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FROM THE SIXTEENTH ANNUAL REPORT OF THE U. S, GEOLOGICAL SURVEY

Ib sLI8;

DINOSAURS OF NORTH AMERICA

YALE UNIVERSITY

WASHINGTON

1896

THE DINOSAURS OF NORTH AMERICA.

BY

OTHNIEL CHARLES MARSH.

133

CONTENTS.

Page.

Un trodustione cases ocr eee oe ce cins eee See Sack Me Ree ESIC oisie en Seeleess 143
Part)l:— 0 riassic, @inosSaursss. 5-061. sales ay oe ns sais Sa ee one sense eae 145
TRTGTONNGEY 3 = Senn ooae baad Seas seb esses Somee bauS0s sosaEosonEsse senead 146
AM ChiSAUTIG iss a ease sais ac acinaisss sees See See Rae ee ele cic ue Steet 147
PITOIRRUNS S506 boncog6s56 6555 s60Ge0 sdae shod cabo sbasodSesusmeacuas 147
FUNG coll oes sedee Baten oecs se ciess Ses ome ey Sanne os abo ce eae 148
Thesforevsim DSi sess sae ese ne eee ee eae ieee, el 49}
PherhindWimbhs) aa. = 22 sees esse ee soeicle = Ses es See oes see 149
ANCHISAUFUS! SOLUS sma ae lalem =) ste ale ee ae reece elo > ee ce eens 149
PATMIMOSRUTUS os or oe Se eee ree eee eR PSS oa 1a ota ae ETT = A 150
Restoration ofgAnchisauluss.- sree cee eter eee estore eee ane eae 150
DIMOsauriant OOLPLINUS sees P eee eee rears eee se eeae eta LOL
Wistrbubionlof sLclasslc GiNOSaULses=s se eeee oe ee eee ee eee eee ee eeeee 152
iPartl—— Jurassic) dinosaurs) |2=-\- oss soe eee jos eee ne emcee ee ncieeeie 152
TIGR OC a so5 ceas esescosse0 soomeses tora Seas cossac esses costes sedesseote 153
13 PND HUG! Sooo reSsau Sooe csocdocdeoos sen Sas coUSHS BeausS qooeSs seaEeEs 153
Morerand hindslim bs) an, soise es oe eee ce ee ea ee eae eee 154
@oplurds Arse stan see 2 es = Se eee erie Cee ee teen HC Me eR eee riee Geter 155
EHO SVGLLODE Dates ecole sa cetert ie ee te ee ea ere ee CO eee see 155
Mhewhin dilimbsis eo. a ses eres Seva eee oe als ter ere eee vanes 156
Ceratosaurus! sie eect ok eee Sane cee ace eee Geena 156
THe skal occ se bes Se etesae seco hers cise sisye si see PE ae ee oem 157
Mhetbrain|see css see sews csaigecas ee {pos nese oceScocosnasascHeso cee s 159

DHEA OWEN AWS a ate so Se cle Vere Oe re et ea Seamed oe 159

PEHOs VOLbebree == Cseeeesecsessese co eee Meee ee ee eee eee days Sees 159
pPbheyscapulanarch: (2h: oce-=.< ote oe aes emer Mea oeeeles eee 160
*Eheypelviciareh 22 25555 sans me- sae noee cr me ceases teste eee eecee 160
Theimetatarsals <o-s5 5-3 2s22- So scee Sacre ewe ee se nee eee iaje teers 162
Restoration of \Ceratosaurus -=22--.9-- 225 soos Sac ee eee Ne eee cess 163

WANT OSANRUS Sees esee ae ois fo seo ee ee ae he eee See Sage Sole eee oe 163
HnropeanyRneropod aan can cerns. 2 ese eee ae eee ee ee erecis ese oee 163
Saulopod sesame cee losee = ona onsen oe eu se se eee eee seas eas tee oe 164
(Atlan tosaurusibedss.s 922-26 sees. Scesese tees eee oe eee ee See sere 164
WamiliesioMoaulopod aiscee sass) sere ee ene eee ene ae eee acer 165
VAGLANCOSAUTIED 2552220 se feces en sta ee Aes ee Seen See Oe eles ae 166
Atlan tosaundsy 2-2 .- en s- 2 seas cee eae ae Eee Ble se cemiceneekeee, 66

JA ARETOTE) cose cosoeed cocoa od cosa bese decans Ssea desc cose casces Hens 166
ANE BACLACAVIDV sas soa seems eee ee se eee ne oan ease eeeese 166

PNG WVOLUG DEG 222 as atess ce eae Sa ees ete SES eee eines 167
IBLONCOSAULUBS Ise = =e aaa se Sora eee eee be micinciors ene ee 168
(Rrescapularnarchhe ses esce serene ee cate sacar s ceiseriee cies ee 168

The cervical] vertebrwe...---....-...---- te Serace ere ets eta cet aS aeleje 169
Phedorsaliventebrecsscne cere seer w os secs ciara e eee siseeiee oeise ec 169

SEH eySaCruMse- ernst ose ae asa en cis ieis aren eee aieticiees ncee smahcmne 170
Dhetcaudaliverte bree sos tye aes soe sei eye eke Sele Saree teen necee es alti
Therpelwiciarch': 2e.2c 2-122 sess se sae eee see eesesinsese-scesseie seer’ 172
FPHEfOLrerli ml DSpee i= seem ciee tees ceeeie eek aise ai ocece ce gacdosene 173

Phew indi limi bs ee cements ae are erie eo eee era aoe seem e a ecer ance 173

136 CONTENTS.

Part II.—Jurassic dinosaurs—Continued. Page.

Sauropoda—Continued.
Atlantosauride—Continued.

Restorationiof Brontosaurus:.--- = 2-2 s see = eee eee eee 173
Barosaurus) ois eh ccs once soe see ee aC eee ee CEE Eee a Eee ee Eee 174
DiplOdocid 20%. < joc= So ace 2 im Stance oe ntae se Sree ee eS ee LT)
Diplod0cusieeeem ee ee are eee ee oem ae ee ee 175
Therskulle. csc. .c22 4s. ses -deereeneece eae see ote ee eee eee 175

The brain (oe ey -hosske sae ecient eee eae sarees avec e eee Meee ae 178

The lower jaws: 22223-2255 .seceeees-e see se seer see ee cece eee 178

The teethizj.2- 22 2c seen este soso seeee sae ones ay Ree eee eee eRe 179

The vertebrae 223.2255 .2o2 = Sie ow see soe eee aces ee eee eee 180

The sternal bones: «2222222225. 25-252ers26 222 eee se senceeee 180

The ‘pelvic girdle 22.2 0.2.2 ccs c tae see asec e pases sacle eae pss 180
Size:and ‘habits 225.222 i222 sbste gee on ee ee eee 180
Morosaurida: = .2<2.2 025 sss 0cc 02 ce sore e once eee eee Cee eee eres 181
IT OVOSAUCUS foc aera eee ae ere eae ee me BCRP ae 181
Tho ikl es peice cite coe caqewinie he Deiter ee ee One eee ee eee 181

The: verbebre@ jn os2-ce secs ccchseeee sete ee ely ce cme ee eee 181

The fore Vinibs < A52s2 soo eee ee ene ese eee aye eeee oes 182
AMIDA Aes s Bobs Saas Sosgon ase ssoooseSessdos ssondiasssbsidces 182
The-hindWimbs see sees aoe wate acdsee pls sek setsee eae eee 183
Plenvro coli te cee = 22 see seen een eee ie ie ene ee eee eee ee eee 183
Plenrocolus.2eaeces- case see seen = eee eee ene fie ese ee eteeeeee 183
The skolie eee. --1----— Bicjcie/a in 10 = oe eek = slate ais aie ae eee ee 183

The vertebre cscs cise ress tee Bee eee eee a one eee 183
Distribution of the; Sanropoda) -5-— --- esse see ee a eee ee eee 185
Comparison with European forms 185
Predentataic5sscccccne toe ee- eae e eeeie 186
Stegosauridss =. 2252222 sas. foe a's soe eee eee nae eee eee eee 186
Sterosauruspeaesee eee DO SE Sasa SS ecseasascesonacsoose eassossoes 186
The skull ¢ esses oS ce eeicias See ee oe ete ee ene ee eer 186

Tho Brain: =. 23. sos cate cas cee =h eee ae ne a es ais 187

The anterior vertebre ..-- 22.3: 2ss0 o2 nee avs (oto ode eae es peers 188

The 'sAernmM 22 - se we eee eee Sete tae =a oases y os atapare alae eee eee ete 189

The caudal vertebriny. see ae. oe eee a eels = wo sya e eaieneinioeeereers 189

AR IENO EN ON AUN, So sen mers ances SSE ROSS He eBaESSOmebS sass 189

ADS" POL wi Goes arse oe ate ee ete ae el alee erences 190

The tore limps cess coe een eae eae Ree. eeeey- ee Sates ee ees 191

The: Ding Wim bs! 22 << ca-.es5 ste eeee ae ee oe et nee eee 191

The dermal atmors-sccscces. coe mse dee aOsee eee eee eee 192
Diracodon: 22 s5060 5.02 Se shes oo See esie SE eee ees eine welt oe ee 193
Charactersiof Sterosauria -2- ooa- eee ee eee ees soe eer 193
Restoration) of Sterosanrus: - oo. ae ee 194
Distribution\of Stesosauria -o2-- 2.22 e5= ee eae eae ea eee eee 195
Camptosauridiey..2252 30252 5c. see sented eee Eee Cee Eee eee 196
Camp tosaurus <--> =ssess =~ == = eee eee ee eae eer 196
Restorationjof Camptosanrus------ - 2-2-4 =a eee een =e 197
Laosaurid x)... 52.25 s.cisc nce assecse/ses- ee ee see Renee cee ee eeeer ees 198
PTY OSAaNLUS..2s22 22 52562 sees ea gcese cee cio ee cece eee eee ater eee 198
TiaOsanrUs y. 5255. 20s Seeeces sees 223s 3-6 Soe eee ele Seen eeraee 199
Wanosanridts) 2:8 «22 2c emec= se See os fan coke ee eee ae eee 199
Nanosaurus)\is5- - S222 $.cs- ence ence sec cose ce see eee eer ee Seee eee 199
Determination of genera.......--.-----.----- ANDi 4 A ee 201

Restoration of Liaossurus..... > sc. scenic oso eee eee eee 202

CONTENTS. 137

Page.

Pancwll—— Gnretaceousrdinosaursinssse cena eae seen ce eee eiae eee 203
PENETO POU aan se seas ete yea Riss anh eat aalcacitee aoe Sang oeeoe cee 203
TOT OO SEINE oe ene poeeod cotede sean snouss Ss Senn A DoCaN ESAs nep nee 203
Ornitlvomimid capes eee ee eee ee Sena ey ee ae cee eee ee 203
Ornithomimusiess sass eee pease eee aie ie Seay se eae eee 204
SRheymetatarsalstsece secs cae eee ee ae eee cae ei ee a eee me OF

Rhos peliva Granch ere ects sae sri Set nre fete Nae eae: Sete si reetaycete 205
Predentata. s52 soe se ose tase Se sisce ace Sees ce ede ates ceseesceeeaess 206
(CCRAL OSG ES. -oe conencissence cseesE secsas Soccdede con dequaRonoseb 5655 206
CRRA NS WEG osmce sescoeneesoe sens bhe5 enbe aoe ncanmooehs soaDEHeeHeE 206
TITCCTER NS Soa Shee obabcsteauardasons coder. doseeE sass BHewab Bebe abes 208
SEO YS Ke Sees sere teers eae ne eH erence enc oe Re YR cy gS 208

Phe: TOStralsDOUC ees e sees en eons steiciser SB AMET Coe ee mae A 208
itheyhornicoresss-seo- see ea aneaine endd saab acoso soneascess eben neeD 209
heyposterioricrest a-s.ctns see eet oe ase Meee he ee cent eee 210
IBaseron Skule re se ons esa ceo et See See ea esa eee eee 210

The lower jaws 2-5. 225 -ssccaoheeseles eee cee nese eee eel See 211
Thelbrain= 252-5054 s25c Sse some sels e eae watya dato eee eS 211

The: teeth: jos-ccsoases ses aeessceee sees co sehesen ee eee secisser 211
Cervicalvandidorsaluvertebiiemes--- oe soso cee eee cee cence earns 212

PUN CY SACLUM et = oe aoe sia) saa oe ae eae etic He ae eee eeeeee 212

the; caudalvertebrias-5=s-\-csse ee coe aie se oa See Se eee 212
ihermscapulariarchtand tore limbsseeeeee es eee eee eee een 213

AHO Pe liv See eres ete ee eee ca arate eT ece eee ee et Serer 213

he; posterior Wimbs 25.32 oe eee = 22 ee ee Sees e eee eae eee 214
‘herdermal arm ons sae -2 tate sae tassios seas aoe noe ae 214
MOTOSAULTUS 221-25 spo eyes a eh = Slee ee ais = Sie see eee Disa Cision eine 214
Mheiskullise= sare see Hel Stepan cic SSS SPOS EE FE NSE pes Ree Boers 214
(COTA NS) sesores scence scocae cosnaa DauRcebiaces sane rons pos aSsHEsddes 216
Sterrholophusterecs- (aces ast cites See eee eS 216
Arathanmas ter a2). aces tec ses cee a saan sae Ae Saco eicoee meses sone 217

AVP OT OGLOMIUS foe pss ea ee ee See ee eee yet Re BU Inet 217
Restorabionjor Triceratops: 252 55-2 2a2e soe sacl Seis eines e eee eee 218
DISHNCHIVECHALACLELS(O STOUD eee -e eee ners Ee eaeeee eee eeeeere 218
Claosanridie) =. oo sss) S23 cess cane oye nce else cine ee Toone ee eS aa ae 219
Clad osanEuse sas aos cee ces see eee ee ca a eS rae SUAS ee oe ee ee eels 219
Whereas. 2 Be oss oe ee ne mie Se OO ERE ee Se Se eeeiene 219

(Phe teethe- eee ac shen cesta eee ere er osiee mae eee ee 991

Whe jbrain sho. casossces eases te See eee eee ee selaee cee eae sass es 222
PPHeWerbeb Teno toe sae ae evens oes Seve ee ee ee eee eee 222
‘Thesfore:andshind limbs= 2. nsec eee eee ae ace cere eae ee: 222
Restorationyor Claosaurus)- 23222225) 125 Soc eae ore eieesecicteneece, 22d,
PRTACHOCOUtIOD ee n5 coc ce= nis, Soe eee ins eee eee ee nse seas eg sees Seee tes 224
al oe OSCAI CUS ys seo ais laksa ee stone eee eee eaten ete = every tel oe erro 225
NOG OSE GR 66 caceudeEso cae eddisnenEe edad cor Gosea deseo meer eee aces 225
INGE OS WU UR ete eae oe Sono eerie oni ete oe a etote ee tor enh ee ei etee es 225
Disiibutionsol Ornithopod aes - sss pessoa esse esses esse eee secs 226
ParihVve—— © ONClUusiON eer at sae as eae eine eerie eee aerate eae arate eteaae erate 227
Chinppinkin Ge GinieKary cogeos coodeccs anccus case asoeeu deceeo bono Heeeae 227
Restorations of European dinosaurs -.-..-...-----....--.---------------- 228
(CONPRORIENIIN Ro oon cance sea0 Saco cEe5 000 cone decous saomSenRoaae DBEs 228

S Cel dosaurusee reas ose cow te eee Cee scie ey eee Sele selene ces sence ace 229
Ishq lit Oi ce cactooses coos20 vecdan cane bees co baos paooHS uBe5s6 Gose 230

Iguanodon ..-.... sorsecaccens csq8es obeed Haseee aceEES soness Hoe dedSe5 230

138 CONTENTS.

Part IV.—Conclusion—Continued. Page.
Affinities: of. dinosaurs ,..:=<55/2 2-2-2 Sse sees oe sae eos seen ease eae eee ee 231
with -Aétosauria’..- 22 sic scctieicoctesseeased seo oae see eee eee ee eee eee 231

‘with: Belodontia\: 222-522 <2 sosjoteccs- kw eemrec onion kote Oe eee 232

With: Crocodilia..2 22.5222 cciecie See Sete ie ae De eos See ke eee 232

WAGH DITAS 2... sos cca t i te ce ec use ee Sloe a me eae eee Se eee eee 237
iantivVe—Classificationiof Dimosaurlas-22se ene ere eres eee eee eee 237
Theropodai. 5: 1.5 \sss6c 25-24 eos iio se beeen aoc eee le seo eee eee 239
Sauropodais = hos secs seces- ce ee sae eae ere eRe eee eee Sones seer 241

Predentatai.......2 2.225200 Vege on - ok ec 8 Be tcis Sete oe Ne ee eae A
Postscript

PE TU STRATTON S:

Page.

PuaTE II. Anchisaurus colurus Marsh. Triassic........--...--..----.------ 248
Ill. Anchisaurns and Ammosaurus. Triassic .--.-.......------------- 250

IV. Restoratior of Anchisaurus colurus Marsh..-.....--..-----.------ 252

iV. Footprints of Triassic dinosaurs=----.-- --- --~ «sem neers) --i-= 254

VI. Hallopus victor Marsh. Jurassic. .----- SSoBesaos seeone Gauecy seeaae 256

WH Coslurusitracilis Marsh. (JUUaSS) Casas sae eee eee 208
VIII. Ceratosaurus nasicornis Marsh. Jurassic ..-.-.-----.------------ 260
1D. COGRATERI DE MERTEOANE, DMACENO conn coscoosan csaccooseeoparcsas 262

X. Ceratosaurus, Allosaurus, Ceelurus. Jurassic......-..-------.---- 264

XI. Allosaurus fragilis Marsh. Jurassi¢c...-.....--..-.-.-:.-----..-.- 266
xd Creosaurus atroxs Marsh) | Jurassicaee=s- eae see eee eee eee seers 268
MIPS Wabrosaurus: -unassiey- ceca: seer ae gece asec ioe cee oe eee eee 270
XIV. Restoration of Ceratosaurus nasicornis Marsh. .-...----.---.------ 272
XV. Atlantosanrus montanus Marsh. Jurassic--.....-:--..--.---.---- 274
MVC Atlantosaurus 1mmanis Marsh. JurassiC=-222e--2 seen ee eee eee 276
XVII. Atlantosaurus and Apatosaurus. Jurassic...-......-------------- 278
xSViLEICeApatosanruss -JULASSiCe ona o see ese eee eee ee eases 280
XIX. Apatosaurus and Morosaurus. Jurassic.----...-.--.------------- 282
xox Broutosaurus.excelsus) Marsh) Jurassiceesse- oe eeeesenemeaeee eos 284
ROE BLOULOSAMTUSFeXCeISUSs | JULASSI Cae ens oee ene eee eee ene eee eee 286
XXII. Sternal plates of Brontosaurus and young Struthio ..-.-......-.-. 288
OM ee Bron LOsaurus excelsus.)) JULaSS1 Coeee see) ee eee eee cee eeee eee 290
LOMNVErCSrOnLOSAULUS eX Celsuss) ULASSI Caeeee ee eer nearer oe aee nen ee ee 292
XMMVE Wiplodocus longus’! Marsh. Jurassi¢s-----ss5-2. 2042-2 -2 sees eee 294
Sav Diplodocusilongus. Jurassicso-- 2-2-2 -s- esse eee se eee ese se=e eee 296
VIE Diplodocusfonges. JUTASsiGs = -e.)-- 2 =a eee = nee ele eee 298
XXVIII. Diplodocus longus. Jurassic....-..---.----. iSong HooAS aie see tore ais 300
XXIX. Diplodocus and Morosaurus. Jurassic....-..--..----.------------ 302
RCRCRSSMOTOSAULUS=. (JUEASSI Cs 2 ese cle coe are lar oe eee ones me eee eee oe eer 304
XXXIT- Morosaurus grandis Marsh. Jurassic.-.----.2-.---------=2-------- 306
XXXII. Morosaurus. Jurassic .----.--- poe Stasis Se eye ae Sees ye eeioee 308
ROOUULMorosaurusientus Marshes (sULasslCeeeee pees eeeeeceseceeeeeeeee 310
MEXEXTVMorosaurus; ‘JUTASSIC:. o2.c 2552) coeeimeee Se see oo = cco e seine eee 312
REMONOVE IMOTOsaULUS. \JULPASSIC) -.2- 65-4 see eaee see ee cess ees seseee 314
XXXVI. Morosaurus and Apatosaurus. Jurassic .........-..-..--.-------- 316
XEROXAV LM MOLOSRULUS ys J ULASSIC! 2c ae elerseemieeielas ttiseeie Ss einass soe bane seseses 318
XONEMAVI Morosanrus prandis., JUTASSIC.-2—- se -ioee assess see ea) co cte eee 320
XXXIX. Brontosaurus, Apatosaurus, Morosaurus, and Diplodocus. Jurassic. 322
Mie Elenuroccelusmanis Marsh) ULAaSsI Cree reeeae ences eee eeasee sa 324
MAGE Plenrocclus Nanus:s J ULassiCas pees = see ees seer ee eet ee eae 326
XLII. Restoration of Brontosaurus excelsus Marsh.---..-----.---------- 328
XLIII. Stegosaurus stenops Marsh. Jurassic...-..-...---------.-------- 330
XLIV. Stegosaurus and Priconodon. Jurassic..-.......----------------- 332

140

PLATE XLY.
XLVI.
XLVII.
XLVIII.
XLIX.

L.

LI.

LII.

LIII.
LIV.

LV.

LVI.
LVII.
LVIII.
LIX.

LX.

LXI.
LXII.
LXIII.
LXIV.
LXV.
LXVI.
LXVII.
LXVIII.
LXIX.
LXX.
LXXI.
LXXII.
LXXIII.
AXEL.
LXXV.
LXXVI.
LXXVII.
LXXVIII.
LXXIX.
LXXxX.
LXXXI.
LXXXII.
LXXXIII.
LXXXIV.

LXXXV.

ILLUSTRATIONS.

Stegosaurus ungulatus Marsh. Jurassic. .........-...--.------
Stegosaurus ungulatus,, Jurassic? 9-2. e2- 225 -e= sees see eeeeeee
Stegosaurus ungulatus. Jurassic.-...-.--..-..-----..---------
Stegosaurus, | VUTASSIC mae msene eee ses =s cee ee eee eee eee
Stegosaurus ungulatus. Jurassic.........-...---..---.--------
Stegosaurus, Jurassie)_--. 2-2 52--22 2-2-5222 ssenae 22 eee ee eee
Diracodon laticeps Marsh. Jurassic....--...------------------
Restoration of Stegosaurus ungulatus Marsh .......-----.------
Camptosaurus medius Marsh. Jurassic...........----.---.----
Camptosaurus dispar Marsh. Jurassic...... ..-.2..--.--------
Camptosaurus, Dryosaurus, and Laosaurus. Jurassic...--.----
Restoration of Camptosaurus dispar Marsh. ..---.....---- iseee
Restoration of Laosaurus consors Marsh.....-.....-..----------
Ornithomimus velox Marsh. Cretaceous...........-.---.------
Triceratops prorsus Marsh. Cretaceous ---....:-.-------------
Sterrholophus and Triceratops. Cretaceous.... ...-..----.-.--
Triceratops. (Cretaceous 22 --. -2ese= see nee ere eee eee eee
Torosaurus:| | Cretaceous) 2---.-24-2c ses) eee eae eee
Ceratops, Sterrholophus, and Torosaurus. Cretaceous.-.---.--.

Triceratops prorsus. Cretaceous) _--. ------ = 22 2242-25-22 eee
Triceratops prorsus. Cretaceous .-----...--..---:-22---2-: 22s
Triceratops prorsus» (Cretaceous) -2e- 44-22 eee eee

Sterrholophus and Triceratops. Cretaceous -.....-..--..------
Triceratops prorsus. (Cretaceous ---2-2--~----— == se) === eee
Sterrholophus and Triceratops. Cretaceous -.........--..-----
Triceratops.) (Cretaceous - <r eeae meeets= = =e ee eee eee
Restoration of Triceratops prorsus Marsh .....-..-....--.------
Claosaurus annectens Marsh. Cretaceous-.....----..----.------
Claosaurus annectens. Cretaceous....-...-----..--------------

Claosaurus, Trachodon, Nodosaurus, Palwoscineus. Cretaceous. -
Skulls of dinosaurs; showing size of brain. ....-...---.---.-.--
Braincasts!of dinosaurs): 2s¢- aoa eee ecee eee ene eee Soe eee
Teeth of predentate dinosaurs] -0----- 2 9 ees ee nee
Pubes.of predentateidinosaurs —- = 222-20 2256 -\ 225 ace eee
Tschiaiof predentate dinosanra) <2 22-42-25 see a= ae eee
Pelves of predentate dinosaurs ...----.---- ---2---------s5----00
Restoration of Compsognathus longipes Wagner --.-..-----
Restoration of Scelidosaurus Harrisonii Owen .....-..---.-.-.
Restoration of Hypsilophodon Foxii Huxley -.--...-.--..-.-.--
Restoration of Iguanodon Bernissartensis Boulenger - a

Fic. 1. Geological horizons of vertebrate fossils in North America... --..--
2. Slab of Connecticut River sandstone; showing foatncinien of ip
dinosaurs on a surface marked by raindrop impressions.-.--.-..-----

(AIH TP

. Left leg and foot of Hallupus victor Marsh....---...--...-----------
. United metatarsal bones of Ceratosaurus nasicornis Marsh ..-.-.----
United metatarsal bones of great Penguin (Aptenodytes Pennantii).
Tooth of Astrodon Johnstoni Weidy- ---2-2--s2-4ss-+--- === Sse
. Cervical rib of Apatosaurus ajax Marsh; outer view....------.------
; Lhe same:rib;)inneriview ....--.2-2 -.02-oesscscee es ace eee eee
. Proximal end of rib of Brontosaurus excelsus Marsh; front view-.---

10:, The\.same bones back view...2.. as 22h ce eee eee eee eee
11., Lhe same; superior view=.--.--0--=- 4-5-1 ses ee eee eee
12. Sternal ribs of Brontosaurus excelsus; outer view.--.-.----------..-
13. The same specimen; inner view--- ---- 2. --s=- = - sea eee

ILLUSTRATIONS.

