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Well-Preserved Skull, Pectoral Girdle, Limb and Vertebral

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Well-Preserved Skull, Pectoral Girdle, Limb and Vertebral ERYOPSID REMAINSREMAII\S FROM THE CONEMAUGH GROUP, BRAXTON COUNTY, WESTUTEST VIRGINIA By JameJames s L. Murphy Case WesternWestern Reserve University Cleveland, OhioObio ABSTRACT Well-preserved skull, pectoral girdle, limb and vertebral ele­ele- mentsrnents of an Eryops specimenspecirnen have been found in a roadcut near Sutton, Braxton County, West Virginia. The amphibianarnphibian remains occurred in a green siltstone of unquestionable mid-Conemaughmid-Conernaugh age. Taxonomic ciif­cLif­ciif- ficultiesficultie s involving-theinvolving-involvingithethe genus GlaukerpetonGlauke rpeton RomeRomerRorner r and speciation within the genus Eryops are briefly discussed.discus sed. INTRODUCINTRODUCTION TION The amphibianarnphibian specimen described in this paper was discovered by the author in July, 1969, in a roadcut between one and 1.l. 1I mile southeast of the southern end of the Elk River bridge at Sutton, Braxton County,Counfy, WestWe st Virginia. Hennen (1917) published a stratigraphic section measured along this highway (now U. S. Route 19)t9) by R. M. Gawthorp. Numerous changes in the path of the highway, uncertainties regarding the aneroid elevations cited inHennenrsin Hennen's descriptionde sc ription of the section, a strong down section dip component,cornponent, vagueness of the upper limittirnit of the described section and lack of key ormarkeror marker beds of distinctive lithology have rnademade reinterpretation of this section difficult. A second visit to the region was madernade in May, 1971,LJ7 I, to confirm the stratigraphic occur-occur­ rence of the fossil. STRATIGRAPHIC OCCURRENCE The 545foot545 foot sequence measured by Gawthorp consists primarily of sandstone, siltstone and variegated shale and c1ay.clay. The only coal in the section (Brush Creek coal, elevation 950t)950') is no longer exposed. The "Ewing Limestone'rLime stone" can still be seen in the ditch on the westwe st sideofside of the road, a few feet below the 1200 foot contour. HennenrsHennen's identifica-identifica­ tion of this limestone with the Ewing Limestone Member is suspect, however, and the nodular limestone probably represents the Rock o 265 , RiffleRiffle RunRun LimestoneLimestone MemberMember associatedassociated withwith thethe HarlemHarlem underclay.underclay. HennenrsHennen'sHen nen's t'Pittsburgh"Pittsburgh redred shalerroccurringshale" occurring 1515 feetfeet belowbelow thisthis freshwaterfreshwater limestonelime stone probablyprobably representsrepre sents thethe RoundRound KnobKnob ShaleShale MemberMember (Pitts-(Pitts­ burghburgh redbedsredbeds ofof some authors).authors). InIn anyany case,case, thethe RoundRound KnobKnob ShaleShale MemberMember lies.,abovelielies s "above thethe EwingEwing LimestoneLimeLimestone stone MemberMembeMember r andand notnot belowbelow it.it. TheThe onlyonly bedbed higherhigher in the sectionsection thatthat cancan bebe deemeddeemed ofof anyany stratigraphicstratigraphic valuevalue is a thin,thin, impureimpure freshwaterfreshwaterfre shwater limestonelimestonelime stone referredreferred toto thethe Elk LickLick LirnestoneLimestoneLime stone MemberMember by Hennen. IfIf this'identificationthis identification isis correct, thenthen thethe overlyingoverlying redbedsredbeds (30(30 feetfeet inin thickness),thickness), rrmassive"massive sandstonerrsandstone" (10(10 feetfeet inin thickness)thickness) and ttgreenish-gray"greenish-gray shalettshale" 15(5 feetfeet inin thickness) represent respeciivelyrespectively thethe Morgantown Redbed and Morgan-Morgan­ towntown SandstoneSandstone Members. TheseThe se units are well exposedexposed inin thethe lowerlower part of the extensive roadcutroadcut at thethe toptop of thethe hiLl,hill, elevation of thethe Elk Lick Limestone MernberMember being approximately 1280 feet. The amphibian remains were found within one to twotwo feet of thethe top of the "massivettrnassive"mas si ve sandstonerrunit,sandstone" unit, elevation approximately 1340 feet,fee t, on thethe east side of the highway, four to five feet above the pavement.pavement. AcceptingAccepting the correla'tionscorrelatiocorrelationsn s and eelevationsl eevvationsations of Hennen and Gawthorp,G aawtwthorp,horp, this unit is the Morgantown SSandstoneandstone MemberMember of the mid portionp ortion of the Conemaugh Group. Although a fewt'ew frafragrnentaryfragmentaryg m entar y eryopsid rremainse mains have been ddes-des­e s­ cribed previously frfromom ststratar ata oofo{f ththee ConemaughConernaugh Group (Case, 19081908;; Romer, 1952),L95Zl, refreferrablee rra ble to eitheithere r EryopsEryoPs orot Glaukerp9l3g!gjot,Glaukerpeton,et on, ththee pre­pre- sent specimen is bettbettereerr ppreseivedpreservedreserve d ththana