Journal of Taphonomy VOLUME 4 (ISSUE 4)

PROMETHEUS PRESS/PALAEONTOLOGICAL NETWORK FOUNDATION (TERUEL) 2006 Available online at www.journalt Van Itenaphonomy.com et al. Journal of Taphonomy VOLUME 4 (ISSUE 4)

Possible Taphonomic Bias in the Preservation of Phosphatic Macroinvertebrates in the Uppermost Maquoketa Formation (Upper Ordovician) of Northeastern Iowa (North- Central USA)

Heyo Van Iten Department of Geology, Hanover College, Hanover, IN 47243, USA

Michael Lichtenwalter Department of Geology, Wichita State University, Wichita, KS 67260, USA

Juliana de Moraes Leme Department of Sedimentary and Environmental Geology, Graduate Program in Sedimentary Geology, University of São Paulo, São Paulo, Brazil

Marcello Guimarães Simões Department of Zoology, Laboratory of Paleozoology, São Paulo State University/UNESP, Botucatu, 18.618-000, SP, Brazil

Journal of Taphonomy 4 (4) (2006), 207-221. Manuscript received 10 March 2006, revised manuscript accepted 3 July 2006. Examination of acid digestion residues can be an indispensable tool in the detection and identification of fragmentary remains of rare and/or fragile, macroinvertebrate fossils preserved in shallow shelf carbonates. We recovered submicroscopic fragments of phosphatic conulariid, Sphenothallus (Cnidaria), and ?Trematis (Linguliformea) skeletons from a slab of highly fossiliferous lime packstone from the uppermost Brainard Shale Member of the Maquoketa Formation (Richmondian, Upper Ordovician) of northeastern Iowa, USA. The bedding planes of this and four similar Brainard Member slabs (total upper bedding surface area approximately 0.38 m2) lack macrofossil specimens of these three taxa, which have never previously been reported from this rock unit. Analysis of the preservation of the abundant calcitic fossils revealed evidence of wave current action, including pervasive disarticulation of the brachiopods, echinoderms, and trilobites, and bimodal alignment of the narrowly conical Cornulites shells and elongate Eoplectodonta valves, almost all of which are also oriented convex up. These results are consistent with the hypothesis that storm wave activity on the Brainard Member sea floor fragmented originally macroscopic conulariid, Sphenothallus, and ?Trematis skeletons, making it difficult to detect these taxa at low magnifications and thus making it appear that they were absent in the original bottom

207 Taphonomic bias in the preservation of phosphatic fossils community. Together with results of similar studies of other Paleozoic rock units, our investigation suggests that there is a systematic, taphonomic bias against conulariids, Sphenothallus, and linguliform (phosphatic) brachiopods in storm-influenced shelf deposits.

Keywords: TAPHONOMY, PRESERVATIONAL BIAS, PHOSPHATIC FOSSILS, CONULARIIDS, Sphenothallus, ORDOVICIAN

Introduction Babcock, 2002; Leme et al., 2003) have shown that conulariids, which together with Estimates of the original taxonomic Sphenothallus are now generally classified diversity of fossil macro-biotas are subject as cnidarians (Van Iten et al., 1992; Van to taphonomic and other biases (Raup and Iten et al., 2006), occur as Stanley, 1978; Donovan and Paul, 1998; “microfossils” (minute skeletal fragments) Kowalewski and Flessa, 1996; Kidwell and in shallow shelf deposits in which Flessa, 1996; Holz and Simões, 2002; conulariid macrofossils are rare or Behrensmeyer et al., 2005; Kidwell et al., (apparently) absent. We here document the 2005). Taphonomic bias (a skewing of discovery of minute (< 1.5 mm long) information in some systematic way; fragments of conulariids, Sphenothallus, Behrensmeyer et al., 2000) can be either and at least one species of ?Trematis natural or analytical in origin, and can act at Sharpe, 1848 in acid residues of a highly all scales from local to global. These facts fossiliferous limestone interbed in the make it difficult for paleontologists to Brainard Shale Member of the Maquoketa accurately reconstruct ancient communities Formation (Richmondian, Upper and ecosystems based on the fossil record Ordovician) of northeastern Iowa (north- (Behrensmeyer et al., 1992; Donovan and central USA). The same interbed also Paul, 1998). Taphonomic bias can be yielded conodont elements, which strictly particularly severe in marine shelf deposits speaking are phosphatic microfossils. None that were subjected to background processes of the macroscopic phosphatic taxa has (e.g., currents and waves that broke, previously been reported or documented abraded, and/or sorted invertebrate shell from any part of the Brainard Member. material) and/or episodic processes (e.g., The carbonate interbeds of the upper storms, which disrupted, transported, and Brainard Member collectively contain buried biomineralized remains). In this several recurring associations of paper we present evidence of a taphonomic invertebrate fossils (Witzke et al., 1997). bias against three groups of phosphatic Packstone-grainstone interbeds commonly benthic invertebrates, namely Linguliformea exhibit a distinctive benthic assemblage, (formerly phosphatic inarticulate called the Eoplectodonta (“Thaerodonta”)- brachiopods; Williams et al., 1996, 2000), Cupulocrinus- Cornulites (ECC) conulariids, and Sphenothallus Hall, 1847, community, which is characterized by in storm-influenced shelf deposits of a numerous specimens of these three genera Paleozoic epeiric sea. Several previous but also contains abundant trilobites as well investigators (Bischoff, 1978; Jerre, 1993; as molluscs and bryozoans (ectoprocts). Van Iten et al., 1996; Richardson and Taxa not previously reported from the ECC