Fig. 14. Sternal rib of same individual; outer view-.....--...--------------
Tbe WG SETS IHS TMAEE AG bo cscs caesar sdotaobe dopaeserso sess saeced
16s Pelwistof Bron tosaurusiexcelSuse ss ease eee eceeieeine acme eee eee =
17. First metacarpal of Brontosaurus amplus Marsh; front view -.------
TE INNS. REE) WANS GIGS TaGirenSc caeaas onecususanes ssne seocas enue cbOsSr
1G). TESTE) ONG OF GENNOsoscsspescoas Sesode coos canase coes cosas ssesue cs
OIL IDSA GG! OF GPM sccs ss5dée Soccbe SeuSse obSeos bts Sass sedoteaooeesES
21. Terminal phalanx of Brontosaurus excelsus; outer view ....---.----
22), UNTER WONOS BBO WIE foocc coca bass coca cogs odes asceeeoousoo Bees
235 TheisameseiNn CLaviO wise ae is sae ee he Oo alse eaialaaeleine see ane
24. Caudal vertebra of Barosaurus lentus Marsh; side view. .---..------
25. The same vertebra, in section; front view. ---...---..-.--.----------
265 The same vertebra bottomeyiewsss5- === see See eee ie eee
Zio kulloieDiplodocus) loncusiVarshieseeeeeeenie ae eae eee nee eee ees
28 Dentary bone of Diplodocus longus. -...-----..-------.- --2---------
29° Sternal plateiof Brontosaurusampluss.ee----s)2 soe sees eee eee
30. Sternal plate of Morosaurus grandis Marsh ........----.-.---..-----
31. Dorsal vertebra of Morosaurus grandis; front view ..-...-.--..-----
S2aeLhe | samenvertobra S10 O\vlO We seem aaa e lesa e eee eee eae
33. Transverse section through centrum of same-......-.----------------
34. Neural cavity in sacrum of Morosaurus lentus Marsh...-....--..----
35. Dorsal vertebra of Pleurocceelus montanus Marsh; side view. -.-...----
36.) he samenverteprar| hO piviOW= esceeer ee ee cean ae eee. cease aeeeen=
Sie TUTE RE OR EG ec SON Gasser oaes eSn6 aGes SoaSan cans ReEdeo Hee RoseSREess
38. Caudal vertebra of same individual; front view--...-...----..-----
38), HENS) EMI GNS BIG) Wy fescs ceos coos cobs cadens sesabe Soo cScoEs
405 -The: samesnbackaviewe qt 2c acces cee ae eee he eee eecelaereaes
41 yThesame; top View =.-2st. ss. -Ss5 weceee ane ena eee. « Semele sernece
42. Dentary bone of Nanosaurus agilis Marsh; seen from the left......--
43. Nlium of same individual; left side.-..---...----.+------5--.--s----
44. Left femur of Nanosaurus rex Marsh; front view.----.-----.--------
ADE rosimalendhOfiSaMe | se. 8 oe aaa eee ee sero S)feeeleeneeereeheeee
AG=hhe same) PONEs) SIUCwWiIOW) 22-21 os oe ale sea lee eee ee eee eee
Alp Chevsame's: back View... 28-- .2eoaees sto sece an teensoseee cee meeee eee
(S35 JDIGCN GIG LQ EE IGS Sn aE Sea ase ra aSes conbencapess suehes seudessoeraS
49. Terminal phalanx, manus of Ornithomimus sedens Marsh; side view.
50s chewsame phalanx stron ti viGwr = 152) = 2c = sa/iees teens eae ceeen ee
Sime Dhesame ssbackevie won fe eee oc. ete aisle elo een eee eerie ER eee
5ISLrOxXiMAlIeNd) Ol SAMO’ = looses oe os sae a ee cle ee Se eue ee siamese es
boa Map ote onverselC ountysiWiyOMIn Ger = ee eee e eae eles cee
54. Skull of Torosaurus gladius Marsh.............--..--.--------------

SoD lin oi @liosaurusjaptlis: Marshes sere screener aerieneseeeeree cee
56. Restoration of Aétosaurus ferratus Fraas........-...----------.-----
57. Diagram of left hind limb of Alligator mississippiensis Gray -..-----
58. Diagram of left hind limb of Aétosaurus ferratus_-..--..-.--...--.--.
59. Diagram of left fore limb of Hallopus victor Marsh.-....---...-----
60. Diagram of left hind limb of same individual....-..--....---.-.-----
61. Left hind leg of Laosaurus consors Marsh.-.-..-...------.------------
62. Diagram of pelvis of Belodon Kapffi von Meyer...---....-.---.----
63. Pelvis of Morosaurus lentus Marsh-.....-.------------------+-------
64. Pelvis of Ceratosaurus nasicornis Marsh -.-.- ee ieee peti One
65. United metatarsal bones of Ceratosaurus nasicornis.--.-.....-.-.----
66. United metatarsal bones of great Penguin. ..-.....---..--.---.------

MEER

THE DINOSAURS OF NORTH AMERICA.

By O. C. MARSH.

INTRODUCTION.

Among the many extinct animals that lived in this country in past
ages, none were more remarkable than the dinosaurian reptiles which
were so abundant during Mesozoic time. This group was then repre-
sented by many and various forms, including among them the largest
land animals known, and some, also, very diminutive. In shape and
structure, moreover, they showed great variety, and in many other
respects they were among the most wonderful creatures yet discovered.

The true place of these reptiles in the animal kingdom has been a
matter of much discussion among anatomists, but the best authorities
now regard them as constituting a distinct subclass of the Reptilia.
Some of the large, earlier forms are apparently related to the Croco-
dilia, while some of the later, small, specialized ones have various
points of resemblance to birds. These diversified characters make it
difficult to classify the dinosaurs among themselves, and have led some
writers to assert that these reptiles do not form a natural group, but
belong to divisions remotely connected and not derived from a common
ancestry.

It is not within the province of the present article to discuss in
detail the classification of this group, nor to treat fully the various
questions relating to the genealogy of dinosaurs, about which little is
really known. It may, however, be stated in few words that three
great divisions of the Dinosauria are now generally recognized, which
may be properly regarded as distinct orders. For these groups the
writer has proposed the names Theropoda, for the one including the
carnivorous forms, and Sauropoda and Predentata, for the two herbiv-
orous groups, the last order being made up of three separate suborders;
namely, the Stegosauria, the Ceratopsia, and the typical Ornithopoda.
The first of these suborders contains large dinosaurs more or less pro-
tected by a dermal covering of bony plates; the second group includes
the huge horned dinosaurs; and the third is made up of the forms that
in shape and structure most nearly resemble birds.

143

144 DINOSAURS OF NORTH AMERICA.

The nearer relations of these groups to one another and to allied
forms will be treated more fully in the concluding portion of this article.

The geological range of the Dinosauria, so far as at present known,
is confined entirely to the Mesozoic, or the Age of Reptiles. The first
indications of the group are found in the lower Triassic, and during
this period these reptiles increased in number and size. In Jurassie
time they were especially abundant, and in size and diversity of form
far surpassed all other forms of vertebrate life then existing. During
the entire Cretaceous they were represented by many strange and
highly specialized types, and at the close of this period all apparently
became extinct.

The wide geographical extent of these reptiles is also of interest.
While North America seems to have contained the greatest number of
different types, some of the larger species are now known to have lived in
the southern half of this continent. Europe stands next to America in
variety and number of these reptiles, large and small. In Asia, Africa,
and Australia, also, characteristic remains have been discovered, and
doubtless many more will be found at no distant day. The geological
horizous in which the dinosaurian remains of the Old World occur are
essentially the same as those in which the corresponding types have
been found in America.

The introduction and succession of the Dinosauria in North America
form a most interesting chapter in the life-history of this continent, and
one that has an important bearing on geology as well. As these rep-
tiles were the dominant types of land animals during the whole of
Mesozoic time, and the circumstances under which they lived were
especially favorable to the preservation of their remains, the latter
mark definite geological horizons, which have proved of great serv-
ice mm ascertaining the age of large series of strata containing few
other characteristic fossils. In this way one important horizon in the
Jurassic and another in the Cretaceous have been accurately
determined by the remains of the gigantic dinosaurs entombed in
them, while still other lines have been approximately drawn by less
characteristic fossils from the same group 01 reptiles.

In describing briefly the various dinosaurs now known to have lived
in North America, it will be most instructive to begin with the oldest,
in the Triassic, and then treat of their successors as they left their
remains in subsequent deposits of Jurassic and Cretaceous age. To
make this succession clear to the reader, the diagram on page 145 (tig. 1)
has been prepared. This diagram represents the principal geological
horizons of vertebrate fossils in North America, as determined by the
writer, and if carefully examined will be found in reality to be a synop-
sis of the whole subject. The first appearance, so far as known, of
each important group of vertebrate animals may be ascertained,
approximately, from the data given. Some of the more recent genera of
each group are also recorded, with the period in which they lived.

MARSH. ] GEOLOGICAL HORIZONS. 145

Recent. | Tapir, Peccary, Bison.
Quaternary. | Bos, Equus, Tapirus, Dicotyles, Megatherium, Mylodon.

| Equus Beds. | Equus, Tapirus, Elephas. |
| Pliocene.| 5,->- § Pliohippus, Tapiravus, Mastodon, Procamelus. |
| Pliohippus Beds. ¢Aceratherium, Bos, Morotherium, Platygonus.
S Miohippus Beds. Miohippus, Diceratherium, Thinohyus, Protoceras. i
<= oy rar ) Oreodon, Eporeodon, Hyenodon, Moropus, Ictops.
3 - | Miocene. Oreodon Beds. (Hyracodon, Agriocherus, Colodon, Leptocherus.
s Brontotherium Beds!) Brontotherium, Brontops, Allops, Titanops, Titano-
iS) |? theritum, Mesohippus, Ancodus, Entelodon.
| Diplacodon Beds. | Diplacodon, Epihippus, Amynodon, Eomeryx.
nate \Dinoceras, Tinoceras, Uintatheriuwm, Paleosyops,
yop
moses Dinoceras Beds. 2 Orohippus, Hyrachyus, Colonoceras, Homacodon.
| | * | Heliobatis Beds. Heliobatis, Amia, Lepidosteus, Asineops, Clupea.
| : a \ Coryphodon, Eohippus, Bohyus, Hyracops, Parahyus.
} | Coryphodon Beds. |)Lemurs, Ungulates, Tillodonts. Rodents, Serpents.
| — = = Er
Ceratops Beds of | Ceratops, Triceratops, Claosaurus, Ornithomimus,
| pees TU Mammals, Cimolomys, Dipriodon, Selenacodon,
#: Laramie Series. | Nanomyops, Stagodon. Birds, Cimolopteryzx.
| ae Fox Hills Group. | ;
j Tetaceous. gatas = = =
| = Golorado Series on. | Birds with Teeth, Hesperornis, Ichthyornis, Apatornis.
= IB tasanodon Beds | Mosasaurs, Edestosaurus, Lestosaurus, Tylosaurus.
ls - "| Pterodactyls, Pteranodon. Plesiosaurs, Turtles. __
3 Dakota Group.
| 2 = a 5
is ; Atlanto3aurus Beds. { Dinosaurs, Brontosaurus, Morosaurus. Diplodocus,
Jurassic. Baptanodon Beds. Stegosaurus, Camptosaurus, Ceratosaurus. Mam-
} dallopus Beds. mals, Dryolestes, Stylacodon, Tinodon, Ctenacodon.
o First Mammals, Dromatherium. First Dinosaurs,
Triassic. tozoum, or Anchisaurus, Ammosaurus, Bathygnathus, Clepsy-
Conn. River, Beds.| _s@urus. Many footprints. Crocodiles, Belodon.
| Fishes, Catopterus, Ischypterus, Ptycholepis.
Permian. Nothodon Beds. | Reptiles, Nothodon, Eryops, Sphenacodon.
, | First Reptiles (?) Hosawrus. Amphibians, Baphetes,
SS ee Coal Measures, or | Dendrerpeton, Hylonomus, Pelion. Footprints,
_—S = . Eosaurus Beds. | Anthracopus, Allopus, Baropus, Dromopus, Hylo-
———— ar boniferous | pus, Limnopus, Nasopus.
Subcarboniferous, | First known Amphibians (Labyrinthodonts).
or Sauropus Beds. A ¥
Footprints, Sawropus, Thenaropus.
‘ Dinichthys Beds. Dinichthys, Acanthodes, Bothriolepis, Chirolepis, Ola-
Devonian. ; NS
Lower Devonian. dodus, Dipterus, Titanichthys.
Upper Silurian.
Silurian. First known Fishes.
Lewer Silurian.
|
|
Cambrian. Primordial.
Huronian.
No Vertebrates known.
SS \] SS aa °
| TES Archean.
RN Laurentian.
| |
| ue 1

Fic. 1.—GEOLOoGICAL HoRIzZONS OF VERTEBRATE FOSSILS IN NORTH AMERICA.

16 GEOL, PT 1——10

146 DINOSAURS OF NORTH AMERICA.

ID IN ARAL Tl,

TRIASSIC DINOSAURS.
THEROPODA.

The remains of dinosaurs first discovered in this country were found
in the Triassic sandstone of the Connecticut Valley, so famous for its
fossil footprints, many of which were long supposed to have been made
by birds. It is a remarkable fact that the first discovery in this sand-
stone was that of the skeleton of a true dinosaur, found in East Wind-
sor, Conn., in 1818, many years before the first footprints were recorded.
This discovery was announced in the American Journal of Science for
November, 1820, and later numbers contain descriptions of the remains,
some of which are now preserved in the museum of Yale University.

Fi, 2.—Slab of Connecticut River sandstone; showing footprints of two dinosaurs on a surface
marked by raindrop impressions. One-tenth natural size. Triassic, Massachusetts.

When the footprints in the Connecticut sandstone first attracted
attention, in 1835, many of these impressions resembled so closely
those made by birds that they were from the first attributed to that
class, and for many years it was not seriously questioned that all the
three-toed impressions, even the most gigantic, were really the foot-
prints of birds. The literature on this subject is very extensive, but
its value to science has been seriously impaired by the discovery of
dinosaurian remains in various parts of the world, which prove that
many of these reptiles were remarkably bird-like and that their tracks
could not be distinguished from those of birds.

MARSH. ] ANCHISAURID®. 147

It was also found that some of the most bird-like footprints of the
Connecticut Valley were not made by birds, but by quadrupeds which
usually walked on their hind feet, yet sometimes put their fore feet
to the ground. Others occasionally sat down, and left an impression
which proved that they, too, were not birds. Still others showed rep-
tilian affinities in various ways; so that to-day it may be stated that
there is no evidence that any of these impressions in the Connecticut
sandstone were made by birds. This is true, also, of similar bird-like
footprints from strata of the same age in different portions of this
country, and will likewise hold good for similar impressions from other
parts of the world. It is quite probable that birds existed during the
Triassic period, but at present there is no proof of it.

ANCHISAURIDZ.

A few bones of a dinosaur were found at Upper Milford, Lehigh
County, Pa., in 1847, in strata regarded as Triassic. The animal was
named Clepsysaurus pennsylvanicus by Dr. Isaac Lea, in the Proceed-
ings of the Academy of Natural Sciences of Philadelphia, in 1851, and
he subsequently described and figured the remains in the Journal of
the Academy in 1853. They are now preserved in the museum of that
society.

The next discovery of importance in this formation was reported
from Prince Edward Island. Canada. The specimen was an upper jaw
with teeth, in good preservation, indicating a true dinosaur of consid-
erable size. This specimen was figured and described under the name
Bathygnathus borealis by Dr. Leidy in the Journal of the Academy of
Natural Sciences of Philadelphia for 1854, and is now in the museum
of that institution.

The next important discovery of a Triassic dinosaur in this country
was made in the Connecticut sandstone about 1856, at Springfield,
Mass., and portions of the skeleton are now preserved at Amherst
College. This animal was a true carnivorous dinosaur, very similar to
the first one described, and from essentially the same horizon. This
discovery was announced by Prof. Edward Hitchcock in 1858, in his
Ichnology of New England, and the remains were described and fig-
ured by Edward Hitchcock, jr., in 1865, in a supplement to the above
volume. The animal was then nawed Megadactylus polyzelus, and
its affinities have since been discussed by various authors.

ANCHISAURUS.

A discovery of greater interest was made in 1884, near Manchester,
Conn. The skeleton of another carnivorous dinosaur of larger size, but
nearly allied to the one last mentioned, was found in a coarse conglom-
erate, in essentially the same horizon of the Connecticut River sand-
stone. This skeleton was probably complete and in position when
discovered, but as its importance was not recognized at the time the
posterior portion only was saved, which was secured later by the writer

148 DINOSAURS OF NORTH AMERICA.

for the Yale University museum. This part consisted of the nearly
entire pelvic arch, with both hind limbs essentially complete and in the
position they were when the animal died. The remains preserved
indicate an animal about 6 or 8 feet in length, which was named Anchi-
saurus major by the writer, in the American Journal of Science for
April, 1889.1 This generic title replaced Megadactylus, which was pre-
occupied. Subsequently, in 1891, this specimen was made the type of
the genus Ammosaurus.

A still more important discovery of another small dinosaur was made
later at the same locality, only a few feet distant from the spot where
the fossil last mentioned was entombed. This reptile, named Anchisau-
rus colurus by the writer, is one of the most perfect dinosaurs yet dis-
covered in the Triassic. The skull and limbs and most of the skeleton
were in fair preservation, and in natural position, so that nearly all
the important points of the osseous structure can be determined with
certainty. Some of these are here placed on record as typical of the

group.
THE SKULL.

The skull was somewhat crushed and distorted, but its main features
are preserved. In PI. II, fig. 1, a side view of this skull is given, one-
half natural size. One prominent feature shown in this view is the
bird-like character of the skull. The nasal aperture is small and well
forward. There is an antorbital opening and a very large orbit. The
latter is elongated-oval in outline. It is bounded in front by the pre-
frontal, above by the same bone and a small extent of the frontal, and
further back by the postfrontal. The postorbital completes the orbit
behind and the jugal closes it below. The supratemporal fossa is large
and somewhat triangular in outline. The infratemporal fossa is quite
large and is bounded below bya slender quadratojugal. The quadrate is
much inclined forward. The teeth are remarkable for the great number
in use at one time. Those of the upper jaw are inclined forward, while
those below are nearly vertical. The lower jaw has the same general
features as this part in the typical Theropoda.

In Pl. ILI, figs. 1 and 2, the same skull is shown, also one-half
natural size. The top of the skull, represented in fig. 1, is consid-
erably broken, and this has made it difficult to trace the sutures, but
the general form and proportions of the upper surface are fairly repre-
sented. In fig. 2 only the back portion of the cranium is shown. The
foramen magnum is remarkably large, and the occipital condyle is
smal] and oblique. The basipterygoid processes are unusually short.

The neck vertebre of this skeleton are long and slender and very
hollow. Their articular ends appear to be all plane or slightly con-
cave. The trunk vertebre are more robust, but their ceutra are quite
long. The sacrals appear to be three in number.

! The original descriptions of nearly all the other fossils discussed in the present paper may be found
in the same journal.

MARSH. ] ANCHISAURIDZE. 149

THE FORE LIMBS.

The scapular arch is well preserved. The scapula, shown in Pl. II,
fig, 2, s, is very long, with its upper end obliquely truncated. The
coracoid is unusually small and imperforate. The sternum was of car-
tilage, some of which is preserved. The humerus is of the same
length as the scapula and its shaft is very hollow. The radius and
ulna also are both hollow, and are nearly equal in size.

There is but one carpal bone ossified in this specimen, and this is
below the ulna. There were five digits in the manus, but only three
of functional importance, the first, second, and third, all armed with
sharp claws. The fifth was quite rudimentary. The fore foot of the
type species of Anchisaurus is shown, one-half natural size, on Pl. III,
fig. 5.

THE HIND LIMBs.

The pelvic bones are shown in fig. 3 of Pl. II. The ilium is small,
with a slender preacetabular process. The ischia are elongated, and
their distal ends are slender and not expanded at the extremity. The
pubes are also long, imperforate, and not coossified with each other.
The anterior part is a plate of moderate width.

The femur is much curved and longer than the tibia. The latter is
nearly straight, with a narrow shaft. The fibula when in position was
not close to the tibia, but curved outward from it. All these bones
have very thin walls. The astragalus is small, closely applied to the
tibia, and has no ascending process. The calcaneum is of moderate
size and free. There are only two tarsal bones in the second row.

The hind foot had four functional digits, all provided with claws.
The fifth was represented only by a rudiment of the metatarsal. The
first digit was so much shorter than either the second, third, or fourth,
that this foot would have made a three-toed track very much like the
supposed bird-tracks of the Connecticut River sandstone.

ANCHISAURUS SOLUS.

A fortunate discovery has recently brought to light almost the
entire skeleton of still another diminutive dinosaur, which may be
referred to Anchisaurus, but clearly belongs to a distinct species. It
was found in nearly the same horizon as the remains above described,
and in the immediate vicinity, so there can be little doubt that it was
a contemporary. The skeleton is embedded in a very coarse matrix, so
difficult to remove that the investigation is only in part completed.
The portions uncovered show the animal to have been about 3 feet in
length, and of very delicate proportions. The bones of the skeleton
are nearly all extremely light and hollow, but most of them are in a fair
state of preservation.

The skull, so tar as it can now be observed, resembles the one just
described. The teeth are numerous, and inclined forward. The orbit

150 DINOSAURS OF NORTH AMERICA.

is very large. The quadrate is inclined forward, and the lower jaw is
robust. The entire skull is about 65™™ long, and the lower jaws are
of the same length.

The neck was very long and slender, the first five cervicals measur-
ing 80"™ in extent. The dorsals are aiso elongated, the last six cover-
ing a space of 135™", The number of vertebree in the sacrum can not
yet be determined. The caudal vertebrex are short, the first ten occu-
pying a space of 140™™,

The humerus has a very large radial crest, and is 66™™" in length.
The rest of the fore limb, so far as made out, is similar to that in the
species described. The tibia is about 88™™ in length. There were five
digits in the hind foot, but the fifth is represented only by the rudi-
mentary metatarsal. The animal was about as large as a small fox.

AMMOSAURUS.

The genus Ammosaurus, represented by remains of larger size from
the same strata, was also a typical carnivorous dinosaur, and appar-
ently a near ally of Anchisaurus. So far as at present known, the
footprints of the two reptiles would be very similar, differing mainly
in size.

On Pl. ITI, fig. 6, is shown an entire hind foot of Ammosaurus, one-
fourth natural size. In this foot the tarsus is more complete than in
Anchisaurus. The astragalus has no true ascending process, the cal-
caneum is closely applied to the end of the fibula, and there are three
well-developed bones in the second row. The fifth digit had only a
single phalanx. The sacrum and ilia of the type species of Ammo-
saurus are shown in fig. 3, and the ischia of Anchisaurus in fig. 4.

RESTORATION OF ANCHISAURUS.,
PLATE IV.

The Triassic dinosaurs known from eastern North America have now
been brietly reviewed. Remains of seven individuals are sufticiently
well preserved to indicate the main characters of the animals to which
they pertained. These were all carnivorous forms of moderate size,
and the known remains are from essentially the same geological horizon.

The genus Anchisaurus, one of the oldest known members of the
Theropoda, is so well represented by parts of four skeletons from these
deposits that a restoration of one species can now be made with con-
siderable certainty. This has been attempted, and the result is given,
one-twelfth natural size, in the accompanying PLIV. The animal was
about 6 feet in length.

The skeleton chosen for this restoration is the type specimen of
Anchisaurus colurus, described by the writer in the American Journal
of Science in 1891 and1893. This skeleton when discovered was entire,
and apparently in the position in which the animal died. Portions of

MarsH.] DINOSAURIAN FOOTPRINTS. 151

the neck and the tail vertebre were unfortunately lost, but the skull
and nearly all the rest of the skeleton were saved. The parts missing
are fortunately preserved in a smaller specimen of an allied species
(Anchisaurus solus) found at the same locality, and these have been
used to complete the outline of the restoration. Portions of two other
specimens, nearly allied, and from the same horizon, were also avail-
able, and furnished some suggestions of value.

The restoration, as shown on Pl. IV, indicates that Anchisaurus
colurus was one of the most slender and delicate dinosaurs yet dis-
covered, being surpassed in this respect only by some of the smaller
bird-like forms of the Jurassic. The position chosen is one that must
have been habitually assumed by the animal during life, but the com-
paratively large fore limbs suggest the possibility of locomotion on all
four feet. The compressed terminal digits of the fore feet, however,
must have been covered by very sharp claws, which were used mainly
for prehension, and not for walking.

The small head and bird-like neck are especially noticeable. The
ribs of the neck and trunk are very slender. The tail apparently
dittered from that of any other dinosaur hitherto described, as it was
evidently quite slender and flexible. The short neural spines and the
diminutive cheyvrons, directed backward, indicate a tail not compressed,
but nearly round, and one usually carried free from the ground.

DINOSAURIAN FOOTPRINTS.

The present restoration will tend to clear up one point long in doubt.
The so-called ** bird tracks” of the Connecticut River sandstone have
been a fruitful subject of discussion for half a century or more. That
some of these were not made by birds has already been demonstrated
by finding with them the impressions of fore feet. Although no bones
were found near them, others have been regarded as footprints of birds
because it was supposed that birds alone could make such series of
bipedal, three-toed tracks and leave no impression of a tail.

lt is now evident, however, that a dinosaurian reptile like Anchi-
saurus and its near allies must have made footprints very similar to, if
not identical with, the ‘‘bird tracks” of this horizon. On a firm but
moist beach only three-toed impressions would have been left by the
hind feet, and the tail could have been kept free from the ground. On
a soft, muddy shore the claw of the first digit of the hind foot would
have left its mark, and perhaps the tail also would have touched the
ground. Such additional impressions the writer has observed in vari-
ous series of typical “bird tracks” in the Connecticut sandstone, and
all of them were probably made by dinosaurian reptiles. On Pl. V and
also p. 146, fig. 2, are shown several series of Triassic footprints, which
were probably all made by dinosaurs. No tracks of true birds are
known in this horizon.

152 DINOSAURS OF NORTH AMERICA.

DISTRIBUTION OF TRIASSIC DINOSAURS.

It is a remarkable fact that the seven skeletons of Triassic dino-
saurs now known from the eastern part of this continent are all car-
nivorous forms and of moderate size. There is abundant evidence from
footprints that large herbivorous dinosaurs lived here at the same time,
but no bones nor teeth have yet been found. In the western part of
this country a few fragments of a large dinosaur have been discovered
in strata of supposed Triassic age, but with this possible exception
osseous remains of these forms appear to be wanting in this horizon.

Fragmentary remains, also, of dinosaurs have been found in the Tri-
assic deposits of Pennsylvania and North Carolina, but they throw little
light on the animals they represent. Footprints, apparently made by
dinosaurs, occur in New Jersey in the same horizon as those of the Con-
necticut Valley. Impressions of similar form have been discovered also
in the Triassic sandstones of New Mexico. A few bones of a large dino-
saurian were found by Prof. J.S. Newberry, in strata apparently of
this age, in southeastern Utah. These remains were named by Pro-
fessor Cope, Dystropheus viemale, in 1877, but their near affinities have
not been determined. A single vertebra, apparently belonging in this
group, had been previously found at Bathurst Island, Arctic America,
and described by Prof. Leith Adams, in 1875, under the generic name
Arctosaurus.

The European Triassic dinosaurs, with which the American forms
may be compared, are mainly represented by the two genera Theco-
dontosaurus Riley and Stutchbury, from the upper Trias, or Rheetic,
near Bristol, in England, and Plateosaurus (Zanclodon) von Meyer,
from nearly the same horizon in Germany. The writer has investigated
with care the type specimens and nearly all the other known remains
of these genera found at these localities.

Remains of dinosaurs have been found in Triassic strata, also, in
India, in South Africa, and in Australia, but the specimens discovered
were mostly fragmentary, and apparently indicate no new types.

BeAG Re tele:
JURASSIC DINOSAURS.

During the Jurassic period the dinosaurs of North America attained
remarkable development, and, asa group, appear to have reached their
culmination. The Theropoda, or carnivorous forms, which were so abun-
dant, though of moderate size, in the Triassic, were represented in the
Jurassic by many and various forms; some were very minute, but others
were of gigantic size and dominated all living creatures during this age.
The herbivorous dinosaurs, however, were the most remarkable of all,
some far surpassing in bulk any known land animals; others, also of
huge dimensions and clad in coats of mail, assumed the most bizarre

MARSH.] HALLOPUS. 153

appearance; while others still, diminutive in size and of light and grace-
ful form, were so much like birds that only a comparative anatomist,
with well-preserved skeletons of both before him, could tell one from
the other. In this case, at least, a single tooth or bone would not
suffice, though a Cuvier sat in judgment.

In the western part of this country, especially in the Rocky Mountain
region, vast numbers of dinosaurs lived and flourished during all Juras-
sic time. Their remains are so abundant, and so perfectly preserved
in many localities, that those already obtained have furnished the basis
for a classification of the whole group. This classification, first pro-
posed by the writer in the American Journal of Science in 1881, and
subsequently emended, may be appropriately used here in considering
the American dinosaurs from this formation. It will be discussed more
fully in the concluding part of the present paper.

THEROPODA.

Near the base of the Jurassic in the Rocky Mountain region an
interesting geological horizon has been defined as the Hallopus beds,
since here only remains of a remarkable dinosaurian, named by the
writer Hallopus victor, have been found. The position of this horizon
is shown in the diagram on page 145 (fig.1). Another reptile, Nano-
saurus, the most diminutive dinosaur known, occurs in the same strata.
This horizon is believed to be lower than that of the Baptanodon beds,
although the two have not been found together. The Hallopus beds
now recognized are in Colorado, below the Atlantosaurus beds, but are
apparently quite distinct from them.

HALLOPUS.

The type specimen of Hallopus, the only one known, is the greater
part of the skeleton of an animal about the size of a rabbit. This was
described by the writer in 1877, and referred to the Dinosauria. On
further investigation it was found to be distinet from all the known
members of that group, and in 1881 it was made the type of a new
suborder, the Hallopoda. One of the most distinctive characters,
which separated it widely from all known dinosaurs, was seen in the
tarsus, which had the caleaneum much produced backward. This
feature, in connection with the greatly elongated metatarsals, suggested
the generic name Hallopus, or leaping foot.

