Oldest known brachiopod burrow: the Lower ...

COMMUNICATION

Oldest known brachiopod burrow: the Lower Cambrian of Labrador S . GEORGE PEMBERTON Department of Geology, McMaster University, Hamilton, Ont., Canada L8S 4M1

Can. J. Earth Sci. Downloaded from www.nrcresearchpress.com by 199.201.121.12 on 06/05/13 For personal use only.

AND

DAVIDR. KOBLUK' Department of Geology, Memorial University, St. John's, N f d . , Canada AIC5S7 Received February 17, 1978 Revision accepted April 27, 1978

A specimen of the ichnospecies Lingulichnus verticalis was recovered from the Lower Cambrian Bradore Formation of southern Labrador. The sample represents the only known Cambrian example of an in situ lingulid, and sheds light on the evolution of the ethology of lingulids. Prior to this it was assumed that Cambrian lingulids maintained a non-burrowing mode of life. On a decouvert un specimen de l'ichnoespece Lingulichnus verticalis dans la formation de Bradore du Cambrien inferieur dans le sud du Labrador. L'echantillon represente le seul exemple connu dans le Cambrien d'un lingulide in situ, et jette un peu de lumiere sur l'evolution de I'ethologie des lingulides. Avant cette decouverte, on supposait que les lingulides du Cambrien avaient un mode de vie non fouisseur. [Traduit par le journal] Can. J . Earth Sci., 15, 1385-1389(1978)

Introduction Almost every significant aspect of the life history, physiology, and ethology of lingulid brachiopods has received attention (see Craig 1952; Chuang 1956, 1962, 1964; Ferguson 1963; Paine 1963). Recently there has been an upsurge of interest in the burrowing methods of lingulids (Thayer and Steele-Petrovic 1975) and in their relationship to the sediment substrate (Paine 1970). There are numerous accounts of fossil lingulids found in the vertical position and considered to be preserved in situ. Table 1 documents the occurrences of in situ or vertical lingulid fossils in Paleozoic rocks. Many more fossil in situ examples probably await recognition, in light of the recent study by Thayer and Steele-Petrovic (1975) on the burrowing dynamics of the recent lingulid Glottidia pyramidata. They demonstrated that the lingulid burrows are U-shaped and that shells may also assume oblique or nearly horizontal positions within the sediment, as illustrated by Yatsu (1902) for recent species and Pickerill (1973) for fossil lingulids. Although fossil shells of lingulid brachiopods are 'Present address: Department of Earth and Planetary Sciences, Erindale College, University of Toronto, Mississauga, Ont., Canada L5L 1C6.

not uncommon, preserved burrows of lingulids are very rare. Two new ichnogenera recently have been established for burrows attributed to lingulids: Lingulichnus (Hakes 1976) and Lingulichnites (Szmuc et al. 1976). Because Lingulichnus has taxonomic priority due to publication date and in order to avoid confusion Szmuc et al. (1977) called for the suppression of the ichnogenus Lingulichnites and placed it in synonymy with Lingulichnus. This paper describes a well-preserved specimen of Lingulichnus verticalis Hakes from the Labrador Group (Bonnia-Olenellus zone) of southern Labrador (Fig. 1). Rocks assigned to the Labrador Group record deposition during initial phases of the Lower Paleozoic transgression onto the eastern continental margin of North America during the late Early Cambrian time. In Labrador the Lower Cambrian comprises two formations: the lower, the Bradore Formation, is a series of conglomerates, sandstones, and minor siltstones; the upper, the Forteau Formation, is a series of siltstones, shales, and fossiliferous limestones containing archaeocyathid reefs (Schuchert and Dunbar 1934; James and Kobluk 1978). The Lingulichnus burrows were found in a red subarkosic sandstone unit near the top of the Bradore Formation. This unit also contains abundant Skolithos linearis burrows.

1386

CAN. J . EARTH SCI. VOL. 15, 1978

TABLE 1. Instances of in situ preservation of Paleozoic lingulids (expanded from Paine 1970)


-

Lithology

Preservation

Ane

Sandstone Shale Sandstone Slate Siltstone Siltstone Sandstone Sandstone Sandstone Coral : Heliolites Coral: Heliolites Chalk Sandy shale Siltstone Sandstone Shale Shale Siltstone Siltstone Shale Shale

Pedicle preserved Pedicle preserved Shells vertical Shells vertical Shells vertical Shells vertical Shells vertical Shells vertical Shells vertical Shells vertical Shells vertical Shells vertical Shells vertical Burrow preserved Pedicle preserved Shells vertical Shells vertical Shells vertical Burrow preserved Shells vertical Shells vertical