208 Van Iten et al. or any other assemblage of the upper fossiliferous mudstones and wackestones to Brainard Member include conulariids and highly fossiliferous packstones and Sphenothallus, which occur as macrofossils grainstones. According to Witzke et al. in other members of the Maquoketa (1997, p. 20), the upward coarsening trend Formation (Van Iten et al., 1996). of the carbonate interbeds reflects We suspected that the apparent “increasing impingement of storm currents absence of conulariids and Sphenothallus in on the bottom associated with depositional the ECC and other assemblages of the upper shallowing.” Currently accepted Brainard Member is an artifact of paleogeographic reconstructions (e.g., Mac taphonomy. More specifically, we Niocaill, 2001) place the Late Ordovician hypothesized (1) that the phosphatic epeiric sea covering northeastern Iowa skeletons of these taxa had been fragmented within 15 degrees of the paleoequator, by storm currents, and (2) that they might where hurricane-like storm activity occurred now be represented by minute skeletal during much of the Early Paleozoic (e.g., fragments. To test these two hypotheses, Prothero and Dott, 2004). we examined acid digestion residues of ECC limestone, and we measured the orientation of macrofossil shells susceptible Materials and Methods to alignment by bottom currents. We also assessed the degree of articulation, abrasion We examined five Brainard Member and fragmentation, and sorting of packstone slabs containing abundant (originally) multi-component (sensu Brett specimens of the ECC assemblage. The and Baird, 1986) macrofossil skeletons. five slabs range from about 2 to 4 cm thick and were collected in northeastern Fayette County, Iowa, the type locality of the Brainard Shale Member Brainard Member (Ladd, 1929; Parker et al., 1959) (Figure 1A). The more or less The Brainard Member is a shallowing flat upper bedding planes, which have a upward sequence exposed in parts of combined surface area of approximately Indiana, Illinois, Wisconsin, and Iowa 0.38 m2, collectively exhibit several (Ladd, 1929; Sivon, 1980; Kolata and thousand macrofossil specimens identifiable Graese, 1983; Witzke and Glenister, 1987; to the genus level. Upper and lower bedding Witzke, et al., 1997). It forms a major part planes were examined under a light of the distal margin of the Taconic clastic microscope, at magnifications ranging from wedge. In eastern Iowa the Brainard 10X to 63X. Azimuthal orientations of Member consists predominantly of gray- Cornulites long axes and Eoplectodonta green dolomitic shale and measures from hinge lines were measured on slabs CHM about 40 to 50 meters thick. Present within 13 and SUI 102512. Orientations of the uppermost several meters of the unit are Cornulites long axes were measured by numerous, thin (<10 cm), fossiliferous estimating the trend of a line connecting the carbonate interbeds (Figure 1B). Moving apex of the shell to the center of the up the section the interbeds change in aperture, which in some specimens is texture from sparsely to moderately missing or covered. A 1500 g sample of

209 Taphonomic bias in the preservation of phosphatic fossils

Figure 1. A, Simplified geologic map of Fayette County, Iowa, showing the approximate location of the site (village of Brainard, Patterson’s springs) from which the five Brainard Member study slabs were collected. B, Simplified stratigraphic column of the Maquoketa Formation (Upper Ordovician) in Dubuque County, Iowa, showing the approximate level (arrow) of the Eoplectodonta-Cupulocrinus-Cornulites (ECC)-dominated assemblage in the Brainard Shale Member. Figure modified from Witzke and Glenister, 1987, fig. 3.