The general structure of the pelvis, especially of the ilium and pubis,
as well as the proportions of the entire hind limb, suggested an affinity
with Compsognathus, from the Jurassic of Bavaria, and the writer, in
his classification of the dinosaurs, in 1882, placed the Hallopoda next
to the suborder Compsognatha, which belongs in the great group of
carnivorous dinosaurs, the Theropoda.

The writer has since reexamined the type specimen and had various
parts of if uncovered, so far as the hard matrix of red sandstone would
permit. This has brought to light other portions of the skeleton, so

154 DINOSAURS OF NORTH AMERICA.

that now many of the more important characters of the group can be
determined with certainty.

FORE AND HIND LIMBS.

In its present condition the specimen shows both the fore and hind
limbs in good preservation, portions of the scapular arch, and appar-
ently the entire pelvis and sacrum, various vertebra, ribs, and other
parts of the skeleton. It is doubtful if any portions of the skull are
sufficiently well preserved for determination. On Pl. VI are given out-
line restorations of the fore and hind limbs of this specimen.

The scapula is of moderate length, and its upper portion broad and
thin. The humerus is slender, with a strong radial crest. The shaft is
very hollow, with thin walls, and the cavity extends almost to the distal
end. The latter is but little expanded transversely. The radius and
ulna are short, and were closely applied to each other. There were but
four digits in the manus, the first being short and stout, and the others
slender.

Fic. 3.—Left leg and foot of Hallopus victor Marsh; side view. Natural size.
a, astragalus; c, caleaneum; d, tarsal; f, femur; ¢, tibia; J7, second metatarsal; V, remnant of fifth
metatarsal.

All three pelvic bones aided in forming the acetabulum, as in typical
dinosaurs. The ilia are of the carnivorous type, and resemble in form
those of Megalosaurus. The pubes are rod-like, and projected down-
ward and forward. The distal ends are closely applied to each other,
but not materially expanded, and in the present specimen are not
coossified with each other. The ischia projected downward and back-
ward, and their distal extremities are expanded, somewhat as in the
Crocodilia.

The femur is comparatively short, with the shaft curved and very
hollow. The tibia is nearly straight, much longer than the femur, and
its shaft equally hollow. The fibula was slender and complete, but
tapered much from above downward. Its position was not in front of
the tibia, as in all known dinosaurs, but its lower extremity was out-
side, and apparently somewhat behind, the tibia.

The astragalus is large, and covered the entire end of the tibia, but
was not coossified with it. The caleaneum is compressed transversely,

MARSH. | C@LURUS. 1595)

and much produced backward. It was closely applied to the outside of
the astragalus, and although agreeing in general form with that of a
crocodile, strongly resembles the corresponding bone in some mammals.
The tarsal joint was below the astragalus and caleaneum. There
appears to be but a single bone in the secend tarsal row, although this
may be composed of two or more elements.

There were but three functional digits in the hind foot, and their
metatarsals are greatly elongated. The first digit seems to be wanting,
and the fifth is represented only by a remnant of the metatarsal. The
posterior limbs, as a whole, were especially adapted for leaping, and are
more Slender than in almost any other known reptile.

The main characters of the posterior limb are shown in fig. 3, on the
opposite page, which represents the bones of the left leg and foot, uat-
ural size, in the position in which they lay when uncovered. All the
bones figured are still firmly embedded in the matrix.

There are but two vertebre in the sacrum. The other vertebrie pre-
served have their articular faces biconcave. The chevrons are slender
and very elongate.

Taken together, the known characters of Hallopus clearly indicate
dinosaurian affinities rather than those of any other group of reptiles,
and if the Dinosauria are considered a subclass the Hallopoda at pres-
ent may be regarded as a group of dinosaurs standing further apart
from typical forms than any other.

CasLURUS.

In the horizon above, the Atlantosaurus beds of the upper Jurassic,
the carnivorous dinosaurs are of larger size, and some of them were
among the most powerful and ferocious reptiles known. The one
nearest Hallopus in size and general characteristics is Ccelurus,
described by the writer in 1879 and now known from several skeletons,
although no good skull has yet been discovered.

The skull of Ccelurus is known only from fragments. The teeth are
typical of the order Theropoda. One is shown on PI. VII, fig. 1. The
most marked feature in all the known remains of Ceelurus is the
extreme lightness of the bones, the excavations in them being more
extensive than in the skeleton of any other known vertebrate. In the
vertebre, for example, the cavities are proportionately larger than in
either pterodactyls or birds, the amount of osseous tissue retained being
mainly confined to their exterior walls. In Pl. VII cervical, dorsal,
and caudal vertebre are figured, with transverse sections of each to
illustrate this point. Even the ribs of Celurus are hollow, with well-
defined walls to their large cavities.

THE VERTEBR2.

The vertebre of Colurus now known are from various parts of the
column, and most of them are in good condition. Three of these are
represented, natural size,in Pl. VII. The cervicals are large and elon-

156 DINOSAURS OF NORTH AMERICA.

gate, and were locked together by strong zygapophyses. The first
three or four behind the axis had the front articular face of the cen-
trum somewhat convex, and the posterior one deeply concave. All
the other cervicals were biconcave, as were also the vertebre of the
trunk and tail. The articular faces of the cervicals are inclined, show-
ing that the neck wascurved. The anterior cervical ribs were coossified
with the centra,as in birds. Figs. 2,2a,and 2b, Pl. VII, represent a
cervical vertebra from near the middle of the neck. The cavities in
the cervicals are connected with the outside by comparatively large
pheumatic openings. The neural canal is very large, and traces of the
neurocentral suture are distinct. :

The dorsal vertebrae of Cclurus are much shorter than the cer-
vicals. The centra have a deep cup in front and a shallow concavity
behind. These articular faces are nearly at right angles to the axis of *
the trunk. The neural spine is elevated and compressed. The trans-
verse processes are elongate. The ribs preserved have undivided
heads. <A posterior dorsal is represented in Pl. VII, figs. 3, 5a, and 30.
Thesuture of the neural arch is distinct in this specimen. The foramina
leading to the cavities in the dorsal vertebrie are quite small.

The caudal vertebrie are elongate and very numerous. They are all
biconcave, and all appear to have been without chevron bones. An
anterior caudal is figured in Pl. VII, fig. 4, and the accompanying
section shews the inner structure. In most of the caudals, the neuro-
central suture has entirely disappeared.

THE HIND LIMBS,

The limb bones of Coelurus are very hollow, and some of them appear
pneumatic. The metatarsals are quite long and slender. The terminal
phalanges of the hind feet are pointed, and in life were evidently covered
with sharp claws. The ilium is of the Megalosaurus type. The pubes
are slender, strongly coossified with each other, and terminated below
by a large foot-like process, as shown in Pl. X, figs. 3 and 4.

The characters of Co@lurus are so distinctive that it appears to
represent a separate family, which has been ealled by the writer the
Celuride. Several species of the genus are known in this country, all
of moderate dimensions, varying in size from that of a fox to that of a
wolf. Nearly all are from the Atlantosaurus beds of the West, but one
small species has been found in the Potomac beds on the Atlantic Coast.

CERATOSAURUS.

The most interesting carnivorous Ginosaur from the American Juras-
sic, and the one best known, is Ceratosaurus, which differs so widely
from the typical forms that it has been regarded as representing a dis-
tinct suborder. The type specimen of Ceratosaurus, described by the
writer in 1884, presented several characters not before seen in the
Dinosauria. One of these is a horp core on the skull; another is a

MARSH.) CERATOSAURUS. V5a

new type of vertebraas strange as it is unexpected; and athird is seen
in the pelvis, which has the bones all coossified, as in existing birds.
Among adult birds Archopteryx alone has the pelvic bones separate,
and this specimen of Ceratosaurus is the first dinosaur found with all
the pelvic bones anchylosed. The metatarsal bones are also coossi-
fied, a feature characteristic of birds, but not known hitherto in any
dinosaur. —

THE SKULL,

The skull of Ceratosaurus nasicornis is very large in proportion to
the rest of the skeleton. The posterior region is elevated, and mod-
erately expanded transversely. The facial portion is elongate, and
tapers gradually to the muzzle. Seen from above, the skull resembles
in general outline that of an alligator. The nasai openings are sepa-
rate and lateral, and are placed near the end of the snout, as shown in
PL VIL.

Seen from the side, this skull appears lacertilian in type, the general
structure being light and open. From this point of view one special
feature of the skull is the elevated, trenchant horn core, situated on
the nasals (Pl. VIII, fig. 1, 6). Another feature is the large open-
ings on the side of the skull, four in number. The first of these is the
anterior nasal orifice; the second, the very large triangular antorbital
foramen; the third, the large oval orbit; and the fourth, the still larger
lower temporal opening. A fifth aperture, shown in the top view of
the skull (Pl. VIII, fig. 3, h), is the supratemporal fossa. These open-
ings are all characteristic of the Theropoda, and are found also in the
Sauropoda, but the antorbital foramen is not known in any other
Dinosauria.

The plane of the occiput, as bounded laterally by the quadrates,
slopes backward. The quadrates are strongly inclined backward, thus
forming a marked contrast to the corresponding bones in Diplodocus
and other Sauropoda. The occipital condyle is hemispherical in gen-
erai form, and is somewhat inclined downward, making a slight angle
with the long axis of the skull. The basioccipital processes are short
and stout. The paroccipital processes are elongate and flattened, and
but little expanded at their extremities. They extend outward and
downward, to join the head of the quadrate.

The hyoid bones appear to be four in number. They are elongate,
rod-like bones, somewhat curved, and in the present specimen were
found nearly in their original position.

The parietal bones are of moderate size, and there is no pineal fora-
men. The median suture between the parietals is obliterated, but
that between these bones and the frontals is distinct.

The frontal bones are of moderate length, and are closely united on
the median line, the suture being obliterated. Their union with the
nasals is apparent on close inspection.

158 DINOSAURS OF NORTH AMERICA.

The nasal bones are more elongate than the frontals, and the suture
uniting the two moieties is obsolete. These bones support entirely the
large, compressed, elevated horn core on the median line. The lateral
surtace of this elevation is very rugose, and furrowed with vascular
grooves. It evidently supported a high, trenchant horn, which must
have formed a most powerful weapon for offense and defense. No
similar weapon is known in any of the carnivorous Dinosauria, but it
is not certain whether this feature pertained to all the members of this
group or was only a sexual character.

The premaxillaries are separate, and each contained only three fune-
tional teeth. In the genera Compsognathus and Megalosaurus, of this
order, each premaxillary contained four teeth; the same number found
in the Sauropoda. In the genus Creosaurus, from the American Juras-
sic, the premaxillaries each contain five teeth, as shown in PI. XII,
figeele

The maxillary bones in the present specimen are large and massive,
as shown in Pl. VIII, fig. 1. They unite in front with the premaxil-
laries by an open suture; with the nasals, laterally, by a close union;
and with the jugal behind, by squamosal suture. The maxillaries are
each provided with fifteen functional teeth, which are large, powerful,
and trenchant, indicating clearly the ferocious character of the animal.
These teeth have the same general form as those of Megalosaurus, and
the dental succession appears to be quite the same.

Above the antorbital foramen on either side is a high elevation
composed of the prefrontal bones. These protuberances would be of
service in protecting the orbit, which they partially overhang.

The orbit is of moderate size, oval in outline, with the apex below.
It is bounded in front by the lachrymal, above this by the prefrontal,
and at the summit the frontal forms for a short distance the orbital
border. The postfrontal bounds the orbit behind, but the jugal com-
pletes the outline below.

The jugal bone is L-shaped, the upper branch joining the postfrontal,
the anterior branch uniting with the lachrymal above and with the
maxillary below. The posterior branch passes beneath the quadrato-
jugal, and with that bone completes the lower temporal arch, which is
present in all known dinosaurs.

The quadratojugal is an L-shaped bone, and its anterior branch is
united with the jugal by a close suture. The vertical branch is closely
joined to the outer face of the quadrate.

The quadrate is very long and compressed antero-posteriorly. The
head is of moderate size, and is inclosed in the squamosal. The lower
extremity of the quadrate has a double articular face, as in some birds.
One peculiar feature of the quadrate is a strong hook on the upper
half of the outer surface. Into this hook a peculiar process of the
quadratojugal is inserted, as shown in PI. VIII, fig. 1.

The pterygoid bones are very large and extend well forward. The

MARSH] CERATOSAURUS. 159

posterior extremity is applied closely to the inner side of the quad-
rate. The middle part forms a pocket, into which the lower extremity
of the basipterygoid process is inserted. To the lower margin of the
pterygoid is united the strong, curved transverse bone which projects
downward below the border of the upper jaws, as shown in PI. VIII,
LES Als ie

There is a very short, thin columella, which below is closely united
to the pterygoid by suture, and above fits into a small depression of
the postfrontal.

The palatine bones are well developed, and after joining the ptery-
goids extend forward to the union with the vomers. The latter are
apparently of moderate size.

The parasphenoid is well developed and has a long, pointed, anterior
extremity.

The whole palate is remarkably open, and the principal bones com-
posing it stand nearly vertical, as in the Sauropoda.

THE BRAIN.

The brain in Ceratosaurus was of medium size, but comparatively
much larger than in the herbivorous dinosaurs. It was quite elongate,
aud situated somewhat obliquely in the cranium, the posterior end being
inclined downward. The position of the brain in the skull, and its rela-
tive size, are shown in PI. VIII, fig.3. A side view of the brain cast is
shown in Pl. LX XVII, fig. 2.

The foramen magnum is small. The cerebellum was of moderate size.
The optic lobes were well developed and proportionately larger than the
hemispheres. The olfactory lobes were large and expanded. The pitu-
itary body appears to have been of good size.

THE LOWER JAWS.

The lower jaws of Ceratosaurus are large and powerful, especially in
the posterior part. In front the rami are much compressed, and they
were joined together by cartilage only, as in all dinosaurs. There is a
large foramen in the jaw, similar to that in the crocodile, as shown in
Pl. VIII, fig. 1, 7’. The dentary bone extends back to the middle of this
foramen. The splenial is large, extending from the foramen forward
to the symphysial surface, and forming in this region a border to the
upper margin of the dentary. There were fifteen teeth in each ramus,
similar in form to those of the upper jaws.

THE VERTEBR2.

The cervical vertebree of Ceratosaurus differ in type from those in
all other known reptiles. With the exception of the atlas, which is
figured in Pl. IX, fig. 1, all are strongly cupped on the posterior end of
each centrum. In place cf an equally developed ball on the anterior
end, there is a perfectly flat surface. The size of the latter is such that
it can be inserted only a short distance in the adjoining cup, and this

160 DINOSAURS OF NORTH AMERICA.

distance is accurately marked on the centrum by a narrow articular
border, just back of the flat, anterior face. This peculiar articulation
leaves more than three-fourths of the cup unoccupied by the succeed-
ing vertebra, forming, apparently, a weak joint. This feature is shown
in Pl. IX, figs. 2, 3, and 4.

The discovery of this new form of vertebra shows that the terms
opisthocelian and proccelian, in general use to describe the centra of
vertebrie, are inadequate, since they relate to one end only, the other
being supposed to correspond in form. The terms convexo-concave,
concavo-convex, plano-concave, ete., would be more accurate and equally
euphonious.

In Ceratosaurus, as in all the Theropoda except Celurus, the cervical
ribs are articulated to the centra, not coossified with them, as in the
Sauropoda. The latter order stands almost alone among dinosaurs in
this respect, as all the Predentata—Stegosauria, Ceratopsia, and the
Ornithopoda—have free ribs in the cervical region.

The dorsal and lumbar vertebrie are biconcave, with only moderate
concavities. The sides and lower surface of the centra are deeply exca-
vated, except at the ends, as shown in Pl. IX, fig. 5. These vertebrae
show the diplosphenal articulation seen in Megalosaurus, and also in
Creosaurus, as shown in PI. XII, fig. 5.

All the presacral vertebr are very hollow, and this is also true of
the anterior caudals.

There are five well-coossified vertebre in the sacrum in the present
specimen of Ceratosaurus nasicornis. The transverse processes are
very short, each supported by two vertebr, and they do not meet at
their distal ends.

The caudal vertebre are biconcave. All the anterior caudals, except
the first, supported very long chevrons, indicating a high, thin tail,
well adapted to swimming (Pl. IX, fig. 6). The tail was quite long,
and the distal caudals were very short.

THE SCAPULAR ARCH.

The scapular arch of Ceratosaurus is of moderate size, but the fore
limbs were very small. The humerus is short, with a strong radial crest.
The radius and ulna are also very short, and nearly equal in size. The
carpal bones were only imperfectly ossified. There were four digits in
the fore foot, and all were armed with sharp claws. The second and
third digits were much larger than the first and fourth, and the fifth
was entirely wanting.

THE PELVIC ARCH.

The pelvic bones in the Theropoda have been more generally mis-
understood than any other portion of the skeleton in dinosaurs. The
ilia, long considered as coracoids, have been usually reversed in posi-
tion; the ischia have been regarded as pubes; while the pubes them-
selves have not been considered as part of the pelvic arch.

MARSH.) CERATOSAURUS. 161

Fortunately, iu the present specimen of Ceratosaurus, the illum,
ischium, and pubes are firmly coossified, so that their identification
and relative positions can not be called in question. The ila, more-
over, were attached to the sacrum, which was in its natural place in the
skeleton, and the latter was found nearly in the position in which the
animal died. The pelves of Ceratosaurus and of Allosaurus are shown
rea Ly Oe

The ilium in Ceratosaurus has the same general form as in Megalo-
saurus. In most of the other Theropoda, also, this bone has essentially
the same shape, and this type may be regarded as characteristic of the
order, except in Triassic forms. In Creosaurus the anterior wing is
more elevated, and the emargination below it wider, as shown in Pl.
XII, fig. 2, but this may be due in part to the imperfection of the border.

The ischia in Ceratosaurus are comparatively slender. They project
well backward, and for the last half of their length the two are in close
apposition. The distal ends are coossified and expanded, as shown in
IB EEXC

The pubes in Ceratosaurus have their distal ends coossified, as in all
Jurassic Theropoda except Hallopus. They project downward and for-
ward, and their position in the pelvis is shownin Pl. X. Seen from the
front, they form a Y-shaped figure, which varies in form in different
genera. The upper end joins the ilium by a large surface, and the
ischium by a smaller attachment. The united distal ends are expanded
into an elongate, massive foot, as shown in Pl. X, which is one of the
most peculiar and characteristic parts of the skeleton. The pubes of
Cceelurus are represented on the same plate.

The extreme narrowness of the pelvis is one of the most marked
features in this entire group, being in striking contrast to its width
in the herbivorous forms found with them. If the Theropoda were
viviparous, which some known facts seem to indicate, one difficulty,
naturally suggested in the case of a reptile, is removed.

Another interesting point is the use of the large foot at the Jower end
of the pubes, which is the most massive part of the skeleton. The only
probable use is that it served to support the body in sitting down.
That some Triassic dinosaurs sat down on their ischia is proved con-
clusively by the impressions in the Connecticut River sandstone. In
such cases the leg was bent so as to bring the heel to the ground. The
same action in the present group would bring the foot of the pubes to
the ground, nearly or quite under the center of gravity of the animal.
The legs aud ischia would then naturally aid in keeping the body bal-
anced. Possibly this position was assumed habitually by these fero-
cious biped reptiles while lying in wait for prey.

The femur is much curved, and the shaft very hollow. The tibia is
shorter than the femur, nearly straight, and has a large cnemial crest.
The astragalus is not coosified with the femur, and has a strong ascend-
ing process. The fibula is well developed, and nearly straight, its distal

16 GEOL, PT 1——11

162 DINOSAURS OF NORTH AMERICA.

end fitting into the caleaneum. The tarsals of the second row are very
thin, and united to the metatarsals below them.

THE METATARSALS.,

One of the most interesting features in the extremities of Ceratosau-
rus 18 seen in the metatarsal bones, which are completely anchylosed,
as were the bones of the pelvis. There are only three metatarsal
elements in the foot, the first and fifth having apparently disappeared
entirely. The three metatarsals remaining, which are the second, third,
and fourth, are proportionately shorter and more robust than in the
other known members of the order Theropoda, and, being firmly united
to each other. they furnish the basis for a very strong hind toot.

; a uc

yp Jip

Fic. 4.—United metatarsal bones of Ceratosaurus nasicornis Marsh; left foot; front view. One-
fourth natural size.

Fic. 5.—United metatarsal bones of great Penguin (Aptenodytes Pennantit G. R. Gr.); left foot;
front view. Natural size.

J, foramen; JJ, III IV, second, third, and fourth metatarsals.

In fig. 4, above, these coosified metatarsals of Ceratosaurus are repre-
sented, and in fig. 5 the corresponding bone of a penguin is given for
comparison.

In comparing these two figures, it will be seen that the three meta-
tarsal elements of the dinosaur are quite as closely united as those of
the bird. To the anatomist familiar with the tarsometatarsal bones of
existing birds the specimen represented in fig. 4 will appear even more
like this part in the typical birds than the one shown in fig. 5.

The position of the foramen, as seen in fig. 4, /, is especially charac-
teristic of recent birds, and, as a whole, the hind foot of this Jurassic
dinosaur was evidently similar to that of a typical bird.

All known adult birds, living and extinct, with possibly the single
exception of Archzopteryx, have the metatarsal bones firmly united,

MARSH.] ALLOSAURUS. 163

while all the Dinosauria, except Ceratosaurus, have these bones sepa-
rate. The exception in each case brings the two classes near together
at this point. and their close affinity has new been clearly demonstrated.

RESTORATION OF CERATOSAURUS.
PLaTE XIV. ¢
The restoration of Ceratosaurus on Pl. XIV represents the reptile one-
thirtieth natural size, and in a position it must have frequently assumed.
ALLOSAURUS.

Of the other carnivorous dinosaurs of the American Jurassic, three
genera, Allosaurus, Creosaurus, and Labrosaurus, are especially worthy
of notice. All were represented by species of large size, the natural
enemies of the gigantic herbivorous forms that were so abundant in the
same period. All had powerful jaws, sharp, cutting teeth, and a flexible
neck. The fore limbs were quite small, and the feet were armed with
strong claws for seizing living prey. The hind limbs were large and
strong, and the animals used them alone in ordinary locomotion. These
three genera may be separated by distinctive characters, and it 1s proba-
ble that they were not all contemporaneous.

The genus Allosaurus contains the largest carnivorous dinosaurs
known. It may be readily distinguished from Ceratosaurus by the ver-
tebr and the pelvis, or the feet.!. The cervicals are opisthoccelian 1n-
stead of plano-concayve, and the pelvic bones and metatarsals are free, as
shown in Pls. X and XI. In Creosaurus, a smaller allied form, the teeth
in the premaxillaries are more numerous, while the sacrum contains
fewer vertebre (Pl. XII). Labrosaurus is evidently a quite different
type, for the dentary bone is edentulous in front, as shown in PI]. XIII.

EUROPEAN THEROPODA.

From the Jurassic of Europe the best-known carnivorous form is
Megalosaurus, so named by Buckland, in 1824, the type specimen havy-
ing been found in England, near Oxford. Although the first genus of
dinosaurs described, but little has been made out in regard to the
structure of the skull, and many portions of the skeleton remain to be
determined. Its nearest American representative is probably Allosau-
rus, and both genera include species of large size.

The most interesting member of the Theropoda known in Europe is
the diminutive specimen described by Wagner, in 1861, as Compsogna-
thus longipes. The type specimen, the only one known, is from the
lithographic slates of Solenhofen, Bavaria, and is now preserved in the
museum in Munich. Fortunately, the skull and nearly all the skeleton
are preserved, and as the specimen has been studied by many anato-
mists its more important characters have been made out. It is regarded
as representing a distinct suborder, and no nearly related forms are
known in Europe. <A restoration in outline of this interesting dinosaur
has been prepared by the writer, and will be found on P]. LX XXII.

' The skull of Allosaurus ferox Marsh has au aperture in the maxillary in front of the antorbital
opening. This aperture is not present in Ceratosaurus

164 DINOSAURS OF NORTH AMERICA.

SAUROPODA.

The herbivorous dinosaurs of the American Jurassic are of special
interest. To begin with the order Sauropoda, which includes the most
primitive and gigantic forms, it is an interesting fact that the first
specimen found in this country was one of the rarest of the group, and
one of the most diminutive. A few teeth and bones only were obtained
by Prof. P. T. Tyson, about 1858, near Bladensburg, Md. The teeth
were named Astrodon by Dr. Christopher Johnston, in 1859, and in
1865 were described and figured by Dr. Leidy. The type specimens are
now in the Yale museum, and one tooth is represented below in fig. 6.
The strata containing these remains are known as the Potomac beds,
but their exact age is a matter of doubt. They have been referred by
some geologists to the Jurassic, and by others to the Cretaceous.

Fig. 6.— Tooth of Astrodon Johnstoni Leidy. Natural size. Potomac, Maryland.
a, outer view; b, end view; c, inner view.

ATLANTOSAURUS BEDS.

The first knewn specimen of Sauropoda from the West was secured
by the writer in August, 1868, near Lake Como, in Wyoming Territory.
This fossil, an imperfect vertebra belonging to the genus since named
Morosaurus, was found in the upper Jurassic clays, in the horizon now
known as the Atlantosaurus beds. The section on page 145 will show
the position of these beds in the geological scale, and their relation to
other deposits in which Dinosauria have been found. This locality has
since become one of the most famous in the entire Rocky Mountain
region, and the writer has secured from it remains of several hundred
dinosaurs, among which are many of the type specimens here described.

Remains of an enormous dinosaurian were found in 1877, near Morri-
son, Colo., by Prof. Arthur Lakes and Capt. H. C. Beckwith, U.S. N.,
and this was the beginning of a series of similar discoveries. These
remains, described by the writer in the American Journal of Science
for July of that year, proved to be those of a dinosaur far surpassing
in size any previously known, and having characters that indicated a
new order of these reptiles.

MARSH. ] FAMILIES OF SAUROPODA. 165

When first found these fossils were supposed to be from the Dakota
group, but their upper Jurassic age was soon after determined by the
writer from evidence that placed the horizon beyond dispute. The
name Titanosaurus montanus was given by the writer to this reptile
when first described, but as the generic designation proved to be preoc-
cupied, Atlantosaurus was substituted.

A third Rocky Mountain locality which proved to be especially pro-
lific in dinosaurs was found the following year, by Mr. M. P. Felch, a
few miles north of Canyon, Colo., and in essentially the same horizon
as the last-mentioned locality. Here were found the type specimens
of some of the most interesting dinosaurs yet discovered in this country,
all of them in fine preservation, and not infrequently in the exact posi-
tion in which they died. Other localities of interest have been found in
the same region.

Another locality of Sauropoda, more recently explored by the writer,
is in South Dakota, on the eastern slope of the Black Hills. This is
the most northern limit now known of the Atlantosaurus beds, which
form a distinct horizon along the eastern flanks of the Rocky Mountains,
marked at many points by the bones of gigantic dinosaurs, for nearly
500 miles. The strata are mainly shales or sandstones of fresh-water
or estuary origin. They usually rest unconformably upon the red Tri-
assic series, and have above them the characteristic Dakota sandstones.

On the western slope of the Rocky Mountains the Atlantosaurus beds
are also well developed, especially in Wyoming, but here they have
immediately below them a series of marine strata, which the writer has
named the Baptanodon beds, from the largest reptile found in them.
This horizon, also of Jurassic age, is shown in the section on page 145,
One of the best exposures of the entire Jurassic series may be seen near
Lake Como, Wyoming.

Besides the dinosaurs, which are especially abundant, the Atlanto-
saurus beds also contain numerous remains of extinct crocodiles, tor-
toises, and fishes, and with them have been found a small pterodactyl
and a single bird. Many small mammals, also, have been described by
the writer from the same beds.

FAMILIES OF SAUROPODA.

