GeorgeE- Mustoe and SamuelP. Girouard,Jr., Geo ogy DepartrnentWestern Wash ngton Universty, Be ngharn Washngton 98225

A FossilTrionychid f rom the earlyTertiary Chuckanut Formation of NorthwesternWashington

Abstract

\Vrshington s \'e(cbrute fossilfecordi\ so sparsethate!en, discover] desenescarcful scnrtiny.AfossilizcdturlecaraDace tbund in 1960in fluviatilcsard stone of theChLrckanut Formaiion of wcnem WhatcomCounly $ a, ,,fig ini | 1idtnritrril.6aillcmheru1 the Tesludinoideasupedrmil). and an adjrcent bonefragmcnt was consideredtobceridence ofsome largeranimal. Rc cianina- tlon indicalcs (har the cafapacercpreserls a member of thc Trionychidae (soft shclled tufiles). Compulerired axial tomogmphv \Lrggeststhal the neafb) bone probably came from $c tu e. Trionychid are abrndant in carl] Tefiiary rocks. bul rheir remarnsIa!c nol beenfound in younger rocks in ihe north$en resion. The only cxranrtrionychid found west of rhe MississipDi is ./l'i.,ir r \prlrl,rJ'ur.which inhabitssmall areasof eastemMontana and the Colorado Rivef fe8inn ot rh( "ourh$e\r. t'hr\rurrrrr- llon in geographicrange probablt resultedli|)lr global cooling lhar surted in the latc ,and by habiut destructioncauscd b,"-episodes of nrounlainbuilding ihat begana lc$ million yearslarcr.

Introduction raphy ofthe PaddenMenlber. but its age is prob ably lateEocene based on stmcturalrelationships The faunalrecord from the earlyTcftiary is sparse andpaleoclimatic evidence. Mustoe and Pevear evcnthough extensive sedimentary deposits liom (1983)described the poorly-preservedcarapace thisperiod are exposed on bothsides of theCas- asa memberof the SuperfamilyTestudinoidea, a cadeRange. These beds of ,siltstone. sand- large group that includes pond and land stone,conglomerate, and were depositedby tortoises.They guessedthat bone fragment ex- meanderingd!e$ that flowed westward across posedin cross-sectionview on one side of the thc broad lloodplain that coveredmuch of west- specimenwas part ofa rib bonefrom somelarger em and centralWashington prior to the uplift of animal. Becauseturtles havc ribs that are fused the North Cascades.Of thesedeposirs, the 6,000 to the adjacent bony carapacelayer. this bonewas nr thick ChuckanutFormation has reccived the presumedto havg come either fiom bonesof a lrroslattention trom geoscientists(Pabst 1968; land-dwellingmammal that werewashed into the Johnson 198.1;Musloc 1993; Musroe and fluvial sediments.or to be skeletalrernains front Gannaway 1997).Plant remainsare abundantin an aquatic reptile. The latter possibiliry is con Chuckanutstrata and animalsare representedby sistentwith discoveriesoffossil crocodilesin the a varictvoftracks. The only vedebratebody los- GreenRiver Forrration of Wyoming (Grande sils that ha\e been fbund are the impressionof 198,+),correlative in age to the ChuckanutFor- the interior surfaceof the carapaceof a tu le and nlation. Becausethe was softer than the r nearbybone fragrnent (Figures l.2). enclosingmatrix, the decision was made not to The l8 x l3 x 7 cm spccimenwas collected in attempt to reveal the bone by mechanicalexca 1960during constructionexcavations south of vationfor fearof destroyingthe specimen.In 1996 BelJinghamat Clark Point(T 37 N. R 2 E. SW geologystudent S. P Girouard.Jr, re-eramined comcr Sec 13)but recognitionof the fossilas a the specimenand decided that both of Mustoe turtle campacedid not occur until two declrdes rntl Perear'.tl98.lt interpretction\uere incor- later when a visiting geologist noticed the rock rect. This paperpresents his findings. at the Clark family home (Guthrie1981). Bed- Anatomica Features rock at Clark Point consistsof arkosicsandstone of the Carapace ol the PaddenStratigmphic Menber, the young- Althoughtheimpression ofthe carapacepresen es estsubunit ofthe ChuckanutFormation. Johnson relativelytew anatomicaldetails, sevcrll char ( 1984)and Mustoeaod Gannaway(1997) pre acteristicssuggest that the spccimenreprescnts sentcdconllicting interpretationsfor the stratig- a mcmber of the Superfamily Trionychidae

