Author Institution: Department of Geology, Bowling Green UniversityShells of Paraspirifer bownockeri (Stewart) from the Silica Formation, Middle Devonian of northwestern Ohio, commonly contain numerous borings of a polychaete worm forming the endolithic trace fossil Vermiforichnus clarki Cameron (1969a) which can be exposed by acidizing the specimens. The borings are most abundant on the brachial valve, and their surface openings tend to be concentrated along major growth lines thence extending dominantly in the general direction of the beaks of the valves. Infestations of the polychaete occurred at 2 different time intervals as indicated by the spacing of the borings on 2 major growth lines with renewed shell growth between them. Growth of the host was severely reduced immediately following the infestation and in some areas damage to the mantle caused deformation in the shell of the host

Hoare, Richard D.

Walden, R. L.

The Ohio Journal of Science

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114 A. E. ANNALA AND L. A. KAPUSTKA Vol. 83Copyright © 1983 Ohio Acad. Sci. 003O-O95O/83/0003-O114 $2.00/0VERMIFORICHNUS (POLYCHAETA) BORINGS IN PARASPIRIFERBOWNOCKERI (BRACHIOPODA: DEVONIAN)1R. D. HOARE and R. L. WALDEN, Department of Geology, Bowling Green State University, BowlingGreen, OH 43403ABSTRACT. Shells of Paraspirifer bownockeri (Stewart) from the Silica Formation,Middle Devonian of northwestern Ohio, commonly contain numerous borings of apolychaete worm forming the endolithic trace fossil Vermiforichnus clarki Cameron (1969a)which can be exposed by acidizing the specimens. The borings are most abundant on thebrachial valve, and their surface openings tend to be concentrated along major growthlines thence extending dominantly in the general direction of the beaks of the valves. In-festations of the polychaete occurred at 2 different time intervals as indicated by the spac-ing of the borings on 2 major growth lines with renewed shell growth between them.Growth of the host was severely reduced immediately following the infestation and insome areas damage to the mantle caused deformation in the shell of the host.OHIO J. SCI. 83 (3): 114-119, 1983INTRODUCTIONPrevious interpretations of the largerborings commonly seen in the brachiopodParaspirifer bownockeri (Stewart) from theSilica Formation in northwestern Ohiohave been alluded to as sponge borings,Clionoides thomasi Fenton and FentonManuscript received 9 April 1982 and in revisedform 6 December 1982 (#82-7).(1932) by Hoare and Steller (1967) (fig. 1),as boring sponges by Kesling and Chilman(1975) and as "Clionoides" sp. by Steller(1965), Kesling et al. (1980) and Sparkset al. (1980). These interpretations werebased on the external configuration of thesurface opening of the boring only. Subse-quent investigation, brought about by theaccidental over-acidization of a specimen,has provided us with the determinationthat these features are borings within theOhioJ . Sci. DEVONIAN POLYCHAETE BORINGS 115FIGURE 1. Anterior view of Paraspirifer bownockeri(Stewart) showing reconstruction of epizoans. Small,rounded structures concentrated along the majorgrowth line were designated as the sponge Clionoidesthomasi Fenton and Fenton, thought to be the causeof the large borings in the shell of the host, SilicaFormation, BGSU-3765, I X . (From Hoare andSteller 1967, used by permission of the OhioJ. Sci.)shell and not borings through the valves.Cameron (1969b), using acidized speci-mens of P. bownockeri, described such bur-rows and related them to the endolithictrace fossil Vermiforichnus clarki Cameron.Assignment of borings, of the type nowreferred to Vermiforichnus, can be found inHantzschel (1975) and are well summa-rized by Cameron (1969b) who also de-scribes probable architects, orientation,distribution and abundance of the borings(1967, 1969a,b). Substrate specificity ofVermiforichnus is discussed by Thayer (1974)and ecological relationships by Watkins(1979, 1981).The specimens of Paraspirifer bownockeriare from the Silica Formation, exposed inan abandoned quarry, now owned by theFrance Stone Co., 4.9 km southwest ofSylvania, SEV4 sec. 7, T. 9 S., R. 6 E ,Lucas Co., Ohio. Some of the specimenswere collected by Anthony Zalinski whodonated them for study. The specimens arein the repository of Bowling Green StateUniversity (BGSU).METHODS AND MATERIALSSeveral specimens of Paraspirifer bownockeri, bothwith and without surface evidence of borings, wereselected, photographed, and emersed in a 30% solu-tion of HCL to dissolve most of the shell material.Duration of time to accomplish the shell removal de-pended upon the degree of pyritization of the shellmaterial, but averaged approximately 5 min. Thisexposed