UNIVERSITY OF AMSTERDAM. from the middle Miocene of the Eastern Netherlands. G. Bianucci & W. Landini. Abstract. could represent a to

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1 Beuforti BULLETIN ZOOLOGICAL MUSEUM UNIVERSITY OF AMSTERDAM Vol. 52, no. 11 December 19,2002 A new shortrostrum odoncete (Mmmli: Cetce) from middle Miocene Estern Nerls G. Binucci & W. Lini Diprtimen di Scienze dell Terr, Universit di P, vi S. Mri, 53,156126, P, Itly Abstrct An incomplete odoncete (Mmmli, Cetce) skull from Middle Miocene Mte Bed (ner Winterswijk in estern prt The Nerls) described s Vnbreeni trigoni, new genus species. The skull exhibits short rostrum with only two mxillry teeth for ech othrow with nrrow othless picl portion exclusively formed by premxill. Considering th lst chrcter, specimen could belong Eurhinodelphinide evenif certin ttribution possible becuse incompleteness specimen. suction feeding mong eurhinodelphinids. Vnbreenin. could represent specilized dpttion botm Key words: Cetce, Odoncete, systemtics, feeding, Miocene, The Nerls INTRODUCTION exhibit rostrum more elongted mible. thn Different trophic ptterns cused wide vrition in skull rchitecture extnt fossil On contrry some odoncetes re chrctered by short rostrum sometimes ssoci very odoncetes (Mmmli, Cetce). Prticulrly, shpe rostrum mible ted with drsticl reduction teeth number. Some se, like extnt Feres number teeth re chrcters more closely Orcinus perhps fossil Prosqulodon, re relted trophic dpttion se mrine shrklike predrs. Ors, with lso reduced mmmls. Some gener, s extnt Pltnt, Ini Lipotes fossil Zrhch number teeth, like extnt Kogi Grmpus, re speciled for cpturing ocpus Eopltnt show very elongted slender squids using suction feeding mechnms gvillike rostrum with lrge number teeth (Heyning & Med, 1996; Werth, 2000). Extreme elongtion or shortening utiled, t lest in extnt species, for rpril feeding ner botm in river or neritic rostrum seem dpttive chrcters subject fst wters (Werth, 2000). A peculir longirostrl evolution judging from some cses s short dpttion, probbly for rpril feeding, tht rostrum Miocene Brchydelph in respect fossil swordfhlike eurhinodelphinids tht or longirostrl ponporiids (De Muizon, 187

2 A Fig. 1. Geogrphic loction (circled str) exmined odoncete specimen strtigrphic l. (1975). section bsed on Bosch et 1988) or erly Miocene Prosqulodon in respect or squlodontidlike odoncetes (Kellogg, 1928). The fossil skull from Miocene Order Cetce Brson, 1762 Suborder Odonceti Flower, 1867 Fmily PEurhinodelphinide Abel, 1901 Mte Bed (Fig. 1) here described could represent new peculir cse shortening rostrum Vnbreeni n. in longirostrl odoncete group. In fct, skull very short exhibits only two mxillry teeth, but it hs lso some eurhinodelphinids TYPE Vnbreeni AND ONLY INCLUDED SPECIES. trigoni n. sp. chrcters, prticulrly nrrow othless picl portion rostrum tht probbly ws DIAGNOSIS. smllsized shortrostrum longer thn mible. The skull described below ws collected by Mr D.J. Mol Mr Von der Hocht in August 1975 kept in Zoologicl Museum Amsterdm (ZMA). odoncete genus tht differs from ll or odoncete gener, except those referred Eurhinodelphinide Messpicetus, by hving nrrow cylindricl picl portion rostrum formed exclusively by premxill lcking lveolr teeth. It differs from ll eurhinodelphinid SYSTEMATIC PALEONTOLOGY gener by smller size, shorter rostrum, rostrum broder t bse, bsence longitudinl sulci Clss Mmmli Linneus, 1758 on dorsl surfce rostrum, reduced 188