NorthwestScience. Vol.75, No.3,2001 2ll

O llr0l br_rtrc Nodhsc{ SoenrifirAsociarnri Allnghr.eserl.d Figure L Chuckanut tuftle fossil. showlng inrprcssionol lenlral surfaceof carapace.Broad corrugalionsrepre- scnt iusing of thc ribs to iblm a conrinuousbon) la,ver.These corrugalions meet :rt a midline axis rhat represeDtserodcd ncural archesoi lhe lerlebfal column. Scalebar = ! cn. Photosused fbr figs. I & 2 ha\'e beenreversed from rjght to lcli 1()a]lo$ easiercomparison $,ith the radiographin lig. 6.

Figure2. Srde!ie\i ofspecinren.with bonefragnren! arkcdbvinowlsamescaleasFigurel).

212 Mustoeand Girouard Figure 3. Iniernal!ie\| oft\\'o t)pes of carapacearchitecrurc. Lcflr T.a.renr5 r.rrr1rr. showingthe dng ofperipheral platesthal sunoundthe uppef shellin rll runles ercept liony chids.Righti /-ir-re,r_!r/,rddra . aoion,vchid.Adapted liom Me)lan d9li7).

laginousnrtrgin typicallycomprises approximately one half of the total carapaceleDgth. In many speciesthe distal endsof the ribs project beyond the perimeterof the central bony disk, but other trionychidslack theseprojections (Meylan, 1987). An importantdistinguishing characteristic of trionychidsis thc absenceol epidermalplates (scutes).Instead, the shell'sexternal surtace is covered with leathery skin (Figure 5). This ab- senceof homy scutesis sharedonly by the huge leatherbacksea tunlcs, Family Demochelyidae (Emstet al. 1994).

Figure,1. Fossil soli shclledturtle 7'il)lirf ,r? rrtlnrnrs fron Eoccnc shalcat N{essel.German}. sho\\ing dorsal !iew ofcarapacc.Thc bump! lerrure ofthe dorsal su acehelps thebon) plalesprovide astrong s b- st|:lleibr the overlling ]calhcry carapace.as illus- In,rrJ In Fi;Lr< 5. Th( (-hu.l'enur.nc\ -en. f pears quite dillerenl liom cilhcr of these figures becluse the lbssil sholvsrhc \ cnlral suriace.Photo courlcsy oi ScnckcnbcrgMuseum. Frankfurt.

(sofi-shelledtuftlcs). Other turtles have carapaces (Easrem thalhave dgid margirs composedof20 to 22 bony Figurc 5. The livnrg lrbr]I spi/rildrr Spiny Soit shell) sho$,sthe leathef) carapacesudace charac' plates.but triorychjds have flexible margins and teristic of membersof the Trionichidae.Photo b) lack peripheralbones (Figures 3,4). The carti' Fl .1.Obsr.