210 Van Iten et al. slab SUI 102512 was digested in 4N formic Degree of articulation of macrofossils acid. Phosphatic microfossils (conodonts) and skeletal fragments were picked from the Inspection of bedding planes and slab edges undissolved residue and then mounted on shows that skeletons originally consisting of aluminum stubs and coated with gold for two or more articulated parts are completely scanning electron imaging. The limestone or largely disarticulated. Trilobites are slabs are reposited in the paleontological nearly exclusively represented by collections of the Department of Geology, disassociated parts (cranidia, free cheeks, Carleton College (Northfield, Minnesota; thoracic segments, pygidia; total of about CC 2157.00), the Clermont Historical 2000 pieces counted on five upper bedding Museum (Clermont, Iowa; CHM 13), and planes). Similarly, pelmatozoan the Department of Geology, University of echinoderms (total of about 2000 pieces Iowa (SUI 51313, 102512, 102518). The counted on five upper bedding planes) are acid residue samples are reposited in the represented predominantly by single stem University of Iowa (Iowa City), under ossicles or by very short sections of collection numbers SUI 102513-102517. articulated stem ossicles. All of the rhynchonelliform brachiopod specimens (total of about 1000 specimens counted on five upper bedding planes) appear to consist Results of a single valve. For example, on the upper bedding plane of SUI 102512, a slab with loosely packed macrofossils, 60 of the Macrofossil content and slab bases 126 complete or nearly complete Eoplectodonta shells consist of the brachial Over 5000 identifiable macrofossils are valve, the inner surface of which is exposed. exposed on the bedding planes of the five The remaining 66 specimens expose the ECC slabs. Inspection of the broken edges exterior surface of the pedicle valve, but it of the slabs indicates that fossils are also appears that these, too, are not articulated to abundant within the slabs. The macrofossils the other valve. Similarly, 30 of the 65 consist predominantly of pelmatozoan Eoplectodonta on the upper surface of CHM echinoderms, rhynchonelliform brachiopods 13 (Figure 2A) are brachial valves, and the (mostly Eoplectodonta, a strophomenid), 35 pedicle valves likewise appear to be trilobites (mostly “Flexicalymene” and disarticulated. Isotelus), and Cornulites, with minor bryozoans (ectoprocts) and gastropods Degree of fragmentation and abrasion of (Figure 2A). Even at a magnification of macrofossils 63X, no conulariid, Sphenothallus, or linguliform brachiopod specimens were Although originally articulated calcitic detected. fossils are now disarticulated, the parts are The bases of the packstone slabs mostly non-fragmented and preserve range from nearly planar to irregular, and relatively delicate structures such as fine show no evidence of scour features such as ridges on the inner surfaces of brachial sole marks or gutter casts. valves. The edges of the skeletal pieces

211 Taphonomic bias in the preservation of phosphatic fossils appear to be non-abraded or chipped. Orientation of Cornulites and Eoplectodonta long axes