Reference This study Walcott (1888) Davidson (1874-1 882) Opik (1930) Bretsky (1970) Pickerill (1973) Ziegler et al. (1968) Pemberton (unpublished thesis data) Martini (1971) Richards and Dyson-Cobb (1976) Newall (1970) Hecker (1960) Cooper (1937) Szmuc et a / . (1976) Hall and Clark (1892) Craig (1952, 1954) Ferguson (1962, 1963) Osgood and Szmuc (1972) Hakes (1976) Edwards and Stubblefield (1947) Young (1866)

Cambrian Ordovician Ordovician Ordovician Ordovician Ordovician Silurian Silurian Silurian Silurian Silurian Devonian Devonian Devonian Mississippian Mississippian Mississippian Mississippian Pennsylvanian Pennsylvanian Carboniferous

TABLE 2. Ichnogenera associated with in situ lingulids Age

Formation

Location

Associated ichnogenera

Reference

Burrow

Skolithos, Monocraterion, Dolopichnus

Present study

Shells vertical, burrow Shells vertical

Skolithos, Planolites, Teichichnus

Pickerill (1973)

Skolithos, Arthrophycus, Daedalus, Planolites, Chondrites

Martini ( 1 971) Pemberton, unpublished thesis data

NE New York SW Ontario

Shells vertical

Skolithos, Monocraterion, Pemberton, Planolites, Rusoph:,cus, unpublished thesis data Dolopichnus, Arenicolites, Chondrites, Teichichnus, Arthrophycus, Diglocraterion

Ohio

Shells vertical

Zoophycos, Palaeophycus

Kansas

Burrow

Tigillites, Planolites, Hakes (1976) Asteriactes, Lockeia, Cochlichnus, Didymaulichnus, Chondrites, Zsopodichnus, Rusophycus, Conostichus, Curvolithus, Microspherichnus

Cambrian

Bradore

Ordovician

Pen-y-Garnedd North Wales

Silurian

Grimsby

NE New York SW Ontario

Silurian

Thorold

Mississippian

Cuyahoga

Pennsylvanian Rock Lake Shale

Preservation

Southern Labrador

Paleontology Lingulichnus verticalis Hakes (1976) Lingulichnites amygdalinus Szmuc, Osgood and Meinke (1976) Description Tongue- to spade-shaped vertical burrow with the widest dimension at the top. The aperture and upper tongue-like part are elliptical in transverse

Osgood and Szmuc (1972)

section, displaying two planes of symmetry; one would pass between the valves and the other bisects the valves and forms a 90" angle with the first. The single most diagnostic feature is the basal projection down from the main chamber. Age Range of Known Forms Lingulichnus is known from only two locations, the Upper Devonian Chagrin Formation of Ohio


COMMUNICATION

I-

1387

Labrador sample

location

FIG.1. The coast of southern Labrador on the Straits of Belle Isle and the location at which the sample material of Lingulichnus was found.

(Szmuc et al. 1976) and the Upper Pennsylvanian Rock Lake Shale Formation of Kansas (Hakes 1976). Examples of lingulid shells found in situ in Paleozoic rocks range in age from Ordovician to Pennsylvanian.

Interpretation The Lower Cambrian form (Fig. 2) is almost identical to the specimen illustrated by Szmuc et al. (1976, Fig. 2B, p. 165); it differs only in its larger size. The upper spade-like chamber in the Labrador specimen is 4.1 cm long and 3.5 cm wide; the basal stem is 5.7cm long and 1cm wide, giving the entire burrow a length of 9.8cm. This burrow is large; however, there are examples of both recent and fossil lingulids that attain these dimensions. In a study of the recent species Lingula unguis, Chuang (1962) describes specimens that are 5.2 cm in length and 2.2cm in width. Pickerill (1973) described specimens of Lingulasma tenuigranulata that attain lengths of up to 4.5 cm and widths of up to 3.2 cm. Discussion Examination of Table 1 shows that most of the examples of vertically orientated lingulids are from fine-grained siliclastic sediments. Until recently it was commonly accepted that lingulids lived in these fine-grained sediments exclusively (Craig 1952; Ferguson 1963). Quantitative studies conducted on a wide range of recent species, however, have shown that extant lingulids prefer shallow sandy areas (Paine 1970) and that the paleoenvironmental distribution of fossil lingulids is produced primarily by a preservational bias (Thayer