Trionychid Tu le from Tefiiary ChuckanutFormation 213 Possibly the Chuckanut fbssil representsan among trionychidscarapace shape remains rela incompletecarapace where periphelal bones were tively constantduring growrh. cither disarticulatedprior to fossilization,or de- stroyedlater by erosion.A ntore likely interpre- Ev dence f rorn Computerized Axia talionis that the absence ofthese marginal plates Tomography is evidencc that the fossil is from a trionychid. Thc sandstoneblock also preserles a tbssilbone Be.ru.e thc \f\crimen pre.erre\ rn irnpre.sion visible in crosssection as a flattenedasymmetric lefl by the interior surtaceof the carapace.it is 26 x 6 mm oval, compdsedof a 0.5 mm thick not possibleto determinethe natureof the origi- cofiical layer sur:roundinga porous ccntral zone nal outer surface.However, a partially preserved (Figure2). ln May, 1996a computerizedaxial layer of mineralized bone bears no trace of im- tomography analysis of the specimenwas per- pressions(sulci) that comrnonly fbrm alongseams formed using a GeneralElecrric Model 9800 CT betu'eenadjacent scutes. The shallow convex scanner.The valueofCT technologyfor the study corrugatedexterior sulfacebears a strongresem of vertebratefbssils was first demonstratedby blanceto shell shapesofextant speciesof lrloa_rx Conroy and Vannier (198.1),and the technique and its kin. though some other types of turtles wasquickly adoptedby veflcbratepaleontologists havesinilar contours. (for a detailedoven,iew seeClark and Morrison The l2 cm lengthof the Chuckanutfossil is 1994).The Chuckanutspecimen was subiected smallcompared to carapacclengths ofmostmodem to 18 scanson the coronal (anteriorto posterior) andtbssil trionychids.LiLrge extant members have andsagittal (nredial to lareral)planes, usually at bony disks that excecd50 cm, and for most spe, an inteNal of 3 n]m betweensuccessivc scans and clesthe adultshave carapacial disk lengthsof 20- at an accelentingvoltage of 120KV ar 100-170 30 cm. Of 23 living species,only five havedisks MA anda scanrate of 37.5mm/s. Because ofthe lessthan 20 cm (Meylan 1987).The Chuckanut density of the matrix the scanimages arc some- specimgnmay representan unusuallysmall vari- what indistinct,butrcsolution is sufficientto show ety, but it may also be remains of a juvenile be- the generaishape and dimensionsof the hidden causcin contrastto many other types of turtles. bone fragment (Figure 6).

Figure 6. Tracingsm.tde fioln five CT scansshow successivecross sectionvie\\'s ofboDe fragmen! that exrendsapproximately l0 mm irlo lhe sandslonematrix Photo showsactual CT scanimage al 12 nm deprh.with included bone marked by affow. The undulating surfacc al lhe top ofthe siab representsthe carapaceimpfession. The size and flarcned shape suggcstthat the bone is probably either a fragnrcn!oLplastron or intemal skeleton.

21,1 Mustoeand Girouard Figure L Sketchesollrionychid rhell architectlrre.shown in \,ennal \ie\l\.,Adapted iiom \{eylan (1987). Lcll: Trio \rJ(t?r. Right I air.l(Drt r p&r.trd .

The preservedponion of the bone is a thin. 'ubtriangularstructure lhul e\lend. lor approri- mately30 mm into the matrix.Although an asym- metricflattengd oval crcss-sectioncan be obseryed at its exposureat the surfaceofthe slab.the bone ha: r compres.edtrapezoidrl crors reetiun nerr theapex. Mustoe and Pevear (1983) assuned the exposedcross-section reprcsented a rib bonetiom a laLrgeranirnal. a diagnosisthat is contradicted by the radiographicimages. Instead, the bone is probably a fragmentol the plastron(Figure 7) or fragmentfrom the pelvis or shouldergirdle (Fig- ure 8). More exact identificationis impossible becauseof thc variationsin skeletalarchitecture found amongdifferent trjonychid generaand the lack of resolutionofthe CT scans.The geometry of plastron shou'smuch variation among extant species,but all trionychids have flattenedplate- like plastral elementswhose size relative to the carapacefalls within the dimensionalratios ofthe Chuckanutspecimen. However. pelvic girdle and shoulderbones also havc elementsthat could be Figure E. 1nlemalarchitecture of lrior_! r grrgetl.,! (Gange,i broken to produce the object shown in the CT Sofishell).wiih lolver \hell (plastfon)removed to scans.Although we can not disprove the possl- sho$ ventralvie\i ofcanpacial bones,lnnb bones. and intemal skeletalelements. bility thatthe bonetiagment reprcsents some other animal,the simplestexplanation is that bothparts of the fossil are from a single tudle.