n ppreviouslyr eviously described materimaterial;a l ; it is, in fact, the finest eeryopseryopsidryopsidid specimsPecimene n yet discoverdiscoveredeedd in rockstocks of this age in the AppalachiAppalachiana n BasiBasin.n . PRELIMINARYPRE LIMINARY DESCRIPTIONDESC RIPTION Preparation Only a small portion of thethe leftleft sideside of thethe skull roofroof and rightright mandiblemandible were exposedexposed inin thethe siltstonesiltstone matrix.matrix. The specimen waswas carefullycarefully prepared, largelylargely with aa White air abrasiveabrasive unit,unit, byby Mr.Mr. PeterPeter Hoover,Hoover, ClevelandClevelClevelandand Natural ScienceScienceMuseum. Museum. AdditionalAdditional elementselements werewere discovereddiscovered duringduring thethe coursecourse ofof thethe preparationpreparation workwork andand thesethese areare alsoalso notednoted below.beiow. SkullSkull (Plate(Plate 1,l, figuresfigurefigures s 1-3)1-l-3)3 ) TheThe skullskull roofroof waswas badlybadly crushedcrushed andand considerablyconsiderably distorted,distorted, particularlyparticularly onon thethe rightright side,side, makingrnakiog accurateaccurate measurementsmeasurements impos­imPos- siblesible (Plate(Plate 1,l, figurefigure 2).2). MaximumMaximum lengthlength ofof thethe skullskull isis estimatedestimated atat 200200 mmmrn fromfrom muzzlernuzzle toto thethe tiptip ofof thethe leftleft quadrate.quadrate. InterorbitalInterorbital width,width, 266266 o a <. ---~ thethe parameterparameter leastleast distorteddistorted byby crushing,crushing, isis 4545 mm.mm. TheThe specimenspecimen isis thr:sthus considerablyconsiderably srnallersmaller thanthan eveneven thethe holotypeholotype ofof EryopsEryops avinoffiavinoffi (Romer)(Romer) andand muchmuch smallersmaller thanthan E.E. me€acePh$megacephalus (Cope),(Cope), E.E. willistoniwillistoni (Moodie)(Moodie)(Moodie ) andand E. grandisgrandis (Marshjl(Marshf(Marsh~ t-[?TheThe u"tir"entire skull roofroof islrnarnentedis-ornamented E. "t"11 byby aa finefine reticulationreticulation oror pitting.pitting. ThereThere areare aboutabout 60-70pits60-70pits perper squaresquare inch,inch, asas countedcounted onon thethe rightright postfrontalpostfrontal atat midmid orbit.orbit. TheThe leftleft nostrilnostril lieslies aboutabout 2020 mmmm fromfrom thethe tiptip ofof thethe rnuzzle.muzzle. TheThe distancedistance betweenbetween thethe nostrilnostril and thethe orbitorbit (left(left side)isside) is approximate-approximate­ lyly 77 rnm.mm. TheThe medianmedian parietalparietal foramenforamen isis obscuredobscured byby crushingcrushing and over-over­ ridi.ngriding of thethe leftleft postparietal.postparietal. IndividualIndividual bonesbones of thethe dermal roofroof areare notnot always easilyeasily delineated, due to thethe crushed naturenature of thethe skull, faintnessfaintne s s of thethethe sutures,suture s, and difficultydifficulty of distinguishingdistinguishing post-mortem breaks fromfrom sutures.suture s. InIn some instancestheinstancesins tances the specimen has broken along sutures, thoughthough not toto such a degreedegree as toto indicateindicatindicatee thatthat thisthis is neces-neces­ sarily a consequence of imrnaturityimmaturity inin the individual.individual. The sutures, in sos o far as theythey can be discerned,discerned, do not differ materially from thethe pat-pat­ terntern described by Sawin (194(1941) l) for E. ryephalus..megacephalus. Unfortuhately,Unfortunately,Unfortunately, the area occupied by the interfrontal is not ex-ex­ posed. TheThe right anterioranterior portion of the skull, including the right pre-pre­ maxillary and nasal,nasaln asal,, appear to have been shoved posteriorly so thatthethatthat the right nasal completely overlaps the interfrontal. The interparietal and interfrontal suture ca-ncanca,n be traced easily enougheno'..lgheno'.lgh anteriorly to the point where it is overlapped by thethe dislocated right nasal. In photographs and eveneven upon cursory examinationexarnination of the specimespecimen,n, it appears that the median suture continues anteriorly, uninterrupted by an interfrontalinterfrontal elernent.element. Close inspection, however,however, suggests that the right nasnasala l has been pushed som.esome 15l5 t020to20 rnmmm posteriorlyand anundetermineddistanceanundetermineddistanc e sinistrasinistrally.lly. This dislocation is thought to be sufficient to cover the interfrontal. Even so, belief in the presence of an interfrontal in this specimen is necessarilyn ecessarily somewhatsornewhat subjective, based as it is upon the hypothetihypotheticalcal restoration of various dermal elementselernents to their original positions. ItIt can be argued that thethe right nasal only slightly overlapsoverlaps thethe leftleft nasal, that a medianrnedian internasal suture continues a!1teriorlya!lteriorlyanteriorly and an interfrontalinterfrontal elementelernent
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