The Sauropoda of the American Jurassic are worthy of special atten-
tion, and so far as now known they may be divided into four families:
the Atlantosauridz, which include the largest forms; the Diplodocide
and Morosauride, both represented by gigantic species; and the small
Pleurocelide, which were apparently the last survivors of the order in
this country. Remains of the first three families are abundant in the
Atlantosaurus beds of the West, but it is not certain that all were con-
temporaneous. The Pleuroceelide are especially characteristic of the
Potomac beds on the Atlantic coast.

All the known members of these families were quadrupedal, with the
fore and hind limbs nearly equal in length. The head was very small

166 DINOSAURS OF NORTH AMERICA.

and the neck long, with its vertebrae opisthoccelian and lightened by
inner cavities, thus allowing free motion.

The limb bones of all were solid, and the feet plantigrade, with five
toes on each. The tail was especially long and massive. The general
form and proportions of these reptiles are indicated in Pl. XLII, which
represents the skeleton of a species of Brontosaurus, one of the typical
genera of the Atlantosauride.

ATLANTOSAURIDE
ATLANTOSAURUS.

The present family was named by the writer in 1877, the type genus
being Atlantosaurus. The type specimen of the first species described,
Atlantosaurus montanus, is the sacrum represented in fig. 1, Pl. XVII,
which shows characteristic features of the sacrum of the entire group
Sauropoda, and thus distinguishes it from that of the other known
dinosaurs. A second and larger species, Atlantosaurus immanis, was
described by the writer in the following year, and on Pl. XVI are repre-
sented two pelvic bones and a femur, which belong to the type specimen,
and give an idea of its gigantic size. The femur is over 6 feet long,
and this, with other portions of the skeleton, indicates an animal about
70 or 80 feet in length. The pubis and ischium, represented in posi-
tion in fig. 1, are especially characteristic of the family, as will be
seen by comparing them with the corresponding parts of other allied
genera, aS Shown in Pl. XXXVI.

At the same locality where these remains were found, portions of a
skull were discovered, one of which is figured on Pl. XV. This speci-
men, which is the posterior part of the skull, is of much interest, and
shows characters which separate it from all other corresponding remains
of dinosaurs. The most marked feature is a distinct pituitary canal
leading from the brain cavity down through the base of the skull, as
shown in fig. 2 of Pl. XV. This canal appears to be a marked char-
acter of the family Atlantosauride. Other points of interest in these
remains will be discussed later in the present paper.

APATOSAURUS.

Another genus of the present family is Apatosaurus, also described
by the writer in 1877, and from the same geological horizon in Colo-
rado. The sacrum represented in fig. 2, Pl. X VII, may be regarded as
the type specimen. It has the same general features as the sacrum of
Atlantosaurus, shown on that plate, but it has only three coossified
vertebre instead of four.

THE SACRAL CAVITY.

The neural canal in this sacrum, and indeed in all the sacra of the
Sauropoda, is much enlarged, being especially expanded above each
vertebral centrum, thus leaving a vaulted chamber in the united neural
arches of the sacral vertebre. A cast of this cavity in the type speci-
men of Apatosaurus is shown in fig. 3, Pl. XVIII.

MARSH.) APATOSAURUS. 167

This enlargement of the neural cord in the sacral region exists to
some degree in reptiles and birds now living, but does not approach that
found in the Sauropoda, or especially that in the Stegosauria, where,
as will be shown later in the present article, this expansion reaches its
maximum, and its functional importance must make it a dominant fac-
tor i the movements of the reptiles in which it is so highly developed.
This great development has been found only in extinct reptiles in which
the brain was especially diminutive, and the relation of the two nervous
centers to each other offers a most interesting problem to physiologists.

THE VERTEBRE.

In Pl. XVIII, fig. 1, is shown a posterior cervical vertebra of Apato-
saurus, and in fig. 2 of the same plate a dorsal vertebra is also repre-
sented, both being typical of the family Atlantosauride. The cervical

7 8

Fic. 7.—Cervical rib of Apatosaurus ajax Marsh; outer view.

Fic. 8.—The same rib; inner view.

Both figures are one-eighth natural size. a, anterior extremity; h, head; 7, posterior process:
t, tubercle.

vertebra, seen from behind, shows the deep, transverse cup of the poste-
rior articular end of the centrum, as well as the coossified cervical ribs,
both typical of the Sauropoda. A cervical rib of one species is shown
in figs. 7 and 8. =

The dorsal vertebra, seen from in front, presents the convex anterior
ball of the centrum, and also the massive neural arch of the vertebra,
with its elevated metapophyses, constituting a neural spine. The
expanded diapophyses, or transverse processes, are especially note-
worthy, as they aid in supporting the massive ribs, their extremities
articulating with the tubercle of the rib, while the head is supported
at the base of the arch by a sessile facet representing the parapoph-
ysis of the cervicals. The small neural canal in each vertebra is also
an interesting feature, especially when contrasted with the expanded
cavity in the sacrum shown in fig. 3 of the same plate.

168 DINOSAURS OF NORTH AMERICA.

The scapula and coracoid of Apatosaurus, shown in PI. XIX, fig. 1,
are also characteristic features of the family they represent. The shaft
of the scapula is not expanded above in any of the genera of the Atlan-
tosauride, although this expansion is characteristic of the genus
Morosaurus and the family Morosauride, as shown in the same plate,
fig. 2. Another important difference is indicated on this plate, in the
coracoids, that of Apatosaurus being nearly square in outline, while in
Morosaurus and its allies the contour of the coracoid is subovate.

BRONTOSAURUS.

The best-known genus of the Atlantosauride is Brontosaurus,
described by the writer in 1879, the type specimen being a nearly
entire skeleton, by far the most complete of any of the Sauropoda yet
discovered. It was found in the Atlantosaurus beds, near Lake Como,
Wyoming, and the remains were nearly in the position in which they
were left at the death of the animal. This fortunate discovery has
done much to clear up many doubtful points in the structure of the
whole group Sauropoda, and the species Brontosaurus excelsus may be
taken as a typical form, especially of the family Atlantosauride. The
animal was about 60 feet in length. A second species, equally gigantic,
has since been found in the same region.

In Pl. XX, fig. 1, a characteristic tooth of Brontosaurus is shown,
which may also be regarded as typical for the family. In fig. 2 of the
same plate the dentary bone is shown, with the teeth in outline. This
bone is one of the most characteristic of the whole skeleton, as will be
seen by comparing it with the corresponding parts of other Sauropoda
represented in the following plates.

The genus Brontosaurus may be readily distinguished from all the
other Sauropoda by the sacrum, which is composed of five anchylosed
vertebrie, none of the other genera in this group having more than four.
The sternum, moreover, consists of two separate bones, which are
parial, and were united to each other on the median line apparently
by cartilage only. In several other respects the genus resembles
Morosaurus.

The present species, aside from its immense size, is distinguished by
the peculiar lightness of its vertebral column, the cervical, dorsal, and
sacral vertebre all having very large cavities in their centra. The
first three caudals, also, are lightened by excavations in their sides, a
feature first seen in this genus, and one not observed in the other
families of this group.

THE SCAPULAR ARCH.

The scapular arch in the present species 1s, fortunately, better known
than that of any other member of the present order. In Pl. XXII the
various bones are represented in position, and in fig. 2 of the same plate
a sternal bone is shown separately. The scapula resembles in general
form the corresponding bone in Apatosaurus, but the shaft is longer
and the upper end somewhat wider.

MARSU.] BRONTOSAURUS. 169

The coracoid approaches more nearly that of Apatosaurus, which is
subquadrate in outline. In Pl. XXII the scapula and coracoid of the
present species are placed nearly in the same plane, and the space
between them probably represents about the amount of cartilage which
originally separated them. Both scapule were found in apposition with
their respective coracoids.

The two sternal bones lay side by side between the two coracoids,
and in this plate they are represented nearly as found. They are sub-
oval in outline, concave above, and convex below. They are parial,
and when in position nearly or quite meet on the median line. Each
bone is considerably thickened in front, and shows a distinct facet for
union with the coracoid. The posterior end is thin and irregular. The
sternal ribs represented in figs. 12-15, p. 171, were found near the sternal
bones. The sternum of a young ostrich is shown for comparison on Pl.
XXII, fig. 3.

THE CERVICAL VERTEBRA.

The cervical vertebre of the present species are quite numerous,
thirteen at least belonging in this part of the column. All are strongly
opisthocelian. The anterior cervicals are very small in comparison
with those near the dorsalregion. From the third vertebra to the mid-
dle of the neck the centra increase in length and especially in bulk,
but the posterior cervicals gradually become shorter. In Pl. XX, figs.
3 and 4, the sixth cervical is represented, and this is typical for the
anterior half of the neck. All the anterior cervicals have coossified
ribs, as in birds. In the posterior cervicals the ribs occasionally become
free (Pl. X XI, fig. 1). The articular facet for the head of the rib rises
gradually on the side of the centrum, the tubercular articulation remain-
ing on the diapophysis. None of the cervicals have a neural spine.
The neural canal is comparatively small. The centra of all the cervi-
cals have deep excavations in the sides, and the transverse processes
are more or less cavernous. The posterior cervicals which bear free
ribs are remarkable for the great size of the zygapophyses, which are
here much larger than elsewhere in the series. The anterior cervicals
have several lateral cavities, while those farther back have only one
large foramen in each side of the centrum, as in the dorsals.

THE DORSAL VERTEBR.

The dorsal vertebre of this species have short centra, more or less
opisthocelian. There is a very large cavity in each side, which is sep-
arated from the one opposite by a thin vertical partition. The neural
canal is much larger than in the cervicals. The anterior dorsals are
distinctly opisthocelian. The neural spine has no prominence in this
region, but rises rapidly farther back. In Pl. XX], figs. 2 and 3, a pos-
terior dorsal is represented, which shows the peculiar character of the
vertebre in this part of the series. The neural spine is greatly devel-
oped and has its summit transversely expanded. The vertebre in this
region, as in all the known Sauropoda, have the peculiar diplosphenal

170 DINOSAURS OF NORTH AMERICA.

articulation. This is shown in fig. 3. In the vertebra figured, at the
base of the neural spine, there is a strong anterior projection, which
was inserted into the cavity between and above the posterior zyga-
pophyses of the vertebra in front. There appear to be no true lumbar
vertebre, as those near the sacrum supported free ribs of moderate
size. The vertebre in this region have both faces of the centrum nearly
flat or biconcave. An anterior dorsal rib is shown below.

THE SACRUM.

The sacrum in the present species consists of five well-coossified ver-
tebree, and in the type specimen the centrum of the last lumbar is
firmly united with it, as shown in Pl. XXIII. The striking feature

Fig. 9.—Proximal end of rib of Brontosaurus excelsus Marsh; front view.
Fic. 10.—The same bone; back view.

Fic. 11.—The same; superior view.

All the figures are one-eighth natural size. c, cavity; h, head; t, tubercle.

about this sacrum is the large general cavity it contained. This was
divided in part by a median longitudinal partition, as shown in
Pl. XXIII, fig. 2. The septum, however, was not continuous the
whole length of the sacrum, so that the two lateral cavities were vir-
tually one. This extended even into the lateral processes. The trans-
verse partitions formed by the ends of the respective centra were also
perforate, so that the sacrum proper was essentially a hollow cylinder.
The cavernous character of the sacrum is one of the peculiar features
of the suborder Sauropoda, and was described by the writer when
the first species of this group was discovered in this country. The

MARSH. ] BRONTOSAURUS. Weal

statement that any of the species has the sacrum solid is evidently
based on erroneous observation.

Another peculiar character of the sacrum in the present genus is its
lofty neural spine. This is a thin, vertical plate of bone with a thick
massive summit, evidently formed by the union of the spines of several
vertebre. In frontit shows rugosities for the ligament uniting it to
the adjoining vertebra, and its posterior margin likewise indicates a
similar union with the first caudal. In this genus, as in all the Sau-
ropoda, each vertebra of the sacrum supports its own transverse proc-:
esses. As shown in Pl. XXIII, the articulation for the ilium is
formed by the coossification of the distal ends of the transverse
processes. The neural canal is much enlarged in the sacrum, but less
proportionally than in Stegosaurus.

14 15

Fic. 12.—Sternal ribs of Brontosaurus exceleus; outer view.
Fic. 13.—The same specimen; inner view.

Fic. 14.Sternal rib of same individual; outer view.

Fia. 15.—The same rib; inner view.

All the figures are one-eighth natural size.

THE CAUDAL VERTEBR.Z,

In the present species the three vertebrz next behind the sacrum
have moderate-sized cavities between the base of the neural arch and
the transverse processes. These shallow pockets extend into the base
ot the processes, but the centra proper are solid. AJl the other can-
dals have the centra, processes, and spines composed of dense bone.
The fourth caudal vertebra, represented in Pl. XXIV, figs. 2 and 3, is

172 DINOSAURS OF NORTH AMERICA.

solid throughout, and the same is true of the chevron, figs. 4 and 5.
The neural spines of the anterior caudal vertebre are elevated and
massive. The summit is cruciform in outline, due to the four strong
buttresses which unite to form it.

The median caudals all have low, weak spines, and no transverse
processes. The posterior caudals are elongate and without spines or
zy gapophyses.

THE PELVIC ARCH.

The pelvic bones in the present species are shown in fig. 16. The
ilium represented is not quite perfect on its upper margin. Its ante-
rior process for the support of the pubis is much larger than the poste-

Fic. 16.—Pelvis of Brontosaurus excelsus; seen from the left. One-sixteenth natural size.
a, acetabulum; f, foramen in pubis; il, ilinm; 2s, ischium; p, pubis.

rior one which meets the ischium. The pubis is elongate and massive.
It sends down a strong wing for union with the ischium, and has in
front of this the usual foramen. The distal end is expanded, and has
on the inner surface a rugose facet for union with its fellow by cartilage.
The ischium is more slender than the pubis, and has its lower end
expanded for symphysial unicn with the one on the other side (PL
XXIV, figs. 1 and 1a). This pelvis is more like that of Atlantosaurus

MARSH.] BRONTOSAURUS. 173

than any other of the known genera of the Sauropoda. The three
bones shown in fig. 16 were found nearly in the position represented.

THE FORE LIMBS.

The fore limbs of Brontosaurus, as in most of the Sauropoda, were
of large size and of massive proportions. The limb bones are all solid,
and those of the feet are quite robust. There were five well-developed
digits in the manus, and the metacarpals were all moderately elongate.
A characteristic example is shown in figs. 17-20, below.

18

19

Fic. 17.—First metacarpal of Brontosaurus amplus Marsh; front view.
Fic. 18.—The same bone; side view.

Fic. 19.—Proximal end of same.

Fic. 20.—Distal end of same.

All the figures are one-fourth natural size.

THE HIND LIMBS.

The hind limbs of Brontosaurus were larger than those in front, and
the bones were all solid, thus being in remarkable contrast to the ele-
ments of the vertebral column. The hind feet were plantigrade, and
had five powerful digits. The first was very stout, and its terminal
phalanx, shown in figs. 21-23, supported a powerful claw.

RESTORATION OF BRONTOSAURUS.
PLatTe XLII.

Nearly all the bones represented in this restoration belonged to a
single individual, which when alive was nearly or quite 60 feet in
length. The position here given was mainly determined by a careful
adjustment of these remains. That the animal at times assumed a posi-
tion more erect than here represented is probable, but locomotion on
the posterior limbs alone was hardly possible.

174 DINOSAURS OF NORTH AMERICA.

The head was remarkably small. The neck was long and flexible,
and, considering its proportions, was the lightest portion of the verte-
bral column. The body was short, and the abdominal cavity of mod-
erate size. The legs and feet were massive and the bones all solid.
The feet were plantigrade, and each footprint must have been about a
square yard in extent. The tail was large and nearly all the bones
are solid.

The diminutive head will first attract attention, as it is smaller in
proportion to the body than in any vertebrate hitherto known. The
entire skull is less in diameter or actual weight than the fourth or fifth
cervical vertebra.

A careful estimate of the size of Brontosaurus, as here restored,
shows that when living the animal must have weighed more than
20 tons. The very small head and brain, and the slender neural cord,
indicate a stupid, slow-moving reptile. The beast was:wholly without
offensive or defensive weapons or dermal armature.

21 22 23

Fic. 21.—Terminal phalanx of Brontosaurus cxcelsus; outer view.
Fic. 22.—The same bone; front view.

Fic. 23.—The same; inner view.

All the figures are one-fourth natural size.

In habits Brontosaurus was more or less amphibious, and its food
was probably aquatic plants or other succulent vegetation. The
remains are usually found in localities where the animals seem to
have been mired. The type specimen was discovered by W. H. Reed,
near Lake Como, Wyoming.

BAROSAURUS.

Another genus of the Sauropoda is indicated by various remains of
a gigantic reptile described in 1890 by the writer. The most charac-
teristic portions examined are the caudal vertebre, which in general
form resemble those of Diplodocus. They are concave below, as in the
caudals of that genus, but the sides of the centra are also deeply
excavated.

In the anterior caudals this excavation extends nearly or quite

MARSH.) DIPLODOCID&. 175

through the centra, a thin septum usually remaining. In the median
caudalsa deep cavity on each side exists, as shown in figs. 24-26, below.

On the distal caudals the lateral cavity has nearly or quite disap-
peared. All the caudal vertebre are proportionally shorter than in
Diplodocus, and their chevrons have no anterior projection, as in that
genus.

The remains on which the present description is based are from the
Atlantosaurus beds of South Dakota, about 200 miles farther north
than this well-marked horizon has hitherto been recognized.'

25 26

Fic. 24.—Caudal vertebra of Barosaurus lentus Marsh; side view.
Fic. 25.—The same vertebra, in section; front view.
Fic. 26.—The same vertebra; bottom view.
All the fignres are one-eighth natural size. a, anterior end; c, face for chevron; f, lateral cavity;
p, posterior end; s, section.

DIPLODOCID #&.
DIPLODOCUS.”
THE SKULL.

The skull of Diplodocus is of moderate size. The posterior region is
elevated and narrow. The facial portion is elongate and the anterior
part expanded transversely. The nasal opening is at the apex of the
cranium, which from this point slopes backward to the occiput. In
front of this aperture the elongated face slopes gradually downward to
the end of the muzzle, as represented in Pl. XXV, fig. 1.

Seen from the side the skull of Diplodocus shows five openings: a
small oval aperture in front, a large antorbital vacuity, the nasal aper-
ture, the orbit, and the lower temporalopening. The firstof these has
not been seen in any other Sauropoda; the large antorbital vacuity is
characteristic of the Theropoda also; while the other three openings
are present in all the known Dinosauria.

On the median line, directly over the cerebral cavity of the brain,
the type specimen of Diplodocus has also a fontanelle in the parietals.
This, however, may be merely an individual peculiarity.

The plane of the occiput is of moderate size, and forms an obtuse
angle with the frontoparietal surface.

The occipital condyle is hemispherical in form, and seen from behind
is slightly subtrilobate in outline. It is placed nearly at right angles

1Strata that may represent this horizon have been observed still farther north, especially in Mon-
tana, but have not yet been identified by characteristic fossils.
2 American Journal of Science, 1878-1884.

176 DINOSAURS OF NORTH AMERICA.

to the long axis of the skull. Itis formed almost wholly of the basi-
occipital, the exoccipitals entering but slightly or not at all into its
composition. The basioccipital processes are large and rugose. The
paroccipital processes are stout and somewhat expanded at their ex-
tremities, for union with the quadrates.

The parietal bones are small and composed mainly of the-arched proc-
esses which join the squamosals. There is no true pineal foramen,
but in the skull here figured (Pl. XXV) there is the small unossified
tract mentioned above. In one specimen of Morosaurus a similar
opening has been observed, but in other Sauropoda the parietal bones,
even if thin, are complete. The suture between the parietals and
frontal bones is obliterated in the present skull, and the union is firm
in all the specimens observed.

The frontal bones in Diplodocus are more expanded transversely than
in the other Sauropoda. They are thin along the median portion, but
quite thick over the orbits.

The nasal bones are short and wide and the suture between them
and the frontals is distinct. They form the posterior boundary of the
large nasal opening, and also send forward a process to meet the
ascending branch of the maxillary, thus taking part in the lateral
border of the same aperture.

The nasal opening is very large, subcordate in outline, and is par-
tially divided in front by slender posterior processes of the premaxil-
laries. It is situated at the apex of the skull, between the orbits, and
very near the cavity for the olfactory lobes of the brain.

The premaxillaries are narrow below, and with the ascending proc-
esses very slender and elongate. Along the median line these processes
form an obtuse ridge, and above they project into the nasal opening.
Each premaxillary contains four functional teeth.

The maxillaries are very largely developed, more so than in most
other known reptiles. The dentigerous portion is very high and slopes
inward. The ascending process is very long, thin, and flattened, inclos-
ing near its base an oval foramen, and leaving a large unossified space
posteriorly. Above, it meets the nasal and prefrontal bones. Along
its inner border for nearly its whole length it unites with the ascending
process of the premaxillary. Each maxillary contains nine teeth, all
situated in the anterior part of the bone (Pl. X XV, fig. 1).

Along their upper margin, on the inner surface, the maxillaries send
off a thickened ridge, or process, which meets its fellow, thus excluding
the premaxillaries from the palate, as shown in fig. 27, opposite. Above
this, for a large part of their length, the ascending processes of the
maxillaries underlap the ascending processes of the premaxillaries and
join each other on the median line.

The orbits are situated posteriorly in the skull, being nearly over the
articulation of the lower jaw. They are of medium size, nearly circular
in outline, their plane looking outward and slightly backward. No

MARSH.) DIPLODOCUS. ICFP

indications of sclerotic plates have been found either in Diplodocus or
in the other genera of Sauropoda.

The supratemporal fossa is small, ovalin outline, and directed upward
and outward. The lateral temporal fossa is elongated, and oblique in
position. bounded, both above and below, by rather slender temporal
bars.

The prefrontal and lachrymal bones are both small; the suture con-
necting them, and also that uniting the latter with the jugal, can not
be determined with certainty.

The postfrontals are triradiate bones. The longest and most slender
branch is that descending downward and forward for connection with
the jugal; the shortest is the triangular projection directed backward
and fitting into a groove of the squamosal; the anterior branch, which
is thickened and rugose, forms part of the orbital border above.

The squamosal lies upon the upper border of the paroccipital process.
The lower portion is thin and closely fitted over the head of the quad-
rate bone.

Fic. 27.—Skull of Diplodocus longus Marsh; seen from below. One-sixth natural size.

b, basioccipital process; eo, exoccipital; m, maxillary; mp, maxillary plate; 0, occipital condyle;
p, palatine; pm, premaxillary; pt, pterygoid; ps, parasphenoid; qg, quadrate; ¢, transverse bone;
v, vomer.

The quadrate is elongated and slender, with its lower end projecting
very much forward. In front it has a thin plate extending inward and
overlapping the posterior end of the pterygoid.

The quadratojugalis an elongate bone, firmly attached posteriorly to
the quadrate by its expanded portion. In front of the quadrate it forms.
for a short distance a slender bar, which is the lower temporal arcade.

The palate is very high and roof-like, and composed chiefly of the
pteryyoids, as shown above in fig. 27. The basipterygoid processes are:
elongate, much more so than in the other genera of Sauropoda.

The pterygoids have a shallow cavity for the reception of these proc-
esses, but no distinct impression for a columella. Immediately in front.
of this cavity the pterygoids begin to expand, and soon form a broad,
flat plate, which stands nearly vertical. Its upper border is thin, nearly
straight, and extends far forward. The anterior end is acute and unites
along its inferior border with the vomer.’ A little in front of the middle.

16 GEOL, PT 1 12

178 DINOSAURS OF NORTH AMERICA.

a process extends downward and outward, for union with the transverse
bone. In front of this process, uniting with it and with the transverse
bone, is the palatine.

The palatine is a small semioval bone fitting into the concave ante-
rior border of the pterygoid, and sending forward a slender process for
union with the small palatine process of the maxillary.

The vomer is a slender, triangular bone, united in front by its base to
a stout process of the maxillary, which underlaps the ascending proc-
ess of the premaxillary. Along its upper and inner border it unites
with the pterygoid, except at the end, where for a short distance it
joins a slender process from the palatine. Its lower border is wholly
free.

THE BRAIN.

The brain of Diplodocus was very small, as in all dinosaurs from the
Jurassic. It differed from the brain of the other members of the
Sauropoda, and from that of all other known reptiles, in its position,
which was not parallel with the longer axis of the skull, as is usually
the case, but inclined to it, the front being much elevated, as in the
runinant mammals (Pl. LX XVI, fig. 4). Another peculiar feature of

Fic. 28.—Dentary bone of Diplodocus longus; seen from the left. One-third natural size.

a, edentulous border; s, symphysis.
the brain of Diplodocus was its very large pituitary body, inclosed in a
capacious fossa below the main brain case. This character separates
Diplodocus at once from the Atlantosauride, which have a wide
pituitary canal connecting the brain cavity with the throat. In the
Morosauride the pituitary fossa is quite small.

The posterior portion of the brain of Dipiodocus, was diminutive.
The hemispheres were short and wide and more elevated than the
optic region. The olfactory lobes were well developed, and separated
in front by a vertical osseous septum. The very close proximity of the
external nasal opening is a new feature in dinosaurs, and appears to be
peculiar to the Sauropoda.

THE LOWER JAWS.

The lower jaws of Diplodocus are more slender than in any of the
other Sauropoda. The dentary especially lacks the massive character
seen in Morosaurus, and is much less robust than the corresponding

MARsH.] DIPLODOCUS. 179)

bone in Brontosaurus. The short dentigerous portion in front is de-
curved (Pl. X XV, fig. 1), and its greatest depth is at the symphysis, as
shown in fig. 28 above. The articular, angular, and surangular bones
are well developed, but the coronary and splenial appear to be small.

THE TEETH.

The dentition of Diplodocus is the weakest seen in any of the known
Dinosauria, and strongly suggests the probability that some of the more
specialized members of this great group were edentulous. The teeth
are entirely confined to the front of the jaws (Pl. X XV, fig. 1), and
those in use were inserted in such shallow sockets that they were readily
detached. Specimens in the Yale museum show that entire series of
upper or lower teeth could be separated from the bones supporting
them without losing their relative position. In Pl. XXVI, fig. 1, a
uumber of these detached teeth are shown.

Fic. 29.—Sternal plate of Brontosaurus amplus; top view.

Fic. 30.—Sternal plate of Morosaurus grandis Marsh.

Both figures are oue-eighth natural size. a, bottom view; b, top view; b’, side view; b’’, end view;
c, face for coracoid; d, margin next to median line; e, inner front margin; p, posterior end.

The teeth of Diplodocus are cylindrical in form and quite slender.
The crowns are more or less compressed transversely and are covered
with thin enamel, irregularly striated. The roots are long and slender
and the pulp cavity is continued nearly or quite to the crown. In the
type specimen of Diplodocus there are four teeth, the largest of the
series, in each premaxillary; nine in each maxillary, and ten in each
dentary of the lower jaws. There are no palatine teeth.

The jaws contain only a single row of teeth in actual use. These
are rapidly replaced, as they wear out or are lost, by a series of succes-
sional teeth, more numerous than is usual in these reptiles. Pl. XX VI,
fig. 2, represents a transverse section through the maxillary, just behind
the fourth tooth. The latter is shown in place, and below it is a series

180 DINOSAURS OF NORTH AMERICA.

of five immature teeth, in various stages of development, preparing to
take its place. These successional teeth are lodged in a large cavity,
which extends through the whole dental portion of the maxillary. The
succession is also similar in the premaxillary teeth and in those of the
lower jaws.

THE VERTEBRA,

The vertebral column of Diplodocus, so far as at present known, may
be readily distinguished from that of the other Sauropoda by both the
centra and chevrons of the caudals. The former are elongated and
deeply excavated below, as shown in PI, X XVI, figs. 4 and 5. The
chevrons are especially characteristic, and to their peculiar form the
generic name Diplodocus refers. They are double, having both anterior
and posterior branches, and the typical forms are represented in figs. 6
and 7 of the above plate.

The cervical and dorsal vertebrie of Diplodocus are represented by
typical examples on Pl. XX VI, fig. 3, and Pl. XX VII, and the sacrum
with ilium attached is shown on Pl. XXVIII.

THE STERNAL BONES.

The sternal bones in Diplodocus are especially large, and in form
resemble those in Brontosaurus excelsus. Those in Brontosaurus amplus
are less robust, and are somewhat similar in shape to those of Moro-
saurus, as shown in figs. 29 and 30.

