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Balanoid from the Miocene of the Peninsula, and Their Relevance to the Extant Boreal Fauna Author(s): Victor A. Zullo and Louie Marincovich, Jr. Source: Journal of Paleontology, Vol. 64, No. 1 (Jan., 1990), pp. 128-135 Published by: Paleontological Society Stable URL: http://www.jstor.org/stable/1305551 Accessed: 02/09/2010 17:45

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http://links.jstor.org 128 JOURNAL OF PALEONTOLOGY, V. 64, NO. 1, 1990

Other localities USGS collection 12996-PC. In small streamknown as Portachuelo, less than 1 km N-NW of Merida USGS collection 12994-PC. eastern of Sahara QuebradaPortachuelo, State, approx. Tebaga Hills, edge 80?Nlatitude, southwestern Venezuelan . Silicified Permian about 35 km west of town Tunisia. Permian Early Desert, ofMedenine, Upper ostracodes,petroliferous dark-gray shale with intercalatedcalcareous Limestone, silicified ostracodes.Collected by H. Faul and C. H. Faul. siltstonein the PalmaritoFormation. Collected P. R. Hoover (1981, See Faul and Faul by (1977). p. 20, text-fig. 1). USGS collection 12995-PC. Yaurichambi,about 45 km NW of La USGS collection 12997-PC.About 1 km N-NE of collection 12996- on to and Lake Bolivia. Yellow or Paz, highway Copacabana Titicaca, PC, beside mule track that connects QuebradaPortachuelo and Mu- whitish 1.5 m thick.Catacora Marl Member of marl, CopacabanaGroup, cuchachi. SilicifiedEarly Permian ostracodes,petroliferous, 10-20 m above lower limit of Lower light-gray CopacabanaGroup. Permian, to tan limestone in PalmaritoFormation. Collected by P. R. Hoover, correlativeof the Wolfcampianof Texas. Collectedby Dr. L. Branisa same area as above. (Sohn, 1980; describedby Pribyland Pek, 1987).

J. Paleont., 64(1), 1990, pp. 128-135 Copyright ? 1990, The Paleontological Society 0022-3360/90/0064-0128$03.00 BALANOID BARNACLES FROM THE MIOCENEOF THE ALASKA PENINSULA, AND THEIR RELEVANCETO THE EXTANT BOREAL BARNACLE FAUNA

VICTOR A. ZULLO AND LOUIE MARINCOVICH, JR. Departmentof EarthSciences, University of North Carolinaat Wilmington,North Carolina28403 and U.S. GeologicalSurvey, Menlo Park,California 94025

ABsTRAcr-Thebarnacle fauna of the Miocene Bear Lake Formationof the AlaskaPeninsula includes Chirona(Chirona) alaskana n. sp., and three of Da Costa conspecificwith or relatedto the extantspecies Balanus balanus (Linnaeus), B. nubilus Darwin, and B. crenatus(Bruguiere). Although the Bear Lake fauna lived in warm temperatewaters, its modern counterpartsare found primarilyin boreo-arcticand cool temperateregions of the North Pacificand North AtlanticOceans. Miocene barnacle faunas in Japanare similarto those of the Alaska Peninsula,lacking relatives of B. nubilus,but includingSemibalanus Pilsbry, which does not appearuntil the Pleistocenein the easternPacific. Elements of this boreo-Arcticfauna do not appearin the North Atlanticbasin until the Pleistocene,suggesting migration of the fauna into the Atlanticwith the openingof the BeringStraits.

INTRODUCTION STRATIGRAPHY BARNACLES OBTAINED from the middle and upper Miocene The Bear Lake Formation is the principal marine Miocene Bear Lake Formation of the Alaska Peninsula are the first unit on the Alaska Peninsula (Burk, 1965), but its biostratig- to be documented from the Tertiary ofAlaska. Barnacle remains raphy has not yet been comprehensively studied. The oldest occur both in the basal Unga Conglomerate Member and the Bear Lake molluscan faunules are of earliest middle Miocene overlying unnamed member. Many of the Bear Lake barnacles age (15-16 Ma) (Marincovich and Kase, 1986; Marincovich, are poorly preserved and no opercular plates have been found, 1988). However, the uppermost beds of the formation are not but the remains are sufficiently distinctive to allow the descrip- well dated, although their molluscan faunules are considered to tion of a new species of Chirona Gray related to extant C. be of late Miocene age (MacNeil in Burk, 1965; Marincovich, evermanni (Pilsbry). The remaining specimens, all referable to 1988). The "basal fifth" of the Bear Lake Formation was defined the genus Balanus Da Costa, include B. cf. B. balanus (Lin- as the Unga Conglomerate Member by Burk (1965, p. 116), and naeus), B. cf. B. nubilus Darwin, and B. cf. B. crenatus (Bru- he assigned the Cape Aliaksin exposures, noted below, to the guiere). Unga Conglomerate. The remainder of the Bear Lake Forma- The most striking aspect of the Bear Lake fauna is its similarity tion, which includes the Milky River and Sandy Ridge strati- to the extant Pacific boreal fauna of the northern rim of the graphic sections discussed here, was referred to as the "unnamed Pacific basin (Table 1). The extant fauna is composed of a mix- upper member" of the formation by Allison (1978, p. 175). ture of endemic, amphiboreal, and temperate species. Species Miocene barnacles were collected from three sections of the of this fauna have been reported from middle Miocene and Bear Lake Formation (Figure 1): Cape Aliaksin, Milky River, younger deposits in Japan (Yamaguchi, 1977, 1987), from Pleis- and Sandy Ridge. The Cape Aliaksin section is the oldest of tocene deposits along the Pacific Coast of the conterminous these and is thought to be of middle Miocene age (about 10-15 United States (Addicott, 1964; Zullo, 1969), Canada (Wagner, Ma), based on its molluscan taxa and a potassium-argon age of 1959), and Alaska (Dall, 1920; Allison, 1973), and from Pleis- 10.4 ? 0.49 Ma for an overlying andesite flow (MacNeil, 1973; tocene localities in the North Atlantic basin (Zullo, 1968). Ad- Marincovich, 1988). The stratigraphic section is 151 m thick ditional precursors of this fauna are known from the Miocene (Lyle et al., 1979, P1. 10), and its base, at sea level, is not exposed. and Pliocene of California (Zullo, 1979; Zullo and Guruswami- United States Geologic Survey (USGS) Cenozoic locality M7148, Naidu, 1982). Elements of this fauna are represented in the where specimens of Chirona (Chirona) n. sp., Balanus cf. B. Pleistocene and Recent of the North Atlantic basin (Darwin, crenatus, and B. cf. B. nubilus were collected, is 68 m above the 1854; Nilsson-Cantell, 1978). The fossil record is summarized base of this section and equivalent to locality 47-WL-77 of Lyle in Table 2. et al. (1979, P1. 10). The "fossil hash" illustrated at this locality ZULLO AND MARINCO VICH-MIOCENE BARNACLES FROM ALASKA 129