many of the borings which are preserved to alarge extent by an internal filling of fine-grainedpyritized sediment. Some of the borings can beseen still embedded within shell material.Measurements of the fillings of the borings weremade under a microscope using an occular microme-ter. Characteristics and location were noted at thesame time for each. The specimens were whitenedwith MgO and rephotographed. Distribution andextent of the borings, as shown in figures 2—5, weremade by inking enlarged photos in comparison withthe specimens.Of the 6 specimens acidized, borings were ex-posed on 4, all of which showed surface openings.Two specimens, lacking surface evidence, were con-firmed as having no borings.We measured boring length (BL), boring diameter(BD) and boring opening diameter (BOD). Thelength of boring, as given, is in part a reconstruc-tion, since portions may have been acidized away orsince the distal end may not be completely exposed.Boring diameter is an average figure based upon atleast 2 measurements of the same structure since theborings are variably exposed in terms of depth. Thediameter of the boring opening was measured priorto acidization but was impossible to determine inseveral instances because of preservation of the brach-iopod host. Characteristics noted were whetherborings branched or not, whether borings were es-sentially straight or strongly curved, whether bor-ings followed the ornamentation or not, whetherborings crossed one another and in which valve theboring was located.RESULTSAs can be seen in figures 6 , 8 , 9 , 12, theopenings of the borings tend to be concen-trated along major growth lines on boththe pedicle and brachial valves. This indi-cates an infusion of the polychaete into thehabitat at a particular time, infesting thebrachiopod primarily along the anterioredge, or line of commissure, and possiblycausing a decrease in growth activity by thehost. A second infestation can be seen infigures 2, 3, 9—12 after renewed growth ofthe host had occurred. In some instancesthe action of the polychaete was detrimen-tal to the host by injuring the mantle,causing shell deformation as seen in figures1, 4 -8 . Such deformations are commonlyoccupied by tubes of the worm Cornulites,the borings extending posteriorly from thearea of deformation (figs. 4—8).116 R. D. HO ARE AND R. L. WALDEN Vol. 83FIGURES 2—5. Diagrammatic representation of Vermiforkhnus clarki Cameron borings in Paraspirifer ,ockeri (Stewart). 2 , 3 , brachial and anterior views of BGSU-4197 showing concentrations of openings of bor-ings along two major growth lines and at least two instances of crossing of borings. 4, 5, brachial and brachiallateral views of BGSU-4195 showing deformations of the host shell, occurrences of the worm tube Cornulitesand crossing and branching borings of'Vermiforkhnus clarki. The second infestation of'Vermiforkhnus had notaffected this specimen. Silica Formation, all IX. Dots indicate position of surface openings of borings anddashed lines are reconstructions or assumption that the boring extended further than was preserved.Evidence of 191 borings is present onthe 4 host specimens. Of these, 112 (59%)occur on the brachial valves. One specimen(BGSU-4195) has a total of 90 boringspresent. Measurements on only 70 of the191 borings present were made since therest are too incomplete to give accuratedata. Table 1 provides the data as to size,shape, orientation and location of the70 borings measured. The borings range inlength from 5.1 to 31.0 mm, averaging14.7 mm. The exact length cannot be de-termined in many cases because of destruc-tion during acidization or lack of exposure,but the measurements provide a fair esti-mate of this dimension.Likewise, the diameter of the boring andof the surface opening of the boring may, insome instances, be misleading. The formerranges from 0.50 to 1.10 mm, averaging0.72 mm, and the latter ranges from 0.50to 1.01 mm, averaging 0.73 mm. At least2 measurements of diameter were made oneach boring and averaged for the diameteras given in table 1 and should present aclose approximation of the true diameter.The size of surface opening is often moreapt to be affected by external processes ofweathering and diagenesis, and the exactmargin of the opening may not be pre-served. Most of the openings are subcir-cular; some are suboval. In some instancesthe proximal end of the boring appears toflare out slightly as if enlarged by activityof the occupant.The borings rarely branch. In only 3% ofthe structures can branching be definitelyseen (figs. 2, 4). Other instances of whatOhio J. Sci. DEVONIAN POLYCHAETE BORINGS 117* 12FIGURES 6—12 Unacidized and acidized views of Paraspirifer bownockeri (Stewart). 