Fish otoliths from the lower Tertiary of Ellesmere Island

Fish otoliths from the lower Tertiary of Ellesmere Island WERNER SCHWARZHANS Stammannstrasse 13, 2000 Hamburg-60, West Germany Received January 24, 1985

Can. J. Earth Sci. Downloaded from www.nrcresearchpress.com by East-China Institute of Technology on 05/28/13 For personal use only.

Revision accepted December 9, 1985 Fish otoliths of five species are present in lower Tertiary (Paleocene to Lower Eocene) rocks at Strathcona Fiord, Ellesmere Island. Two species are new, one is conspecific with a species known from the Lower Eocene of southern England, and two remain in open nomenclature. Paleobiogeographic and other implications of the fauna are that first, there is no resemblance to central European faunas; second, there is a resemblance to northern European faunas from Great Britain and the Soviet Union, pointing to cooler climatic conditions; and third, composition of the fauna suggests the prevalence of deeper shelf conditions. Les roches du Tertiare infkrieur (Paleockne h ~ o c k n einfkrieur) du fjord de Strathcona, Ele E l l e s m e ~ ,contiennent des otolithes de cinq espbces de poisson. Deux espkces sont nouvelles, une appartient h une es@ce connue de 1'Eockne infkrieur du sud de 1'Angleterre et les deux autres restent ouvertes h la nomenclature. Les enseignements palkobiogkographiques et autres sur la faune sont premibrement, aucune ressemblance avec les faunes de I'Europe central; deuxibmement, il existe une ressemblance avec les faunes du nord de I'Europe, de la Grande Bretagne a 1'Union Soviktique, kv6lant l'existence de conditions climatiques plus froides; et troisikmement, la composition de la faune indique cornme conditions pdominantes celles qu'on trouverait sur une plate-forme plus surbaisske [Traduit par la revue] Can. J. Earth Sci. 23, 787-793 (1986)

Introduction The fish otoliths described were collected by P. Ramaekers of Saskatoon, Saskatchewan, on Ellesmere Island in the Northwest Temtories during a field trip in the early 1970's. Specimens (NMC 40400 -40439) are deposited in the Paleobiology Division of the National Museum of Canada, Ottawa.

of about 3 rnrn length that cannot be identified specifically.

Geographic and geologic setting All the otoliths were collected from surface exposures on the shore of Strathcona Fiord, a side branch of Bay Fiord, in the northwestern region of Ellesmere Island (Fig. 1). They were obtained from the Eureka Sound Formation, which, according to a personal communication (1975) from P. Ramaekers, is believed to be Paleocene to Early Eocene in age. This view is supported by the indentification of Argentina pennata (Stinton, 1966), originally described from the Lower Eocene London Clay of southern England.

Discussion Sole living genus of the family with five Recent species. Habitat is epipelagic in all tropical and subtropical oceans. For comparison, otoliths of four Recent species are figured: E. lacerta Valenciennes, 1946 (Fig. 2), E. hawaiensis Regan, 1909 (Fig. 3), E. aflnis Regan, 1909 (Fig. 4), and E. saurus Linnaeus, 1766 (Fig. 5); also figured are otoliths from Megalops cyprinoides (Broussonet, 1782) (Fig. 6) of the closely related family Megalopidae (one genus, two Recent species).

Description of species SUPERORDER Elopomorpha ORDER Elopiformes SUBORDER Albuloidei FAMILY Pterothrissidae

Pterothrissus Hilgendorf, 1877 Type species Pterothrissus gisu Hilgendorf, 1877. Discussion Sole living genus of the family with two Recent species, P. gisu from Japan and P. belloci Cadenat, 1937 from central West Africa, both living on the upper continental slope. In Cretaceous and early Tertirary times, the Pterothrissidae apparently were distributed much more widely (see Schwarzhans 1981). Pterothrissus sp. Material One specimen (NMC 40400); a badly eroded juvenile otolith Printed in Canada 1 Imprime au Canada

SUBORDER Elopoidei FAMILY Elopoidae

Elops Linnaeus, 1766 Type species Elops saurus Linnaeus, 1766.