THE PELVIC GIRDLE,

A most characteristic bone of the two families of Sauropoda first
described is the ischium. In the Atlantosauridz the ischia are mas-
sive and directed downward, with their expanded extremities meeting
on the median line. In the Morosauride the ischia are slender, with
the shaft twisted about 90°, directed backward, and the sides meeting
on the median line, thus approaching this part in the more specialized
dinosaurs. The ischia referred to the genus Diplodocus (Pl. XX VIII,
fig. 3) are intermediate in form and position between those above men-
tioned. The shaft is not expanded distally, nor twisted, but was
directed downward and backward, with the sides meeting on the
median line.

The feet of Diplodocus are shown in Pls. XXVIII and XXIX.

SIZE AND HABITS.

The type specimen of Diplodocus, to which the skull here figured
belongs, indicates an animal intermediate in size between Atlanto-
saurus and Morosaurus, probably 40 or 50 feet in length when alive.
The teeth show that it was herbivorous, and the food was probably
succulent vegetation. The position of the external nares would seem
to indicate in some measure an aquatic life.

MARSH. ] MOROSAURID®. 181

MOROSAURIDA.
MOROSAURUS.

The genus Morosaurus, the type of the family, was described by the
writer in 1878, in the American Journal of Science, which contains
most of the original descriptions of Sauropoda found in this country.

THE SKULL.

The head in this genus was very small. The posterior part of the skull
resembled that in Diplodocus, but the front was much more massive.
The lower jaw was especially powerful, as shown by the dentary bone
figured in Pl. XXX, fig. 3. This figure also shows the size and posi-
tion of the teeth, one of which is figured in Pl. XX NI, figs. 1 and 2.

Fic. 31.—Anterior dorsal vertebra of Morosaurus grandis; front view.

Fic. 32.—_The same vertebra; side view.

Fic. 33.—Transverse section through centrum of same.

All the figures are one-eighth natural size. b, ball; ¢c, cup; d, diapophysis ; f, cavity in centrum;
m, metapophysis ; 7, neural canal; ns, neural snture ; z, anterior zygapophysis ; z', posterior zyga-
popbysis.

The brain was very small. Its form and position in the skull are
shown in fig. 2 of Pl. XXX. At the back of the skull there are two
peculiar bones, called by the writer the postoccipital bones, which are
shown in Pl. XXX, fig. 1.

THE VERTEBRAE.

The neck was elongated, and except the atlas all the cervical verte-
bre have deep cavities in the sides of the centra, similar to those in
birds of flight. They are also strongly opisthoccelous. The atlas and

182 DINOSAURS OF NORTH AMERICA.

axis are not anchylosed together, and the elements of the atlas are
separate (Pl. XX XI).

The dorsal vertebre are distinctly opisthocwlous. The posterior dor-
sals have elongated transverse neural spines, and have deep cavities
in the sides. An anterior dorsal is shown in figs. 31-35, p. 181. There
are four vertebrie in the sacrum, all with cavities in the centra. Their
transverse processes, or sacral ribs, are vertical plates with expanded
ends. The anterior caudal vertebrie are plano-concave, and nearly or
quite solid. The tail was elongated, and the chevrons are similar to
those in crocodiles (Pl. XX XIX). The vertebrae of Morosaurus are
represented on Pls. XX XI-XXXIV.

THE FORE LIMBS.

The scapula is elongated and very large, and the shaft has a promi-
nent anterior projection. The coracoid is small, suboval in outline,
and has the usual foramen near its upper border. These two bones
are well represented in PI. XIX, nearly in the relative position in
which they were found. The humerus is very large and massive, and
its radial crest prominent. This bone is nearly solid, and its ends
were rough and well covered with cartilage. This is true, also, of all

Fig. 34.—Cast of neural cavity in sacrum of Morosauruslentus Marsh; side view. One-fourth nat-
ural size.

i’, intervertebral foramina; v, v’, v’’, v!’’, cavities in first, second, third, and fourth sacral
vertebra.

the large limb bones in this genus. The radius and ulna are nearly
equal in size. The carpal bones are separate and quite short. The
tive metacarpals are elongated, and the first is the stoutest. The toes
were thick, and the ungual phalanges were evidently covered with hoofs.
In Pl. XN XVIII, fig. 1, the restoration of the scapular arch and entire
fore limb of one species of Morosaurus well illustrates this part of the
skeleton.

THE PELVIS.

The pelvic bones are distinct from each other and from the sacrum.
The ilium is short and massive, and shows on its inner side only slight
indications of its attachment to the sacrum. More than half the
acetabulum is formed by the ilium, which sends down in front a strong
process for union with the pubis, and a smaller one behind to join the
ischium (Pl. XXXYV, fig. 1,a and b). The acetabulum is completed
below by the pubis and ischium. The pubis is large and stout, and

MansH.] PLEUROCGLID®. 183

projects forward and downward, uniting with its fellow on the median
line in a strong ventral symphysis. Its upper posterior margin meets
the ischium and contains a large foramen. The ischium projects down-
ward and backward, and its distal end is not expanded. The relative
position and general form of the three pelvic bones in this genus are
shown in Pl. XXXVI, fig. 1, and the entire pelvic arch in Pl]. XXXI.
The ischia of two species are shown on Pl. XX XV. The sacrum of one
species of Morosaurus is shown on Pl. XX XI, and that of another on
Pl. XXXII. A east of the sacral cavity of the latter is represented in
fig. 34, p. 182.
THE HIND LIMBS.

The femur is long and massive, and without a true third trochanter,
although arugosity marks its position. The great trochanter is obtuse
and is placed below thehead. The ridge which plays between the tibia
and fibula is distinct. The tibia is shorter than the femur. It is with-
out a spine or fibular ridge, and its distal end shows that the astrag-
alus was separated from it by a cushion of cartilage. The fibula is
stout, its two extremities nearly equal, and its distal end supports the
caleaneum. The tarsal elements of the second row are unossified. The
five well-developed digits are similar to those in the manus. The first
metatarsal is much the largest (Pl. X XIX, fig. 2). The feet are also
shown on Pls. XX XVII and XX XVIII.

PLEUROCQ@LID.
PLEUROCGLUsS. !
THE SKULL. .

The genus Pleuroccelus includes the smallest individuals of the
Sauropoda found in this country, most of them not being larger than
existing crocodiles, and some even smaller. The skull is quite small,
and resembles in its structure that of Morosaurus, but has points of
similarity also with that of Brontosaurus. The teeth resemble those of
Diplodocus most nearly, but have shorter roots and are much more
numerous, the entire upper and lower jaws being furnished with teeth.
The dentary bone is similar in shape and proportions to that of Bron-
tosaurus, differing widely from that of Diplodocus and Morosaurus:
It is slender and rounded at the symphysis, instead of having the mas-
sive, deep extremity seen in Morosaurus. The maxillary also is much
less robust. The supraoccipital agrees closely in shape with thatof
Morosaurus, and forms the upper border of the foramen magnum, as
in that genus. In Pl. XU, fig. 1, is shown the dentary of Pleurocelus,
with the teeth in outline, and beside it are typical examples of the teeth.

THE VERTEBRA.
The cervical vertebre are very elongate and strongly opisthoccelous.

The deep cavities in the sides of the centrum are separated only by a
thin septum of bone, as shown in fig. 3 of the same plate. The dorsal

1 American Journal of Science, 1888.

184 DINOSAURS OF NORTH AMERICA

vertebre are much longer than the corresponding vertebrae of Moro-
saurus, and have a very long, deep cavity in each side of the centrum,
to which the generic name refers. All the trunk vertebrie hitherto
found are proportionately nearly double the length of the corresponding
centra of Morosaurus, and the lateral cavity is still more elongate.
These points are shown in the posterior dorsal vertebra represented in
figs. 4and 5o0f Pl. XL. The neural arch in this region is lightened by
cavities, and is connected with that of the adjoining vertebrie by the
diplosphenal articulation. A dorsal centrum of another species is
shown below in figs. 35-37.

The sacral vertebrie in Pleuroccelus are more solid than in Moro-
saurus, but more elongate. The surface for the rib, or process which
abutsagainst the ilium, is well in front, more so than in any of the known

.—The same vertebra; top view.
—The same; back view.

Fig. 38.—Caudal vertebra of same individual; front view.

Fic. 39.—The same vertebra; side view.

Fic. 40.—The same; back view.

Fic. 41.—The same; top view.
+ All the figures are one-half natural size. a, anterior end; f, cavity in centrum; 7, neural canal;
p, posterior end.
Sauropoda. Behind this articular surface is a deep pit, which somewhat
lightens the centrum. These characters are seen in the sacral vertebra
represented in figs. 6 and 7 of Pl. XL.

The first caudal vertebra has the centrum very short, and its two
articular faces nearly flat, instead of having the anterior surface deeply
concave, as in the other known Sauropoda. An anterior caudal is
shown in figs. 38-41, above. The neural spines in this region are com-
pressed transversely. The middle and distal caudals are comparatively
short and the former have the neural arch on the front half of the
centrum, as shown in figs. 8 to 11 of Pl. XL.

The bones of the limbs and feet preserved agree in general with those

MARSH. ] DISTRIBUTION OF SAUROPODA. 185

of the smaller species of Morosaurus, but indivate an animal of slighter
and more graceful build. The metapodials are much more slender and
the phalanges are less robust than in the other members of the order, as
shown in PI. XLI.

DISTRIBUTION OF THE SAUROPODA.

In the preceding pages the most important forms of the Sauropoda
now known from North America have been briefly described and illus-
trated. The only remains known from other parts of America are a few
fragmentary specimens recently found in Patagonia, and described by
Lydekker, under the generic names Argyrosaurus and Titanosaurus,
in the Anales del Museo de La Plata, 1893. The specimens now known,
although in poor preservation, show distinctive characters of the order
Sauropoda, and indicate reptiles of gigantic size. The discovery is
interesting and will doubtless soon be followed by others of more
importance.

In England remains of Sauropoda have long been known, and the
first generic name given was Cardiodon, proposed by Owen, in 1841, and
based on teeth alone. A number of other geveric names have since
been proposed, and several are still in use. Among these are Cetio-
saurus and Bothriospondylus Owen, Pelorosaurus Mantell, 4 pysaurus
and Hoplosaurus Gervais, Ornithopsis Seeley, and Eucamerotus Hulke.
The absence of the skull, and the fact that most of the type specimens
pertain to different parts of the skeleton, render it difficult, if not impos-
sible, to determine the forms described, and especially their relations
to ore another.

COMPARISON WITH EUROPEAN FORMS.

In examining the European Sauropoda with much care the writer
was impressed by three prominent features in the specimens investi-
gated:

(1) The apparent absence of any characteristic remains of the Atlan-
tosauridz, which embrace the most gigantic of the American forms.

(2) The comparative abundance of another family, Cardiodontide,
nearly allied to the Morosauridz, but, as a rule, less specialized.

(5) The absence, apparently, of all remains of the Diplodocide.

A number of isolated teeth and a few vertebre of one immature irdi-
vidual appear to be closely related to the Pleuroceelide, but this, for
the present, must be left in doubt.

A striking difference between the Cardiodontidé and the allied Amer-
ican forms is,that in the former the fore and hind limbs appear to be
more nearly of the same length, indicating a more primitive or general-
ized type. Nearly all the American Sauropoda, indeed, show a higher
degree of specialization than those of HKurope, both in this feature and
in some other respects.

The identity of any of the generic forms of European Sauropoda
with those of Americais at present doubtful. In one or two instances
it is impossible, from the remains now known, to separate closely allied

186 DINOSAURS OF NORTH AMERICA.

forms from the two countries. Portions of one Wealden animal, refer-
red by Mantell to Pelorosaurus, are certainly very similar to some of
the smaller forms of Morosaurus, especially in the proportions of the
fore limbs, which are unusually short. This fact would distinguish
them at once from Pelorosaurus, and until the skull and more of the
skeleton are known they can not be separated from Morosaurus.

The only Sauropoda reported from other parts of the world are some
fragmentary remains from India, referred by Lydekker to the genus
Titanosaurus, and more recently other remains from Madagascar, which
the same author has placed in the genus Bothriospondylus. The wide
distribution of the forms already known indicates that many future dis-
coveries may be expected.

PREDENTATA.

The third order of the Dinosauria, according to the system of classi-
fication here adopted, is the one named by the writer the Predentata,
a name derived from the fact that all the members of the group have a
predentary bone, which is wanting in all other dinosaurs, and in fact
in all other vertebrates, living and extinct. This order includes three
suborders: the Stegosauria (plated lizards), the Ceratopsia (horned liz-
ards), and the Ornithopoda (bird-footed). These are all herbivorous
forms, and most of them contain species of very large size. The Steg-
osauria were mainly confined to the Jurassic, the Ceratopsia entirely to
the Cretaceous, while the Ornithopoda were abundant in each of these
periods. Of the Jurassic forms the Stegosauria will be first discussed,
especially the typical family Stegesaurid, which contains the Ameri-
can forms.

STEGOSAURIDA.

The genus Stegosaurus, the type of the family, was described by the
writer in 1877 from a specimen found in the Atlantosaurus beds of Colo-
rado. Subsequently other remains were discovered and described by
the writer, the more important being from near Lake Como, Wyo., and
Canyon, Colo., localities which have furnished so many type specimens
of the Sauropoda and other dinosaurs.

STEGOSAURUS.
THE SKULL.

The skull of Stegosaurus is long and slender, the facial portion being
especially produced. Seen from the side, with the lower jaw in posi-
tion, it is wedge-shaped, with the point formed by the premaxillary,
which projects well beyond the mandible, as shown in fig. 1, Pl. XLIII.
The anterior nares are large and situated far in front. The orbit is
very large and placed well back. The lower temporal fossa is some-
what smaller. All these openings are oval in outline and are on a line

MARSH.] STEGOSAURUS. 187

nearly parallel with the top of the skull. In this view the lower jaw
covers the teeth entirely.

Seen from above, as shown in fig. 3, Pl. XLITI, the wedge-shaped form
of the skull is still apparent. The only openings visible are the supra-
temporal fosse. The premaxillary bones are short above, but send back
a long process below the narial orifice. The nasal bones are very large
and elongate. They are separated in front by the premaxillaries, and
behind by anterior projections from the frontal bones. The prefrontals
are large, and are placed between the nasals and the prominent, rugose
supraorbitals. The frontals are short, and externally join the post-
frontals. The parietals are small and closely coossified with each
other.

Viewed from in front, the skull and mandible present a nearly quad-
rate outline (Pl. XLIII, fig. 2), and the mutual relations of the facial
bones are well shown. In this view is seen, also, the predentary bone,
a characteristic feature of the mandible in this genus. The lateral
aspect of this bone is shown in fig. 1 of the same plate.

The teeth in this genus are entirely confined tothe maxillary and
dentary bones, and are not visible in anyof the figures here given.
They are small, with compressed, fluted crowns, which are separated
from the roots by a more or less distinct neck. The premaxillary and
the predentary bones are edentulous. A typical tooth of Stegosaurus,
and one of an allied genus. Priconodon, are represented on Pl. XLIV,
figs. 1 and2.

The present skull belongs to the type specimen of a very distinct
species, Stegosaurus stenops. The skull and nearly complete skeleton of
this specimen, with most of the dermal armor in place, were found
almost iv the position in which the animal died.

This reptile was much smaller than those representing the other
species of this genus. Its remains were found by Mr. M. P. Felch in
the Atlantosaurus beds of the Upper Jurassic, in southern Colorado.
In this geological horizon all known American forms of Stegosaurus
have been discovered.

THE BRAIN.

Little has been known hitherto of the brain in dinosaurs, but fortu-
nately one specimen of Stegosaurus has the brain case well preserved
and apparently without distortion. Figs. 3 and 4 of Pl. XLIV show
the form and general characters of this brain cavity. The brain of
this reptile was much elongated, and its most striking features were
the large size of the optic lobes and the small cerebral hemispheres.
The latter had a transverse diameter only slightly in excess of the
medulla. The cerebellum was quite small. The optic nerve corre-
sponded in size with the optic lobes. The olfactory lobes were of large
size. As a whole, this brain was lacertilian rather than avian. A
brain cast of a young alligator is given on Pl. LX XVII for comparison.

188 DINOSAURS OF NORTH AMERICA.

The contrast in the development of the cerebral region is marked, but
in some other respects the correspondence is noteworthy.

In comparing the proportionate size of the brain of this living reptile
with that of Stegosaurus, as given on the same plate, the result proves
of special interest. The absolute size of the two brain casts is approxi-
mately as 1 to 10, while the bulk of the entire bodies, estimated from
corresponding portions of each skeleton, was as 1 to 1,000. It follows
that the brain of Stegosaurus was only 74, that of the alligator, if the
weight of the entire animal is brought into the comparison. If the
cerebral regions only of the two brains were compared the contrast
would be still more striking. This comparison gives, of course, only
approxunate results, and some allowance should be made for the pro-
portionally larger brain in small animals.

The brain of Stegosaurus ungulatus is clearly of a lower type than
that of Morosaurus, which, as the writer has shown, was several times
smaller in diameter than the neural canal in its own sacrum. In the
latter genus the braim was proportionally shorter, and the cerebral
region better developed, as shown in the plate cited, The absolute size
of this brain as compared with that of Stegosaurus is about 16 to 10,
the brain of the alligator figured being regarded as 1. Taking again
the body of the alligator as the unit, and Stegosaurus as 1,000, that of
Morosaurus would be about 1.500. Stegosaurus had thus one of the
smallest brains of any known land vertebrate. These facts agree fully
with the general law of brain growth in extinct mammals and birds as
nade out by the writer.!

THE ANTERIOR VERTEBRAE.

The vertebrae of Stegosaurus preserved all have the articular faces
of their centra concave, although in some the depression is slight.
They are all, moreover, without pneumatic or medullary cavities. On
Pl. XLV a selection from the vertebral series of one skeleton is given,
which shows the principal forms. Figs. 1 and 2 represent a median
cervical. The other neck vertebr have their centra of similar length,
but the diameter increases from the axis to the last of the series. Some
of the anterior cervicals have a small tubercle in the center of each end
of the centra, a feature seen also in some of the caudals. All the cer-
vicals supported short ribs.

The dorsal vertebra have their centra rather longer and more or less
compressed. The neural arch is especially elevated. The neural canal
is much higher than wide. The head of the rib fits into a pit on the
side of the neural arch. Figs. 3 and 4 of Pl. XLV represent a poste-
rior dorsal with characteristic features. The ribs are massive, and are
strengthened by their form, which is T-shaped in transverse section.

10dontornithes, a monograph on the extinct toothed birds of North America: U.S. Geol. Expl.
Fortieth Par., Vol. VII, pp. 8, 121, 1880. Dinocerata, a monograph of an extinct order of gigantic
mammals: Mon. U.S. Geol. Survey, Vol. X, Author's Edition, pp. 57-59, 1884.

MARSH. STEGOSAURUS. 189

THE SACRUM.

The true sacrum of Stegosaurus is composed of four well-coossified
vertebre. In fully adult animals the pelvic arch may be strengthened
by the addition of one or more Jumbar vertebrie, as in the specimen
figured in Pl. XLVI, fig. 5, where two are firmly consolidated with the
sacrum. ‘The centra of the sacral vertebre are solid, like the others in
the column. Their neural arches are especially massive, and the spines
have high and expanded summits. The transverse processes of the
sacral vertebre are stout vertical plates, which curve downward below
and unite to meet the ilia. Each vertebra supports its own process,
although there is a tendency to overlap in front. There is a gradual
increase in size from the first to the last sacral vertebra, and the first
caudal is Jarger than the last sacral. The neural cavity of the sacrum
is described below.

THE CAUDAL VERTEBRE.

The caudal vertebree present the greatest diversity, both in size and
form. The anterior caudals are the largest in the whole vertebral
series, and are highly modified to support a portion of the massive der-
mal armor. The articular faces of their centra are nearly plane and
very rugose. The neural spine has an enormous development, and its
summit is expanded into a bifurcate rugose head. These caudals are
very short, and their neural spines nearly or quite in apposition above.
Their centra have no distinct faces for chevrons. The transverse proc-
esses are expanded vertically, and their extremities curve downward.
Farther back the same general characters are retained, but the centra
are more deeply cupped and the spines less massive. Figs. 5, 6, and 7 of
Pl. XLV show anterior caudal vertebre. Thechevrons here have their
articular ends separate and rest upon two vertebrae, as shown on the
same plate.

In the median caudals, figs. 8 and 9, the spine has greatly diminished
in height, and the faces for chevrons are placed on prominent tubercles
on the postero-inferior surface. The lower margin of the front articular
face 1s sharp and the chevrons do not meet it. In the more distal
caudals the neural spine and zygapophyses are reduced to mere rem-
nants, but the chevron facets remain distinct. These vertebree, as well
as those farther back, have their centra much compressed. The caudal
vertebre are remarkably uniform in length throughout most of the
series.

THE SACRAL CAVITY.

During an investigation of one skeleton of this genus the writer
found a very large chamber in the sacrum, formed by an enlargement
of the spinal canal. This chamber was ovate in form, and strongly
resembled the brain case in the skull, although very much larger,
being at least twenty times the size of the cavity which contained the
brain. This remarkable feature led to the examination of the sacra of
several other individuals of Stegosaurus, and it was found that all had

190 DINOSAURS OF NORTH AMERICA.

a similar large chamber in the same position. The form and propor-
tions of this cavity are indicated in Pl. XLVI, figs. 2 and 3, which
represent a cast of the entire neural canal inclosed in the sacrum.
The large vaulted chamber, it will be observed, is contained mainly in
the first and second sacral vertebrie, although the canal is consider-
ably enlarged behind this cavity. The sections represented in fig. 4
are in each case made where the transverse diameters are greatest.

The remarkable feature about this posterior brain case, if so it may
be called, is its size in comparison with that of the true brain of the
animal, which is also indicated in the same plate, and m this respect
it is entirely without a parallel. A perceptible swelling in the spinal
cord of various recent animals has indeed been observed in the pectoral
and pelvic regions, where the nerves are given off for the anterior and
posterior limbs; and in extinct forms some very noticeable cases are
recorded, especially in dinosaurs, but nothing that approaches the sacral
enlargement in Stegosaurus has hitherto been known. The explanation
may doubtless in part be found in the great development of the pos-
terior limbs in this genus; but in some allied forms—Camptosaurus, for
example, where the disproportion between the fore and hind limbs is
quite as marked—the sacral enlargement of the spinal cord is not one-
fourth as great as in Stegosaurus.

It is an interesting fact that in young individuals of Stegosaurus
the sacral cavity is proportionately larger than in adults, which corre-
sponds to a well-known law of brain growth.

The physiological effect of a posterior nervous center so many times
larger than the brain itself is a suggestive subject which need not here
be discussed It is evident, however, that in an animal so endowed
the posterios part was dominant.

THE PELVIS.

The ilium in Stegosaurus is a very peculiar bone, unlike any hitherto
known in the reptiles. Its most prominent feature is its great anterior
extension in front of the acetabulum. Another striking character is
seen in its superior crest, which curves inward, and firmly unites with
the neural arches of the sacrum, thus roofing over the cavities between
the transverse processes. The acetabular pertion of the ilium is large
and shallow (Pl. XLVI, fig. 5). The face for union with the ischium
is large and rugose, but that for the pubis is much less distinet. The
postacetabular part of the ilium is very short, scarcely one-third as
long as the anterior projection.

The ischium of Stegosaurus ungulatus is short and robust, and has a
prominent elevation on the upper margin of the shaft (Pl. XLVILI,
fig. 2). Its larger articular face meets a postacetabular process of the
ilium, and a smaller articulation joins the pubis. The shaft of the
ischium is twisted so that it resembles somewhat the corresponding
bone of Morosaurus. The pelvis of Stegosaurus stenops 1s Shown in the
same plate, fig. 3.

MARSH.] STEGOSAURUS. 191

The pubic element of the pelvis of Stegosaurus ungulatus is in general
form somewhat like that of Camptosaurus. The prepubis consists of
a strong spatulate process, projecting forward nearly horizoutally. Its
proximal end articulates with the preacetabular process of the ilium.
The postpubic branch extends backward and downward, nearly to the
end of the ischium. The two bones fit closely together in this region,
The usual pubic foramen is in this species replaced by a notch, opening
into the acetabular cavity. In a smaller species, Stegosaurus affinis,
the postpubic bone is slender and more rod-like, not flattened as in the
specimen here figured.

THE FORE LIMBS.

On Pl. XLVII some of the bones of the scapular arch and anterior
limbs of Stegosaurus are figured. The scapulaand coracoid are of the
true dinosaurian type. The former has its upper portion rather short
and moderately expanded. The coracoid was closely united to the
scapula by cartilage. It is perforated by the usual foramen, which in
some cases may become a notch.

The humerus (fig. 5) is short and massive. It has a distinet head
and a strong radial crest. The shaft is constricted medially, and is
without any medullary cavity. The ulna (fig. 4) is also massive, and
has a very large olecranal process. Its distal end is comparatively
small. Theradius is sinaller than the ulna. The fore limb, as a whole,
was very powerful and adapted to varied movements. There were
five well-developed digits in the fore foot, as shown on Pl. XLVIII,
fig. 1.

THE HIND LIMBS.

The femur of Stegosaurus (Pl. XLVII, fig. 1) is by far the largest
bone in the skeleton. It is remarkably long and slender. There is no
distinct head, and the great trochanter is nearly or quite obsolete. The
shaft is of nearly uniform width and very straight. There is no evi-
dence of a third trochanter. The distal end of the femur is peculiar
in having very-flat condyles, with only a shallow depression between
them. The external one has only a rudiment of the ridge which passes
between the heads of the tibia and fibula, and is very characteristic of
true dinosaurs and birds.

The tibia (fig. 2) is very much shorter than the femur. Its superior
end is unusually flat, indicating that it met the condyles of the femur
so as to bring the two bones at times nearly or quite into the same
line. The shaft of the tibia is constricted medially, leaving a wide
space between it and the fibula. The distal end of the tibia is blended
entirely with the convex astragalus, so as to resemble strongly the cor-
responding part in birds.

The fibula (fig. 2) is slender, and has its smaller end above. This
extremity is applied closely to the head of the tibia by a rugose suture,
so as to unite readily with it. Its upper articular surface is nearly or
quite on a level with that of the tibia. The distal end of the fibula is

192 DINCSAURS OF NORTH AMERICA.

expanded, and in the specimen figured is firmly coossified with the cal-
caneum. The two coalesce with the tibia and astragalus, and form @
smooth convex articulation for the ankle joint. There were only three
functional digits in the hind feet, as shown on Pl. XLVIII, fig. 2.

THE DERMAL ARMOR.

The most remarkable feature about Stegosaurus is the series of ossi-
fications which formed its offensive and defensive armor. These consist
of numerous spines, some of great size and power, and many bony
plates of various sizes and shapes, well fitted for protecting the animal
against assaults. Some of these plates are a meter, or more than 3 feet,
in diameter.

The spines were of different forms and varied much in size. Four
of these are represented on Pl. L. All of those preserved are unsym-
metrical, and most of them are in pairs. One of the largest is shown
in fig. 2, which gives the more usual form and proportions. This speci-
men is over 2 feet in length.

The osseous dermal covering of the Stegosauria was first described
by the writer from specimens found associated with several skeletons,
but not in place, and hence the position of the various parts was a
matter of considerable doubt. Subsequent discoveries have shown the
general arrangement of the plates, spines, and ossicles, and it is now
evident that, while all the group were apparently well protected by
offensive and defensive armor, the various species, and perhaps the
sexes, differed more or less in the form, size,and number of portions of
their dermal covering. This was especially true of the spines, which
are quite characteristic in some members of the group, if not in all.

The skull was evidently covered above with a comparatively soft
integument. The throat and neck below were well protected by small,
rounded and flattened ossicles having a regular arrangement in the
thick skin. One of these ossicles is shown in Pl. XLIX, fig. 1. The
upper portion of the neck, back of the skull, was protected by plates,
arranged in pairs on either side. These plates increased in size farther
back, and thus the trunk was shielded from injury. From the pelvic
region backward a series of huge plates stood upright along the median
line, gradually diminishing in size to about the middle of the tail. One
of these is shown in Pl. XLIX, fig.4. Some of the species, at least, had
somewhat similar plates below the base of the tail, and one of these
bones is represented in fig. 5 of the same plate.

