Brief Note Stratigraphic Significance of a Dunkleosteus Plate from the Upper Riceville Shale1

Home , Cleveland Shale, Cussewago Sandstone

BRIEF NOTE STRATIGRAPHIC SIGNIFICANCE OF A DUNKLEOSTEUS PLATE FROM THE UPPER RICEVILLE SHALE1

JAMES L. MURPHY, The Ohio Historical Society, Columbus, OH 43211

OHIO J. SCI. 79(5): 233, 1979

Discovery of a Dunkleosteus arthrodiran Hay field Shale: (m) (cm) fish plate in dark shale and siltstone 4. Tnterbedded blue gray shale and siltstone, abun- (Riceville Shale) beneath the Cussewago dant mica and plant frag- Sandstone near Mcadville, Crawford Co., ments, burrow and flute Pennsylvania may help to clarify the re- casts; minute worm tubes lationship of Devonian-Mississippian and Modiolus bivalves strata in eastern Ohio and western Penn- near base 2 46 sylvania. Construction of Interstate Cussewago Sandstone: 3. Coarse, friable sandstone, Route 1-79 in 1969 exposed an important thick-bedded, containing stratigraphie section along Van Home shale pebbles 1 2 Run, slightly more than one mile south- Upper Riceville Shale: west of Meadville, Crawford Co., Penn- 2. Thin-bedded siltstones sylvania, on the north side of the high- and interbedded dark gray way. The author collected a Dunkleo- to black shale containing an abundant "Knapp" ma- steus arthrodire plate here and was able rine fauna with Mississip- to measure a stratigraphie section before pian aspects (Syringo- the road cut was seeded and covered with thyris, Sphenotus aeolus) straw. Construction had exposed a large as well as sponges and amount of the shale and siltstone im- and worn Dunkleosteus mediately beneath the Cussewago Sand- plate 4 4 stone. The loose, blasted rock has since Lower Riceville Shale: 1. Thin-bedded siltstone with been used for road fill, and the cut has minor amounts of olive- been deepened so that the fossiliferous brown shale; marine fos- beds immediately below the Cussewago sils common, replaced by Sandstone are now difficult of access. iron oxide; fauna (Cyrto- spirifer, Reticularia) iden- tical with that of upper- MEASURED SECTION most Chagrin Formation of Ohio 3 5 Stratigraphie Unit Thickness (m) (cm) This stratigraphie section was compared Orangeville Formation: with the well known Bartholomew section Bartholomew siltstone member: west of Little's Corners, Hayfield Town- 7. Fine-grained siltstone with ship (White 1881, de Witt 1951, pl. 2) abundant small worm bur- and with the Riceville section (White rows 28 1881, Caster 1934) 0.6 mile southwest of 6. Gray, micaceous shale, un- Riceville, Athens Twp. The former lo- fossiliferous 3 50 cation is the type locality for the Hay- Berea Sandstone: field Shale and the Bartholomew siltstone 5. Fine-grained, micaceous member of the Orangeville Shale. In sandstone with abundant considering the Meadville section, it plant fragments 1 22 should be noted that the terms "Upper iManuscript received 2 June 1978 and Riceville" and "Lower Riceville" are not revised form 16 November 1978 (#78-32). as yet formally defined rock-stratigraphic 233 21M JAMES L. MURPHY Vol. 79 units but informally denned divisions of on the size of the plate, its completeness, the Riceville Shale based upon paleonto- and the relative lack of wear compared to logical criteria. definitely reworked Dunkleosteus speci- Lateral and anterior views of the mens from the Cleveland and Bedford Dunkleosteus plate are shown in figure 1. formations of Ohio. Specific identifica- tion of the plate remains uncertain, but the moderate size and rounded outline indicates D. intermedius rather than D. terrelli or D. curtus. The specimen has been deposited at Orton Museum, Ohio State University (OSU-29724). The occurrence of a large Dunkleosteus plate immediately beneath the Cussewago Sandstone at Meadville has considerable stratigraphic significance, particularly when the lithology of the enclosing sedi- ment is considered. The specimen was found in place, in a thin, light gray siltstone interbedded with dark gray, almost black, micaceous shale. Marine inver- tebrates occur in the siltstone but were not observed in the dark shale. Biotur- bation had mixed the black shale and light colored siltstone in places. The dark shale of the stratigraphic unit in which the specimen was found is believed to represent an eastern extension of the uppermost Cleveland Shale of Ohio (Szmuc, 1970). Such an interpretation is greatly strengthened by the occurrence of Dunkleosteus. In eastern Ohio FIGURE 1. Lateral and anterior views of the Dunkleosteus intermedius plate. (OSU- Dunkleosteus is restricted to the Cleveland 29724). Maximum dimensions measured Shale, though small reworked fragments parallel to the anterolateral sensory canal occur in the basal Bedford Formation 18.9 cm and at right angles to it 23.1 cm. west of Cleveland. The present dis- Bar scale equals 5.0 cm. covery strongly indicates that the eastern- most extension of black shale