Elops ramaekersi n. sp. (Figs. 7 a -c, 8 a and b ) Name In honour of Dr. Paul Ramaekers. Holotype Figure 7 (right sagitta), NMC 40401. Type locality Car 19, Strathcona Fiord, Ellesmere Island. Age Eureka Sound Formation, Paleocene to Early Eocene. Paratypes Five specimens, same locality, NMC 40402 -40406. Diagnosis Cauda straight; ventral rim slightly bent; dorsal rim with strongly developed postdorsal region and distinct notch just above tip of cauda. Description Otoliths large, fairly elongate, and thick; not bent along horizontal axis. Rostrum not fully preserved in any specimen

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Outer face flat or slightly convex in both directions, with numerous long radial f~rrowsoriginating from marginal crenulation. Dimensions


BAY

FIORD Holotype Figure 8

Length (mm)

Height (mm)

Index (1:h)

-5.3 -5.8

3.0 3.6

< 1.75 < 1.61

Discussion This is the first certain fossil otolith record of the genus Elops. One doubtful, other fossil species, E. undulatus Stinton, 1966, has been reported from the Lower Eocene of the London Basin. It is based on juvenile otoliths of less than 2 rnrn length. The holotype, being the best-preserved specimen, is likely from a subadult fish. It shows a finer marginal crenulation and fine radial furrows on the inner face, both lost in the just slightly larger paratype (Fig. 8). The postdorsal region shows the strongest variability, although overall characters remain stable. SUPERORDER Protacanthopterygii ORDER Salmonifonnes SUBORDER Argentinoidei FAMILY Argentinidae

Argentina Linnaeus, 1758 Type species Argentina sphyraena Linnaeus, 1758. FIG. 1. Location of Ellesmere Island and Strathcona Fiord and schematized geological map showing distribution of Tertiary Eureka Sound Formation and of Cretaceous sediments. (Triassic and Paleozoic strata are not shown.)

but believed sharp; not very long. Ventral rim slightly curved, rather smooth. Dorsal rim flat, straight anteriorly, with markedly protruding coarsely crenulate to undulate posterior region followed by distinct notch just above tip of cauda. Posterior tip of otoliths pointed rather than rounded. Inner face flat horizontally, slightly convex in vertical axis. Sulcus straight, slightly supramedian, with indistinct partition into smaller ostium and longer cauda-a typical archaesulcoid sulcus morphology. Cauda deep, widening somewhat to posterior tip, which closely approaches posterior tip of otolith. Ostium widens slightly ventrally, more distinctly so dorsally. Dorsal rim sharply bent upward. Area deep, narrow, and far from cauda, creating rather wide crista superior. Ventral furrow feeble. Short radial furrows, originating from the marginal crenulation, are sometimes present.

Discussion The A. sphyraena species - group, living on the upper continental slope, has a typical antitropical distribution; it likely originated in the northern hemisphere (see Schwarzhans 1984). Argentina pennata (Stinton, 1966) (Figs. 9 a and b, 10) Synonymy Hypomesus pennatus Stinton, 1966, p. 421, P1. 66, fig. 6. Argentina pennata (Stinton) Schwarzhans, 1984, p. 243, Fig. 622. Material Sixteen specimens, mostly broken (NMC 40407 -40422). Dimensions

Figure 9 Figure 10

Length (mm)

Height (mm)

-4.2 -4.0

3.4 3.1

Index (1:h)