The offensive weapons of this group were a series of huge spines
arranged in pairs along the top of the distal portion of the tail, which
was elongate and flexible, thus giving effective service to the spines,
as in the genus Myliobatis.

In Stegosaurus ungulatus there were four pairs of these spines,
diminishing in size backward. Two of the larger of these are shown
on PI. L, figs.2 and 3. In some other forms there were three pairs,
and in S. st<nops but two pairs have been found.

Marsu.] DIRACODON. 193

In one large species, Stegosaurus sulcatus, there is at present evidence
of only one pair of spines. These are the most massive of any yet
found, and have two deep grooves on the inner face, which distinguish
them at once from all others known. One of these grooved spines is
represented on Pl. L, figs. 4, 5, and 6,

The position of these caudal spines with reference to the tail is indi-
cated in the specimen figured on Pl. LI, which shows the vertebree,
spines, and plate as found.

DIRACODON.

The American genera of the Stegosauria are Stegosaurus and Dirac-
odon. Of the former there are several well-marked species besides
S armatus, the type. Of the latter genus but one is known at present,
Diracodon laticeps, the remains of which have hitherto been found at a
single locality only, where several individuals referred to this species
have been discovered. Aside from the form of the skull, these speci-
mens have in the fore foot the intermedian and ulnar bones separate,
while in Stegosaurus these carpals are firmly coossified.

All the American Stegosauridie have the second row of carpals
unossified and five digits in the manus. In the hind foot the astrag-
alus is always coossified with the tibia, even in very young specimens,
while the calceaneum is sometimes free. The second row of tarsals is
not ossified in any of the known specimens. Only four digits in the
hind foot are known with certainty, and one of these 1s quite small.
All forms have at least three well-developed metatarsals, which are
short and massive, but longer and much larger than the metacarpals.

In one large specimen, of which the posterior half of the skeleton was
secured, no trace of dermal armor of any kind was found. If present.
during life, as indicated by the massive spines of the vertebra, it is
difficult to account for its absence when the remains were found, unless,
indeed, the dermal covering had been removed after the death of the
animal and previous to the entombment of the skeleton where found.
In this animal the ilia were firmly coossified with the sacrum, thus form-
ing a strong bony roof over the pelvic region, as in birds.

This specimen represents a distinct species, Stegosaurus duplex. It
was originally referred by the writer to S. wngulatus. In the sacrum
of this species each vertebra supports its own transverse process, or
rib, as in the Sauropoda, while in S. wngulatus the sacral ribs have
shifted somewhat forward, so that they touch, also, the vertebra in
front, thus showing an approach to some of the Ornithopoda.

CHARACTERS OF STEGOSAURIA.

The large number of specimens of the Stegosauria now known from
the American Jurassic, and the fine preservation of some of the remains,
aid in forming a more accurate estimate of the relations of the group
to the other dinosaurs than has hitherto been possible. The presence

16 GEOL, PT 1 13

194 DINOSAURS OF NORTH AMERICA.

of a predentary bone, and the well-developed postpubis, are important
characters that point to the Ornithopoda as near allies, with a common
ancestry. These positive characters are supplemented by some points
in the structure of the skull and the form of the teeth.

There are, however, a large number of characters in which the Stego-
sauria differ from the Ornithopoda, and among these are the following:

(1) All the bones of the skeleton are solid.

(2) The vertebrze are all biconcave.

(3) All the known forms have a strong dermal armor.

(4) The second row of carpals and tarsals are unossified.

(5) The astragalus is coossified with the tibia.

(6) The spinal cord was greatly enlarged in the sacral region.

RESTORATION OF STEGOSAURUS.
PiaTeE LII.

In this restoration the animal is represented as walking, and the
position is adapted to that motion. The head and neck, the massive
fore limbs, and, in fact, the whole skeleton, indicate slow locomotion
on all four feet. The longer hind limbs and the powerful tail show,
however, that the animal could thus support itself, as on a tripod, and
this position could perhaps have been easily assumed in consequence of
the massive hind quarters.

In the restoration as here presented the dermal armor is the most
striking feature, but the skeleton is almost as remarkable, and its high
specialization was evidently acquired gradually as the armor itself
was developed. Without the latter many points in the skeleton would
he inexplicable, and there are still a number that need explanation.

The small, elongated head was covered in front by a horny beak.
The teeth are confined to the maxillary and dentary bones, and are not
visible in the figure here given. They are quite small, with compressed,
fluted crowns, and indicate that the food of this animal was soft, suc-
culent vegetation. The vertebr are solid, and the articular faces of
the centra are biconcave or nearly flat. The ribs of the trunk are
massive and placed high above the centra, only the tubercle being
supported on the elevated diapophysis. The neural spines, especially
those of the sacrum and anterior caudals, have their summits expanded
to aid in supporting the massive dermal armor above them. The limb
bones are solid, and this is true of every other part of the skeleton.
The feet were short and massive, and the terminal phalanges of the
functional toes were covered by strong hoofs. There were five well-
developed digits in the fore foot, and only three in the hind foot, the
first toe being rudimentary and the fifth entirely wanting.

In life the animal was protected by a powerful dermal armor, which
served both for defense and offense. The throat was covered by a thick
skin, in which were embedded a large number of rounded ossicles, as
Shown in the plate. The gular portion represented was found beneath

MARSH. ] DISTRIBUTION OF STEGOSAURIA. 195

the skull, so that 1ts position in life may be regarded as definitely set-
tled. The series of vertical plates which extended above the neck,
along the back, and over two-thirds of the tail, is a most remarkable
feature, which could not have been anticipated and would hardly have
been credited had not the plates themselves been found in position.
The four pairs of massive spines characteristic of the present species,
which were situated above the lower third of the tail, are apparently
the only part of this peculiar armor used for offense. In addition to
the portions of armor above mentioned there was a pair of small plates
just behind the skull, which served to protect this part of the neck.
There were also, in the present species, four flat spines, which were
probably in place below the tail, but as their position is somewhat in
doubt they are not represented in the present restoration.

All these plates and spines, massive and powerful as they now are,
were in life protected by a thick, horny covering, which must have
greatly increased their size and weight. This covering is clearly indi-
cated by the vascular grooves and impressions which mark the surface
of both plates and spines, except their bases, which were evidently
implanted in the thick skin.

The peculiar group of extinct reptiles named by the writer the Steg-
osauria, of which a typica: example is represented in the present resto-
ration, is now nearly as well known as any other dinosaurs. They are
evidently a highly specialized suborder of the Predentata, which have
the Ornithopoda as their most characteristic members, and all doubt-
less had a common ancestry.

Another highly specialized branch of the same great order is seen
-in the gigantic Ceratopsia of the Cretaceous, which the writer has.
recently investigated and made known. The skeleton of the latter
group presents many interesting points of resemblance to that of
the Stegosauria, which can hardly be the result of adaptation alone,
but the wide difference in the skull and in some parts of the skeleton
indicates that their affinities are remote. A comparison of the present
restoration with that of Triceratops on Pl. LX XI will make the con-
trast between the two forms clearly evident.

DISTRIBUTION OF STEGOSAURIA.

All the typical members of the Stegosauria are from the Jurassic
formation, and the type specimen used in the present restoration was
found in Wyoming, in the Atlantosaurus beds of the upper Jurassic.
Diracodon, a genus nearly allied to Stegosaurus, occurs in the same
horizon. Paloscincus Leidy, 1856, from the Cretaceous, and Pricono-
don of the writer, 1888, from the Potomac formation, are perhaps allied
forms of the Stegosauria, but until additional remains are found their
exact affinities can not be determined. Apparently the 6ldest known
member of this group in America is the Dystropheus Cope, 1877, from
the Triassic of Utah.

?

196 DINOSAURS OF NORTH AMERICA.

One of the best-preserved specimens of the Stegosauria in Europe
was described by Owen, in 1875, as Omosaurus armatus, and the type
specimen is in the British Museum. It is from the Kimmeridge clay
(Upper Jurassic) of Swindon, England The skull is wanting, but the
more important parts of the skeleton are preserved. Various portions
of the skeleton of several other individuals have also been found in
England, but the skull and teeth still remain unknown.

Another genus of the Stegosauria, representing a distinct family, is
Scelidosaurus, established by Owen in 1859, from the Lias of England.
The greater part of the skeleton is known. <A restoration in outline,
made by the writer for comparison with that of Stegosaurus, is shown
on Pl. LXAXNIII. The Euskelesaurus of Huxley, 1867, from the Trias
of South Africa, is apparently a member of this group.

CAMPTOSAURIDA.

Another important family of Jurassic Dinosaurs is the Camptosan-
ride, so named from the type genus Camptosaurus, described by the
writer in 1879, the type specimen being from the Atlantosaurus beds
of Wyoming. This genus includes several species of herbivorous
dinosaurs, which belong to the true Ornithopoda, or bird-footed forms.
The species were all bipedal, with the fore limbs much smaller than
those behind, and all the limb bones light and hollow. The head was
comparatively small, the neck of moderate length and quite flexible,
and in life the animals were evidently agile and graceful in movement.
Some of the smaller species were quite bird-like in form and structure.
The three American genera, Camptosaurus, Dryosaurus, and Laosau-
rus, are all from the same general horizon.

CAMPTOSAURUS.,

The large dinosaur described by the writer as Camptosaurus dispar,
of which a restoration is given on Pl. LVI, is now so well known that
it may be taken as.a form typical of the group. It is exceeded in size
by Camptosaurus amplus Marsh, but there are at least two smaller
species of the genus (C. medius and C. nanus). So far as at present
known these species are found in successive deposits of the same gen-
eral horizon, the smallest below and the largest above.

Camptosaurus amplus 1s represented by remains which show that this
reptile when alive was about 50 feet in length. The type specimen
of C. dispar was about 20 feet in length and 10 feet in height.
C. medius was about 15 feet long. The smallest species of the
genus, C. nanus, was not more than 10 feet m length, and perhaps
6 feet in height when standing at rest. One of the striking features
of this diminutive species is its long sigmoid scapula, shown in fig. 2,
PI. LV. This is in strong contrast with the short, straight scapula
of C. dispar, seen on Pl. LIV, fig. 1. The limb bones of all the species
of this genus are very hollow.

MARSH. } CAMPTOSAURID. MOK

The skull, brain, and teeth of C. medius are shown on PI. LIII.
The peculiar peg-and-notch articulation in the sacral vertebrie of this
genus, already described elsewhere, is indicated on Pl. LIV, figs. 5 and
4, and a summary of the principal characters of the genus, and of the
nearest allied genera, will be found on p. 201.

RESTORATION OF CAMPTOSAURUS.
PLatTe LVI.

The restoration here given is based upon the type specimen of Camp-
tosaurus dispar, one of the most characteristic forms of the great group
Ornithopoda, or bird-footed dinosaurs. The reptile is represented on
Pl. LVI, one-thirtieth natural size. The position chosen was deter-
mined after a careful study not only of the type specimen, but of sev-
eral others in excellent preservation, belonging to the same species or
to others nearly allied. It is therefore believed to be a position fre-
quently assumed by the animal during life, and thus, in some measure,
characteristic of the genus Camptosaurus. The type specimen of the
present species, when alive, was about 20 feet in length, and 10 feet
high in the position here represented.

The genus Camptosaurus is a near ally of Iguanodon of Europe, and
may be considered its American representative. Camptosaurus, how-
ever, is a more generalized type, as might be expected from its lower
geological horizon. It resembles more nearly some oi the Jurassic forms
in England generally referred to Iguanodon, but as these are known
only from fragmentary specimens their generic relations with Campto-
saurus can not now be determined with certainty.

In comparing Camptosaurus, as here restored, with a very perfect
skeleton of Iguanodon from Belgium, as described and figured, various.
points of difference as well as of resemblance may be noticed. Theskull
of Camptosaurus had a sharp, pointed beak, evidently encased during
lifein a horny sheath. This was met below by a similar covering, which
inclosed the predentary bone. The entire front of the upper and lower
jaws was thus edentulous, as in Iguanodon, but of different shape. The
teeth of the two genera are of similar form, and were implanted in hke
manner in the maxillary and dentary bones. In Camptosaurus there
is over each orbit a single supraorbital bone, curving outward and
backward, with a free extremity, asin the existing monitor, a feature
not before observed in any other dinosaur except Laosaurus, an allied
geuus, also from the Jurassic of America. Other portions of the skull
of Camptosaurus, as well as the hyoid bones, appear to agree in general
with those of Iguanodon.

The vertebre of Camptosaurus are similar in many respects to those
of Iguanodon, but differ in some important features. In the posterior
dorsal region the transverse processes support both the head and tuber-
cle of the rib, the head resting on a step, as in existing crocodiles.
The five sacral vertebree, moreover, are not coossified even in adult

198 DINOSAURS OF NORTH AMERICA.

forms, and to this character the name Camptonotus, first given to the
genus by the writer in 1879, especially refers. Another notable feature
of the sacral vertebrie of the type specimen should be mentioned. The
vertebra of the sacrum, especially the posterior four, are joined to each
other by a peculiar peg-and-notch articulation. The floor of the neural
canal of each vertebra is extended forward into a pointed process
(somewhat like an odontoid process), which fits mto a corresponding
cavity of the centrum in front. This arrangement, while permitting
some motion between the mdividual vertebrie, helps to hold them in
place, thus compensating in a measure for absence of anchylosis. A
similar method of articulation is seen in the dermal scales of some
ganoid fishes, but so far as the writer is aware nothing of the kind has
been observed before in the union of vertebrae.

In Camptosaurus the sternum was entirely unossified, and no trace
of clavicles has been found. The pelvis of Camptosaurus differs
especially from that of Iguanodon in the pubis, the postpubie branch
being even longer than the ischium, while in Iguanodon this element is
much shortened.

In the fore foot of Camptosaurus there were five functional digits,
the first being flexible and nearly parallel with the second, thus difter-
ing from the divergent, stiff thumb of Iguanodon, The hind feet had
each three functional digits only, the first being rudimentary and the
fifth entirely wanting, as shown in Pl. LVI. The entire skeleton of
Camptosaurus was proportionately more slender and delicately formed
than that of Iguanodon, although the habits and mode of life of these
two herbivorous dinosaurs were doubtless very similar.

The type specimen of Camptosaurus dispar, used as the basis of the
present restoration, is from the Atlantosaurus beds of the Upper
Jurassic of Wyoming. This species and other allied forms will be
described in full in an illustrated memoir now in preparation by the
writer for the United States Geological Survey. The present restora-
tion is reduced from a large drawing made for that volume.

LAOSAURIDA.
DRYOSAURUS.

Another genus of Jurassic dinosaurs, allied to Camptosaurus, but
differing from it in many important respects, is Dryosaurus. The type
was described by the writer in 1878 under the name Laosaurus altus,
and a tooth, the pelvis, and a hind leg were also figured. Additional
material since received shows that this genus is quite distinct from
Laosaurus, to which it was at first referred, and is intermediate
between Camptosaurus and that genus, as is Shown in a summary of
the characters of these genera given later in the present article.

The only species of Dryosaurus at present known is the type first
described, and this form is now called Dryosaurus altus (Pl. LY,
fig. 4). Several specimens of this dinosaur are preserved in the Yale

MARSH. ] NANOSAURID®. 199

museum, and they show it to have been in life about 10 or 12 feet.
long, and one of the most slender and graceful members of the group.
The known remains are all from the Atlantosaurus beds of Colorado
and Wyoming.

LAOSAURUS.

The present genus includes several species of diminutive dinosaurs,
all much smaller than those above described, and possessing many fea-
tures now seen only in existing birds, especially in those of the ostrich
family. The two species of the genus first described by the writer
(Laosaurus celer, the type, and Laosaurus gracilis) show these avian
features best of all, and it would be difficult to tell many of the isolated
remains from those of birds. A larger species, which has been called
Laosaurus consors, is known by several skeletons nearly complete.
The type specimen, here figured in part on PI. LV, figs. 1 and 3, is the
most perfect of all, and this was collected by the writer in 1879. The
animal when alive was about 8 or 10 feet in length. The known remains
are from the Atlantosaurus beds of Wyoming.

One of the distinctive features of this genus, which separates it at
once from those above described, is the pubis. The prepubis, or ante-
rior branch of this bone, which was very large and broad in Campto-
saurus, still long and spatulate in Dryosaurus, is here reduced to a
pointed process not much larger than in some birds. These differences
are Shown in Pl. LIV and in Pl. LY, figs, 3 and 4.

The European representative of Laosaurus is Hypsilophodon Huxley,
from the Wealden of England. That genus, however, differs from the
nearest allied forms of this country in several well-marked characters.
Among these the presence of teeth in the premaxillary bones and a
well-ossified sternum are features not seen in American Jurassic forms.
The fifth digit of the manus, moreover, in Hypsilophodon is almost at
right angles to the others, and not nearly parallel with them,as in
Dryosaurus. It agrees with the latter genus in having the tibia longer
than the femur. An outline restoration of Hypsilophodon, made by
the writer for comparison with allied American forms, is given on PI.
LXXXIVv.

NANOSAURID ZL.
NANOSAURUS.

The smallest known dinosaur, representing the type species of the
present genus, was described by the writer in 1877, under .he name
Nanosaurus agilis. The type specimen consists of the greater portion
of the skull and skeleton of one individual, with the bones more or less
displaced and all entombed in a slab of very hard quartzite. The whole
skeleton was probably thus preserved in place, but before its discovery
a part of the slab had been split off and lost. The remaining portion
shows on the split surface many important parts of the skeleton, and
these have been further exposed by cutting away the matrix, so that

200 DINOSAURS OF NORTH AMERICA.

\

the main characters of the animal can be determined with considerable
certainty.

A study of these remains shows that the reptile they represent was
one of the typical Ornithopoda, and one of the most bird-like yet dis-
covered. A dentary bone in fair preservation (fig. 42) indicates that
the animal was herbivorous, and the single row of pointed and com-
pressed teeth, thirteen in number and small in size, forms a more regu-
lar and uniform series than in any other member of the group. The
ilium, also, shown in fig. 43, is characteristic of the Ornithopoda, having
a slender, pointed process in front, but one much shorter than in any of

Fic. 42.—Dentary bone of Nanosaurus agilis Marsh; seen from the left.
Fic. 43.—Ilium of same individual; left side.
Both figures are natural size.

Fic. 44.—Left femur of Nanosaurus rex Marsh; front view.
Fie. 45.—Proximal end of same.

Fic. 46.—The same bone; side view.

Fic. 47.—The same; back view.

Tic. 48.—Distal end of same.

All five figures are one-half natural size.

the larger forms. The posterior eud is also of moderate size. All the
bones of the limbs and feet are extremely hollow, strongly resembling
in this respect those of birds. The femur was shorter than the tibia.
The metatarsals are greatly elongated and very slender, and there were
probably but three functional toes in the hind foot.

A second form referred by the writer to this genus, under the name
Nanosarrus rex, may perhaps belong to the genus Laosaurus. The
femur is shown in figs. 44 to 48, above. The animal thus represented

MARSH.] DETERMINATION OF GENERA. 201

was considerably larger than the present type species and from a some-
what higher horizon in the Atlantosaurus beds.

The type specimen here described, which pertained to an animal
about half as large as a domestic fowl, was found in Colorado. This
reptile was a contemporary of the carnivorous Hallopus, likewise one of
the most diminutive of dinosaurs, and one of the most remarkable.

DETERMINATION OF GENERA.

The various dinosaurs thus briefly referred to under their respective
genera have many other points of interest that can not be here dis-
cussed, but their resemblance to birds is worthy of some notice. This
is apparent in all of them, but in the diminutive forms the similarity
becomes more striking. In all the latter the tibia is longer than the
femur, a strong avian character, and one seen in dinosaurs only in the
small bird-like forms.! In Nanosaurus nearly all, if not all, the bones
preserved might have pertained to a bird, and the teeth are no evidence
against thisidea. In the absence of feathers an anatomist could hardly
state positively whether this was a bird-like reptile or a reptilian bird.

The main characters of the four genera above discussed are as follows:

CAMPTOSAURUS.

Premaxillaries edentulous, with horny beak. Teeth large, irregular,
and few in number. A supraorbital fossa. Cervical vertebrie long and
opisthocelous. Lumbars present. Five vertebre in sacrum, with
peg-and-notch articulation. Sternum unossified. Limb bones hollow.
Fore limbs small. Five functional digits in manus. Prepubis long
and broad ; postpubis elongated. Femur longer than tibia. Metatar-
sals short. Three functional digits in pes, the first rudimentary and
the fifth wanting.

DRYOSAURUS.

Premaxillaries edentulous, with horny beak. Teeth of moderate size.
A supraorbital fossa. Cervicals long and biconcave. No lumbars.
Six coossified vertebrz in sacrum, without peg-and-notch articulation.
Sternum unossified. Limb bones hollow. Fore limbs very small. Five
digits in manus. Prepubis long and narrow; postpubis elongate and
slender. Posterior limbs very long. Femur shorter than tibia. Meta-
tarsals long and hollow. First digit in pes complete ; fifth metatarsal
represented by short splint only.

LAOSAURUS.

Premaxillaries edentulous. Teeth small and irregular. -Cervicals
short and flat. Six coossified vertebrie in sacrum; no peg-and-notch
articulation. Sternum unossified. Fore limbs small. Limb and foot
bones hollow. Prepubis very short and pointed; postpubis slender.
Femur shorter than tibia. Metatarsals elongate. First digit in pes
- functional; fifth rudimentary.

1Besides the genera here mentioned, Celurus, Compsognathus, and Hallopus also possess this
character.

202 DINOSAURS OF NORTH AMERICA.

NANOSAURUS.

Teeth compressed and pointed, and in a single uniform row. Cervi-
cal and dorsal vertebre short and biconcave. Sacral vertebree three(?).
Anterior caudals short. Ilium with very short, pointed front and nar-
row posterior end. Fore limbs of moderate size. Limb bones and
others very hollow. Femur curved and shorter than tibia. Fibula
pointed below. Metatarsals very long and slender.

The genera thus defined contain all the known forms of the typical
Ornithopoda from the American Jurassic. They are, moreover, the
earliest representatives of this group known in this country from osse-
ous remains, as such fossils have not yet been found in the Triassic,
where the oldest dinosaurs occur. Some of the bird-like footprints in
the Connecticut River sandstone may indeed have been made by dino-
saurs of this group, but there is no positive evidence on this point.
The American Cretaceous forms of the typical Ornithopoda, so far as
at present known, are all of large size and highly specialized, and this
appears to be true also of the Old World species.

RESTORATION OF LAOSAURUS.
PriatTe LVII.

The present restoration in outline of Laosaurus consors, one-tenth
natural size, will serve to show the form and proportions of one of the
most bird-like of the smaller Jurassic Ornithopoda and its contrast
with the more massive Camptosaurus from the same horizon. A com-
parison of this restoration with that of Hypsilophodon from the English
Wealden (Pl. LX XXIV) is especially instructive, as the two animals
were near allies, although from different geological horizons.

The position here chosen for the restoration of Laosaurus is one
which would seem to have been natural to the animal when standing
at rest. This would mean a height of about 4 feet, with 8 feet in
length. That the animal was bipedal inits usual locomotion on land is
assumed in this case from the general structure, especially the very
small and weak fore limbs, and the large size and strong articula-
tions of the posterior limbs. When walking upright, as here repre-
sented, it seems probable that the animal would touch the ground with
its tail; but this is by no means certain. That reptiles of similar
structure and proportions could walk on their hind feet without leav-
ing a mark of the tail is clearly indicated by many long series of bipedal
footprints left in the sandstone of the Connecticut Valley, some of
which have already been described and figured in this paper. In the
present species the tail was powerful and more or less compressed,
thus suggesting its use in swimming.

MARSE.] DRYPTOSAURID&E. 203

IP ARIAL IIEIL.
CRETACEOUS DINOSAURS.

During Cretaceous time in North America the dinosaurs were still
abundant, and most of them were much more specialized than those
that lived in the preceding periods. Some of the Cretaceous forms
were the strangest of the whole group, of gigantic size and bizarre
appearance. Others were diminutive in size and so bird-like in form
and structure that their remains can be distinguished with difficulty,
if at all, from those of birds.

Of the carnivorous dinosaurs known from Cretaceous deposits the
family Dryptosauride is especially conspicuous, on account of the large
size and ferocious nature of all its representatives. Inthe later Creta-
ceous a second family, the Ornithomimide, was also abundant, and
among its members were some of the most minute and bird-like of
dinosaurs hitherto discovered. Of the herbivorous forms the huge,
horned Ceratopside, the most remarkable of all dinosaurs, were for a
limited period the dominant reptiles in western North America. Liv-
ing at the same time with these were the Claosauride, large bipedal
dinosaurs, of sluggish disposition, that dwelt along the shores of the
lakes and rivers of that time. Besides these were still others related
to the Jurassic Stegosaurus, among them the Nodosauride, quadrupedal
forms with heavy dermal armor. All these became extinct at the close
of the Cretaceous, and no remains of dinosaurs have been found in
place in any later deposits.

THEROPODA.

DRY PTOSAURIDA.

This family is well represented throughout the Cretaceous in North
America, but up to the present time only fragmentary remains have
been found, so that little is known about the skull, pelvis, and feet, the
most characteristic portions of the skeleton. So far as now determined
they appear to be nearly allied to Megalosaurus of Europe and include
Allosaurus from the Jurassic of this country.

Remains of the genus Dryptosaurus (Leelaps) have been found at
various localities on the Atlantic Coast, especially in the marl region of
New Jersey. Many of these fossils have been described by Prof. Cope.!

ORNITHOMIMID.

This family can be separated sharply from all other dinosaurs by the
hind feet, which contain three functional metatarsals, the middle one, or
third, of which has its proximal end much diminished in size and crowded
backward behind the second and fourth, as in many existing birds.

1 Extinct Batrachia, Reptilia, and Aves of North America, p. 100, 1870.

204. DINOSAURS OF NORTH AMERICA.

Another important character, seen also in the genus Ceratosaurus of
the Jurassic, is found in the pelvis, the bones of which are firmly coossi-
fied with each other and with the sacrum.

ORNITHOMIMUS.

The most marked characters of the genus Ornithomimus already
determined are manifest in the limbs and feet, and these have been
selected for description in the present article. A typical example is
shown on Pl. LVIII, figs. 1-4, which is the type specimen, the species
being Ornithomimus velox Marsh.

On the distal part of the tibia represented in fig. 1 the astragalus is
seen in place, with a very large ascending process, larger than in any
dinosaur hitherto known. The calcaneum is also shown in position,
but the slender fibula is absent. This bone was complete, but of little
functional value. The tibia and all the larger limb bones were hollow,
with thin walls, as indicated in the section, fig. 1, ¢.

In fig. 5 the corresponding parts of a young ostrich are shown for
comparison. The slender, incomplete fibula is in place beside the tibia.
The astragalus with its ascending process, and the distinct calcaneum,
are also shown in position. The almost exact correspondence of these
different parts in the bird and reptile will be manifest to every anato-
mist.

THE METATARSALS.

The most striking feature of the foot belonging with the reptilian
tibia is shown in the metatarsals represented in fig. 2, A. These are
three in number, and are in the same position as in life. They are the
three functional metatarsais of the typical Ornithopoda and of birds.
The distal ends of these bones correspond in size and relative position
in the two groups, but here, in the present specimen, the reptilian
features cease, and those of typical birds replace them. In all the
reptiles known hitherto, and especially in dinosaurs, the second, third,
and fourth metatarsals are prominent in front, at their proximal ends,
and the third is usually the largest and strongest. In birds the place
of the third is taken above by the second and fourth, the third being
crowded backward and very much diminished in size.

This character is well shown in fig. 6, which represents the second,
third, and fourth metatarsals of a young turkey, with the tarsal bones
absent. In the reptilian metatarsals seen in fig. 2 the same arrange-
ment is shown, with the tarsals in place. The second and fourth
metatarsals lave increased much in size in the upper portion, and
meet each other in front.