TABLE 1 -Distribution of the extantboreal balanomorph barnacle fauna TABLE 2--Geologic and geographicdistribution of the extant boreal of the Pacificbasin. barnaclefauna.

Boreal Upper Middle Boreal Ameri- Boreal Extanttaxon Pleistocene Pliocene Miocene Miocene Asian can Atlan- Taxon Pacific Pacific basin tic Armatobalanus engbergi NA - - - Armatobalanus engbergi (Pilsbry) - X - - Balanus balanus NA, At - (NA) (NA) Balanus balanus(Linnaeus) - X X X NA, J, At (NA), J (NA), J J Balanus crenatus(Bruguiere) Xt Xt X Xt Balanus glandula NA - - Balanus glandula Darwin - X - - Balanus nubilus NA (NA) (NA) (NA) Balanus nubilus Darwin - X - - Balanus rostratus NA, J J J J Balanus rostratus Hoek Xt X - - Chironaevermanni NA, J, At* J J, (NA) J, (NA) Chirona evermanni (Pilsbry) F X - - Chthamalus dalli NA - - Chthamalus dalli Pilsbry X X - - Hesperibalans Hesperibalanushesperius (Pilsbry) X Xt - - hesperius NA, J J, (NA) J, (NA) J Semibalanusbalanoides (Linnaeus) - X X Xt Semibalanus Semibalanuscariosus (Pallas) X X - - balanoides NA, At - Semibalanus F, fossil occurrencesonly; t, found also in temperateregions. cariosus NA, J J J J NA, ;J, northernJapan; At, North Atlantic;( ), allied extinct species in ;*, allied extant species in region. by Lyle et al. (1979, fig. 16) consists mostly of barnacle fragments and evidently was deposited in a high-energy, nearshore envi- ronment. Mollusks from this and other localities at Cape Al- climates in Japan were tropical to warm temperate (Yamaguchi, iaksin also are mostly fragmented (MacNeil, 1973; Marinco- 1987), and those of the Alaska Peninsula were warm temperate vich, 1981). (Allison, 1978). According to Yamaguchi (1977, 1987), the Jap- The Bear Lake Formation at the Milky River section is about anese Miocene through Pleistocene species representative of the 810 m thick (Lyle et al., 1979, P1. 2). Its base is concealed by Pacific Boreal fauna taxa are conspecific with modem species. tundra vegetation and its top is unconformably overlain by The subgenus Chirona and species conspecific with or related volcanic rocks (Lyle et al., 1979). Balanus cf. B. nubilus was to Balanus crenatus and B. balanus are represented both in collected from a sandstone bed (USGS Cenozoic locality M8662) Japan and the Alaska Peninsula. In addition, Semibalanus Pils- 557 m stratigraphically above the base of this section, or 265 bry and Hesperibalanus Pilsbry are reported from Japan in rocks m stratigraphically above a prominent, dark-colored, 19-foot- of this age (Yamaguchi, 1987), and a species related to Balanus thick conglomerate bed that is clearly shown in Lyle et al. (1979, nubilus is present in middle Miocene strata of the Alaska Pen- figs. 6, 7). Specimens of Balanus cf. B. balanus were also col- insula. No data are available on the middle Miocene barnacle lected from this section, but their precise stratigraphic position fauna of the Pacific Coast of the conterminous United States, is unknown. Mollusks from below and above the locality con- but the late Miocene fauna, as represented in central California taining Balanus cf. B. nubilus are of middle Miocene age. by the Pancho Rico Formation (now considered late Miocene The Sandy Ridge section is approximately 200 m thick. Its in age) and in northern California by the Wilson Ranch beds, base is an angular unconformity, below which are sedimentary includes Hesperibalanus proinus (Woodring), Balanus irradians rocks, devoid of megafossils, which are thought to belong to the Zullo and Guruswami-Naidu (related to B. balanus), Balanus Paleogene Stepovak Formation. The Bear Lake Formation is aff. B. nubilus, B. proxinubilus Zullo (related to B. nubilus), and unconformably overlain by unfossiliferous conglomerate. Chi- B. crenatus leipochoma Zullo (related to B. crenatus) (Zullo, rona (Chirona) n. sp. occurs in very fine-grained, cross-bedded 1979; Zullo and Guruswami-Naidu, 1982). Unlike species in sandstone at USGS Cenozoic locality M8179, which is 19 m the Japanese fauna, these Pacific Coast species are extinct. above the base of the Bear Lake section. Mollusks found with Knowledge of the Pliocene fauna of the north Pacific is limited this barnacle suggest a late Miocene age. to the records provided by Yamaguchi (1977, 1987) from Japan, and by Faustman (1964) from the Humboldt embayment in PALEOECOLOGY northern California. The Japanese Pliocene fauna includes the Based on an analysis of the molluscan fauna, Allison (1978) same five species as the Miocene fauna, and the upper Pliocene concluded that warm temperate conditions prevailed during Rio Dell Formation of the Humboldt embayment has yielded deposition of most of the Bear Lake Formation. He further the earliest northeastern Pacific record of the extant species concluded that the Unga Conglomerate Member and the un- Hesperibalanus hesperius (Pilsbry). More southerly barnacle named upper member of the Bear Lake Formation are inner- faunas of the Pacific Coast of North America are dominated by shelf deposits, and that beds containing the mussel Mytilus gra- species whose moder counterparts are restricted to warm tem- tacapi Allison and Addicott and the mactrid Pseudocardium sp. perate and subtropical , but Hesperibalanus proinus and are indicative of shallow, exposed-coast, high-energy environ- Balanus proxinubilus continue into the Pliocene in southern ments. A similar environment is suggested for the Bear Lake California (Zullo, 1979). barnacles, because their modern counterparts are typically found Pleistocene faunas of the north Pacific basin are better known. in moderate- to high-energy environments in the lower intertidal The Japanese boreal fauna remains unchanged, although Chi- and shallow-subtidal zones, and some of the Bear Lake speci- rona evermanni disappeared from Japan at the end of the Pleis- mens are attached to heavy-shelled fragments of Mytilus. tocene (Yamaguchi, 1987). All of the extant boreal Pacific bal- anomorph species are known from Pleistocene deposits on the OF THE BARNACLE FAUNA HISTORY PACIFIC BOREAL Pacific coast of North America (Wagner, 1959; Zullo, 1969), During the middle Miocene, precursors of the extant Pacific and an extinct verrucomorph, Verruca alaskana Pilsbry, was Boreal fauna were living in northern Japan and the western Gulf described from Intermediate Beach at Nome, Alaska (MacNeil of Alaska under marine climatic conditions that were much et al., 1943). warmer than those of the modern boreal environment. Marine The first records of the boreo-arctic barnacle fauna of the 130 JOURNAL OF PALEONTOLOGY, V. 64, NO. 1, 1990