Tlionychid Turtle from Tetiary ChuckanutFormation 215 Discussion so conlmon in the nearby Eocene Bridgcr For- mation that a pioneer vcftebratepaleontologist Menrbers of the Trionichidae include 22 cxtant 'Trionychidae declarcd ran riot" (Hay, 190tt.p. fbrms and approxinrately230 fossil speciesthat 39).Rich ct al. ( 1996,p. 424)reported "bro- date back to the late Mesozoic. Nearly all of the thar ken bonesof Teni;fy extinctmembers have been placed in thc genus soft-shciledturtles are so comlnon Irioz_rr, creating a taxonomic wastebasketthat on bare hills ncar the Continental Di- videof NofihAmerica. includes many fossils that lack an;itornicalfea in south-centralWyorning. tures found in living membersof thc genus that they make up a largepafi of the pebbles." (Gaffney1979). Phylogeneticrclationshipsamong The abscnceofextant tdonychidsin the noflh- modern trionychids arc not well understood,and \\"esternU.S. is intriguing. Givcn the abundance inpofiant taxonomicissues remain unresolved. of turtle fossils. why do \\"e not find more evi- Meylan ( 1987)used cladistic analysis to divide denceofancestral trionychids? We presentlylack 7)-i.rr)rinto nine genera,a revisionthat is not an answer to this question. The early Tertiarv universallyacceptcd (e.g., Webb 1990). Forthese ChuckanutFormation specimen provides the first reasons\r'e have not classifiedthe Chuckanut evidenceof Trionychidtuft les in Washington.and specimenat thc genuslevel. membersof thissupcrtrmily have not beeniden Trionychids prcsentJylive in North America. tified tiom younger depositsthat contain turtle Africa, Asia, andthe Indo-Australianarchipelago. tbssils.The extensive senri-tropical fluviatile en- Fossilforms indicatetheir rangconce included vironmentsthat produccdthe ChuckanutFornra- South America and Europe as well. Three spe- lion and corelative deposits offered favorable cies presentlylive in North America. Irioar,-r habitatsfor many typesofaquatic tut1les.Indeed, ,xrclich (smooLhsoftshell) inhabits thc Missis- fossil turdes.with their durablcand easily recog- sippi Valley region. Z .rl7hy'alrs(spiny softshell) nizableshells, rnake up the majority ofearly Tcr- dwells in a large area of the ccntral and south- traryvetebrate discoveries from mshington. Thc eastemU.S. as well as smallaleas of Vermont. oldest turtlc renrrins leported f'rom Washington easternMontana. and the ColoradoRiver drain- are from the Middle EoceneRoslyn Fomation. age of the south$,est.I /er4r (Florida softshell.) which has yieided carapacesof the chelydridid occurs only in Florida and border area of adja- (snappingt\trt|e) Ach e ro nt e m) s ha c km ani ( Ha "- ccnt states(Emst et al. 1994).Modern trionychids 1902, 1908)and thc derrnatemididpond turtle dwell in aquatic environnents that range from Baptetnysflwidtilis (Wheelerl9-55). Remains of swamps and marshesto rivers atd lakes. They the giant tofioise Geor:leloirchave bcen tbund in are predatorsthat consumesnails. insects. cray- the Miocene EllensburgFormation of central fish, srrallfish, andfrogs. depcnding to a lesser Washington(Fry 1973,Custafson 1978). along extenton scavenglngand consumption ofaquatic with other unidentifiedtufiles (Warren 19,+1. plants.Anlong turtles they are some of the last Sniley 1963,Bryant 1968). Turtlcs are common estswimmers (Webb 1962).and their uniqueshell lbssils at anothersite in centml Washington.the ,Lrchitectureallows theln to makerapid predatory Iate PlioceneWhite Bluffs faunaof the Ringold strikesagainst fish andother su, inrming prey.The Formation. Taxainclude thc tertoise.Te.rldo sp. flexiblc carapaciaLlmargin makcs trionvchids well (Meriam and Buwalda1917. Gusrafson l97U). adaptedfor muddy environments.and thel use Clemm\s nqnnorttaJ. or wcsterl pond turt]e undulatingmolions ofthe shell'sedge to dig into (Brattstromand Stum 1959),and rhe painted tudle the bottom sedinlcnt tbr protection (Emst et al. Clry.reia,rrsp. (Gustafson 1978). The latc Piiocene 199:l).Trionychids typically haveelongated nccks Tauntonfauna of the Ringold Fomation hasalso and long pointedsnouts. teatures that allow them yielded a diversctuftle assemblagc,but unfortu- to rcmainconcealedin mud. strikeat preyor reach nately thesespccimens have not been described to the surfaceto breath. in detailrMorgrn rnLl Morgan 1995r. Thegeographic range oftrionychids included Washington'sgeologic history provides a lbun- much of the westem U.S. during the early Tcr- dation for speculatingon possible lactors that tiary.An unidentifiedtrionychid is the most com- shapedthe riseand fall ofTrionychid populations. mon turtle in the EocencGreen Rivel Formation Beginningin the late Eocenethe regionalclimate of Wvoming(Grande 1984), and shell fossils are becamecooler and drier andlou'land semitropical