3 The Mte, Tble 1. Vnbreeni trigoni n., n. sp., mesurements (in mm). Asterk indictes estimted mesurements. Length rostrum >90 Width rostrum t bse 95 Height rostrum t bse 47 Width premxille t bse rostrum 47 Width rostrum 60 mm nteriorly its bse 35* Gretest preorbitl width 145* Gretest suprorbitl width 140 number mxillry teeth bsence TYPE LOCALITY. between loclity Alten ventrl shrp keel t bse rostrum. It differs from Messpicetus by smller size, shorter Winterswijk wns in estern prt The Nerls (51 58' N 6 44'E). rostrum reduced number mxillry teeth. It lso differs from Messpicetus ll or HORIZON AND AGE. Mte Bed, s with Ziphiide by hving lrge nteriorly vrible silt cly content tht represents extended hmulr process pterygoid. It dif lower prt Alten Member (Bosch et l., fers from ll Squlodontide Pltntide by hving pltine covered in middle by 1975). In strtype section, where specimen exmined ws collected, Mte Bed mxill pterygoids; shortrostrum Kogi represented by bout three meters drk green from ll Physeteroide for lesser crnil gluconite s very rich in qurtz with symmetry, presence spirculr plte on shells phosphorite concretions. The inferior premxille hlf portion Mte Bed strtype section bsence dorsl concvity skull; from shortrostrum ws designed s typicl reference section Brchydelph Hitell rctic Acme Zone. On bs for lcking constriction premxill t bs rostrum, hving correltions with or deposits in North Se Bsin, Mte Bed ws referred Middle deep nrbitl ch hving pterygoid sinus foss extended nteriorly bse Miocene (Bosch et l., 1975, encl. 2). rostrum; from shortrostrum phocoenids DESCRIPTION AND COMPARISON. Smll skull size for lcking thickening portion premxill nteriorly externl nres; due only shortening rostrum but from shortrostrum Prosqulodon for smller size, reduction lso smll cerebrl skull whose width t orbit 140 mm (see lso Tble 1). number teeth, for hving deep nrbitl ch strong preorbitl process. The nterior portion rostrum, s in ETYMOLOGY. genus nme in honour eurhinodelphinids in ziphiid Messpicetus (Binucci et l., 1994b), very nrrow, cylindricl Dr P.J.H. vn Bree Zoologicl Museum formed exclusively by premxill. The (University Amsterdm) for h dtinguhed pex rostrum msing so it possible reserch ctivity outsting contribution evlute tl length th cylindricl por knowledge extnt fossil mrine mm tion. However, considering tht section mls. Gender feminine. preserved nterior portion very smll, we cn suppose tht long portion rostrum msing. The bse rostrum very brod Vnbreeni trigoni n., n. sp. Figs. 24 consequently short rostrum exhibits tringulr outline in dorsl view. MATERIAL. Holotype: ZMA , incomplete skull lcking most nterior portion rostrum posterior hlf portion neurocrnium. The postcrnil skelen preserved. The nrbitl ch, s observed in mny eurhinodelphinid skulls (Myrick, 1979; De Muizon, 1988b; Binucci et l., 1994), wide deep. In th chrcter Vnbreeni n. 189

4 Fig. 2. Holotype incomplete skull Vnbreeni trigoni n., n. sp. (ZMA ) in dorsl view (A) ventrl view (B). differs from shortrostrum Brchydelph could differ from eurhinodelphinids Prosqulodon tht hve very deep nrbitl ches. Th chrcter, however, could hve been which hve mesorostrl gutter closed nteriorly. Neverless specimen my hve suffered emphsed by mechnicl brsion. possible deformtions, moreover, closure The premxille re seprted medilly by mesorostrl groove could hve been in wide mesorostrl groove tht reches its mxi msing nterior portion rostrum. Lterlly, mum width just nteriorly rostrum bse dorsl surfce premxille tht seems be open lso in nterior preserved portion. In th context Vnbreeni n. in continuity mxille, without longitudinl sulci observed in eurhinodelphinids in 190