FIGUREI-Locality map showingcollecting sites for barnacles.

North Atlantic basin are also from Pleistocene deposits. Al- Although the distribution of the extant fauna suggests that though high-latitude Neogene faunas in the Atlantic basin are the North American region was the center of diversification of poorly understood, those Pliocene and older Atlantic faunas that the boreal Pacific fauna, the geologic ranges of extant species have been described contain warm temperate species of Tethyan on both sides of the basin indicate a more complex history for affinities (e.g., Darwin, 1854; Zullo, 1968). The Atlantic Pleis- the fauna. Based on a comparison of the geologic ranges of tocene boreo-arctic fauna includes species- and genus-group taxa in Japan with those from the (Linnaeus), Chirona hameri (Ascanius), Balanus balanus, and Pacific Coast of North America, it would appear that several B. crenatus. Considering the young geologic record of these species elements of the extant boreal fauna had their origin in the Mio- in the Atlantic basin, it is likely that all were derived by mi- cene of the Asian Pacific region, and extended their geographic gration from the North Pacific after opening of the Bering Straits ranges into the northeastern Pacific during the late Pliocene and at the end of the Pliocene. Chirona has been reported from the Pleistocene (Table 2). Semibalanus and the extant species Chi- European Paleogene, but this record is based on Balanus un- rona (Chirona) evermanni, Balanus crenatus, and B. rostratus guiformis Sowerby, which is a member of the extinct genus are not recognized in the North American Cenozoic prior to the Archaeobalanus Moroni. Balanus balanus has been reported Pleistocene, yet appear to have a long history in Japan extending from the Neogene of western , but these records are either back to the middle Miocene. Hesperibalanus hesperius also makes unsubstantiated or are based on records of the Italian Pliocene its first appearance in Japan during the middle Miocene, and is species B. curvirostratus Menesini. not recorded from North America until the late Pliocene. On The extant Asian Pacific boreal fauna is depauperate when the other hand, the fossil record of those extant species endemic compared to that of the Pacific Coast of North America (Table to the northeastern Pacific boreal fauna is restricted to Pleis- 1). All five of the Asian Pacific species occur throughout the tocene localities along the Pacific Coast of North America. shallow-water regions of the basin, whereas six species are re- Thus, the greater diversity of the North American boreal fau- stricted in their distribution to the North American side of the na appears to be the result of the addition of Asian Pacific species basin. Three species of the boreal Pacific fauna range through that migrated into the region primarily during the Pleistocene. the Arctic basin into the north Atlantic (Nilsson-Cantell, 1978). This model presents difficulties, however, because it does not ZULLO AND MARINCO VICH-MIOCENE BARNACLES FROM ALASKA 131 take into account that Hesperibalanus and species related to flattened and T-shaped, developed only in the basal part of the Balanus crenatus, B. balanus, and B. rostratus are represented shell wall below the sheath, and nondenticulate basally. The in the Miocene and Pliocene of the Pacific Coast by extinct alar-parietal border in C. hameri is simple, marked by a slight species with close affinities to their moder counterparts. In change in elevation and direction of growth. This border in C. addition, the oldest record of Hesperibalanus is from the late alaskana is marked by an acute and rather wide ledge formed Eocene of the Gulf and southeastern Atlantic Coastal Plains of at the edge of the paries and overhanging the ala. The deep, North America, and additional species are known from the narrow furrow formed by the overhanging ledge is a conspicuous Oligocene of northwestern and the Pacific feature of the shell of C. alaskana. Northwest (Zullo and Kite, 1982). Without knowledge of the Chirona evermanni differs from C. alaskana in having a tu- Japanese Neogene record, a case could be made for the origin lipiform shell with transversely rugose and longitudinally striate of much of the North Pacific boreal fauna from precursors in or costate parietes. The development of internal ribs and alar- the temperate Neogene faunas of the Pacific basin. However, parietal ledges are similar in both species, but the ledges are the Miocene ages attributed to extant species in Japan suggest much more conspicuous in C. alaskana. Juveniles of C. ever- that the precursors of the boreal fauna must be sought in the manni with shells under 10 mm in basal diameter and height Paleogene. Yamaguchi (1987) concluded that the shift in the lack radii, but the presence of well-developed radii in specimens distribution of these species from warm- to cold-water regions of only slightly larger size indicates that growth of the radii is was the result of extinction of warm-water populations of pre- rapid once the 10-mm size is achieved. It is tempting to suggest viously eurythermal species, or migration of stenothermal-warm that the delay in development of radii in C. evermanni reflects species into colder waters under changing ecological conditions. the derivation of this species from an ancestral form similar to C. alaskana. SYSTEMATIC PALEONTOLOGY The fossil record of Chirona (Chirona) in the northeastern Subclass CIRRIPEDIABurmeister, 1834 Pacific is otherwise limited to records of Chirona evermanni Order THORACICA 1854 Darwin, from the Pleistocene of Douglas Island, southeastern Alaska Suborder BALANOMORPHA 1916 Pilsbry, (UCMP localities B-6891, B-6892, B-7070, B-7071, B-7075), BALANOIDEA 1817 Superfamily Leach, the Qualicum district of Vancouver Island (Wagner, 1959), the Newman and (sensu Ross, 1976) Second Terrace at Nome, Alaska (Dall, 1920), and Amchitka ARCHAEOBALANIDAENewman and 1976 Family Ross, Island, Aleutians (Allison, 1973). Chirona evermanni appears ARCHAEOBALANINAENewman and 1976 Subfamily Ross, to have a much longer history in Japan, where it has been Genus CHIRONA 1835 Gray, reported from the middle Miocene through the Pleistocene by Subgenus CHIRONAGray, 1835 Yamaguchi (1987). Extant C. evermanni is restricted to the Gulf CHIRONA (CHIRONA) ALASKANA n. sp. of Alaska, the , and the Bering and Okhotsk Figure 2.1-2.5 Seas. Holotype. -Shell without opercular plates, USNM no. 433350. Etymology. -This species is named for the state of Alaska. Type locality.- Unga Conglomerate Member, Bear Lake For- Material.--One complete shell without basis or opercular mation, U.S. Geological Survey locality M7148, Cape Aliaksin plates and five partial compartmental plates, USGS locality stratigraphic section. M7148 (type locality); 10 partial compartmental plates, USGS Diagnosis.--Shell large, up to 65 mm in carinorostral diam- locality M8179; two complete shells, USGS locality M8663. eter and 50 mm in height, conic, with smooth parietes; radii Occurrence.- Middle and upper Miocene, Unga Conglom- absent, except for rostral plate, with steep summits and smooth erate Member and unnamed upper member, Bear Lake For- sutural edges; alae broad with convex summits; edge of parietes mation, Alaska Peninsula. bordering alae produced into overhanging ledge. Repository. -Holotype USNM 433350 and paratypes 433351 Description. -Shell large, conic, with moderately toothed, and 433352 from USGS locality M7148, paratypes USNM diamond-shaped orifice and smooth parietes; radii absent on 433353 and 433354 from locality M8663, and paratype lot all plates except rostrum; radii of rostral plate very narrow with USNM 433355 from locality M8179 are deposited in the col- steep summits and smooth sutural edges; alae broad, with mod- lection of the Department of Paleobiology, National Museum erately convex summits; edge of parietes bordering alae pro- of Natural History, Washington, D.C. duced into wide, relatively thin, overhanging ledge; length of sheath about one-third length of compartmental plates; basal Family BALANIDAELeach, 1817 (sensu Newman and Ross, 1976) edge of sheath only slightly raised above inner shell wall; internal Subfamily BALANINAELeach, 1817 (sensu Newman, 1980) longitudinal ribs low, numerous, closely spaced, with flattened Genus BALANUSDa Costa, 1778 T-shaped crests, well developed near basal margin, but fading BALANUScf. B. BALANUS(Linnaeus, 1758) out about half the distance between basal margin and basal edge Figure 2.6-2.7 of sheath; basal margins of internal ribs not denticulate; basis Discussion.- The shells are of moderate size, with the largest, thin, solid. somewhat crushed specimen having a carinorostral diameter of Discussion.--Only two extant species have been ascribed to 35 mm and a height of 30 mm. The parietes are strongly and the subgenus Chirona: C. evermanni (Pilsbry) from the Pacific regularly costate, and the radii are well developed with hori- boreal province and C. hameri (Ascanius) from the Atlantic zontal summits. The pareital tubes are large, rectangular, and boreal province. Chirona alaskana, although clearly related to without transverse septa. The inner lamina of the shell wall both species, is readily distinguished by the lack of radii on adult bears the numerous secondary septa characteristic of Balanus compartmental plates with the exception of the rostral plate. balanus and B. rostratus. The new species resembles C. hameri in having a conic shell Extant Balanus balanus is found in the northeastern Pacific with smooth parietes, but can be further distinguished by the basin from south to Puget Sound, in the , character of its internal parietal ribs and the border between the and in the North Atlantic south to the English Channel and parietes and alae. In C. hameri, fine, sharp-edged internal ribs Long Island Sound. Balanus rostratus is restricted to the North extend from the sheath to the basis and the basal edges of the Pacific, ranging from Japan to Puget Sound. Balanus irradians, ribs are finely denticulate. The internal ribs of C. alaskana are a species related to B. balanus and B. rostratus, occurs in the 132 JOURNAL OF PALEONTOLOGY, V. 64, NO. 1, 1990