- 1.28

~1.27

FIGS.2 - 10. Fig. 2. Elops lacerta Valenciennes, 1846, from off Mauretania. Recent. x 6.5. Fig. 3. Elops hawaiensis Regan, 1909, from off Hawaii. Recent. x6.5. Fig. 4. Elops afinis Regan, 1909, from off Pacific coast of Mexico. Recent. x6.5. Fig. 5. Elops saurus Linneaus, 1766, from off South Africa. Recent. ~ 6 . 5 Fig. . 6. Megalops cyprinoides (Broussonet, 1782), from off Queensland, northeastern Australia. Recent. X20. Figs. 7 a-c, 8 a and b. Elops ramaekersi n. sp. (7) Holotype, NMC 40401; (7a, 8a) views of inner face; (76, 8b) views from anterior; ( 7 4 view from dorsal. Strathcona Fiord, Ellesmere Island, Car 19. Paleocene to Lower Eocene. X 13. Figs. 9 a and b, 10. Argentina pennata (Stinton, 1966). (9a, 10) Inner face; (96) view from dorsal. Strathcona Fiord, Ellesmere Island: (9) Car 18; (10) Car 19. Paleocene to Lower Eocene. x 13.


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larger than those from Great Britain and also show a more strongly undulated dorsal rim. This is believed to be an ontogenetic effect. The identification of A. pennata supports the suggested stratigraphic position of the collected strata. Primuevomesus t i crenulatus Stinton, 1965, a monospecific fossil genus known from the Paleocene of the London Basin, also resembles A. pennata. Unfortunately, this species is based on eroded type material, prohibiting detailed recognition but permitting its replacement into the genus Argentina. SUPERORDER Paracanthopterygii ORDER Gadifonnes SUBORDER Gadoidei FAMILY Gadidae (including Merlucciidae)

Palaeogadus von Rath, 1859 Type species Palaeogadus troschelii von Rath, 1859. Discussion Palaeogadus is a fossil genus established from complete skeletons. It is particularly well known from the Carpathian, Balkan, and Caucasus mountains of eastern Europe. Palaeogadus sp. (Fig. 1 1 a and b) Material Two broken specimens (NMC 40423 -40424). Dimensions

Figure 1 1

FIGS. 1 1 - 14. Fig. 1 1 a and b. Palaeogadus sp. ( a ) Inner face; ( b ) view from dorsal. Strathcona Fiord, Ellesmere Island, Car 18. Paleocene to Lower Eocene. x 9 . Figs. 12 a - c , 13, 14. Melanonus ellesrnerensis n. SP. (12) Holoty~e,NMC 40425; (12% 13, 14) inner face; (12b) view from anterior; (12c) view from dorsal. Strathcona Fiord, Ellesmere Island, Car 19. Paleocene to Lower Eocene. x 16.

Diagnosis Compact otoliths with rather short rostrum (ultimate tip broken in all Ellesmere specimens); postdorsal angle pronounced; dorsal rim crenulated; ventral rim very deep,-regular, rather smooth; upper margin of ostium limited by wellexpressed antirostrum; postcaudal depression not developed, but one to two furrows cut into caudal tip from posterior-and posterior -dorsal. Discussion Of all Ellesmere otoliths, this is the most common species. It closely resembles the otoliths described by Stinton (1966) from the Lower Eocene London Clay, where it also is very common. Most specimens from Ellesmere Island are somewhat

Length (mm)

Height (mm)

6.4

4.3

Discussion Neither specimen is well enough preserved to allow specific identification. A similar otolith from the Lower Eocene of the London Basin, Merluccius shepherdi Schubert, 1916, is readily distinguished by the more median position of the anterior tip of the otolith and by its much less convex inner face in the vertical direction. In this respect, Raniceps altus Nolf, 1972, from the Lower Oligocene of Belgium, and Raniceps elegans Stinton, 1977, from the Middle Eocene of Great Britain and Belgium, are more alike. Both species likely represent a distinct fossil genus close to Palaeogadus. In Fedotov's (1976) excellent work Gadidae of the Palaeogene-Neogenefrom the USSR (osteologic studies of skeletons), several otoliths were figured in situ. Of those, only P. g e m n u s Fedotov, 1970 shows some resemblance. FAMILY Melanonidae Melanonus Giinther, 1878

Type species Melanonus gracilis Giinther, 1878. Discussion Sole living genus of this family, with a nearly cosmopolitan mesopelagiL distribution. Two Recent species are known, as are a few fossil species from the Miocene-Pliocene rocks of the Mediterranean region and of New Zealand.

