Paleozoic Gastropoda from the Moose River Synclinorium, Northern Maine GEOLOGICAL SURVEY PROFESSIONAL PAPER 503-A Paleozoic Gastropoda from the Moose River Synclinorium, Northern Maine By ARTJiUR J. BOUCOT and ELLIS L. YOCHELSON CONTRIBUTIONS TO PALEONTOLOGY GEOLOGICAL SURVEY PROFESSIONAL PAPER 503-A An investigation of fossils primarily of Devonian age UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1966 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY William T. Pecora, Director For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402- Price 30 cents (paper cover) CONTENTS Page Page Abstract __________________________________________ _ A1 Register of localities ___________________________ -- __ _ A15 Introduction ______________________________________ _ 1 References cited __________________ ---- __ ------------ 17 Occurrence and distribution of the gastropods _________ _ 3 Index ____________________________________________ _ 19 Systematic paleontology ____________________________ _ 3 ILLUSTRATIONS [Plates follow index] PLATE 1. Gastropoda and miscellaneous fossils 2-3. Gastropoda Page FIGURE 1. Correlation table______________________ A2 2. Sketch of "Euomphalopterus" __ _ _ _ _ _ _ _ _ _ _ 17 TABLE Page TABLE 1. Distribution of gastropods in Paleozoic rocks of the Moose River synclinorium ________________ - ____ -- __ ------ A4 III CONTRIBUTIONS TO PALEONTOLOGY PALEOZOIC GASTROPODA FROM THE MOOSE RIVER SYNCLINORIUM, NORTHERN MAINE By ARTHUR J. BoucoT and ELLIS L. Y OCHELSON .ABSTRACT units which has been determined from study of other Large-scale collecting in the middle Paleozoic strata of the fossil groups (chiefly brachipods and corals). Moose River synclinorium has yielded a few gastropods-one Except where indicated, the taxonomic classification Ordovician species, six species from the Silurian, and two from follows that published by Knight, Batten, and Y ochel­ rocks of Silurian or Devonian age, one of these also oceurring son (1960). Specimens are rare and some are not well in rocks of undoubted Silurian age. The Devonian rocks yielded 17 species, one of which also occurs in the Silurian preserved; an open nomenclature has been used for rocks, and by far the bulk of the specimens. most of the taxa. Future detailed study of middle The few specimens and their unsatisfactory state of preser­ Paleozoic gastropod faunas will undoubtedly increase vation have resulted in use of open nomenclature for the most the degree to which material can be identified, but be­ part. Eleven taxa are identified only to the generic level, and cause of limited present knowledge in this particular six are tentatively compared to previously named species. The generic assignment is questioned in four of the identified spe­ field, a conservative taxonomic approach is warranted. cies ; in only one taxon is the generic and specific designation The morphologic terms used follow those given by Cox of common usage accepted without question. (1955). The new bellerophontacean subfamily Plectonotinae is diag­ With the exeeption of a few specimens in limestone, nosed. Orossoceras is proposed as a new genus of Devonian the fossils occur in indurated, cleaved, slightly meta­ age with 0. belandi, new species, as the type. The genus is placed within the Platyceratacea. Platyceras (Orthonychia) morphosed ( ehlorite zone) mudstone and siltstone. aroostookensis is proposed as a replacement name for P.? ( 0.) Most of the specimens were obtained by splitting slabs compressa Williams and Breger, 1916, not P. compressum Net­ of matrix on a rock trimmer. These slabs were then tleroth, 1889. The occurrence of ophiuroid remains and "Nidul­ soaked in hydrochloric acid and, after all shell material ites," two faunal elements which do not fit conveniently into had been dissolved, latex rubber impressions were made other faunal studies, is noted. from the internal and external molds. These impres­ INTRODUCTION sions have been figured, though for a few species they have been supplemented by illustrations of the mold, This paper describes and illustrates gastropods ob­ or of the steinkern if it was not destroyed during prep­ tained for the most part by Boucot during several years aration. The original specimens commonly are in sev­ of field investigation in the Moose River synclinorium eral pieces. More than 8 tons of rock were split to ob­ of northern Maine. Boucot ( 1961) has delineated the tain the specimens described herein. general stratigraphy of the area; Oliver (1960) has In addition to tlhe gastropods, the occurrence of N idu­ described the Early Devonian corals. With the excep­ lites and ophiuroid remains is noted. These uncommon tion of one pleurotomariacean gastropod, all specimens fossils do not fit