deposition Though fractured by blasting, the speci- in latest Cleveland times occurred in the men is a nearly complete left anterodorsal Meadville area and that the uppermost plate. A fragment about 5 cm2 is missing Cleveland Shale or the Cleveland-Bed- from the dorsal margin and several ford transition zone is contemporaneous smaller fragments are missing from other with strata included in Caster's Knapp portions of the plate margin. Maximum faunal zone (the upper part of de Witt's dimensions measured parallel to the an- Riceville Shale). terolateral sensory canal and at right Caster (1934) suggested that the Mar- angles to it are 18.9 and 23.1 cm respec- vin Creek Limestone and the genetically tively and maximum thickness is 2.0 cm. related Kushequa Shale, both members of The mesial ridge which supports the an- his Knapp monothem, contain earliest terior condyle is 4.6 cm high. William Mississippian faunas. This opinion was J. Hlavin (formerly of Cleveland Museum confirmed by more recent work (Holland of Natural History) has noted that the 1958, Sass 1960) on the Knapp inverte- plate exhibits considerable wear along the brates. The Kushequa Shale (the lower anterior and dorsal margins, but it is part of the Knapp beds) is not found west unlikely that the plate is actually re- of Warren Co., Pennsylvania, but the worked or that it could have been trans- upper (Marvin Creek beds or equivalent) ported very far. This opinion is based strata do continue westward as far as Ohio J. Sci. DUNKLEOSTEVS PLATE 235 Riceville and Meadville, where they have shale on the basis of the Dunkleosleus oc- been included in the Riceville Shale by currence at Meadville. The depositional White (1881), de Witt (1951), and Pep- relationship of the Cussewago Sandstone, per el al (1954). Caster's recognition of the Upper Riceville, and the Lower these Knapp-equivalent beds in the Riceville shales is precisely analogous to Meadville area has been confirmed by my that of the deltaic Bedford/Berea, pro- recent field work and the discovery of the delta lower Bedford/Cleveland transition Knapp Syringothyris zone at the arthro- zone, and the Chagrin Formation of Ohio, dire locality as well as at the Taylor although the Cussewago deltaic sequence Strand School section one mile west of was deposited slightly earlier and over a Taylor Strand School, Athens Twp., smaller geographic area. where it occurs in the basal Cussewago LITERATURE CITED Sandstone. The Knapp faunal zone is Caster, Kenneth E. 1934 The stratigraphy also present below the Cussewago Sand- and paleontology of northwestern Pennsyl- stone at de Witt's (1951, pi. 2) locality L, vania. Part 1: Stratigraphy. Bull. Amer. 0.8 mile south-southwest of Beech School, Paleontol. 21: 1-185. Woodcock Twp., where several complete de Witt, Wallace, Jr. 1951 Stratigraphy of the Bcrea Sandstone and associated rocks in echinoids {Hyattechinus pentagonus Jack- northeastern Ohio and northwestern Penn- son) and Syringothyris have been found. sylvania. Bull. Gcol. Soc. Amcr. 62: 1347- At all points examined west of French 1370. Creek, I found the base of the Cussewago Holland, F. D., Jr. 1958 The brachiopoda of the Oswayo and Knapp Formations of the Sandstone is either covered or lies un- Perm-York embayment. Unpubl. PhD. conformably upon fossiliferous siltstone Thesis, Univ. of Cincinnati, Cincinnati, OH. of the Upper Devonian Chagrin Forma- Pepper, James F., Wallace de Witt, Jr., and tion. The base of the Cussewago Sand- David F. Demarest 1954 Geology of the stone has not been observed in Ohio Bedford Shale and Berea Sandstone in the (Szmuc 1970; Rau 1969). Erosion an- Appalachian Basin. U. S. Geol. Prof. Paper 259: 1-109. tecedent to deposition of the deltaic Cus- Rau, Jon L. 1969 Hydrogeology of the Berea sewago Sandstone apparently removed and' Cussewago Sandstones in northeastern the Upper Riceville and Cleveland Shales Ohio. U. S. Geol. Surv. Hydrologic Investi- in the area northwest of Meadville. gations Atlas HA-341. Sass, Daniel B. 1960 Some aspects of the The existing paleontologic and strati- paleonthology, stratigraphy, and sedimenta- graphic evidence indicates that the Cusse- tion of the Corry Sandstone of northwestern wago Sandstone is a deltaic facies essenti- Pennsylvania. Bull. Amer. Paleontol. 41: ally contemporaneous with the prodelta 251-381. Szmuc, Eugene J. 1970 The Mississippian marine Upper Riceville or Knapp shale System, p. 23-67. In: Banks, P. O., and and siltstone facies. The uppermost Rodney M. Feldmann (ed.) Guide to the Cleveland Shale can be considered a geology of northeastern Ohio. No. Ohio black shale facies deposited further off- Geol. Soc. Kent State Univ. shore from the stratigraphically higher White, I. C. 1881 The geology of Erie and Crawford Counties. Second Geol. Surv. Cussewago delta sands and can be cor- Pennsylvania Prog. Rept. 1879. QQQQ: 1- related with the Upper Riceville prodelta 355.