Degree of size and shape sorting As shown in Figure 2, Cornulites and Eoplectodonta shells on the upper surface of Calcitic macrofossils appear to be unsorted CHM 13 appear to show strong preferential both with respect to size and shape. alignment of their long axes. Similar Identifiable (to genus level) shells or shell alignment of Cornulites and Eoplectodonta pieces range from approximately 2 mm specimens is apparent on the upper surface (partial crinoid ossicles) to 40 mm (orthid of SUI 102512. These impressions are brachiopod valves) long, and exhibit a confirmed by rose diagram plots of the variety of shapes including discoidal azimuthal orientations of these macrofossils (crinoid stem ossicles), saucer-like (Figure 3). On both slabs, the hinge lines of (rhynchonelliform brachiopod valves), and Eoplectodonta (Figure 3A, C) tend to be conical (Cornulites and gastropods). aligned in the same general direction as the long axes of most of the Cornulites shells (Figure 3B, D). Moreover, the orientation Orientation of rhynchonelliform brachiopod of the narrowly conical Cornulites shells is shells bimodal, with the apical ends of about half the Cornulites in the dominant long axis Nearly all of the convex articulate trend (roughly northwest-southeast in brachiopod valves (brachial and pedicle) on Figure 2) pointing in nearly the opposite the upper bedding planes of all five general direction as the apical ends of the examined slabs are oriented with the convex other half. Although different in shape from side facing upward. For example, all of the Cornulites, the Eoplectodonta valves also 65 more or less complete Eoplectodonta appear to exhibit a bimodal orientation valves on CHM 13 (Figure 3) are oriented pattern, with about half the Eoplectodonta convex up. The same is true of the 126 valves lying in the dominant hinge line more or less complete Eoplectodonta valves trend (roughly northwest-southeast in on SUI 102512. On slab SUI 102518, 209 Figure 2) being oriented with their anterior of the 219 readily identifiable (more or less ends pointing in nearly the opposite general complete and/or largely uncovered) direction as the anterior ends of the other articulate brachiopod valves (predominantly half. Eoplectodonta) are oriented convex up. On the underside of this slab, 40 of the 60 more or less complete valves are oriented concave Acid digestion up. Inspection of the edges of the slabs Examination of the formic acid residues indicates that most of the brachiopod valves revealed additional, phosphatic fossils, within the slabs also are oriented convex up. namely conodont microfossils (80 elements) In addition, there is no evidence of vertical and minute fragments of originally size grading of these or other fossils. macroscopic conulariids (13 fragments), Sphenothallus (656 fragments), and

212 Van Iten et al.

Figure 2. A, Portion of the upper surface of slab CHM 13, showing abundant Eoplectodonta (e.g., horizontal arrow) and Cornulites (e.g., vertical arrow) specimens as well as echinoderm ossicles (e.g., oblique arrow) (coin diameter = 18 mm). B, Outline drawing of slab CHM 13, showing measured Cornulites (solid cones) and Eoplectodonta (open valves). Scale bar = 10 cm.

213 Taphonomic bias in the preservation of phosphatic fossils

Figure 3. A, Rose diagram showing the orientations of the hinge lines of 65 Eoplectodonta on the upper surface of slab CHM 13. B, Rose diagram showing the estimated orientations of the long axes of 29 Cornulites on the upper surface of slab CHM 13. C, Rose diagram showing the orientations of the hinge lines of 84 Eoplectodonta on the upper surface of slab SUI 102512. D, Rose diagram showing the estimated orientations of the long axes of 119 Cornulites on the upper surface of slab SUI 102512.

214 Van Iten et al. phosphatic brachiopods (483 fragments) bacterial or fungal in origin (see for (Figure 4). The brachiopod fragments example Grahn, 1981). At least some of the (Figure 4.8) exhibit a distinctive ornament conulariid fragments appear to be resembling a more or less rectangular assignable to the genus Conularia Miller in meshwork. They are here tentatively Sowerby, 1821, the faces of which generally assigned to the genus Trematis Sharpe, are characterized by relatively strong, 1848, which occurs in other Upper nodose transverse ribs and by distinct Ordovician formations of the north-central interspace ridges that extend the full width United States (Williams et al., 2000). The of the interspaces (e.g., Babcock and Sphenothallus specimens (Figure 4.6-4.7) Feldmann, 1986; Jerre, 1993; Van Iten et consist of short fragments of the originally al., 1996). One fragment (Figure 4.5) may much longer lateral thickenings of the represent the genus Ctenoconularia slender skeletal tube (e.g., Van Iten et al., Sinclair, 1952, which is characterized by 1992, fig. 1; Van Iten et al., 1996, pl. 1, fig. interspace ridges extending only half-way 1). They may be distinguished from other across the interspaces. We also found a phosphatic shell fragments by their finely single fragment of Metaconularia Foerste, lamellar microstructure, more or less 1928, but this specimen was subsequently crescentic or gently curved transverse cross lost. section, and lack of external ornament such as ridges or nodes. In low-energy deposits (dark grey shales) of the lower Maquoketa Discussion Formation, more or less complete Sphenothallus tubes measure up to 90 mm The Brainard Member in eastern Iowa and long (Van Iten et al., 1996). Nearly all of adjacent parts of northwestern Illinois has the conulariid specimens (Figure 4.1-4.5) been sampled intensively by amateur fossil consist of one or two transverse ribs and collectors and by professional interspaces (interrib areas). The transverse paleontologists and stratigraphers (including ribs exhibit worn or broken nodes having a the senior author of this paper), although at subcircular or rectangular transverse this point there are no published papers on outline, and the interspaces are smooth the conodonts or other microfossils of the (Figure 4.1) or exhibit fine interspace ridges upper Brainard Shale in the area here (Figure 4.2-4.5). One specimen (Figure 4.4) considered. No previous investigator has contains part of a sulcate corner or midline. ever reported the presence of macroscopic Most of the conulariid fragments exhibit conulariids, Sphenothallus, or ?Trematis in numerous, microscopic circular pores or any part of this rock unit [see for example holes measuring less than 10 microns in the published faunal lists of upper Brainard diameter (arrows in Figures 4.1-4.3). fossil assemblages in Ladd (1929), Frest et Similar holes have been detected in a al. (1997), and Witzke et al. (1997)], and number of conulariid genera (Kozlowski, there are no reports (or documented 1968; Bischoff, 1978; Van Iten et al., 2005; evidence) of microscopic remains of these Van Iten et al., in press), and have variously three taxa in publications discussing the been interpreted as primary microstructural micropaleontology of the Brainard Shale in features or as microscopic borings, possibly other states (e.g., Froming, 1971). Our