FIG.2. Lingulichnus verticalis from the Lower Cambrian of southern Labrador. Scale bar is 1 cm. The specimen is housed in the paleontological collection of the Royal Ontario Museum. Number R.O.M. 37226.

and Steele-Petrovic 1975). The reasons for this preference for sandy areas have been outlined by Thayer and Steele-Petrovic (1975) as follows: (1) Fine-grained material can pass between the setae and can thus foul the mantle cavity. (2) Finegrained sediments usually exhibit high water contents and low shear strengths and thus are unable to support the pedicle. (3) Because of the low shear strength, fine-grained sediments are easily resuspended, causing clogging of suspension-feeding organisms (Rhoads and Young 1970). The Lower Cambrian Bradore Formation is interpreted, on the basis of physical sedimentary


1388

CAN. J. EARTH SCI. VOL. 15. 1978

unguis (L.). Videnskabelige Meddelelser fra Dansk Naturstructures, to be a series of tidal-dominated, nearhistorisk Forening, 124, pp. 199-215. shore sand shoals (Swett and Smit 1972). These 1964. The circulation of the coelomic fluid in Lingula sandstone units are devoid of body fossils so that unguis. Proceedings of the Zoological Society of London, 143, ichnofossils present the only clue to the biologic pp. 221-237. component. The sample of Lingulichnus occurs in COOPER,G. A. 1937. Brachiopod ecology and paleoecology. Commission on Paleoecology National Research Report, a medium-grained sandstone near the top of the 1936-1937, pp. 26-53. Bradore Formation and is found in association with CRAIG,G. Y. 1952. A comparative study of the ecology and the ichnogenera Skolithos, Monocraterion, and paleoecology ofLingula. Transactions of the Edinburgh GeoDolopichnus. Table 2 summarizes the known logical Society, 15, pp. 111-119. ichnogenera that are associated either with Lin1954. The paleoecology of the Top Hoise Shale (Lower Carboniferous) at a locality near Kilsyth. Quarterly Journal of gulichnus or with vertical in situ lingulid shells. the Geological Society of London, 110, pp. 103-109. These data indicate that in situ lingulids generally DAVIDSON, T. 1874-1882. A monograph of British fossil are found with ichnofossils that characterize relabrachiopods. Palaeontological Society, 4, pp. 1-383. tively shallow, sandy areas (the Skolithos zone of EDWARDS, W., and STUBBLEFIELD, C. J. 1947. Marine bands and other faunal marker-horizons in relation to the sedimenSeilacher (1967)). Therefore, the distribution of tary cycles of the Middle Coal Measures of Nottinghamshire Lingulichnus and its association with other ichnoand Derbyshire. With an appendix on the petrography of two genera conform with the known paleoecology of sedimentary cycles by K. C. Dunham. Quarterly Journal of lingulid body fossils. This points out the importhe Geological Society of London, 103, pp. 209-260. L. 1962. The paleoecology of aLowerCarboniferous tance of establishing zoological affinities for ichno- FERGWSON, marine transgression. Journal of Paleontology, 36, pp. fossils, since in high energy environments even 1090-1 107. organisms with hard parts may be represented only 1963. The paleoecology of Lingula squamiformis Philby their traces. lips during a Scottish Mississippian marine transgression. Another consequence of the occurrence of the Journal of Paleontology, 37, pp. 669-681. Lower Cambrian Lingulichnus burrow concerns HAKES,W. G. 1976. Trace fossils and depositional environment of four clastic units, Upper Pennsylvanian megacyclothems, the evolution of the ethology of lingulids. The burnortheast Kansas. University of Kansas Paleontological Conrowing mode of life of lingulids is known previously tributions, Article 63, pp. 1-46. from as far back as the Ordovician (see Table 1). HALL,J., and CLARK, J. M. 1892. An introduction to the study of the genera of Paleozoic Brachiopoda. New York Geological Rudwick (1970) indicated that Cambrian forms lack Survey, 8, pp. 1-367. the parallel-sided shell form characteristic of those that are known to burrow and suggested that these HECKER,R. F. 1960. Bases de la paleoecologie. Bureau Recherche~Geologiques Minieres, 44, pp. 1-61. (Translated forms normally led an epifaunal life. However, the from the Russian.) discovery of Lingulichnus in Lower Cambrian JAMES,N. P., and KOBLUK, D. R. 1978. Lower Cambrian patch reefs and associated sediments: southern Labrador, Canada. strata suggests that the infaunal habitat was Sedimentology. In press. exploited by at least some lingulids as early as the I. P. 1971. Regional analysis of sedimentology of Lower Cambrian and probably has remained essen- MARTINI, Medina Formation (Silurian), Ontario and New York. Ameritially unchanged since that time. can Association of Petroleum Geologists Bulletin, 55, pp. .