5 3. Fig. Vnbreeni eopltntids (De Muizon, with spondnce posterior portion lr skull Holotype incomplete pltes for premxillry mxille lck constriction odoncetes shortrostrum nres vible, re The pre bs t or portion lterlly. The broder thn left, which evidences bse could bs cetes In like plte n could represent in flt some primitive odon ziphiids, bsin, The tht mrgin. Probbly smll observed in tht mible thn rostrum, show In s ll slight cses in ll no pos evi physeterids observed. The strongly smller. sulcus tht extends n. in one hd Vnbreeni right only two ech with wht it for teeth n. ros incure n ccordnce leving if even show or incures posterior in probble ws short free nterior pre mxillry othless portion. Medilly mong bly originlly th plte uncovered closed groove thin covers, very lrge lmost by fsure Posteriorly vomer. medil conjunction completely, bitl cover lmin tht mxill tht extended pltine bone. It trin pointed ngle in its nterior wide extension in its poste portion. The posterolterlly preserved tion right side plte re nteriorly my be referred rior exhibits mxille, filled by sediment, tht prob extremity with from eurhinodelphinids, posrbitl frgment skull, nteroposte rostrum, mxillry Moreover, nrrow preserved posterior Vnbreeni gulr in shpe with mxillry fr mm nrrower longitudinl tht portion seems evident. does premxill. mxille. In dorsl surfce lterl left prenril some dor dorsolter posteriorly olted neurocrnium, dence orbit cover 10 mm portion left mrgin shows similr er rudimentry two th structures, feeble othrow. very preserved right mrgin it preserved, rudimentry formen. The mxillry terior elevtion skull. in on strongly preserved portion spirculr sloping Neverless which one Anteriorly rostrum squlodontids. view, with skull, nterior side pprently incure bout 10 elongted depression vible frontl insted, s, lterl completely slly. Consequendy, exposed lit by deform right In smll circulr skull; howsymmetry represent seems tht mxill right on fossiliztion. during rostrum rostrum posterior lveolum most deep only th my hve been ccentuted mxill but view. process shows rostrum trl bent tht exter nrbitl lveoli. The phocoenids nterior ventrl view well The dorsl surfce mxill flt, except tion In in smll. thick tht chrcterizes in nterior ever brded Moreover present. tle (ZMA ) sp. tht very ccentuted in Brchydelph. n. spircu preservtion, ening portion premxill nteriorly nl, corre insted observed in mny tht rostrum vible. re n. preserved foss sc bd formin premxill, premxillry if brded. Due even In 1988b). widening trigoni por pltine delimits medilly infror formen. Medilly completely pltine mxill so does two 191

6 Fig. 4. Reconstruction preserved portion skull Vnbreeni trigoni n., n. sp. (ZMA ) in dorsl view (A), ventrl view (B), lterl view (C). sutur shows n evident posterior excvtion. An pltines were in contct ech or. The lterl pltinemxillry sutur forms regulr intermedite condition seems be present in rch, differing from tht Pltntide Wipti which, judging from picture by Squlodontide whose mxill covers prtilly pltine (De Muizon, 1991); consequendy Fordyce (1994, fig. 7), shows posterior concvity in left pltinemxillry sutur. 192

