University of Nebraska - Lincoln University of Nebraska - Lincoln

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1-2012

An Elusive Carnivore Skeleton Discovered at The Ashfall Fossil An Elusive Carnivore Skeleton Discovered at The Ashfall Fossil

Beds Beds

Rick E. Otto University of Nebraska - Lincoln, rick.otto@unl.edu

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Otto, Rick E., "An Elusive Carnivore Skeleton Discovered at The Ashfall Fossil Beds" (2012). Programs Information: Nebraska State Museum. 29. https://digitalcommons.unl.edu/museumprogram/29

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PaleontologistNickFamosoexaminesCynarctusskullandjawsrecoveredin2008.

AnElusiveCarnivoreSkeletonDiscoveredatTheAshfallFossilBeds

OneofthemostexcitingrecentdiscoveriesattheAshfallsitewasasmall“dog”skeletonduringthesummerof2010.ThefindwasrealizedwheninternsBillMausbachandAmandaMillhousewereintheprocessofrevealingalargemalerhino.Whileexcavatingapedestalaroundthefrontlegsoftherhino,Billfoundasetofbonesfromamuchsmalleranimal–hiddenundertherhino’sleg.Weeksofpainstakingpickandbrushworkrevealedthattherewasasmallcarnivore–

ofsomekind-underneaththematurebarrel-bodiedrhinoskeleton.Everyoneknowsthatgoodthingscantakealongtime,andpatienceandperseverancearenecessaryinpaleontology.Itwasnotuntilthefollowingsummer,2011,thatBill,alongwithmuseumchiefpreparatorGregBrown,exposedthemodest-sizedskeletoninmoredetail.Theteethintheskullwerebrushedcleananditwasindeedadog.A“dog”inabroadertaxonomicsense,becausethisfox-sizedspecies,(aswellasthelargestdogspeciesfrom12millionyearsago,Epicyon)allbelongtoasub-familyoffossildogsknownasbone-crushers,orBorophaginae(boro-fa-jeen-ae).Thereweresevenoreight

speciesofborophaginesinNorthAmericaatAshfalltime,whileonlytwoorthreespeciesofCaninae,thelineagethateventuallyevolvedintowolvesandcoyotes..

Bone-crushersingeneralhavebroadmolarswithbluntcusps,anadaptationsimilartohyenasforcrackingbone.Boneitselfisnotverydigestible,butthemarrowinsideoflegbonesandribsishighlynutritious;richinfatandasourceofprotein.AninterestingthingaboutthelittledoguncoveredatAshfall,isthatitistoosmalltohavebeenmuchofabone-crusher.Themolarteetharemorebluntthanthebiggerspeciesofbone-crushingdogs,and,inmanywaysresemblethecheekteethofraccoons.Theshearingteetharesmallaswell.Itisverylikely“raccoon-dogs”astheyaresometimescalled,wereomnivoreslikeraccoonsandprobablylivedinsimilarways;stalkingfrogsandcrayfishalongstreambanks,andaroundwaterholes;munchingoninsects,orfeedingonfruitandnuts. Cynarctus(sine-ark-tuss)wasfirstdescribedfromalowerjawfoundinnortheastColoradoaround1900.WilliamDillerMatthewoftheAmericanMuseumofNaturalHistorycoinedthetermCynarctus,andnotedthereducedsizeoftheshearingtoothandbroadenedmolars.Inthe1930’spaleontologistPaulMcGrewproposedthatCynarctusbeincludedintheraccoonfamily

BillMausbachandRickOttodiscussthefreshlyexposedCynarctusskeleton.

(Procyonidae).Someyearslater,RichardTedfordoftheAmericanMuseumofNaturalHistoryplacedCynarctusintheBorophaginae.FourspeciesofCynarctusarenowrecognized,andthegenusisonlyknownfromNorthAmerica.CynarctuscrucidenswasdescribedbyformerUNSMdirectorErwinBarbour(andHaroldCook)in1914.CynarctusvoorhiesiwasnamedinhonorofAshfallpaleontologistMikeVoorhiesbyXiaomingWangandTedfordin1999.Afterdetailedstudy,theAshfallspecimencouldbeoneofthepreviouslymentionedspecies,C.crucidens,orC.voorhiesi.

ThisisnotthefirstfossilofCynarctustohavebeenrecoveredattheAshfallsite.Occasional“raccoon-dog”fossilswerefoundbyMikeVoorhiesandcrewin1978,andasinglelowerjawin1995.Thisisthefirstskeleton,anditistheonlyknownskeletonofanyspeciesofCynarctusfromthefossilrecord.In2008,whenanexcavationcrewwasclearingapathinthefossilbedforthefoundationoftheHubbardRhinoBarn,severalisolatedlegs,ribs,andlowerjawswerefound,includingacompleteskull.Tostresstherarityofwell-preservedfossilsfromthetaxa,thisistheonlycompleteskullthathaseverbeenrecovered.References

Barbour,E.H.andH.J.Cook.1914.TwonewfossildogsofthegenusCynarctusfromNebraska.NebraskaGeologicalSurvey4:225-227.

Matthew,W.D.1902.NewCanidaefromtheMioceneofColorado.BulletinoftheAmericanMuseumofNaturalHistory16:281-290

McGrew,P.O.1937.ThegenusCynarctus.JournalofPaleontology11:444-449.

Wang,X.andR.H.Tedford.2008.Dogs:TheirFossilRelatives&EvolutionaryHistory.NewYork:ColumbiaUniversityPress.

Wang,X.andR.H.Tedford,B.E.Taylor1999.PhylogeneticSystematicsoftheBorophaginae(Carnivora:Canidae)BulletinoftheAmericanMuseumofNaturalHistory243:1-391.CreditsCynarctusillustrationbyMarkMarcusonPhotographsbyRickE.Otto