6—8, brachial unacidized,brachial acidized and brachial lateral acidized views, Silica Formation, BGSU-4195, IX. 9—12, brachialunacidized, brachial acidized, anterior unacidized and anterior acidized views, Silica Formation,BGSU-4197, IX.118 R. D. HOARE AND R. L. WALDEN Vol. 83TABLE 1Measurements of Vermiforichnus clarki Cameron borings inParaspirifer bownockeri from the Silica Formation (mm).BGSUNo.4194419541964197ValveBrachial (9)**Pedicle (3)Brachial (9)Pedicle (2)Brachial (9)Pedicle (1)Brachial (29)Pedicle (8)BL*Range7.2-25.27.3-16.26.9-31.010.0-13.28.1-25.09.3-29.38.2-16.8Aver.14.110.915.111.615.511.316.111.9BD*Range.50-1.00.51 - .80.70-1.00.62- .90.51-1.10.50-1.00.56- .99Aver..59.61.82.76.77.61.70.71BOD*Range.50-1.00.55- .81.73-1.00.82-1.00.61 - .62.62-1.01.60- .65Aver..56.65.87.91.61.62.75.62*BL = boring length; BD — boring diameter; BOD = boring opening diameter**( ) Number of borings measuredappear to be branching at first glance aresituations where one boring crosses belowanother one (fig. 2). In a few situationsthe condition of the surface after acidizingthe specimens prevents determination ofbranching versus crossing relationships.Of the borings present, 13% do cross an-other burrow.In terms of shape and orientation theborings tend to be straight to slightlycurved and, more rarely, strongly curved.In most cases they generally approximatethe orientation of the major ornamentationof the host. Fifty-three percent are essen-tially straight and 44% come close to theornamentation pattern. Numerous bor-ings, 26%, vary from following the patternto crossing it.DISCUSSIONParaspirifer bownockeri was abundantlyinhabited by the polychaete worm formingthe trace fossil Vermiforichnus clarkiCameron during the deposition of theMiddle Devonian Silica Formation. Thebrachial valve of the host was bored morecommonly than the pedicle valve since thelatter was lying on the substrate (Sparkset al. 1980). The infestation of the larvae ofthe worms appears to have been essentiallyinstantaneous, attaching primarily alongthe line of commissure, most abundantlyin the anterior region. Renewed growth bythe host shows few specimens of Vermi-forichnus after the initial infestation for aperiod of time until a second infestationoccurred. This may have been a result oflarvae coming into the habitat or larvaeproduced from the epizoan polychaetes al-ready present on the host.The activity of the epizoan polychaetewas detrimental to .the host causing a nearcessation of growth. In some instances theedge of the mantle of the host may havebeen damaged causing shell deformation.These deformations often became occupiedby the worm Cornulites.LITERATURE CITEDCameron, B. 1967 Fossilization of an ancient(Devonian) soft-bodied worm. Science 155:1246-1248.1969a New name for Palaeosabellaprisca (McCoy), a Devonian worm-boring, and itspreserved probable borer. J. Paleontol. 43:189-192.1969b Paleozoic shell-boring an-nelids and their trace fossils. Amer. Zool. 9:689-703.Fenton, C. L. and M. A. Fenton 1932 Boringsponges in the Devonian of Iowa. Amer. Mid.Nat. 13: 42-53.Hantzschel, W. 1975 Trace fossils andproblematica. In: C. Teichert, (ed.), Treatise oninvertebrate paleontology, Pt. W Miscellanea,Supplement 1 (2nd edit.), Geol. Soc. Amer. andUniv. Kansas Press, 269 p.Hoare, R. D. and D. L. Steller 1967 A Devonianbrachiopod with epifauna. Ohio J. Sci. 67:291-297.OhioJ. Sci. DEVONIAN POLYCHAETE BORINGS 119Kesling, R. V. and R. B. Chilman 1975 Strataand megafossils of the Middle Devonian SilicaFormation. Univ. Mich. Mus. Paleontol. Paperson Paleontol. 8, 408 p., R. D. Hoare and D. K. Sparks 1980Epizoans of the Middle Devonian brachiopodParaspirifer bownockeri: their relationships to oneanother and to their host. J. Paleontol. 54:1141-1154.Sparks, D . K . , R . D . Hoare and R.V.Kesling 1980 Epizoans on the brachiopodParaspirifer bownockeri (Stewart) from the MiddleDevonian of Ohio. Univ. Mich. Mus. Paleontol.Papers on Paleontol. 23, 105 p.Steller, D. L. 1965 The epifaunal elements onthe Brachiopoda of the Silica Formation. Unpubl.M.A. Thesis, Bowling Green State Univ., Bowl-ing Green, OH, 79 p-Thayer, C. W. 1974 Substrate specificity of De-vonian epizoa. J. Paleontol. 48: 881-894.Watkins, R. 1979 Benthic community organiza-tion in the Ludlow Series of the Welsh Border-land. Brit. Mus. Nat. Hist. Bull. (Geol.) 31:175-280.1981 Epizoan ecology in the typeLudlow Series (Upper Silurian), England. J.Paleontol. 55: 29-32.

Vermiforichnus (Polychaeta) Borings in Paraspirifer Bownockeri (Brachiopoda: Devonian)

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Vermiforichnus (Polychaeta) Borings in Paraspirifer Bownockeri (Brachiopoda: Devonian)

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