7 The Posteriorly pltine broken so it consequences shortening rostrum, chrcter tht reles for homoplsy with possible evlute its complete extension. In some frequency in different odoncete groups. Some exmples re Prosqulodon in contrst preserved portion re no trce pterygoid sutur pterygoid sinus foss so ir or squlodontids, Brchydelph in contrst nterior mrgins finhed t lest 25 mm before or ponporiids (Fig. bse rostrum. Th condition excludes 5), ll extnt phocoenids in contrst some fossil phocoenid gen tht Vnbreeni n. my belong ziphiids, er (e.g. Lomcetus). Among shortrostrum which hve lrge nterior extension odoncetes re re some tx (e.g. Kogi pterygoid sinus, pltntids squlodontids which hve pterygoids covering pltine in middle (De Muizon, 1994), mny delphinid which hve pterygoid sinus foss extended more nteriorly thn rostrum bse. Grmpus) which suffered lso n lmost complete or tl lcking mxillry teeth, like Vnbreeni n. In Dutch skull secondry shortening rostrum could hve mde useless extreme elevtion plte tht observed in or eurhinodelphinids. In fct, in se The right side pltus lcks lrge pltine lmin present on left side conse odoncetes th structure could function s quently whole ventrl surfce right support long rostrum /or, s hypo mxill vible. On th surfce re vible some longitudinl stritions tht probbly represent sized by Fordyce & Brnes (1994), for insertion lrge muscles. A similr structure lso observed mxillrypltine sutur. On whole, in longirostrl odoncetes belonging or plte convex with tringulr trnsverse section but without shrp ventrl keel tht chr fmilies (e.g. ziphiid Messpicetus). The secondry shortening rostrum in Vnbreeni n. cterizes Eurhinodelphinoide (De Muizon, would hve cused considerble decrese 1991). rostrum height in respect tht or The ventrolterlsurfce preserved portion neurocrnium brded consequendy it possible evlute extension eurinodelphinids, even if it remins reltively high. Also lcking longitudinl sulci on rostrum my be relted its shortening; in fct lchryml, frontl mxill possible very elongted slender rostrum presence n nrbitl lobe pterygoid or eurhinodelphinids present longitudinl sinus. deep sulci which mke section similr n upsidedown 'T', shpe tht confers greter ETYMOLOGY. species nme from rigidity greter restence flexion. Ltin djective trigonius = tringulr, referred shpe rostrum in dorsl view. The rostrum skull here exmined being shorter did need Tshped structure be hve sufficient rigidity refore it lost DISCUSSION longitudinl sulci. Considering smll size short rostrum, it We consider probble tht Vnbreeni n. belongs Eurhindelphinide, even if preserved rostrum th new genus lcks some would be possible refer th skull young specimen Eurhinodelph or Schizodelph whose finds re in reltively frequent North Atlntic chrctertic eurhinodelphinid fetures s re. In fct length rostrum in extreme elongtion, polydonty, ventrl eurhinodelphinids increses with ge niml (Myrick, 1979) s in extnt species keel t bse rostrum lterl longitudinl sulci on dorsl surfce rostrum. Neverless we do exclude tht future dcovery more complete skull ( (e.g. Stenell, see Perrin, 1975). However, ongeneticl elongtion rostrum chrcter relted n increse number teeth prticulrly er bones) might llow refer so, in ll cses, skull exmined, even if Vnbreeni n. different or even new fmily, but we lso think tht eurhinodelphinid fetures th skull be considered ll my belonging young niml, would hve mntined two single teeth lso s dult. Th chrcter contrsts with poliodont stte ll known s eurhinodelphinid gener. Finlly, Myrick (1979) 193

8 Fig. 5. Compron skull in dorsl view Eurhinodelph (A), Vnbreenin. (B), Squlodon (C),Prosqulodon (D), Ponpori (E), Brchydelph (F). Reduced t sme suprorbitl width. observed tht in young Eurhinodelph ern hypos which considers reduction in Rhbdosteid (= Schizodelph) skulls rostrum less dentition in extnt odoncete s chrcter brod t bse thn in dult, th in fvorbly selected for evolution suction contrst with rostrum very brod t bse Vnbreeni skull. A specultive interprettion on trophic feeding (Heyning CONCLUSION & Med, 1996). dpttion new smll odoncete here The Middle Miocene smll skull here exmined described my be mde on bs compron with extnt trophic ptterns. Prticulrly, belongs new odoncete genus probbly we hypose tht Vnbreeni n. utiled its pointed rostrum serch ner botm preys relted eurhinodelphinds in hving very nrrow othless nterior portion rostrum mntining probble dpttion (for nlogy but lcking some peculir eurhinodelphinid with extnt longirostrl odoncetes) bot fetures, s possible consequence shortening m feeding or eurhinodelphinids. More rostrum. The shortening rostrum over, we ssume tht Duch odoncete hd considered derived chrcter probbly due more speciled fetures in respect eurhin sunction feeding dpttion th odon odelphinds prticulrly tht it ws prevlently teuthophgus tht it used sunction ctch cete. The hypos sunction feeding corroborted lso by extreme reduction mx prey (Fig. 6). Th in ccordnce with wht illry teeth. Both Vnbreeni n. eurhinodelphinids observed in ll shortrostrum extnt odoncetes with reduced dentition with mod were probbly symptric, living in neritic /or river wters but perhps th 194