215 Taphonomic bias in the preservation of phosphatic fossils

Figure 4. Examples of macroscopic phosphatic taxa present as submicroscopic shell fragments in the Eoplectodonta- Cupulocrinus-Cornulites (ECC) assemblage of the uppermost Brainard Mem- ber of the Maquoketa For- mation (Upper Ordovician) near Elgin, northeastern Iowa. 1, Conularia sp. (SUI 102513A), fragment of a single face (with two transverse ribs) showing several broken, more or less circular nodes and abundant microscopic circular pores (arrows), x120; 2, Conu- laria sp. (SUI 102513B), fragment of a single face (with a single transverse rib) showing broken, elongate nodes, narrow interspace ridges, and abundant microscopic circular pores (arrows) , x90; 3, ? Conularia sp. (SUI 102513C), fragment of a single face (with a single transverse rib) showing subrectangular nodes and interspace ridges, and abundant microscopic circular pores (arrows) , x250; 4, ? Conularia sp. (SUI 102513D), fragment of a corner sulcus and two faces with transverse ribs and interspace ridges, x70; 5, Ctenoconularia sp. (SUI 102513E), fragment of a single face (with two transverse ribs) having narrow interspace ridges that extend only about halfway across the interspace, x90; 6, Sphenothallus sp. (SUI 102514A), outer surface of a fragment of an exfoliated longitudi- nal thickening, x70; 7, Sphenothallus sp. (SUI 102514B), inner surface of another fragment of an exfoliated longitudi- nal thickening, x120; 8, ?Trematis sp. (SUI 102515A), fragment of a phosphatic brachiopod, x60.

216 Van Iten et al. results show that these phosphatic Kidwell and Bosence, 1991; Tomašových, invertebrate taxa are present in the upper 2004) confirm this pattern, which is Brainard Member, where they are generated when shells undergo suspension represented by submicroscopic fragments in settling during deposition (Kidwell and at least one carbonate interbed containing Bosence, 1991; Tomašových, 2004; Simões the Eoplectodonta- Cupulocrinus- et al., 2005). Cornulites assemblage. Furthermore, the As noted above, Witzke et al. (1997) high degree of disarticulation and non- hypothesized that the upper Brainard sea random orientation (convex up) and floor was influenced by storms. Storm- alignment of calcitic ECC macrofossils are generated packstone beds (tempestites) consistent with the hypothesis that the upper similar to the packstone slabs here Brainard sea floor was affected by bottom examined characterize the distal facies of currents, which, as proposed earlier in this the Upper Ordovician (Edenian- paper, may have fragmented phosphatic Maysvillian) Kope and Fairview formations shell material. More specifically, the of the Cincinnati, Ohio region (Jennette and bimodal alignment of Cornulites and Pryor, 1992). In these beds, which likewise Eoplectodonta shells (evident on the upper contain high diversity benthic macrofaunas, surfaces of at least two slabs, including the concavo-convex strophomenid brachiopod slab from which fragments of phosphatic valves “locally form imbricated and shells were recovered) is indicative of edgewise accumulations (shingle oscillatory or wave current action, with the beds)” (Jennette and Pryor, 1992, p. 77), direction of oscillation oriented and calcitic skeletons commonly show little perpendicular to the dominant trend of the breakage. Although shingle accumulations long axes of the shells (Holz and Simões, are not evident in the five Brainard Member 2002). Other textural characteristics, slabs here studied, the senior author has including the muddy nature of the rock seen such features in other ECC samples matrix and the absence of obvious shell collected in east-central Iowa. Also like the abrasion and size/shape sorting, indicate Brainard Member slabs, the bases of the that wave action was not a background Kope-Fairview packstones lack scour process of the upper Brainard bottom features. Taken together, these environment, but rather was episodic in characteristics indicate that the Kope- nature. Probably, the brachiopods and Fairview packstones, and by analogy the Cornulites shells were reoriented by distal ECC packstones of the Brainard Shale, storm-induced currents. This is because probably represent parauthochthonous brachiopod-rich concentrations generated accumulations of skeletal debris that was under proximal, high-energy conditions “more or less winnowed in place without (e.g., storms) tend to show a predominance significant lateral transport” (Jennette and of large, closed articulated shells at the base Pryor, 1992, p. 77). Probably as a of the concentration, the biofabric of which consequence of both background is defined by nested or stacked shells that (winnowing, bioturbation) and episodic are oriented concave up. Both laboratory events (distal storm currents), the examined (Simões et al., 2005) and field observations Brainard Shale packstone slabs exhibit clear (Fursich and Oschmann, 1986, 1993; disharmonious time-averaging (see