4 1 3

5 6

2 I; ZULLO AND MARINCO VICH-MIOCENE BARNACLES FROM ALASKA 133

2

FIGURE 3-Balanus cf. B. nubilus,USGS locality M8662, hypotype lot USNM 433363. 1, group of cup-shapedbases (arrowindicates area of enlargementin Figure2), x 1; 2, enlargementof basis marginshowing proliferation of radialtubes (arrow),x 7. upper Miocene Wilson Ranch beds of northern California, and and the upper Pliocene San Diego Formation of southern Cal- both B. balanus and B. rostratus are found in the Pleistocene ifornia (Zullo, 1979). Another related upper Miocene species of the northeastern Pacific region (Zullo and Guruswami-Naidu, occurs in the Wilson Ranch beds of Sonoma County, California 1982). Yamaguchi (1977, 1987) reported B. rostratus from mid- (Zullo and Guruswami-Naidu, 1982). Balanus connelli Corn- dle Miocene through Holocene deposits in Japan. Balanus bal- wall from the Oligo-Miocene Sooke Formation of Vancouver anus is known from several Pleistocene localities in the North Island may be the oldest species referable to the lineage of B. Atlantic basin (Zullo, 1968). nubilus. Material. -Four complete shells without opercular plates; Material.-Group of bases and partial shell, USGS locality largest specimen on thick-shelled Mytilus fragment; USGS lo- M8662, unnamed upper member, Bear Lake Formation; two cality M8664, unnamed upper member, Bear Lake Formation. partial compartmental plates, USGS locality M7148, Unga Con- Repository.-Hypotypes USNM 433356-433359 are depos- glomerate Member, Bear Lake Formation. ited in the collection of the Department of Paleobiology, Na- Repository. -Hypotype lot USNM 433363 from locality tional Museum of Natural History, Washington, D.C. M8662 and hypotype lot USNM 433364 from locality M7148 are in the collection of the Department ofPaleobiology, National BALANUScf. B. NUBILUS Darwin, 1854 Museum of Natural History, Washington, D.C. Figure 3.1, 3.2 BALANUScf. B. CRENATUS Discussion. -Two partial compartmental plates and a group (Bruguiere, 1789) 2.8-2.10 of cup-shaped bases, the largest measuring 30 mm in diameter, Figure represent a species conspecific with or related to extant Balanus Discussion.--Four large, thick-shelled barnacles attached to nubilus. The bases have large, irregularly spaced tubes in the a mytilid represent a species similar to Balanus crenatus. The top layer underlain by a thick zone composed of numerous, largest complete specimen has a carinorostral diameter of 30 irregularly spaced, minute tubes, a feature characteristic of B. mm and a height of 23 mm. The shells are irregularly and nubilus. The compartmental plates are similar also to B. nubilus, coarsely ribbed, the orifice is deeply toothed, the radii are narrow having large, irregular, partietal tubes separated by thin-walled with steeply sloping summits and crenate sutural edges, and the parietal septa. parietal tubes bear transverse septa. The isolated compartmental Extant Balanus nubilus ranges from southern Alaska to north- plates of this species from the Unga Conglomerate exhibit the ern Baja California, and is known from numerous Pleistocene cellular nature of the space between the lower edge of the sheath deposits from Oregon to Baja California. Balanus proxinubilus and the inner shell wall that is typical of B. crenatus. Zullo, a Neogene species related to B. nubilus, occurs in the Extant Balanus crenatus is an amphiboreal species also found upper Miocene Pancho Rico Formation of central California in the Arctic Ocean. In the North Pacific it ranges south to