Acknowledgements This work developed out of a project on the Lower Cambrian of Labrador, organized by Noel P. James of Memorial University of Newfoundland and funded by the National Research Council of Canada. Additional support was available through a McMaster University travel assistance grant to S. G . Pemberton, and an Erindale College, University of Toronto, internal grant to D. Kobluk. R. T. Paine provided photographs of modern lingulids. The manuscript was reviewed by R. G . Osgood, R. K. Pickerill, and N. P. James. BRETSKY, P. W. 1970. Upper Ordovician ecology of the central Appalachians. Peabody Museum Bulletin, 34, pp. 1-150. CHUANG, S. H. 1956. The ciliary feeding mechanism of Lingula unguis (L.) (Brachiopod). Proceedings of the Zoological Society of London, 127, pp. 167-189. 1962. Statistical study of variations in the shell of Lingula

1249-1261. NEWALL,G. 1970. A symbiotic relationship between Lingula and the coral Heliolites in the Silurian. Geological Journal, Special Issue 3, pp. 335-344. OPIK,A. 1930. Brachiopoda protremata der Estlandischen Ordovizischen Kukruse-Stufe. Acta Commentationes, University Tartu, 17, pp. 1-261. &GOOD, R. G., and S z ~ u c E. , J. 1972. The trace fossil Zoophycos as an indicator of water depth. Bulletin of American Paleontology, 62(271), pp. 1-22. PAINE,R. T. 1963. Ecology of the brachiopod Glottidia pyramidata. Ecological Monographs, 33, pp. 187-213. 1970. The sediment occupied by recent lingulid brachiopods and some paleoecological implications. Palaeogeography, Palaeoclimatology, Palaeoecology, 7, pp. 21-31. PICKERILL, R. K. 1973. Lingulasma tenuigranulata-Paleoecology of a large Ordovician linguloid that lived within a strophomenid-trilobite community. Palaeogeography, Palaeoclimatology, Palaeoecology, 13, pp. 143- 156. RHOADS,D. C., and YOUNG,D. K. 1970. The influence of deposit-feeding organisms on sediment stability and community trophic structure. Journal of Marine Research, 28, pp. 150-178.

1

1 I I

COMMUNICATION


RICHARDS, R. P., and UYSON-COBB, M. 1976. A Lingula-Heliolites association from the Silurian of Gotland, Sweden. Journal of Paleontology, 50, pp. 858-864. RUDWICK, M. J. S. 1970. Living and fossil brachiopods. Hutchinson, London. pp. 1-199. SCHUCHERT, C., and DUNBAR,C. 0 . 1934. Stratigraphy of western Newfoundland. Geological Society of America, Memoir 1, pp. 1-123. SEILACHER, A. 1967. Bathymetry of trace fossils. Marine Geology, 5, pp. 413-428. SWETT,K., and SMIT,D. E. 1972. Paleogeography and depositional environments of the Cambro-Ordovician shallowmarine facies of the North Atlantic. Geological Society of America Bulletin, 83, pp. 3223-3248. S z ~ u c E. , J., OSGOOD,R. G., and MEINKE,D. W. 1976. Lingulichnites, a new trace fossil genus for lingulid brachiopod burrows. Lethaia, 9, pp. 163-167.

1389

1977. Synonymy of the ichnogenus Lingulichnites Szmuc, Osgood and Meinke 1976, with Lingulichnus Hakes 1976. Lethaia, 10, p. 106. THAYER, C. W., and STEELE-PETROVIC, H. M. 1975. Burrowing of the lingulid brachiopod Glottidia pyramidata: its geologic and paleoecologic significance. Lethaia, 8, pp. 209-221. WALCOTT,C. D. 1888. A fossil Lingula preserving the cast of the peduncle. Proceedings of the United States National Museum, 11,p. 480. YATSU,N. 1902. On the habits of the Japanese Lingula. Annotationes Zoologicae Japonenses, 4, pp. 61-67. YOUNG,J. 1866. Notes on the occurrence and range of Lingula in the Carboniferous series of the west of Scotland. Transactions of the Geological Society of Glasgow, 2, pp. 144-149. ZIEGLER, A. M . , COCKS,R. M., ~ ~ ~ B A M B R. A CK.H1968. , The composition and structure of Lower Silurian marine communities. Lethaia, 1,pp. 1-27.