217 Taphonomic bias in the preservation of phosphatic fossils

Kowalewski, 1996), which is indicated by on the Brainard Member sea floor the mixture of minute fragments of comminuted originally macroscopic trilobites, conulariids, ?Trematis sp., and conulariid, Sphenothallus, and ?Trematis other skeletal remains including well skeletons, making it difficult to detect these preserved, non-fragmented, unsorted taxa at low magnifications and thus making rhynchonelliform brachiopod shells. it appear that they were absent in the ECC Based on the foregoing assemblage. Submicroscopic fragments of considerations, then, it appears that the conulariids have also been recovered from hypothesis that Brainard Member low energy facies in the Maquoketa conulariid, Sphenothallus, and ?Trematis Formation (Van Iten et al.,1996), but these skeletons were fragmented by (storm) rocks have yielded hundreds of macroscopic currents is viable, at least at this point. Of specimens, including thin-walled (< 0.1 mm course, shell fragmentation in general can thick) Metaconularia measuring almost 20 result from a variety of causes other than cm long. Assuming that the ECC current action (Zuschin et al., 2003), assemblage represents a time-averaged, including for example predation, bioerosion within-habitat benthic community, the and dissolution, and sediment compaction. present low abundance of conulariids in the Before it can be concluded that the assemblage may have resulted from a fragmentation of phosphatic skeletons here combination of two factors, namely observed was caused uniquely or mainly by mechanical fragility and rarity in the bottom currents, alternative hypotheses will original fauna. Previous authors have to be examined, in part perhaps documented conulariid microfossils in through analyses of the mechanical shallow shelf strata in the Ordovician properties of these skeletons. (Richardson and Babcock, 2002, Leme et Finally, the results of this study bear al., 2003), Silurian (Bischoff, 1978; Jerre, on a fundamental general problem in 1993), and Devonian (Bischoff, 1978) paleontological research: To what extent systems, from localities in North and South does the fossil record reflect the original America, Sweden, and Australia. Together taxonomic composition of ancient biotas? with our results, this work suggests that Previous authors (e.g., Feldmann and paleontologists sampling the macrobiotas of Babcock, 1986; Jerre, 1993) proposed that Paleozoic marine deposits similar in origin conulariid exoskeletons were relatively to the upper Brainard Shale should also fragile and thus susceptible to post-mortem conduct acid digestion work. Such work break-up. As demonstrated recently by could substantially increase the chances of Rodrigues et al. (2003), Devonian detecting relatively fragile, originally conulariids living in shallow platformal phosphatic components of the macrobiotas bottoms (above storm wave base) subject to of storm-influenced shelf settings. episodic storms, were disrupted and transported into more offshore areas (below storm wave base), where they are (now) Acknowledgements represented by small and fragmented remains only. Our results are consistent Permission to examine Brainard Shale with the hypothesis that storm wave activity limestone slabs in the paleontological

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