FIGURE 2-1-5, Chironaalaskana n. sp., USGS locality M7148. 1-3, lateraland rostralviews of holotype, USNM 433350, x 1; 4, interior of rostral plate, paratypeUSNM 433351, x 1.2; 5, exterior of carinolateralshowing alar development, paratypeUSNM 433352, x2.2. 6, 7, Balanuscf. B. balanus,hypotype USNM 433356, USGS localityM8664. 6, exteriorof erodedcarina showing secondary parietal rib development on inner lamina (arrow), x2.5; 7, lateral view of ribbed shell, x 1.2. 8-10, Balanus cf. B. crenatus,USGS locality M7148. 8, group of shells on Mytilus, hypotype lot USNM 433361, x 1.5; 9, base of sheath of lateralplate showing secondaryseptation of space between sheath and shell wall, hypotype USNM 433360, x 7; 10, eroded exteriorof same lateralplate showingtransverse septa in parietaltubes, x 7. 134 JOURNAL OF PALEONTOLOGY, V. 64, NO. 1, 1990 northern Japan and Santa Barbara, California. Yamaguchi (1987) County Museum of Natural History, Contributionsin Science 397, reported B. crenatus from middle Miocene through Pleistocene 20 p. deposits in Japan. An extinct subspecies, B. crenatus leipochoma -, ANDT. KASE.1986. An occurrenceof Turritella(Hataiella) sagai in Zullo, occurs in the upper Miocene of central and Alaska:implications for the age of the BearLake Formation.Bul- California, letin B. crenatus s.s. is known from Pleistocene from central of the National ScienceMuseum, Tokyo, SeriesC, 12(2):61-66. deposits W. A. 1980. On the barnacles California north to Alaska NEWMAN, biogeographyofbalanomorph (Addicott, 1966) Nome, (Zullo, 1969; of the southernocean new balanid taxa; a two and UCMP localities including subfamily, Dall, 1920; B-6891, B-6892, B-7070, generaand threespecies. Proceedings of the InternationalSymposium B-7071, B-7075). on MarineBiogeography and Evolutionin the SouthernHemisphere, Material. -Four shells on Mytilus, 18 partial compartmental New ZealandDepartment of Scientificand IndustrialResearch In- plates, USGS locality M7148, Unga Conglomerate Member, formationSeries, 137:279-306. Bear Lake Formation. -, ANDA. Ross. 1976. Revision of the balanomorphbarnacles; Repository. -Hypotype USNM 433360 and hypotype lots includinga catalogof the species. San Diego Society of NaturalHis- USNM 433361 and 433362 are in the collection of the De- tory, Memoir 9, 108 p. C. A. 1978. of National Museum of Natural His- NILSSON-CANTELL, CirripediaThoracica and Acrothora- partment Paleobiology, cica. MarineInvertebrates of No. 5. Universitetsforla- D.C. , tory, Washington, get, Oslo, 133 p. REFERENCES PILSBRY, H. A. 1916. The sessile barnacles(Cirripedia) contained in ADDICOTT,W. 0. 1964. A late Pleistocene invertebrate fauna from the collectionsof the U.S. National Museum;including a monograph southwesternOregon. Journal of Paleontology,38:650-661. of the American species. United States National Museum Bulletin -. 1966. Late Pleistocenemarine paleoecologyand zoogeography 93, 366 p. in centralCalifornia. U.S. GeologicalSurvey Professional Paper 523- WAGNER,F. J. E. 1959. Paleoecologyof the marinePleistocene faunas C, 21 p. of southwesternBritish Columbia. Geological Survey of CanadaBul- ALLISON,R. C. 1973. Marinepaleoclimatology and paleoecologyof a letin 52, 67 p. Pleistocene invertebratefauna from Amchitka Island, Aleutian Is- YAMAGUCHI,T. 1977. Taxonomic studies on some fossil and Recent lands, Alaska. Palaeogeography,Palaeoclimatology, Palaeoecology, JapaneseBalanoidea, Pt. 2. Transactionsand Proceedingsof the Pa- 13:15-48. laeontologicalSociety of Japan, 108:161-201. 1978. Late Oligocenethrough Pleistocene molluscan faunas in 1987. Changesin the barnaclefauna since the Miocene and the the region. Veliger,21:171-188. infraspecificstructure of Tetraclitain Japan(Cirripedia, Balanomor- BRUGUIERE,M. 1789. Encyclop6dieM6thodique: Histoire Naturelle pha). Bulletinof MarineScience, 41:337-350. des Vers, 1(1):158-173. ZULLO,V. A. 1968. Balanus hopkinsi,new species, and B. balanus BURK,C. A. 1965. Geology of the Alaska Peninsula-islandarc and (Linnaeus, 1758) (Cirripedia,Thoracica) from Plio-Pleistocenesed- continental margin. Geological Society of America, Memoir 99, iments on Tj6rnes,northern . Occasional Papers of the Cali- 250 p. fornia Academy of Sciences, 69, 11 p. BURMEISTER,H. 1834. Beitrigezur Naturgeschichteder Rankenflisser -. 