Melanonus ellesmerensis n. sp. (Figs. 12 a - c , 13, 14)


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3 FIG. 15. Distribution of the genera Palaeogadus and Arnentina and the family Mvcto~hidaein the northern hemis~heredurine Paleocene and Eocene times (according to otdiths and skeletons with otoiiths in situ). The ar&w kdic'ates the assumed avenue of ciistribution Lo the Ellesmere (large open circle) and North Sea basin localities. Full circles are Paleocene to Lower Eocene localities: London Basin (Stinton 1965, 1966, 1975); Belgian Basin (Nolf 1970, 1972b,c, 1978), and Copenhagen (Koken 1885). Full triangles are Middle Eocene to Lower Oligocene localities: San Diego, California (Fitch 1969); Brazos County, Texas, and Clayborne County, Alabama (Frizzell 1965; Frizzell and Lamber 1961, 1962; Frizzell and Dante 1965; Koken 1888); Barbados (Casier 1958, 1966); Aquitaine, France (Sulc 1932); Bretagne and Paris Basin, France, and Belgian Basin (Nolf 1970, 1972~);Hampshire Basin, England (Stinton 1966, 1975, 1977); Bohemia, Carpathians, Romania, and Caucasus (Danilchenko 1960; Fedotov 1976). The ~aleocontinentalreconst~uctionfor the Paleocene map (60 Ma) is from Smith and Briden's (1981) north polar projection.

Name

After the type area. Holotype

Figure 12 (right sagitta), NMC 40425. Type locality

Car 19, Strathcona Fiord, Ellesmere Island. Age

Eureka Sound Formation, Paleocene to Early Eocene.

Paratypes

Seven specimens from Car 19, three specimens from Car 18, and one specimen from Car 22; NMC 40426-40436.

Diagnosis

Otolith compressed; rostrum strong; excisura marked; sulcus deep; colliculi moderately wide. Description

Otoliths rather compressed, very thick. All rims smooth and rounded. Ventral and dorsal rims gently curved. Centre of dorsal rim in middle; that of ventral rim slightly anterior of middle. Posterior tip of otolith blunt. Anterior tip with massive rostrum, strongly protruding, and obtuse but marked excisura close to upper part of opening of sulcus. Inner face nearly flat, with median to slightly supramedian sulcus moderately wide, rather deep, and divided into equally

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proportioned and shaped ostium and cauda-a typical homosulcoid sulcus morphology. Opening of sulcus pseudobiostial. Colliculi oval, moderately wide, equal in size, and not approaching rims of otolith. Collum very narrow. No indication of pseudocolliculum. Area undeveloped. Ventral furrow extremely faint, running close and parallel to ventral rim. As otoliths very thick, outer face markedly convex in both directions, lacking sculpturing. Dimensions Length Height Thickness Index (mm) (mm) (mm) (1:h) Holotype Figure13 Figure14

2.9 3.3 2.4

2.1 2.6 1.5

0.9

-

-

1.39 1.24 1.54

Discussion This is the oldest fossil record of the family Melanonidae, a family hitherto known only from Miocene and younger rocks. Allometric ontogenetic growth is prominent. The smaller otoliths are more elongate (index I: h about 1.5; Fig. 14) than the larger ones (index 1:h about 1.2; Fig. 13). Also, the thickness increases strongly with growth. In smaller specimens the dorsal rim is somewhat more strongly curved and, in some, undulated (Fig. 14); they commonly show a mediodorsal angle. The larger otoliths tend to reduce the height of the dorsal field by smoothing of the dorsal rim (Fig. 13). The posterior tip of the otolith is blunt in large specimens (Fig. 13), more rounded in smaller ones. The holotype was chosen to represent an intermediate ontogenetic stage. All the rims, particularly the dorsal, show minor variations. In some the rosirum is less massive than in the figured specimens, which reduces slightly the 1:h index. The width and depth of the sulcus also vary somewhat. The specimens NMC 40437-40439 contain a number of unidentifiable fossil fragments.