well with any of the major faunal discussed are from rocks of Silurian and Devonian age. studies, but it semns worthwhile to report their occur­ One new Silurian bellerophontacean is reserved for rence in Maine. publication elsewhere by Boucot. Although John M, The locality numbers and the register of localities are Clarke described specimens from this area in 1909, no in the Silurian-Devonian (SD) catalog of the U.S. Geo­ other work has been done on these mollusks in the inter­ logieal Survey. A stratigraphic table prepared by vening years. Boueot (1961) is reproduced here as figure 1. All the In general aspect, the gastropod faunas resemble formations mentioned in the text are shown in this fig­ those of similar age known from the Appalachians, ure except an unnamed conglomerate, an approximate both to the north and to the south. Although the gas­ equivalent of the Silurian Hardwood Mountain Forma­ tropods are of limited stratigraphic utility because of tion, that occurs in the Attean quadrangle of northern their rarity, occurrences support the correlation of rock Maine. A1 A2 CONTRIBUTIONS TO PALEONTOLOGY WEST SIDE DEER ISLAND LOBSTER OF AREA SPENCER ENCHANTED LITTLE BIG AGE JIM POND BECK POND LAKE MOOSEHEAD MOOSEHEAD STREAM POND WOOD POND LAKE LAKE /:~~ /;/~ /~/&_~// LU /%/;%/// / 0: / ///%///;/ < //0, ,/:/::;/ ::z:::: Tomhegan ;:;."~/%//::// //~ 0 :I: Formation ///%/ ~ u Tomhegan Cl) Formation ~~~~%/ / // // Tarratine Formation z: >- <C z: z < Seboomook Tarratine Seboomook Seboomook Seboomook 0 ::.:::: Seboomook > en Formation Formation Formation Formation Seboomook Formation LU 0:: Formation Q 0 Formation c.::J 0::: LU a:l 0::: Parker Bog L.l...l Q Formation _J Whisky LU :I: Quartzite L.l...l c.::J w....< Oz: Hobbstown ~< ub:: Formation OL.I...I Capens c:::u z: Formation :::> ~ ~ ~ "t) ~ z: "t) c:::c:c Lobster "'0 Hardwood Hardwood LU- ~ o....C::: «< Mountain Mountain c...=> Lake :::>:::::! ~ ~ :;:::;~ Formation Formation en Formation e a.> ::::::: ~ -.::1 ~ ~:.0 :::> :;:::;~ c :::> z: <C 0: :::> ~ _J ~ u; :::> Volcanic z: <C rocks c::5 :;:: undiffer­ 0 Q entiated 0::: 0 Sedimentary Sedimentary and volcanic and volcanic Sedimentary Sedimentary rocks, undif­ rocks, undif­ and volcanic Sedimentary and volcanic ferentiated ferentiated rocks, undif­ and volcanic rocks, undif­ ferentiated rocks, undif­ ferentiated ferentiated Basement Basement Basement Basement complex complex complex complex FIGURE !.-Correlation table of Paleozoic strata in the Moose River synclinorium of northern Maine (after Boucot, 1961). PALEOZOIC GASTROPODA, MOOSE RIVER SYNCLINORIUM, MAINE A3 OCCURRENCE AND DISTRIBUTION OF THE hegan Formation, which has been collected about one­ GASTROPODS fourth as intensively as the Tarratine, has yielded fewer Mollusks constitute but a sm~an fraction of the fossils specimens but 11 taxa. Only three taxa are common collected from the Moose River synclinorium. At most to the two formations. The two formations thus con­ localities brachiopods are the dominant faunal element; tain the bulk of the taxa discussed in this paper. in some locali,ties corals are dmninant. Mollusks, the The Seboomook Formation, the lateral equivalent of third most corrunon group, are mueh less abundant than the Tarratine, eontains only two species, both of whieh either of these phyla,. Pelecypods and gastropods con­ are common in the Tarratine. The slightly older Beck stitute virtually all of the mollusean fauna, the pele­ Pond Limestone has yielded only a few platyceratids. eypods being more emnmon than the gastropods. We These are identified as PlatycerM ( Platyostoma) ven­ estimate that there were about one thousand brachio­ f1'icosu/n1, the san1e species as in the younger beds, but pods collected for eaeh gastropod obtained. that particular species category is admittedly broad. Among these few gastropod specimens, t:he pla.tycera­ Less than a dozen specimens are known from the tids are, by far, the most abundant; 1nembers of this Silurian, but they are quite distinct from those of the family 'are"several times as abundant as all other gastro­ Devonian. Euon1phalopterus, Poleu/nuita, and Or-io­ pods combined. Among the remaining specimens, four stmna are characteristic Silurian gastropods. groups--bellerophontaceans, pleurotmnariaeeans, all other archaeogastropods combined, and all high -spired SYSTEMATIC PALEONTOLOGY 1 gastropods combined-are subequal in abundance, pleu­ Class GASTROPODA rotomari'aceans being the most common of the four. So Subclass PROSOBRANCHIA few specimens are involved, however, that the number Order ARCHAE.OGASTROPODA of specimens within each group cannot be considered Suborder BELLEROPHONTINA Ulrich and Scofield, 1897 Superfamily BELLEROPHONTACEA M'Coy, 1851 significant.