216 Mustoeand Girouard rain tbrestswere displrced by temperatcvcgcta- to thc SupcrfamilyTrionychidac (sofrshclled tion. Theseecological shifts probably led to pro- turtles). Computerizedaxial tomography of an fbund changcsin thc llora andfauna, as evidenced adjacent bone fragment demonstratesthat dris fossil by the differencesthat $'e observetoday in plants likcll robc l skclcrrlrcmnlnt from rhc umc ln i- and aninals fion subtlopicalregions and warm nal. The Chuckanutspecimen provides the llrst temperateenvironments. After a prolulged pe- evidenccoftrionychids in thcPacific NorLhwcst. riodof gcomorphicslability during the early Ter but fossilizedremains of this group arecommon tiary, flu\ial environmertswere disruptedby the in early Tertiary rocks in the northern Rocky upliftofthe Noth Casc;rdeRangc and by 30 million Mountainrcgion. Trionychids have not beenfound years ago surfaceprocesses \\"ere dominated by in youngerrocks of westernNorth America, but erosionrather than dcposition. lncreased volca- other types of turtle fossils are not uncotrmon. nic activity may have causedfufiher ecological Clim..rti.irtrling th.rlhegan lhe lrle tocene mJ) disruption.Thc scarcityof animalfossils makes havecaused a restrictionin rangefor tufiles, and theseancient transitions difficult to reconstruct. subsequentmountain building eventsdestroyed hou'ever. Perhapstrionychids were one of the many lowland aquaticcnvironments Rcpeatcd organismsthat bccame extincl duing the early episodesofcontinental glaciation during the Pleis- Tertiary,but the absenceoflate Terliary sedimen- toccncprobably reduced tunle populations even lary rocks in westemWashington hinders us from funher andtopographic barriers hindered the return makingaccuratcjudgncnls. ln anycase. repeated of pond dwelling tufiles to their earlier ranges. advancesof the continentalglaciers through the Howevet thelateTediary tbssil record fiom central Pugetlowlands during the Pleistocenenlay have Washingtonand the scarcityofextant trionychids causcdlocal extinctionofturtles andother aquatic westof theMississippi both suggestthat this group animals.Although variousspecies ofpond turlles disappearedfrom the northwestlong before the are abundantin lakcs and rivers in central and onsetof Pleistoceneglaciation . eastemWashington, these populations nray have been re-establishedduring the last 10,000yeius Acknowledgements from stocksthat inhabited non-glaciatcd rcgions This paper summarizesthe results of investiga- 1()the south and east.The North Cascadespro- tionsinitiated by thelate Samuel P Girouard,Jr., vide a geographicbarrier to themigration of turtles an undergraduatepaleontology student at the into the northwestpad of the state.Thc present University of Washingtonat the time of his un- scarcity of trionychids west of the Mississippi cxpccteddeath in 1999.Sam wishedto thank the Valley suggeststhat the menrbcrsof this family lbllowingpeople fbr theirhelp: Dennis Braman. disappearedmuch earlier.In this respectthey are Donald Brinkman, Philip Currie, Elizabeth renrinisccntof trccssuch as Pl.rturrrJ (sycamorc) Nicholls. and Darren Tanke at the Royal Tyrrell that floudshed in the northwestduring the early Museum of Palaeontology,Dmmheller. Alberta, Tertiary,but which survivein NonhAmcrica only contributedhelpful discussions rurd access to speci- in thccastem U.S. Sycanores have been success mens RobertEvander provided much hospital- full.vre introducedin moderntimes, and in many ; ity during a visit to the collectionsof the Ameri Washingtontowns they ale one ofthe most com can Museum of Natural History. Ncw York. and mon ornamentaltrees. Likewise, thc Chuckanul Museumpaleontologist Eugene Gaffhey reviewed trionychid turtle may be an exanple of an animal an early version of the manuscript;Glenn Kays tamily thatno longerinhabits thc rcgionbecause at the University of North Da&otashared his knowl- ofpastgcologic and climatic events, even though edgeof Cenozoictrionychids. Douglas Clark of present envilonmental conditions appearto be Bellinghamdiscovered and later donated the speci- hospitable. nen studjedin this paper to the WesternWash- Summary inglon University Geology Department,where it is presentlyon displa)'(WWU #00-3-12). Radi- The ventralsurface of a turtle calapacepreseNed ology techniciiurKurt Klucking perlbrmedthe CT in sandstonelion the early Tediary Chuckanut scanat St. Joscph'sHospital Imaging Ccntcr in Formationat Bellinghrm.WA probablybelongs Bellingham.