The third metatarsal, usually the largest and the most robust
throughout, here diminishes in size upward, and takes a subordinate,
posterior position, as in birds. The correspondence between the
metatarsals of the bird and reptile are here as strongly marked as in
the tibiz and their accompanying elements, above described.

MABSH.] ORNITHOMIMUS. 205

In fig. 3 of the plate the three phalanges represented belong with
the second metatarsal, and were found together in place.

The three metacarpals represented in fig. 4 were found together in
position, near the remains of the hind limb here described. Their very
small size is remarkable, and they may possibly belong to a smaller
individual, but with this exception there is no reason why they do not
pertain to the same specimen as the hind foot. The remains of this
species were found by George L. Cannon, jr., in the Ceratops beds of
Colorado.

THE PELVIC ARCH.

A larger species from the same horizon, Ornithomimus sedens, more
recently described by the writer, is based upon the nearly comnlete

Fic- 49.—Terminal phalanx, manus of Ornithomimus sedens Marsh; side view.
Fic. 50.—The same phalanx; front view.

Fic. 51.—The same; back view.

Fic. 52.—Proximal end of same.

All the figures are one-half natural size.

pelvis, with various vertebre, and some other parts of the skeleton.
The most striking feature of the pelvis is the fact that the ilium,
ischium, and pubis are firmly coossified with one another, as in recent
birds. This character has been observed hitherto among dinosaurs
only in the genus Ceratosaurus, described by the writer from the Juras-
sic of Wyoming. The present pelvis resembles that of Ceratosaurus
in its general features, but there is no foramen in the pubis.

There are five vertebre in the sacrum, firmly coossified with one
another, as are also the sacral spines. The sacral vertebrie are grooved
below, with the sides of the centra excavated. The caudals have the
diplosphenal articulation, and the first caudal bears a chevron. All
the bones preserved are very delicate, and some of them, at least, are

206 DINOSAURS OF NORTH AMERICA.

apparently pneumatic. The sacrum measures 15 inches in length, and
the twelve caudals following occupy a space of 31 inches. The known
remains indicate a reptile about 8 or 10 feet in length. A terminal
phalanx of the fore foot is represented on page 205.

In the same horizon occur the remains of a very minute species,
which agrees in all its characters, so far as determined, with the mem-
bers of this genus. The most characteristic portions secured are the
metatarsal bones, and these show the same features exhibited in the
type species of the genus, O. velox. They are, however, so much
smaller as to suggest that they may pertain to a bird. Various por-
tions of the second, third, and fourth metatarsals are known, and the
distinctive feature is seen in the third, which has the upper part of the
shaft so attenuated that it may not reach to the tarsus. The second
and fourth metatarsals are very long and slender. This unique animal
was about the size of the common fowl]. The species has been called
Ornithomimus minutus.

The large species described by the writer as Ornithomimus grandis
belongs in essentially the same horizon. Portions of two other skele-
tons have since been obtained, which apparently pertain to this species.
In one of these the femur, tibia, and fibula are in good preservation,
and they clearly demonstrate that this reptile was one of the largest of
the Theropoda. The femur and tibia have each a very large cavity in
the shaft, with well-defined walls. Even the fibula has a cavity in its
upper portion. In the other specimen the second metatarsal is in fair
preservation and shows the same form as in the type of the genus.

There is much probability that this gigantic carnivore was one of
the most destructive enemies of the herbivorous Ceratopsidie, next to
be described.

PREDENTATA.
CERATOPSIDE.

The huge horned dinosaurs, from the Cretaceous, recently described
by the writer,! have now been investigated very carefully, and much
additional light has been thrown upon their structure and affinities.
A large amount of new material has been secured, including several
skulls, nearly complete, as well as various portions of the skeleton.

CERATOPS BEDs.

The geological deposits, also, in which their remains are found have
been carefully explored during the last few years, and the known locali-
ties of importance examined by the writer, to ascertain what other
fossils occur in them and what were the special conditions which pre-
served so many relics of this unique fauna, The definite horizon in
which these strange reptiles occur has been called by the writer the
Ceratops beds, from the type genus Ceratops, and its position 1s shown
in the section on page 145,

} American Journal of Science, 1888-1894.

MARSH. ] CERATOPS BEDS. 207

This geological horizon is a distinct one in the upper Cretaceous,
and is indicated for more than 800 miles along the eastern flank of the
Rocky Mountains. It is marked at nearly every outcrop by remains of
these reptiles, and hence the strata containing them have been called
the Ceratops beds. They are fresh-water or brackish deposits which
form a part of the so-called Laramie, but are below the uppermost beds
referred to that group. In some places, at least, they rest upon marine
beds, which contain invertebrate fossils characteristic of the Fox Hills
deposits. The most important localities in the Ceratops beds are in
Wyoming, especially in Converse County.

lush

Ay bt, |

Harrison

Fic. 53.—Map of Converse County, Wyoming; showing localities where skulls of the Ceratopsidx
have been discovered.

The position of each skull is indicated by a cross (+), and more-than thirty of these specimens
were found within the area bounded by the Cheyenne River and the dotted line. he localities given
are based upon field notes made by Mr. J. B. Hatcher.

The fossils associated with the Ceratopside are mainly dinosaurs,
representing one or two orders and several families. Plesiosaurs, croc-
odiles, and turtles, of Cretaceous types, and many smaller reptiles,
have left their remains in the same deposits. Numerous small mam-
mals, also of ancient types, a few birds, and many fishes, are likewise
entombed in this formation. Invertebrate fossils and plants are not
uncommon in the same horizon.

208 DINOSAURS OF NORTH AMERICA.

TRICERATOPS.
THE SKULL.

The skull of Triceratops, the best-known genus of the family, has many
remarkable features. First of all, its size, in the largest individuals,
exceeds that of any land animal hitherto discovered, living or extinet,
and is surpassed only by that of some of the cetaceans. The skull rep-
resented (one-ninth natural size) on Pl. LIX is one of the most perfect
yet discovered. Those shown on PI. LX, figs. 1-3, are both of compara-
tively young animals, but are about 6 feet in length. The type speci-
men of Triceratops horridus was an old individual, and the head, when
complete, must have been 7 or 8 feet long. Two other skulls, nearly
perfect, from the same horizon, have equal or still greater dimensions.

Another striking feature of the skull is its armature. This consisted
of a sharp, cutting beak in front, a strong horn on the nose, a pair of
very large pointed horns on the top of the head, and a row of sharp
projections around the margin of the posterior crest. All these had a
horny covering of great strength and power. For offense and defense
they formed together an armor for the head as complete as any known.
This armature dominated the skull, and in a great measure determined
its form and structure. In some forms the armature extended over
portions of the body.

The skull itself is wedge-shaped in form, especially when seen from
above. The facial portion is very narrow, and much prolonged in front.
In the frontal region the skull is massive and greatly strengthened, to
support the large and lofty horn cores which formed the central feature
of the armature. The huge, expanded, posterior crest, which over-
shadowed the back of the skull and neck, was evidently of secondary
growth, a practical necessity for the attachment of the powerful liga-
ments and muscles that supported the head (P]. LX, figs. 2 and 4).

THE ROSTRAL BONE.

The front part of the skull shows a very high degree of specialization,
and the lower jaws have been modified in connection with it. In front
of the premaxillaries there is a large, massive bone not before seen in
any vertebrate, which the writer has named the rostral bone (0s ros-
trale). It covers the anterior margin of the premaxillaries, and its
sharp inferior edge is continuous with their lower border. This bone
is much compressed, and its surface is very rugose, Showing that it was
covered with a strong, horny beak. It is a cartilage ossification, and
corresponds to the predentary bone below.

The latter in Triceratops is also sharp and rugose, and likewise was
protected by astrong, horny covering. The two together closely resem-
ble the beak éf some turtles, and as a whole must have formed a most
powerful weapon of offense.

In one skull figured (PI. LX, fig. 1) the rostral bone was free, and was
not obtained. This was aiso true of the predentary bone and the nasal

wansH.] TRICERATOPS. 209

horn core. Hence these parts are represented in outline, taken from
another specimen in which they are all present and in good preservation.
In another skull represented (Pl. LIX, and Pl. LXI, figs. 1-3), the
rostral bone and nasal horn core are in position and firmly coossified
with the adjoining elements.

The premaxillary bones are large and much compressed transversely.
Their inner surfaces are flat and meet each other closely on the median
line. In old specimens they are firmly coossified with each other and
with the rostral bone. Each sends upward a strong process to sup-
port the massive nasals. Another process, long and slender, extends
upward and backward, forming a suture with the maxillary behind,and
uniting in front with a descending branch of the nasal. The premaxil-
laries are inuch excavated externally for the narial aperture, and form
its lower margin. They are entirely edentulous.

The maxillaries are thick, massive bones of moderate size, and sub-
triangular in outline when seen from the side. Their front margin is
bounded mainly by the premaxillaries. They meet the prefrontal and
lachrymal above, and also the jugal.. The alveolar border is narrow
and the teeth are small, with only a single row in use at the same time.

The nasal bones are large and massive, and greatly thickened ante-
riorly to support the nasal horn core. In two of the skulls figured
these bones are separate, but in older individuals they are firmly coossi-
fied with each other and with the frontals. The nasal horn core ossifies
from a separate center, but in adult animals it unites closely with the
nasals, all traces of the connection being lost. It varies inuch in form
in different species.

THE HORN CORES.

The frontal bones are quite short and early unite with each other and
with the adjoining elements, especially those behind them. The frontal
or central region of the skull is thus greatly strengthened to support the
enormous horn cores which tower above. These elevations rest mainly
on the postfrontal bones, but the supraorbitals and the postorbitals are
also absorbed to form a solid foundation for the horn cores.

These horn cores are hollow at the base (PI. LX, fig. 3), and in gen-
eral form, position, and external texture agree with the corresponding
parts of the Bovide. They vary much in shape and size in different
species. They were evidently covered with massive, pointed horns,
forming most powerful and effective weapons.

The orbit is at the base of the horn core, and is surrounded, espe-
cially above, by a very thick margin. It is oval in outline and of mod-
erate Size.

The postfrontal bones are very large, and meet each other on the
median line. Posteriorly they join the squamosals and the parietals.
At their union with the latter there is a median foramen (PI. LX, fig.
3, £2), Which may correspond to the so-called ‘‘parietal foramen.” In
old individuals it is nearly or quite closed. When open it leads into

16 GEOL, PT 1 14

210 DINOSAURS OF NORTH AMERICA.

a large sinus, extending above the brain case into the cavities of the
horn cores. This foramen has not before been observed in dinosaurs.

THE POSTERIOR CREST.

The enormous posterior crest is formed mainly by the parietals, which
meet the postfrontals immediately behind the horn cores. The poste-
rior margin is protected by a series of special ossifications, which in
life had a thick horny covering. These peculiar ossicles, which extend
around the whole crest, the writer has called the epoccipital bones (P1.
LX, figs. 1-3, e, and Pl], LXI, fig. 8, e). In old animals they are firmly
coossified with the bones on which they rest.

The lateral portions of the crest are formed by the squamosals,
which meet the parietals in an open suture. Anteriorly they join the
postfrontal elements, which form the base of the horn core, and Jater-
ally they unite with the jugals. The supratemporal fosse he between
the squamosals and the parietals.

BASE OF SKULL.

The base of the skull has been modified in conformity with its upper
surface. The basioecipital is especially massive, and strong at every
point. The occipital condyle is very large, and its articular face nearly
spherical, indicating great freedom of motion. The basioccipital
processes are short and stout. The basipterygoid processes are longer
and less robust.

The foramen magnum is very small, scarcely one-half the diameter
of the occipital condyle. The brain cavity is especially diminutive,
smaller in proportion to the skull than in any other known reptile.

The exoccipitals are also robust, and firmly coossified with the basi-
occipitals. They form about three-fourths of the occipital condyle, as
in some of the chameleons. The supraoccipital is very small, and its
external surface is excavated into deep cavities. It is coossified late with
the parietals above and with the exoccipitals on the sides (P1. LX, fig. 2).

The quadrate is robust and its head much compressed. The latter
is held firmly in a deep groove of the squamosal. The anterior wing
of the quadrate is large and thin, and closely united with the broad
blade of the pterygoid.

The quadratojugal is a solid, compressed bone, uniting the quadrate
with the large, descending process of the jugal. In the genus Tricera.
tops the quadratojugal does not unite with the squamosal. In Cera-
tops, Which includes some of the smaller, less specialized forms of the
family, the squamosal is firmly united to the quadratojugal by suture.

The quadratojugal arch in this group is strong and curves upward,
the jugal uniting with the maxillary, not at its posterior extremity,
but at its upper surface (PI. LX, fig. 1). This greatly strengthens the
center of the skull, which supports the horn cores, and also tends to
modify materially the elements of the palate below. The pterygoids,

warss.] TRICERATOPS. PAI

in addition to their strong union with the quadrate, send outward a
branch, which curves around the end of the maxillary.

The palatine bones are much smaller than the pterygoids. They are
vertical, curved plates, outside and in front of the pterygoids, and
uniting firmly with the maxillaries. The vomers join the pterygoids
in front; where they appear as thin bones, closely applied to each other.

The transyerse bones give some support to the mavillaries, which
are further strengthened by close union with the pterygoids. They
meet the pterygoids behind and the palatines in front.

THE LOWER JAWS.

The lower jaws show no specialization of great importance, with the
exception of the predentary bone already described (PI. LXJ, figs. 4-6).
There is, however, a very massive coronoid process rising from the
posterior part of the dentary (Pl. LX, fig.1). The articular, angular,
and surangular bones are all short and strong, but the splenial is very
long and slender, extending to the predentary. The angle of the lower
jaw projects but little behind the quadrate.

The skull shown on Pl. LIX was discovered in the Ceratops beds of
Wyoming by the writer’s able assistant, Mr. J. B. Hatcher, who also
found many other remains of dinosaurs.

THE BRAIN.

The brain of Triceratops appears to have been smaller in proportion
to the entire skull than in any known vertebrate. Its relative size is
shown on PI. LX XVI, fig. 1.

The position of the brain in the skull does not correspond to the
axis of the latter, the front being elevated at an angle of about 30°
(Pl. LXI, fig. 7).

The brain case is well ossified in front, and in old animals there is a
strong septum separating the olfactory lobes.

THE TEETH.

The teeth of Triceratops and its near allies are very remarkable in
having two distinct roots. This is true of both the upper and lower
series. These roots are placed transversely in the jaw, and there is a
separate cavity, more or less distinct, for each of them. One of these
teeth from the upper jaw, represented by several figures (PI. LX, figs.
9 and 10, and P]. LXX VIII, fig. 4), is typical of the group.

The teeth form a single series only in each jaw. The upper and lower
teeth are similar, but the grinding face is reversed, being on the inner
side of the upper series and on the outer side of the lower series. The
sculptured surface in each series is ov the opposite side trom that in use.

The teeth are not displaced vertically by their successors, but from the
side. The crown of the young tooth, also with two strong roots, cuts its
way between the alveolar margin and the adjacent root of the old tooth,
but sometimes, as might be expected, advances between the two roots.

212 DINOSAURS OF NORTH AMERICA.

The teeth in this family are entirely confined to the maxillary and
dentary bones. The rostral bone, the premaxillaries, and the pre-
dentary are entirely edentulous.

CERVICAL AND DORSAL VERTEBRAE.

The atlas and axis of Triceratops are coossified with each other, and
at least one other vertebra is firmly united with them. These form a
solid mass, well adapted to support the enormous head (Pl. LXIV,
fig. 1). The cup for the occipital condyle is nearly round and very
deep. The rib of the second vertebra is coossified with it, but the
third is usually free. The centrum of the fourth vertebra is free, and
the remaining cervicals are of the same general form, all having their
articular faces nearly flat.

The anterior dorsal vertebrie have very short centra, with flat artic-
ular ends, and resemble somewhat those of Stegosaurus, especially in
the neural arch. This is shown in Pl. LNIV, figs. 3 and 4.

The posterior trunk vertebrie have also short, flat centra, but the
diapophyses have faces for both the head and tubercle of the ribs, as
in crocodiles, a feature but recently seen in dinosaurs.

THE SACRUM.

The sacrum was strengthened by union of several vertebrae, ten
being coossified in one specimen of Triceratops (P]. LXV). The middle
or true sacral vertebre have double transverse processes, diapophyses
being present and aiding in supporting the ilium. This character has
been seen hitherto in the Dinosauria only in Ceratosaurus and some
other Theropoda.

The main support of the pelvis was borne by four vertebrae, which

vidently constituted the original sacruin. In front of these, two others
have only simple processes, and apparently were once dorsals or lum-
bars. Three vertebrae next behind the true sacrum have also single
processes, and the fourth, or last of the series, has the rib process weak,
and not reaching the ilium (Pl. LXV). Seen from the side the sacrum
is much arched upward, and the neural spines of the true sacrum are
firmly coossified. In the median region the sacral vertebre have their
centra much compressed, but the last of the series are widely expanded
transversely. The whole appearance of the sacrum is remarkably avian.
The neural canal of the sacral vertebrw has no special enlargement,
thus differing widely from that in Stegosaurus.

THE CAUDAL VERTEBRE.

The caudal vertebrae are short and the tail was of moderate length.
The first caudal has the anterior face of the centrum concave vertically,
but flat transversely, and a short, massive neural spine with expanded
summit (Pl. LXIV, figs. 5-7). In the median caudals the centra have
biconcave articular faces and weak neural spines. The distal caudals
are longer than wide, with the ends concave and nearly round.

MARSH.) TRICERATOPS. 213

THE SCAPULAR ARCH AND FORE LIMBS.

The scapula is massive, especially below. The shaft is long and nar-
row, with a thin edge in tront and a thick posterior margin above the
glenoid fossa. The distal portion has a median external ridge and a
thick end (PI. LXVI, fig. 1, se).

The coracoid is rather small, and in old individuals may become
united to the scapula. It is subrhombie in outline, and is perforated
by a large and well-defined foramen. No indications of asternum have
yet been found in this group.

The humerus is large and robust and similar in form to that of
Stegosaurus. In one individual it is nearly as long as the femur, prov-
ing that the animal walked on all four feet. The radius and ulna are
comparatively short and stout, and the latter has a very large olecra-
non process, as shown in Pl. LN VI, fig. 3.

There were five well-developed digits in the manus. The metacar-
pals are short and stout, with rugose extremities. The distal phalanges
are broad and hoof-like, showing that the fore feet were distinctly
ungulate (Pl. LXIX),.

THE PELVIS.

The pelvis in this group is very characteristic, and the three bones,
ilium, ischium, and pubis, all take a prominent part in forming the
acetabulum. The relative size and position of these are shown in P].
LXVIUI, fig. 1, which represents the pelvic elements as nearly in the
same plane as their form will allow, while retaining essentially their
relative position in life.

The ilium is much elongated, and differs widely from that in any of
the known groups of the Dinosauria. The portion in front of the ace-
tabulum forms a broad, horizontal plate, which is continued backward
over the acetabulum, and narrowed in the elongated, posterior exten-
sion. Seen from above, the ilium, as a whole, appears as a nearly hor-
izontal, sigmoid plate. From the outside, as shown in the figure, the
edge of this broad plate is seen.

The protuberance for the support of the pubis is comparatively
small and elongated. The face for the ischium is much larger, and
but little produced. The acetabular face of the ilium 1s quite narrow.

The pubis is massive, much compressed transversely, with its distal
end widely expanded, as shown in the figures (Pl. LX VII). There is
no true postpubis, but only a small postpubie process. The pubis
itself projects forward, outward, and downward. Its union with the
ilium is not a strong one, and is similar to that seen in the pubis of
Stegosaurus.

The ischium is smaller than the pubis, but more elongate. Its shaft is
much curved downward and inward, and in this respect it resembles
somewhat the corresponding part of the pubis of the ostrich. There
is no indication that the two ischia met closely at their distal ends,
and they were probably united only by cartilage.

214 DINOSAURS OF NORTH AMERICA.

A comparison of this pelvis with that of Stegosaurus (PI. LX XXT)
shows some points of resemblance, but a wide difference in each of the
elements. The pubis corresponds in its essential features to the pre-
pubis of Stegosaurus, but the postpubis is represented only by a short
process.

THE POSTERIOR LIMBS.

The femur is short, with the great trochanter well developed. The
shaft is comparatively slender, and the distal end much expanded.
The third trochanter is wanting, or represented only by a rugosity
(Pl. LX VIII, fig. 1).

The tibia is of moderate length, and resembles that of Stegosaurus.
The shaft is slender, but the ends are much expanded. The fibula is
very slender, and the distal end was closely applied to the front of the
tibia (P]. LX VIII, fig. 2). In adult individuals the astragalus is firmly
coossified with the distal end of the tibia, as in Stegosaurus.

The metatarsal bones which were functional are rather long, but
massive. Their phalanges are stout, and the distal ones broad and
rugose, indicating that the digits were terminated by very strong hoofs
(Pl. LXIX, figs. 7-12).

All the limb bones and vertebrae in Triceratops and the nearly allied
genera are solid.

THE DERMAL ARMOR.

Besides the armature of the skull, the body also in Triceratops was
protected (Pl. LXX). The nature and position of the defensive parts
in the different forms can not be determined with certainty, but vari-
ous spines, bosses, and plates have been found that clearly pertain to
the dermal covering of Triceratops, or nearly allied genera. Several of
these ossifications were probably placed on the back, behind the crest
of the skull, and some of the smaller ones may have defended the throat,
as in Stegosaurus.

TOROSAURUS.

In the type specimen on which this genus was based the greater
portion of the skull is preserved, and this presents so many points of
interest that a figure of it, one-twentieth natural size, is here given in
Pl. LNII, fig. 1. The second species is represented also by the skull,
which, although not complete, supplements the type in several important
respects, and figures of its posterior portions are likewise given in the
same plate and in fig. 54, on the opposite page. Both specimens are of
gigantic size, one skull measuring 53 feet across the parietal crest, and
the other is nearly as large. They differ widely, moreover, from the
huge horned dinosaurs hitherto found in the same general horizon, and
in the skull present characters of much interest.

THE SKULL.

In Torosaurus latus, the species first described, the skull appears
wedge-shaped when seen from above, as Shown in Pl. LXII. The facial
portion is very short and pointed, and somewhat suilline in form. The

MARSE.] TOROSAURUS. 215

nasal horn core is compressed, with a sharp apex directed forward.
The frontal horn cores are large and strongly inclined to the front,
extending apparently in advance of the nasal protuberance. The long,
slender squamosals diverge rapidly as they extend backward, their
outer margins being nearly on a line with the facial borders in the
maxillary region.

The parietal forms more than half of the upper surface of the skull,
and’ is the most characteristic element in its structure. In the poste-
rior part are two very large apertures, oval in outline, with their outer
margin at one point formed by the squamosal. The rest of the border
is thin and somewhat irregular, showing that the openings are true

SS

Fic. 54.—Skull of Torosaurus gladius Marsh; seen fromabove. One-twentieth natural size.
e, supratemporal fossa; e’, epijugal bone; f’, parietal fontanelle; h, horn core; h’, nasal horn core;
—p, parietal; s, squamosal; x, pineal foramen (?).

fontanelles. This is still better seen in the second species represented
in the same plate, fig. 2, and in fig. 54, above. In the latter specimen,
however, these vacuities are entirely in the parietal, a thin strip of bone
separating them on either side from the squamosal. A second pair of
openings, much smaller, apparently the true supratemporal fossze, are
shown in the type specimen. These are situated mainly between the
parietal and squamosal, directly behind the bases of the large horn cores
(Pl. LXU, fig. 1, ¢). The same apertures are represented in the genus
Triceratops by oblique openings, as in the skull shown on PI. LX, fig. °
3, ¢, where the front border of each is formed by the postfrontal.
Between these openings, in the type of Torosaurus, is a third pair of
apertures (Pl. LXII, fig.1,¢’). These are quite small, nearly circular in
outline, and entirely in the parietal, although probably connected

216 DINOSAURS OF NORTH AMERICA.

originally with the supratemporal fosse. Another pair of still smaller
foramina may be seen in the same skull, close to the median line, and
separated from each other by the anterior projection of the parietal.
A deep groove leads forward to each of these foramina, along the
suture between the parietal and the postfrontal. The position and
direction of these perforations suggest that they may correspond to the
foramen seen in Triceratops, and shown on Pl. LX, fig. 5,2. The same
foramen is Shown above in fig. 54. :

The extreme lightness and great expanse of the posterior crest in
Torosaurus make it probable that it was encased in the integuments of
the head, and that no part of it was free. The outer borders of both
the parietal and the squamosals show no marginal ossifications, as in
the other known genera of the group, but the presence of a large,
separate, epijugal bone in one specimen suggests that epoccipitals nay
yet be found.

The open perforations in the parietal, which have suggested the name
Torosaurus, readily separate this genus from all the gigantic species
hitherto known in the Ceratopsidz, but may perhaps be found in some
of the smaller and less specialized forms, from lower horizons of the
same formation.

CERATOPS. ;

The genus Ceratops so far as at present known is represented by indi-
viduals of smaller size than those of Triceratops, and in some instances,
at least, of quite different proportions. The type specimen is shown
in Pl. LNIII. A third genus, Sterrholophus, can be readily distin-
guished from the other two by the parietal crest, which had its entire
posterior surface covered with the ligaments and muscles supporting
the head. In Ceratops and Triceratops a wide margin of this surface
was free, and protected by a thick, horny covering. There is some
evidence that still other forms, quite distinct, left their remains in
essentially the same horizon, but their true relation to the above genera
can not be settled without further discoveries.

STERRHOLOPHUS.

With the successive changes in the parietal in the Ceratopside, there
were corresponding variations in the squamosals, and these bones also
will serve to distinguish the principal genera from one another. In PI.
LXIII1 the squamosals of three genera of this group are shown, and the
wide difference between them, when seen from the inside, is especially
noticeable. In fig. 4 of this plate, the long, slender, right squamosal
of Torosaurus, with its smooth outer border, is well represented. In
fig. 5 is seen the same bone of Sterrholophus, with a serrate outer
margin and smooth inner surface, also shown in fig. lof Pl. LX. Next,
in fig. 6 is the small, short squamosal of Ceratops, nearly bisected by its
deep quadrate groove. The free sculptured border of both the parietal
and squamosals of Triceratops is clearly shown in Pl]. LX, fig. 4, where
the contrast with the corresponding parts in fig. 2 is noteworthy.

MARSH. ] CERATOPSID&. PAL

AGATHAUMAS.

Three other generic names have been applied by Cope to remains of
Ceratopside found in this country, namely, Agathaumas, Polyonax,
and Monoclonius. The first of these was based on part of a skeleton,
without the skull, found in Wyoming. The second name was given
to various fragments from Colorado, including parts of horn cores,
regarded as ischia, but all these may be the same generically as the
preceding specimen. The third name, Monoclonius, was used for a
skeleton from Montana, with parts of the skull and teeth preserved.
This animal was one of the smallest of the group, while the other
remains pertained to reptiles of larger size, but not of the gigantic
proportions of those more recently described. So far as can be judged
from the descriptions and figures of the type specimens, the three
generic names just cited can not be used for any of those previously
mentioned in this article. A comparison of the principal characters
will place this beyond reasonable doubt.

In the type of Agathaumas the remains best preserved are from the
pelvic region, which, according to Cope,' possesses the following fea-
tures: The ilium has no facet nor suture for the pubis at the front of
the acetabulum, and the base of the ischium is coossified with the ilium.
There are eight, or perhaps nine, sacral vertebrae, with the neural
spines of the first five mere tuberosities. The diapophyses are in pairs,
and the last sacral vertebra is reduced and elongate. These charac-
ters, and some others found in the description cited, are certainly dis-
tinctive, but do not apply to any of the allied fossils described by the
writer. Portions of the type specimen, moreover, are in the Yale
museum, as well as other remains from near the same locality. The
fossils described as Polyonax, and other similar specimens collected in
the same region, afford at present no evidence for separation from
Agathaumas.

MONOCLONIUS.

The small dinosaur for which the name Monoclonius was proposed
is perhaps generically distinct from Agathaumas, but no conclusive
evidence or this has yet been presented. The description given makes
the teeth, dorsal vertebre, and pelvis different from those of any of
the larger forms, and the T-shaped parietal (figured first by Cope as
an episternal bone) is especially distinctive. None of the other known
Ceratopsid have the parietal fontanelles except Torosaurus, one of
the most gigantic forms discovered, and this genus differs from Men-
oclonius, as described, in various important points. The very long
frontal horn cores, directed forward, the narrow, elongate squamosals,
the absence of a median crest on the parietal, as well as the form and
anterior connections of this bone, all serve to distinguish clearly the
former from the latter.