Faunal reconstruction Compared with those from Europe and New Zealand, fossil otoliths from North America have rarely been described. This does not reflect the rarity of otoliths but that they have attracted little interest in North America previously. The importance of the small fauna from Ellesmere Island lies in its geographic remoteness: it is the first to be described from the Arctic Ocean basin. Bathymetry The fauna contains two representatives of bentho-pelagic fishes from the upper continental rise, Argentina and Pterothrissus; one epipelagic fish, Elops; and one mesopelagic fish, Melanonus. Palaeogadus is a fossil genus. This is good evidence for a fauna living on the deeper shelf, in water of about 100-200 m depth and with considerable open-marine influence. Climatic implications Pterothrissus and Elops are today tropical to subtropical fishes, but they are believed to have been distributed much more widely in early Tertiary times. Argentina pennata is related to the A. sphyraena species-group, which shows a typical antitropical distribution pattern indicative of a temper-

ate climate. This also is true for Palaeogadus, which is well known from the northern and eastern European Tertiary rocks. Myctophid otoliths have not been found; they form the most common mesopelagic element in subtropical and tropical faunas (Fig. 15) but are rare in temperate and boreal waters. Faunal correlation Faunal correlation (Fig. 15) is limited by the small number of species and by the remoteness of the locality. Pterothrissus had a very wide distribution in early Tertiary time (see Schwarzhans 1981). For both Melanonus and Elops, this is the first true early Tertiary otolith evidence. As they do not occur in the extensively known European Eocene fauna, they may well be of different paleobiogeographic origin; for instance, they may have come from Pacific waters. The only positive evidence for faunal correlation is provided by the occurrence of Argentina pennata, elsewhere known from the Eocene sediments of the London Basin, and Palaeogadus sp. Gadidae are widespread in the Eocene strata of northern and eastern Europe but are unknown from southern and western Europe. In the European Paleocene and Eocene strata, fishes of Tethyan origin are dominant by far. Representatives of a possible "paleo-North Sea" fauna are scarce and limited to northern and eastern Europe, which is believed to have been slightly colder. Paleo-North Sea influence seemingly is strongest in the Eocene sediments of the London Basin. The presence of Argentina pennata in the London Basin and in Ellesmere Island points to an avenue of migration between the Arctic Ocean and the "paleo-North Sea." Early Tertiary otolith records from elsewhere in North America (southern California and the Gulf Coast) do not show any resemblance to the small fauna from Ellesmere Island.

Acknowledgment I express my heartfelt thanks to Dr. Paul Ramaekers for his generous assistance and for making his collection available for investigation. CASIER,E. 1958. Contribution i l'ttude des poissons fossiles des Antilles. SchweizerischepalaeontologischeAbhandlungen, 74, pp. 1-95. 1966. Sur la faune icthyologique de la formation de Bissex Hill et de la strie octanique, de l'ile de la Barbade et sur l'bge de ces formations. Eclogae geolicae Helvetiae, 59, pp. 493 -5 13. DANILCHENKO, P. G. 1960. Bony fishes of the Maikop deposits of the Causasus. [Translated from the Russian (1967) by A. Mercado.] Israel Progress in Science, Jerusalem, pp. 1-247. FEDOTOV, V. F. 1976. Gadidae of the Palaeogene-Neogene from the USSR. Trudy Paleontologicheskogoinstituta, ~ k a d e h i ~ nauk a SSR, 157, pp. 5 -83. FITCH,J. E. 1969. Fossil lanternfish otoliths of California, with notes on fossil Myctophidae of North America. Contributions in Science (Los Angeles), 173, pp. 1-20. FRIZZELL, D. 1965. Otolith-based genera and lineages of fossil bonefishes (Clupeiformes, Albulidae). Senckenbergiana Lethaea, 46a, pp. 85-110. FRIZZELL, D., and DANTE,J. 1965. Otoliths of some early Cenozoic fishes of the Gulf Coast. Journal of Paleontology, 39, pp. 687-718. FRIZZELL, D., and LAMBER, C. K. 1961. New genera and species of myripristid fishes in the Gulf Coast Cenozoic, known from otoliths (Pisces: Beryciformes). University of Missouri, School of Mines and Metallurgy, Bulletin, Technical Series, 100, pp. 1-25. 1962. Distinctive "Congrid type" fish otoliths from the