Trionychid Turtle from Teftiary ChuckanutFomration 217 LiteratureCited Merrialn,J. C.. and J. P Buwalda.1917. Age of strau rc ferredio rhc EllcnsburgFormation in the While Blufl,i BrattstroD.B. H., andi. Stunr.1959. A new speciesof fossil ot thc Coluilbia River. Llniversity olCalilbmia Pub- turilcliom |he PlioceneofOregon. r'ilh notcsonother licalions.Bulletin of the Deparlmentof ceolpgy fossil C1.,m'rl.riro scslem Nofth America. South 10(15):255-166. pl. I3. cm Calilbmia Academy of ScienccsBulledn 58(2): N{eylan,P A.. 1987,Thc phylogeneticrelationships of soli 65 71. shelledrunles (Family Trionychidae):Bulletin of rhe Bf)anr. L. J. 196E.A nc$ speciesof mu\telid from lhe American\'{uscum of Natunl History.\'. 186(1):1U1 EllensbufgFofmation. Washinglon.Los Angeles pp CountyVuseum Contributions to Scicnce139: 6 p. Nlorgan, J. K., and \. ll. Nlorgar 1995. A nelv spccic\ o1' Clark, S.. and L Nlorri\on. 1994. CT scan of fossils. tr P Capronrer!x (M,rmmalia:Ariiodacryla) liom rhe l-ciggi and NIa). P editors. VerlcbralcPaleontologi, TauntonLocalFauna of\lashinglon. and rhecorrela- calTechniques.Volun1e 1 C:u$ridge Universitylrfess. tion $ith other BlancaDfaunas of Washington and Cambridge:323-129. Idaho.Journal of Vcrtebr,tlePaleonrology l5(l)r 160 Conro!. G. C.. and M. W vannier 198'1.Noninvasjvc three |]0. d imension al computcr imrging of nratrix-filled fossil Mustoe. G. E., 1993.Eoccnc lracks liom the Chuckanul skull\ by high resolutioncompuler tonograph]. Sci- Formadon.roih\!est WashingiontCanadian Journal cncc 226: ,156-'158. ofEanh Sciences30. p. 1205 1208. Ernst. C. H.. Ii. W Barbour.:md J. E. Lo\'ich, 199,1.Turllcs N{ustoe.G. 8., and W. L. Ganna\ray. 1997.Paleogcography ol the LrnrtedStates and Canada.Smirhsonian Insri- ard palconlologvofthe edrli,Tertiar], Chuckanut For- tutionalPres!. Washington. D.C.:578 p. n]aliol1.