1969. A late Pleistocenemarine invertebrate fauna from Bandon, (Cirripedia).G. Reimer, Berlin, 60 p. Oregon.Proceedings of the CaliforniaAcademy of Sciences, 36(12): DA COSTA,E. 1778. HistoriaNaturalis Testaceorum Brittaniae, or the 347-361. BritishConchology. London, 254 p. 1979. ThoracicanCirripedia of the lower Pliocene PanchoRico DALL,W. H. 1920. Pliocene and Pleistocenefossils from the Arctic Formation,Salinas Valley, Monterey County, California. Los Angeles coast of Alaska and the auriferousbeaches of Nome, Norton Sound, Museum of NaturalHistory, Contributionsin Science, 303, 13 p. Alaska. U.S. GeologicalSurvey ProfessionalPaper 125-C:23-37. , ANDR. GURUSWAMI-NAIDU.1982. Late Miocene balanid Cir- DARWIN,C. 1854. A Monographof the Sub-class Cirripediawith ripedia from the basal Wilson Ranch beds ("Merced"Formation), Figuresof All the Species.The ,the Verrucidae.Ray Society, Sonoma County, northernCalifornia. Proceedings of the California London, 684 p. Academy of Sciences,42(21):525-535. ANDL. E. KITE. 1982. Barnacles of the Jacksonian FAUSTMAN, W. F. 1964. Paleontologyof the WildcatGroup at Scotia -, (upper Eocene) and CentervilleBeach California.University of CaliforniaPublica- GriffinsLanding Member, Dry BranchFormation in South Carolina tions in GeologicalSciences, 41(2):97-160. and Georgia.South CarolinaGeology, 28(1):1-21. GRAY, J. E. 1835. On the proofs of a gradualrising of the land in ACCEPTED 14 OCTOBER 1989 certain parts of Sweden. Philosophical Transactionsof the Royal Society of London, 125:35-37. LEACH, W. E. 1817. Distributionsystematique de la class Cirrip6des. APPENDIX:LOCALITY DESCRIPTIONS Journalde de Chimie et d'Histoire 85:67-69. Physique, Naturelle, United States GeologicalSurvey (USGS) LINNAEUS,C. 1758. SystemaNaturae. Holmiae, Editio Decima, Re- formata,Vol. 1, 824 p. M7148 Unga ConglomerateMember, Bear Lake Formation, Cape Al- LYLE,W. M., J. A. MOREHOUSE,I. F. PALMER,AND J. G. BOLM. 1979. iaksin stratigraphicsection, Port Moller 1:250,000quadrangle, Tertiary formations and associated Mesozoic rocks in the Alaska 55030'10"N,160050'7"W, Alaska Peninsula.Along northwest Peninsulaarea, Alaska, and theirpetroleum reservoir and source-rock coastline of Cape Aliaksin, immediately above intertidal zone potential. Alaska Division of Geological and GeophysicalSurveys, along northeasternshore of Beaver Bay. L. Marincovich,Jr., Geologic Report 62, 65 p. collector. Type locality of Chirona alaskana; Balanus cf. B. MACNEIL,F. S. 1973. Marine fossils from the Unga Conglomerate crenatus;Balanus cf. B. nubilus. Memberof the Bear Lake Formation,Cape Aliaksin, Alaska Penin- M8179 Bear Lake Formation,unnamed upper member, Sandy Ridge sula, Alaska. Science Reportsof the Tohoku University, Sendai,Ja- stratigraphic section, Chignik (A-6) 1:63,360 quadrangle, pan, SecondSeries (Geology), Special Volume, No. 6 (HataiMemorial 56?3.6'N, 160?54.7'W,Alaska Peninsula. Conglomeratebed Volume):117-123. about 16.7 m above "basal conglomerate."L. Marincovich, -, J. B. MERTIE, JR., ANDH. A. PILSBRY.1943. Marine invertebrate Jr., collector. Chironaalaskana. faunasof the buriedbeaches near Nome, Alaska.Journal of Paleon- M8662 Bear Lake Formation,unnamed upper member, Milky River tology, 17:69-96. stratigraphicsection, Chignik (A-7) 1:63,360 quadrangle,ap- MARINCOVICH,L., JR. 1981. Tyrannoberingius rex, a new genus and proximately 56?02'N, 160?03'W, Alaska Peninsula. Fossils species of Miocene gastropodfrom Alaska.Journal of Paleontology, collectedin thin conglomeratebed locatedabout 265 m strati- 55:176-179. graphicallyabove "19-foot-thick"conglomerate bed. L. Ma- 1988. Miocene mollusks from the lower part of the Bear Lake rincovich, Jr., collector.Balanus cf. B. nubilus. Formationon Ukolnoi Island,Alaska Peninsula, Alaska. Los Angeles M8663 Bear Lake Formation,unnamed upper member, Milky River ZULLO AND MARINCO VICH-MIOCENE BARNACLES FROM ALASKA 135