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lower Tertiary of the Gulf Coast (Pisces: Anguilliformes). Proceedings of the California Academy of Sciences, 4 , Series G, Dallas Hanna Anniversary Volume, 32, pp. 87- 101. KOKEN,E. 1885. Otolithen. I n Uber eine Palaozane Fauna von Kopenhagen. Edited b y A. V. Koenen. Abhandlungen der K. Gesellschaft der Wissenschaften ZU Gottingen, 32, pp. 113 - 116. 1888. Neue Untersuchungen an tertiaren Fischotolithen (Nord Amerika). Zeitschrift der Deutschen geologischen Gesellschaft, 40, pp. 274 -305. NOLF, D. 1970. Sur la faune ichthyologique d'un falun dans l'argile des Flandres, prks de Courtrai (Belgique). Bulletin de la SociktC belge de gtologie, de paltontologie et d'hydrologie, 79, pp 11-24. 1972a. Sur les otoliths des sables de Grimmertingen (Oligockne infkrieur de Belgique). Bulletin de 1'Institut royal des sciences naturelles de Belgique, 48, pp. 1-23. 1972b. Sur la faune ichthyologique des formations du Panisel et de den Hoom (Eockne belge). Bulletin de la SociCtC belge de gCologie, de palContologie et d'hydrologie, 81, pp. 1 1 1- 138. Fercourt i (Eockne 1 9 7 2 ~Les . otolithes du calcaires grossier ? du bassin de Paris). Bulletin de la SociCtC belge de gkologie, de palContologie et d'hydrologie, 81, pp 139-157. 1978. Les otolithes de telCosttens des formations de Landen et de Heers (PalCockne de la Belgique). Geologica et Palaeontolo-

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gica, 12, pp. 223-234. SCHWARZHANS, W. 1981. Die Entwicklung der Familie Pterothrissidae (Elopomorpha; Pisces), rekonstruiert nach Otolithen. Senckenbergiana Lethaea, 62, pp. 77 -91. 1984. Fish otoliths from the New Zealand Tertiary. New Zealand Geological Survey, Report 113, pp. 1 -269. STINTON, F. C. 1965. Teleost otoliths from the lower London Tertlaries. Senckenbergiana Lethaea, 46a, pp. 389 -425. 1966. Fish otoliths from the London Clay. In Faune ichthyologique du London Clay. Edited b y E. Casier. Bntish Museum (Natural History), memoir, pp. 404 -478. 1975. Fish otoliths from the English Eocene I. Palaeontographical Society Monographs, London, pp. 1-56. 1977. Fish otoliths from the English Eocene 11. Palaeontographical Society Monogmphs, London, pp. 57- 126. SULC,J . 1932. Les otolithes du Paltogkne dcs environs de Bianitz. Rozspmvy Stitniho geologickeho dstavu CeskoslovenskC republiky, 7, pp. 45-94. WEILER,W. 1959. Miozane Fisch-Otolithen aus der Bohrung S. Pablo 2 im Becken von Vemcruz in Mexico. Neues Jahrbuch fiir Geologie und Palaontologie, Abhandlungen, 109, pp. 147 - 172. WHITE,E. I . 1956. The Eocene fishes of Alabama. Bulletin of American Paleontology, 36, pp. 123 - 152.