\ol1 hwest\Vashingron. Washingron ceolog,v Fr]'. W E 1911. Fos\il giant tortojsc of genus Ceochelone 25(3):3-18. liom thc Lare Miocene-Earh Plioceneofnorrh cen, Mustoe.G. E.. andD. R. Pevedr. I 983. Verlebratclbssils from tralOregon. Norlh$esr Science.lT(1): 219-285. lhe Chuckanut Formation of nordlwest \Vashington. Callney, E. S., I979. Description ofa large trion),chid tLrrtle Northwes! Scicnce5l(2): I I9- 124. shell liomthe EoceneBridge Formationof\\'!oning. Obs!. F.J.. 1988.Tunles tortoisesand |erapins: Sr. Marrin's Contributions lo Ceolog), Universit! of Wvoning Press.Netl York, 231 p. 17(l):53-57. Pabst,NI. ts.. l968.Thc Flora ofthe ChuckanutFormarion of Grande. L. 198,t.Paleortolog!' of the Green Rircr Folma northwesrcm\\hshington. the Equisirales Filicales. tior with a review ofthc flsh tauna.ceological Sur- andConiferales: Universilv oi CaliforniaPublicalion s vc] of$)oning Bulletin63: 333p. in Geological Scicnces76, 85 p. Gustaf\on, E. P 1978.Thc ve ebrulelaunas ofthe Pliocenc Rich. P V.. T. H. Rich, N,l.A. Fenton.and C. L. Fenron, 1996. Ringold Fornation. south-centralWashington. Uni- The fossil book. a recod of prehistoric ljfei Dover versitv ofOregon \{uscun ol Natural History tsulle Publications.N{ineola. NY. l,l0 p. tin l3r 6: p. Snile). C. J. 1961. The Ellcnsburg Flofa of $hshington. CulMe. D. 198L The secretof theChuckanuls [sic] \r asfesting Universjty of C.tlifornia Publication! in ceological on a coffee rable.Thc Bcllingham Herald, Thur\da,v Scicnce35(3): 159-276. Octoberli 5E. Wan cD.C. R.. 19.1LThe Hood River conglomeratein Wish Hai. O. P 1902. Bibliograph) and cataloguc of the lbssil ingioniAmerlcanJoumalol Science239(2)r 106 127. Veftebrata of No(h Amcrica. U.S. ceological Sur, \!'ebb. R. G.. 1962.NothAmerican recenrsofl shelledtufile\ !e! Bullclin 197:868 p. (Fanily Tdontchidac)i Universiti' of Kansas Publi Hay. O. P 1908.The fossilturdesofNorthAmerica. Camegie cationsin r*aruralHistory l3: 429 6ll Institulion of\lashington 75: 568 p. \\'cbb, R. G., 1990. 7,,1.7n,\x.Calalog ofAmerican Amphib Johnson.S. Y 198'1.Stratigraph]', agc. and paleogeography ransRcporl,l87: 1,7. ofthe EoceneChuckanu! Fonnation. nofh$,e\t rlhsh Wheeler. H. E. 1955. Defmatemidid turde liom the Roslyn ington.Canadian Joumal of Eafih Sciences2l: 92 lbnnalion of Washington labslracll. Geological So r06. cietyofAmerica uullctin66(12): 1668-1669.

Received2 May 2000 Acceptedfttr puhlication 25 Jaanry 2001

218 Mustoe and Girouard