stratigraphicsection, Chignik (A-7) 1:63,360 quadrangle,ap- B-7070 DouglasIsland, Juneau (B-2) quadrangle, Alaska, 1947 edition. proximately 56?02'N, 160?03'W, Alaska Peninsula. Fossils Just north of Auke Lake enteringsettlement of Auke Bay on collected in thin conglomeratebed located about 492 m strati- GlacierHighway. Road cut acrossfrom Auke Creek,consisting graphicallyabove "19-foot-thick"conglomerate bed. L. Mar- of 2.1 m of graymarine till overlainby 2.1 m of brownishsand incovich, Jr., collector. Chironaalaskana. and gravel and 0.3 m of peaty sand. Elevation about 30 m M8664 Bear Lake Formation,unnamed upper member, Milky River above sea level. C. Wagner,collector. Chirona evermanni from stratigraphicsection, Chignik (A-7) 1:63,360 quadrangle,ap- marinetill; Balanus crenatus. proximately 56?02'N, 160?03'W, Alaska Peninsula. Exact B-7071 DouglasIsland, Juneau and Vicinityquadrangle, Alaska, 1950 stratigraphicposition unknown.L. Marincovich,Jr., collector. edition. Treadwell Ditch Trail at Paris Creek. Stream bluff Balanus cf. B. balanus. exposing up to 6.1 m of marine till, extending about 61 m upstreamfrom old bridgeon the southerntributaries of Paris University of California(Berkeley) Museum of Paleontology(UCMP) Creek,which branch off above the ditch. Elevationabout 137.2 m above sea level. C. Wagner,collector. Chironaevermanni, B-6891 DouglasIsland, Juneau (B-2) quadrangle, Alaska, 1947 edition. Balanus crenatus. End of North Douglas Road, in 4.5-9.1 m road cut between B-7075 Juneauand 1950 1.5 and 15.2 m east of BPR benchmark461 04.2. Marinetill DouglasIsland, Vicinityquadrangle, Alaska, edition. On road from the town of Douglas to the Treadwell between 15.2 and 24.4 m from shorelineat high tide. C. Wag- Mine. North of the caretaker'shouse and about 45 m south of ner, collector. Chironaevermanni, Balanus crenatus. the entrance for the TreadwellMine. Fossils from 0.91 B-6892 Juneau 1947 edition. signpost DouglasIsland, (B-2)quadrangle, Alaska, m bank of marinetill overlain by 0.3 m of brown, peaty soil. At end of North DouglasRoad within0.9 m of BPR benchmark Elevation about 30 m above sea level. C. collector. 461 04.2. Fossils from 1.5-m of slate and silt. Wagner, exposure pebbles Chironaevermanni, Balanus crenatus,B. rostratus. This unit appearsto representan old beach deposit cut into the marinetill of UCMP localityB-6891. C. Wagner,collector. Chironaevermanni. Balanus crenatus.