9 Fig. 6. Hypoticl reconstruction externl morphology hed feeding Vnbreeni trigoni n., n. sp. odoncete reled more speciled diet bsed sion Tertiry deposits (OligocenePliocene) in on smll The squids. shortening rostrum surely gve dvntge Vnbreeni n. in respect eurhinodelphinids in swimming WinterswijkAlmelo region (estern prt Nerls). Script Geol. 29: FORDYCE, R.E., Wipti mrewhenu, new genus new species (Wiptiide, new fmily), n rchic mnoeuvrbility for cpturing prey escpe ttck possible predrs. ACKNOWLEDGEMENTS Lte Oligocene dolphin (Cetce: Odonceti: Pltnoide) from New Zel. In: Bert A & T.A. Demere (eds). Contributions in Mrine Mmml Pleobiology honoring Frnk C. Whitmore, Jr. Proc. Sn Diego Soc. Nt. Ht. 29: We re very grteful Dr PJ.H. vn Bree (Zoologicl Museum, University Amsterdm) for suggesting study th We lso specimen. thnk for ir help suggestions K. Post (Ntuurmuseum Rotterdm), O. Lmbert (Institut Royl des Sciences Nturelles de Belgique, Brussels) C. Sorbini (Diprtimen di Scienze dell Terr, Universit di P). M. Gini (Diprtimen di Scienze dell Terr, Universit di P) cknowledged for phos specimen exmined. FORDYCE, R.E. & L.G. BARNES, The evolutionry hry whles dolphins. Ann. Rev. Plnet. Sci. 22: HEYNING, J.E. &J.G. MEAD, Suction feeding in beked whles: morphologicl observtionl evidence. Contrib. Sci. Nt. Ht. Mus. Los Angeles County 464: 112. KELLOGG, A.R., The hry whles ir dpttion life in wter. Qut. Rev. Biol. 3 (1): MYRICK, A.C., Vrition, tphonomy dpttion Rhbdosteide (=Eurhinodelphide) (Odonceti, Mmmli) from Clvert Formtion Mryl Virgini. PhD. Ds. Univ. Cliforni, Los Angeles: MUIZON, C. DE., Les Vertebres fossiles de l REFERENCES Formtion Pco (Perou). Troieme prtie: Les Odoncetes (Cetce, Mmmli) du Miocene. Trv. BIANUCCI, G., W. LANDINI & A. VAROLA, New Inst. fr. Etud. ines 42: remins Cetce Odonceti from 'Pietr leccese' Boll. Soc. Pleont. (Apuli, Itly). It. 33: BIANUCCI, G W. LANDINI & A. VAROLA, 1994b. Reltionships Messpicetus longirostr (Cetce, Ziphiide) from Miocene South Itly. Boll. Soc. Pleont. It. 33: BOSCH, M. VAN DEN, M.C. CADEE & A.W. JANSSEN, MUIZON, C. DE., 1988b. Le polyphyletme des Acrodelphide. Odoncetes longirostres du Miocene Bull. Mus. ntn. Ht. nt. Pr 10: europeen. MUIZON, C. DE., A new Ziphiide (Cetce) from Erly Miocene Wshingn Stte (USA) phylogenetic nlys mjor odoncetes: groups Bull. Mus. ntn. Ht. nt. Pr 12 (34): Lithostrtigrphicl biostrtigrphicl subdivi MUIZON, C. DE., Are squlodonts relted 195

10 pltnids?. In: Bert A & T.A. Demere (eds). Contributionsin Mrine Mmml Pleobiology honoring Frnk C. Whitmore, Jr. Proc. Sn Diego Soc. Nt. Ht. 29: PERRIN, W.F., Vrition spotted spinner porpoe (genus Stenell) in estern Pcific Hwii: Bull. Scr. Inst. Ocen. Univ. Cliforni 21: WERTH, A., Feeding in mrine mmmls. In: Schwenk, K. (ed.). Feeding. Acdemic Press, New York: Received: July 5,