the bacterial communities within and surrounding a decaying carcass (Mähler et al., 2023), and the process by which kaolinite aids exceptional fossil preservation is yet to be fully deciphered (Naimark et al., 2016; Wilson & Butterfield, 2014).”

“A biofilm-clay template may provide biochemical protection by reducing or inhibiting microbial respiration and autolytic enzymes, increasing the short-term recalcitrance of more labile leaf tissues, and enabling kerogen formation (Salmon et al. 2000; Wilson and Butterfield 2014).”

“The polychaete, Alitta virens, used in these experiments is abundant along the southeast coast of England and has been used as a model organism in previous taphonomic experiments [6,8,21].”

“In addition, there isevidencethat anabundance ofthe clay mineralkaolinite inBurgess Shale – type settings played a role in helping to stabilize organic remains against decomposition (Wilson and Butterfield 2014; Anderson et al. 2018).”

“The same drop in pH was reported for kaolinite by Wilson and Butterfield (2014) from their burying experiments, but these results should be taken carefully as they require some methodical clarification and comparison with additional carcasses-free controls.”

“Full preservation of the external sheath, the inner stem, and most of the outer stem, as well as parts of the digestive tract and interior calyx structure, indicates a low degree of degradation (Wilson and Butterfield, 2014; Kimmig and Pratt, 2016; Naimark et al., 2016).”

“…et al., 2014), phosphorus (Raff et al., 2008), calcium (Butterfield, 2003), silicon (Strang et al., 2016), or "tanning" by aluminum (Naimark, Boeva, et al., 2018; Naimark, Kalinina, Shokurov, Boeva, et al., 2016; Naimark, Kalinina, Shokurov, Markov, et al., 2016; Wilson & Butterfield, 2014).”

“A similar process was suggested for a number of soft-bodied fossils (Gámez Vintaned et al. 2009; Wilson and Butterfield 2014; McMahon et al. 2016) and observed on invertebrates experimentally fossilised in fine-grained sediment (Naimark et al. 2016).”

“…of clay–organic matter complexes (Anderson et al., 2020; Newman et al., 2019; Orr, 2014; Playter et al., 2017) which foster fossilization both mechanically and chemically by providing organic tissues with a protective coating (McMahon et al., 2016; Naimark et al., 2016; Wilson & Butterfield, 2014).”

“…for its association with the macroscopic variety of BST preservation (Butterfield, 1995; Anderson et al., 2021; Woltz et al., 2023) and has been documented to produce an early diagenetic tanning effect on cuticular tissues in actualistic taphonomic experiments (Wilson and Butterfield, 2014).”

“Partial burial of the carcass in the bottommud exposed the shell and hind limbs to clay minerals, which could have facilitated fixation of the organics in the integument (Drouin et al., 2010; Forchielli et al., 2014; Wilson and Butterfield, 2014).”

“11 : 240154 to heterotrophic decay bacteria [68], with kaolinite also increasing the decay resistance of organics by facilitating their polymerization [69].”

“…clay minerals slow down the activity of decaying bacteria under oxic conditions through the destruction of bacterial membranes (Amonette et al., 2003; Butterfield, 1990; Guida et al., 1991; Imlay et al., 1988; Kapoor & Arora, 1998; McMahon et al., 2016; Petrovich, 2001; Wilson & Butterfield, 2014).”

“For example, experiments with burying polychaetes and crustaceans demonstrated for some sediments (kaolinite, montmorillonite), a sharp decrease in salinity accompanied by conservation of organic remains (Wilson and Butterfield, 2014; Naimark et al., 2016a, 2016b).”

“For example, substrate composition and permeability are commonly important factors in these experiments (Wilson and Butterfield 2014), but removing the organism from its sediment matrix for evaluation can be difficult, damaging, and potentially alter results and interpretations.”

“The lack of annulation or segmentation in the HTP fossils is not necessarily indicative of a preferred placement into either priapulids or polychaetes (Liu et al. 2014; Wilson and Butterfield 2014; Parry et al. 2016; Hou et al. 2017a; Slater et al. 2017).”

“1999; Wilson & Butterfield 2014; Naimark et al .”

“59 Complex algal structures, such as stolons, often have important taxonomical roles, therefore studying their preservation potential and morphological alterations during decay is particularly helpful when interpreting the algal fossil record.”

“…of host sediments, as these attributes have been experimentally and analytical shown to influence decay and preservation pathways for skin, feathers, and other ultrastructural soft tissues (Wilson and Butterfield 2014; Moyer et al. 2016; Naimark et al. 2016, 2018; Anderson et al. 2018, 2020).”

“The impact of sediment composition on soft tissue preservation has also been investigated (Anderson et al. 2011; Wilson & Butterfield 2014; Murdock et al. 2016).”

“Recent studies suggest that the composition of clay minerals in the early oceans may also have served to inhibit bacterial activity (Wilson and Butterfield, 2014; McMahon et al., 2016; Naimark et al., 2016).”

“1998; Wilson & Butterfield 2014; McMahon et al .”

“This is consistent with the antibacterial properties of kaolinite, which are mainly attributed to the toxicity of metal cations like Al 3+ (Wilson and Butterfield 2014; McMahon et al. 2016; Naimark et al. 2016; Corthésy et al. 2024).”

“However, the negative covariance shows that molecules with high preservation potentials (lipids and structural carbohydrates) are selected against ASW, kaolinite and calcite ( i , s i = −0.137, Cov c −0.957, and −0.067, respectively; figure 5), supporting Wilson & Butterfield's [31] results.”

“…argued that clay, depending on its mineralogy, may act as a decay retardant by bonding to tissues, thereby enhancing their preservation (Anderson et al., 2018, 2021; Naimark, Kalinina, Shokurov, Boeva, et al., 2016, Naimark, Kalinina, Shokurov, Markov, et al., 2016; Wilson & Butterfield, 2014).”

“…would be produced during the course of microbial decay of molts and carcasses washed into the traps by the release of organic acids, H + , and the formation of carbonic acid from carbon dioxide (Fenchel and Finlay, 1995; Atlas and Bartha, 1998; Wilson and Butterfield, 2014; Naimark et al., 2016).”

“2014; Wilson & Butterfield 2014; Parry et al .”

“…and Kear, 1993a), how microbial decay drives the formation of geochemical conditions favourable for mineralisation (e.g. Sagemann et al. 1999; Clements et al. 2022), and that sediment composition plays an important role in maintaining the integrity of carcasses (e.g. Wilson and Butterfield, 2014).”