J. Paleont., 64(1), 1990, pp. 135-141 Copyright ? 1990, The Paleontological Society 0022-3360/90/0064-0135$03.00 THE EARLY SILURIAN MYELODACTYLIDCRINOID EOMYELODACTYL US FOERSTE

JAMES D. ECKERT Departmentof GeologicalSciences, University of Rochester,Rochester, New York 14627

ABSTRACT-TWOnew species of Eomyelodactylus,E. sparteusand E. uniformis,are describedfrom the LowerSilurian of New York. Macnamaratylusmurrayi Bolton from the Lower Silurian of Ontario, Canada, is redescribedand assigned to Eomyelodactylus. Together,these species permit detailed descriptionof this poorly known myelodactylidgenus.

INTRODUCTION SYSTEMATIC PALEONTOLOGY THE MYELODACTYLIDAEis a remarkable family of disparid inadunate crinoids characterized by a specialized, bilat- Subphylum CRINOZOAMatsumoto, 1929 Class CRINOIDEA 1821 erally symmetrical column. A high degree of flexibility inherent Miller, Subclass INADUNATAWachsmuth in the column allowed the proximal portion to form a recurved and Springer, 1885 coil into which the crown could be withdrawn and concealed Order DISPARIDAMoore and Laudon, 1943 between two rows of cirri. With the exception of possible mye- Superfamily MYELODACTYLACEAMiller, 1883 MYELODACTYLIDAE 1883 lodactylid columnals from the Upper Ordovician (Ashgillian) Family Miller, Boda Limestone of Sweden (Donovan, 1985), Eomyelodactylus Diagnosis. -Monocyclic inadunates with distinctive coiled and Foerste from the Lower Silurian is the oldest, yet most poorly recurved column bearing two rows of cirri; crown small, com- known representative of its family. Discovery of new myelo- monly concealed within coil by cirri; compound ray, if present, dactylid material from the Lower Silurian of New York and in C ray only; anal sac long, narrow; arms dividing isotomously Ontario permits detailed description of Eomyelodactylus for the or heterotomously several times. first time and provides important insight into the evolution and Included genera. -Myelodactylus Hall, 1852, L. Sil. (late phylogeny of these unique crinoids. Llandoverian)-L. Dev. (Gedinnian); Brachiocrinus Hall, 1858, For convenience in discussing myelodactylid morphology, the L. Dev. (Gedinnian); Crinobrachiatus Moore, 1962, U. Sil. term "neck" is adopted from Springer (1926, p. 4) for the re- (Wenlockian); Eomyelodactylus Foerste, 1919, L. Sil. (Llan- curved junction of the column. Otherwise, terminology follows doverian); Herpetocrinus Salter, 1873, U. Sil. (Wenlockian). that of Ubaghs (1978) and Donovan and Franzen-Bengtson Remarks. -The Myelodactylidae is one of very few families (1988). of crinoids defined mainly on features of the column and cirri. Specimens discussed herein are deposited in the United States Morphology of the column encompasses a good deal of varia- National Museum (USNM), the Geological Survey of Canada tion; it is pentameric and dominantly elliptical in cross section (GSC), and the Buffalo Museum of Science (BMS). in Eomyelodactylus, bimeric and elliptical to trapezoidal in Her-