\ Vertebrata of the Cretaceous formations of the West, p. 53, 1875.

218 DINOSAURS OF NORTH AMERICA.

RESTORATION OF TRICERATOPS,
PLATE LXXI.

The abundant material now available for examination makes it pos-
sible to attempt a restoration of one characteristic form of this group,
and the result is given in Pl. LXNXI. This figure, about one-fortieth
natural size, is reduced from a large outline plate of a memoir now in
preparation by the writer for the United States Geological Survey.

This restoration is based mainly on two specimens. One of these is
the type of Triceratops prorsus Marsh, in which the skull, lower jaw,
and cervical vertebre are in remarkable preservation. The other
specimen, although somewhat larger, is referred to the same species.
It consists of parts of the skull, of vertebrie, the pelvic arch, and
nearly all the important limb bones. The remaining portions are
taken mostly from other remains found in the same horizon and locali-
ties, and at present are not distinguishable specifically from the two
specimens above mentioned. Theskullas here represented corresponds
in scale to the skeleton of the larger individual.

In this restoration the animal is represented as walking, and the
enormous head is in a position adapted to that motion. The massive
fore limbs, proportionally the largest in any known dinosaur, corre-
spond with the head, and indicate slow locomotion on all four feet.

The skull is, of course, without its strong horny covering ou the
beak, horn cores, and posterior crest, and hence appears much smaller
than in life. The neck seems short, but the first six cervical vertebrae
are entirely concealed by the crest of the skull, which in its complete
armature would extend over one or two vertebrie more. The posterior
dorsals with their double-headed ribs continue back to the sacrum
itself, there being no true lumbars, although two vertebrie, apparently
once lumbars, are now sacrals, as their transverse processes meet the
ilia, and their centra are coossified with the true sacrum. The four
original sacral vertebrie have their neural spines fused into a single
plate, while the posterior sacrals, once caudals, have separate spines
directed backward.

No attempt is made in this restoration to represent the dermal armor
of the body, although in life the latter was more or less protected.
Various spines, bosses, and plates, indicating such dermal armature,
have been found with remains of this group, but the exact position of
these specimens can be, at present, only a matter of conjecture.

This restoration gives a correct idea of the general proportions of the
entire skeleton in the genus Triceratops. The size, in life, would be
about 25 feet in length and 10 feet in height.

DISTINCTIVE CHARACTERS OF GROUP.

This group so far as at present investigated is very distinct from all
other known dinosaurs, and whether it should be regarded as a family,

MARSH] CLAOSAURID.E. AUS)

Ceratopsid, as first Geseribed by the writer, or as a suborder, Ceratop-
sia, as later defined by him, will depend upon the interpretation and
value of the peculiar characters manifested in its typical forms.

The main characters which separate the group from other families of
the Dinosauria are as follows:

(1) A rostral bone, forming a sharp, cutting beak.

(2) The skull surmounted by massive horn cores.

(5) The expanded parietal crest, with its marginal armature.

(4) A pineal foramen (?).

(5) The teeth with two distinct roots.

(6) The anterior cervical vertebree coossified with each other.

(7) The dorsal vertebrie supporting, on the diapophysis, both the head
and tubercle of the rib.

(8) The jumbar vertebre wanting.

The animals of this group were all herbivorous, and their food was
probably the soft, succulent vegetation that flourished during the Cre-
taceous period. The remains here figured are from the Ceratops beds
of the upper Laramie, on the eastern slope of the Rocky Mountains.

The only known European member of this group is the Struthiosau-
rus Bunzel, 1871, apparently identical with Cratzeomus Seeley, 1881.
It is from the Gosau formation of Austria, and the locality was visited
by the writer in 1864. Although ouly fragments, mostly of the skel-
eton and dermal armor, are known, some of these are very character-
istic. One specimen figured by Seeley, and regarded as a dermal plate
bearing a horn-like spine, is certainly part of the skull. It is very
Similar in form to some of the horn cores of the smaller species of
Ceratops.

CLAOSAURIDE.

The next most important family of herbivorous dinosaurs from the
Cretaceous of North America is the Claosaurid, and of these the type
genus is Claosaurus, described by the writer in 1890, from a specimen
found by him in Kansas in 1872. Several fortunate discoveries since
made have rendered this genus one of the best known of American
forms, and hence the principal characters of the skull and skeleton are
here given in detail.

CLAOSAURUS.
THE SKULL.

The skull of Claosaurus is long and narrow, with the facial portion
especially produced. The anterior part is only moderately expanded
transversely. Seen from the side (Pl. LX XII, fig. 1), the skull shows
a blunt, rugose muzzle, formed above by the premaxillary and below by
the predentary, both probably covered in life with a thick, corneous
integument.

Behind the upper part of this muzzle is an enormous lateral cavity,
which includes the narial orifice, but was evidently occupied in life
mainly by a nasal gland, somewhat like that in the existing monitor,

220 DINOSAURS OF NORTH AMERICA.

and seen also in some birds. This cavity is bounded externally by the
nasal bone and the premaxillary. The median septum between the two
narial orifices was only in part ossified, the large oval opening 10w
present in the skull probably having been closed in life by cartilage.

The orbit 1s very large and subtriangular in outline. It 1s formed
above by the pretrontal, frontal, and postfrontal, and below mainly by
the jugal. There are no supraorbital bones. A distinct Jlachrymal
forms a portion of the anterior border. The infratemporal fossa is
large, and is bounded above by the postfrontal and squamosal, and
below by the jugal. The quadrate forms a small portion of the posterior
border.

Seen from in front (Pl. LX-XII, fig. 2), the skull of Claosaurus is sub-
ovate in outline, with the narrow portion above. The premaxillaries
and the predentary bone forming the rugose muzzle are especially mas-
sive and prominent, and the powerful lower jaws seem out of propor-
tion to the more delicate bones of the cranium.

Seen from above (P]. LN XII, fig. 3), the structure of the skul! itself
is shown to the best advantage. In front are the large premaxillavies,
deeply excavated for the nasal openings. These bones are separate,
and each sends back a long, slender process inside the anterior pro-
jection of the nasal, and a still longer process forming the lower border
of the narial orifice, ana extending to the lachrymal. The front of the
premaxillaries is especially massive, and its surface rugose, indicating
that it had been covered with a horny beak. The lower border is sharp,
conforming te the corresponding surface of the predentary bone, which
was doubtless also inclosed in a horny covering. The premaxillaries
were entirely without teeth.

The nasal bones are long and slender, and especially produced in
front, where they embrace the posterior median extensious of the pre-
maxillaries. They also meet the lateral processes of the premaxillaries
behind the nasal openings, and likewise touch tke lachrymals. Farther
back they meet the prefrontals and closely unite with the frontals, as
shown in Pl. LXNXIT.

The frontal bones are quite short, and nearly as wide as long. They
are united to each other by a well-marked suture. Their upper surface
is smooth, and there is a slight depression on either side, posterior to
the suture with the prefrontals. Each frontal bone forms a portion of
the upper border of the orbit, and behind this meets the postfrontal.
Posteriorly the trontals form the anterior border of the supratemporal
fossee, and between these unite by suture with the coossified parietals.

The latter bones are quite small, and appear on the upper surface of
the skull mainly as a narrow ridge separating the supratemporal fosse,
and ending behind in a point, between the median processes of the
squamosals. The parietals expand below, where they cover the pos-
terior portion of the brain cavity.

The squamosal bones are robust, and their position and connections

MARSH] CLAOSAURUS. 221

are well shoyn on PI. LN NII, figs. i and 38. On the median line above
they meet the narrow extension of the parietals, and exterior to this
they form the posterior borders of the supratemporal fossie. In front
they unite by a strong process with the posterior branch of the post-
frontals. Their posterior border 1s joined mainly to the exoccipitals.
On the outer surface of each squamosal there is a deep pit to receive
the head of the quadrate, and in front of this a short, narrow process
extends down the quadrate, forming a part of the border of the infra-
temporal fossa.

The quadrate bone and its main connections are shown on Pl. LX XII,
figs. 1-3. It is firmly supported above by the squamosal, but its dis-
tinet, rounded head indicates the possibility of some motion. On the
outer surface in front it joins by open suture the strong jugal bone, and
below this unites with the small, discoid quadratojugal, Its inner
margin extends forward into a broad, thin wing for union with the
pterygoid. The lower extremity is massive, and moderately expanded
transversely for articulation with the lower jaw.

The jugal is one of the most characteristic parts of the skull, as may
be seen from the figures on Pl. LNXII. Its main portion is robust,
much compressed, and conyex externally. On its upper margin it
forms the lower border of the orbit and of the infratemporal fossa,
sending up a strong process between them, which extends inside and
in front of the postorbital branch of the postfrontal. In front it is
strongly united to the maxillary, and above joins by suture with the
lachrymal.

The maxillary bone 1n Claosaurus is of moderate dimensions, and
seen from the outside is overshadowed by the premaxillary and jugal,
as shown in the same plate, fig. 1. Its lower dentary border is thickly
studded with a regular series of teeth, which slightly overlap those of
the lower jaw. From above only a small portion of the maxillary is
visible, as seen in Pl. LX XII, fig. 3.

The lower jaws are long and massive. The predentary bone is robust,
aud especially fitted for meeting the strong beak above. The dentary
bones are large aud powerful, with elevated coronoid processes. The
angular and surangular bones are, however, quite short and not espe
cially strong.

THE TEETH.

The teeth of Claosaurus are confined entirely to the maxillary and
dentary bones. In each the teeth are very numerous, and are arranged
in vertical series, so that they succeed each other as the functional
teeth are worn away. Thisis seenin Pl. LX XVIII, fig. 2, which shows
the form of the teeth and their relations to each other in the same
series. The number of teeth in each depends upon the position, the
series near the middle of the jaw having the greatest number, some-
times six or more, The teeth of the upper jaw have the external face
of the crown covered with enamel and ridged. In the lower jaw this

222 DINOSAURS OF NORTH AMERICA.

is reversed, the ridged face of the crown being on the inside. This
arrangement greatly increased the cutting power of the jaws. The
food was probably soft vegetation.

THE BRAIN.

The brain of Claosaurus was very small, its size in proportion to the
skull being represented-in Pl. LX XVI, fig. 2, which also shows the
exact position of the brain in the cranium. A cast of the brain cavity
is shown in Pl. LNXVII, fig. 3, one-fourth natural size. The brain as
a whole was considerably elongated, especially the posterior half. The
olfactory lobes were well developed, and not separated by an osseous
septum. The cerebral hemispheres were comparatively large, forming
nearly or quite half the entire brain. The optic lobes were narrow,
but considerably elevated. The cerebellum was rather small, and also
much compressed. The medulla was of good size, and nearly cireular
in transverse outline. “The pituitary body was quite large. The inter-
pretation of some of the more minute features of the brain is a matter
of difficulty, and will be more fully discussed elsewhere.

THE VERTEBRX,

The main characters of the vertebral column of Claosaurus are well
shown in the restoration (Pl. LXXIV). There are thirty vertebre
between the skull and sacrum, nine in the sacrum, and about sixty in
the tail. The whole vertebral column was found in position except the
terminal caudals, which are here represented in outline. The cervical
vertebre are strongly opisthoccelian, and the first eleven have short
ribs. The dorsals are also opisthoc@lian. There are no true lumbar
vertebrie, as the last of those in front of the sacrum support free ribs.
The anterior caudals are opisthocelian. The first and second have no
chevrons. Behind these the chevron bones are very long, indicating a
powerful, compressed tail, well adapted for swimming.

In the median dorsal region, between the ribs and the neural spines,
are numerous rod-like ossified tendons, which increase in number in the
sacral region and along the base of the tail, and then gradually dimin-
ish in number and size, ending at about the thirty-fifth caudal. These
ossified tendons are well shown in the restoration, and are of much
interest. They are not unlike those in Iguanodon described by Dollo,
but asa rule are more elongate, and appear to lack the definite arrange-
ment in rhomboidal figures observed in that genus.

THE FORE AND HIND LIMBS.

The fore limbs are unusually small in comparison with the posterior,
and the relative size of the two is shown on PI. LXXIII. The scapular
arch presents many points of interest. The scapula is large, and so
much curved that its shaft is nearly at right angles to the articular
faces of its lower extremity (Pl. LX XIII, fig. 1, s). On the anterior

MaxsH.] CLAOSAURUS. 223

margin, above the articulation for the coracoid, is a strong protuber-
ance, with a well-detined facet, adapted to the support of the clavicle,
if such a bone were present. The coracoid is very small, and is per-
forated by a large foramen. The two peculiar bones now generally
regarded as belonging to the sternum were separate, as shown in Pl.
DXXV, fic. 4.

The humerus is comparatively short, and has a prominent radial
erest. The radius and ulna are much elongated, the latter being longer
than the humerus, and the radius about the same length. The ulna
has a prominent olecranon process, and is a stouter bone than the
radius. The carpal bones were quite short, and appear to have been
only imperfectly ossified. The fore foot, or manus, was very long, and
contained three functional digits only. The first digit was rudimentary,
the second and third were nearly equal in length, the fourth was shorter
and Jess developed, and the fifth entirely wanting, as shown in PI.
PXXT, fig. 1.

In the functional digits (11, 111, iv) the phalanges are elongate, thus
materially lengthening the fore foot. The terminal phalanges of these
digits are broad and flat, showing that they were covered with hoofs,
and not with claws. The limb as a whole was thus adapted to loco-

5
Ls
Fic. 55.—Ilium of Claosaurus agilis Marsh; seen from the left. One-sixth natural size
a, acetabular border: is, face for ischium; p, face for pubis.

motion or support, and not at all for prehension, although this might
have been expected from its small size and position.

The elongation of the forearm and manus is a peculiar feature, espe-
cially when taken in connection with the vngulate phalanges. It may,
perhaps, be explained by supposing that the animal gradually assumed
a more erect position until it became essentially a biped, while the fore
limbs retained in a measure their primitive function, and did not become
prehensile as in some allied forms.

The pelvis is shown in Pl. LXNIII, figs. 2 and 3, and has been
fully described by the writer. Its most notable features are secn in
the pubis and ischium, the former having a very large expanded pre-
pubis, with the postpubis rudimentary, while the shaft of the ischium
is greatly elongated. The ilium of the type species is shown in fig. 55.

The femur is long, and the shaft nearly straight. The great trochanter
is well developed, while the third trochanter is large and near the middle
of the shaft, as shown in Pl. LX XIII, fig. 2. The external condyle of

224 DINOSAURS OF NORTH AMERICA.

the distal end is projected well backward, indicating great freedom of
motion at the knee.

The tibia is shorter than the femur and has a prominent cnemial
crest. The distal end is much flattened, and the astragalus is closely
adapted to it. The fibula is very straight, with its lower end flattened
and closely apphed to the front of the tibia. The calecaneum is large,
with its concave upper surface closely fitted to the end of the fibula.
Of the second row of tarsals only a single one appears to be ossified,
and that is very small and thin, and placed between the caleaneum and
the fourth metatarsal, nearly or quite out of sight.

The hind foot, or pes, had but three digits, the second, third, and
fourth, all well developed and massive. ‘The terminal phalanges were
covered with broad hoofs. Thefirstand fifth digits were entirely wanting.

A comparison of the limbs and feet of Claosaurus, as here described
and figured, with those of three allied forms from the Jurassic, Stego-
saurus, Laosaurus, and Camptosaurus, as shown on Pls. XLVIII, LIV,
and LY, is especially instructive. These three genera have already
been quite fully deseribed and figured by the writer, but new points
of interest have been made out by the recent investigation of more
perfect material. The present figures will show more accurately some
of the mutual relations of these early herbivorous dinosaurs to one
another, as well as to their successors in Cretaceous time. The gradual
changes that can be traced from one to the other will be discussed in
a later communication.

All the limb bones in Claosaurus are solid, thus distinguishing it from
Trachodon(Hadrosaurus). The separate ischiam not coossified with the
pubis, the absence of a fourth digit in the hind foot, and other marked
characters, also make the genus distinct from Pteropelyx, the skull of
which is not known.

RESTORATION OF CLAOSAURUS.
PLATE LXXIV.

The reptile here restored was nearly 30 feet in length when alive, and
about 15 feet in height in the position represented in Pl. LX XIV.
The remains were obtained in the Ceratops beds of the Laramie, in
Wyoming. Among the associated fossils ave the gigantic Triceratops
and Torosaurus, which were also herbivorous dinosaurs, and with them
were found the diminutive Cretaceous mammals recently described by
the writer.

TRACHODONTID 2.

The genus Trachodon of Leidy, which has been admirably described
under the name Hadrosaurus by that author,'is a near ally of Clao-
saurus, but quite distinct. The generic name Diclomius Cope should
be regarded as a synonym of Trachodon. The teeth of one species of
this genus are shown in Pl. LX XY, figs. 1 and 2.

>

‘Cretaceous Reptiles of the United States, p. 76, 1865.

MARSH. NODOSAURIDAX 225

PAL.EOSCINCUS.

A new reptilian genus and species, Pulwoscincus costatus, was pro-
posed by Dr. Leidy, in 1856, for a single tooth found by Dr. Hayden in
the Judith Basin. This tooth was more fully described and figured by
Leidy in 1859. The specimen showed well-marked characters, and
many similar teeth have since been found, both in the Judith Basin
and in various other localities of the same horizon.

A smaller species, apparently of the same genus, is not uncommon
in the Ceratops beds of Wyoming, and a characteristic tooth is shown
on Pl. LX XV, fig. 5. This is the type specimen of the species Palco-
scincus latus. The crown of the tooth in this species is broader and
the apex more pointed than in the first species described, and this is
clearly shown in comparing the present figures on Pl. LX XV with those
given by Leidy.

NODOSA URID 2A.

NODOSAURUS.

Another genus of Stegosauria, from a lower horizon in the Creta-
ceous, was discovered several years since, in Wyoming, and the type
specimen is now in the Yale museum. This genus, Nodosaurus, was
described by the writer in 1889. The skull is not known, but various
portious of the skeleton were secured. One characteristic feature in
this genus is the dermal armor, which appears to have been more com-
plete than in any of the American forms hitherto found. This armor
covered the sides closely, and was supported by the ribs, which were
especially strengthened to maintain it. In the present specimen por-
tions of it were found in position. It was regularly arranged in a series
ot rounded knobs in rows, and these protuberances have suggested the
generic name.

Near the head the dermal ossifications were quite small, and those
preserved are quadrangular in form, and arranged in rows. The
external surface is peculiarly marked by a texture that appears inter-
woven, like a coarse cloth. This has suggested the specific name, and
is well shown in Pl. LX XV, fig. 5.

The fore limbs are especially massive and powerful, and are much
like those of the Jurassic Stegosaurus. There were five well-developed
digits in the manus, and their terminal phalanges are more narrow
than usual in this group. The ribs are T-shaped in transverse section,
and thus especially adapted to support the armor over them. The
caudal vertebre are more elongate than those of Stegosaurus, and the
middle caudals have a median groove on the lower surface of the
centrum. 5

The animal when alive was about 30 feet in length. The known
remains are from the middle Cretaceous of Wyoming.

16 GEOL, PT 1 15

226 DINOSAURS OF NORTH AMERICA.

DISTRIBUTION OF ORNITHOPODA.

The great group which the author has called the Ornithopoda is
well represented in Europe by Iguanodon and its allies. The remark-
able discoveries in the Wealden of Belgium of a score or more skele-
tons of Iguanodon have furnished material for an accurate study of
the genus which they represent, and, indirectly, of the family. The
genus Iguanodon, founded by Mantell in 1824, is now the best known
of European forms, while Hypsilophodon Huxley, 1870, also from the -
Wealden, is well represented, and its most important characters are
fully determined. For comparison with American forms, restorations
of both Hypsilophodon and Iguanodon are given on Pls. LX XXIII and
LXXXIV. The other genera of this group, among which are Mochlodon
Bunzel, 1871, Vectisaurus Hulke, 1879, and Sphenospondylus Seeley,
1883, are described from less perfect material, and further discoveries
must decide their distinctive characters.

None of these genera are known from America, but allied forms are
not wanting. <A distinct family, the Trachodontidie, is especially abun-
dant in the Cretaceous, and another, the Camptosauride, includes most
of the Jurassic species. The latter are the American representatives
of the Iguanodontide. The nearest allied genera are, apparently,
Tguanodon and Camptosaurus for the larger forms, and Hypsilopho-
don and Laosaurus for those of small size. A few isolated teeth from
each country suggest that forms more nearly related may at any time
be brought to light.

Many generic names have been proposed for members of this group
found in America and in Europe, but in most cases they are based on
fragmentary, detached specimens, which must await future discoveries
before they can be assigned to their true place in the order.

In conclusion, it may be said that the three great groups of Dinosauria
are each well represented in Europe as well as in America. Some of the
families, also, of each order have representatives in the two regions,
and future discoveries will doubtless prove that others occur in both.

No genera common to the two continents are known with certainty,
although a few are so closely allied that they can not be distinguished
from one another by the fragmentary specimens thatnowrepresent them.

From Asia and Africa, also, a few remains of dinosaurs have been
described, and the latter continent promises to yield many interesting
forms. Characteristic specimens, representing two genera, one appar-
ently belonging to the Stegosauria, and one to the Theropoda, are
already known from South Africa, from the region so rich in other
extinct Reptilia.

From Australia no Dinosauria, except a single specimen, have as
yet been recorded, but many more will undoubtedly be found there, as
reptiles of this great group were the dominant land animals of the
earth during all Mesozoic time.

MARSH] CONCLUSION. 227

IDALTRIY IEW
CONCLUSION.

The brief review of North American Dinosaurs given in the preced-
ing pages, in connection with the accompanying illustrations, will make
the reader acquainted with the more important type specimens of this
interesting group of reptiles, as now known from this continent. To
discover and bring together these remains, representing several hun-
dred individuals, from widely separated localities and various geological
horizons, has been a long and laborious undertaking, attended with
much hardship, and often with danger, but not without the pleasure
that exploration in new fields brings to its votaries. These researches,
especially in the West, have been continued by the writer more than a
score of years, and have Jed him across the Rocky Mountains a still
greater number of times. The field work thus prosecuted has been of
great service in the subsequent study of the specimens secured, espe-
cially in determining the natural position in life of each animal
investiguted.

In comparing the type specimens of these various animals, one with
another, as they were found and as they appeared when removed from
the vesture of their entombment, many questions have suggested them-
selves that can not be answered in the present limited paper. Resem-
blances and differences are striking, both in structure and form, in these
ancient reptiles, but the true meaning of such features is a difficult
problem to solve. Onthe interpretation of characters thus exhibited in
these animals depend both the laws of their classification and theories
of their origin.

COMPARISON OF CHARACTERS.

In the concluding part of the present paper a number of plates
(LXXVI-LXXXT) have been given with a view to illustrate especially
the corresponding parts of various animals of different orders, show-
ing the wide divergence in some points of nearly allied forms, and the
approach in particular features of types clearly distinct.

In Pl. LX XVI four skulls of as many typical genera of herbivorous
dinosaurs (Triceratops, Claosaurus, Camptosaurus, and Diplodocus)
are represented, with a cast of the brain cavity of each in position.
All are so drawn that they can be readily compared, thus exhibiting in
a striking manner both the diminutive size of the brain in each in pro-
portion to that of the skull, and also the form of the brain cavity, when
seen from above. In the next plate (LX XVII) the brain casts alone of
several dinosaurs, as seen from the side, are exhibited, and with them
for comparison the corresponding cast of a young alligator. The spe-
cial features of the dinosaur brain are well shown in these two plates.

Pl. LX XVIII will make clear the wide divergence of forms of teeth
in four different families of predentate dinosaurs. The typical genera,

228 DINOSAURS OF NORTH AMERICA.

Camptosaurus, Claosaurus, Stegosaurus, and Triceratops, each have
teeth of a distinct type, yet it seems possible to trace the gradation of
one to the other through different intermediate forms. In Triceratops
the teeth have two distinct roots, a feature unknown in any other rep-
tiles, living or extinct, but characteristic of mammals.

The series of pubic bones of herbivorous dinosaurs shown on PI.
LXXIX is especially instructive, as they indicate how the anterior and
posterior elements of the pubis may vary in the Predentata, and thus
afford good characters for classification. The same is true, but ina
less degree, of the ischia represented on Pl. LX XX, which all pertain
to one group of dinosaurs. The comparison may even be carried much
further, as in the two other orders (the Theropoda and Sauropoda)
some families have ischia of the type here represented, as shown on
Pls. XXVIII and XXXV.

The pelves represented on Pl. LXXXI, pertaining to the three pre-
dentate genera, Camptosaurus, Triceratops, and Stegosaurus, will sup-
plement the facts presented on the two preceding plates. The series
might be much further extended, and prove equally instructive. This
will be done by the writer in the monographs now in preparation, as in
these the whole subject of dinosaurian reptiles will receive careful con-
sideration.

RESTORATIONS OF EUROPEAN DINOSAURS.

The remaining restorations of dinosaurs in this paper are four in
number, and represent some of the best-known European forms, types
of the genera Compsognathus, Scelidosaurus, Hypsilophodon, and
Iguanodon, These outline restorations have been prepared by the
writer mainly for comparison with the corresponding American forms,
but in part to insure, so far as the present opportunity will allow, a
more comprehensive review of the whole group. Thespecimens restored
are all of great interest in themselves, and of special importance when
compared with their nearest American allies.

COMPSOGNATHUS.
PLatTE LXXXII,

The first restoration, that of Compsognathus longipes Wagner, 1861,
shown one-fourth natural size on PI. LX XXII, is believed to repre-
sent fairly well the general form and natural position, when alive, of
this diminutive carnivorous dinosaur that lived during the Jurassic
period. The basis for this restoration is (1) a careful study of the type
specimen itself, made by the writer in Munich in 1881; (2) an accurate
cast of this specimen, sent to him by Professor von Zittel; and (3) a
careful drawing of the original, made by Krapf in 1887. The original
description and figure of Wagner (Bavarian Academy of Sciences, 1861),
and those of later authors, have also been used for some of the details.

wanse.] SCELIDOSAURUS. 229

No restoration of the skeleton of this unique dinosaur has hitherto
been attempted.

Compsognathus has been studied by so many anatomists of repute
since its discovery that any attempt to restore the skeleton to a natural
position will be scrutinized from various points of view. Interest in
this unique specimen led the writer long ago to examine it with care,
and he has since made a minute study of it, as related elsewhere, not
merely to ascertain its anatomy, but also to learn, if possible, what its
relations are to another diminutive form, Hallopus, from a lower hori-
zon in America, which has been asserted to be a near ally. Both are
carnivorous dinosaurs, probably, but certainly on quite different lines
of descent.

The only previous attempt to restore this remarkable dinosaur was
by Huxley when in America in 1876. He made arapid sketch from the
Wagner figure, and this was enlarged for his New York lecture. This
sketch represents the animal sitting down, a position which such dino-
saurs occasionally assumed, as shown by the footprints in the Connect-
icut Valley, which Huxley examined in place at several localities with
great interest.

In the present restoration of Compsognathus (P]. LX XXII) the
writer has tried to represent the animal as walking in a characteristic
lifelike position.

SCELIDOSAURUS.
PLatTe LXXXIIT.

The second of these restorations is that of Scelidosaurus Harrisonii
of Owen, shown one-eighteenth natural size on Pl. LXXXIII. This
reptile was an herbivorous dinosaur of moderate size, related to Stego-
saurus, and was its predecessor from a lower geological horizon in
England. This restoration is essentially based upon the original
description and figures of Owen (Paleontographical Society, 1861).
These have been supplemented by the writer’s own notes and sketches,
made during examinations of the type specimen now in the British
Museum.

Scelidosaurus is a near relative, as it were, of oneof the American
forms, Stegosaurus, now represented by so many specimens that the
skull, skeleton, and dermal armor are known with much certainty.
The English form usually called Omosaurus is still more nearly allied
to Stegosaurus, perhaps identical with it.

A restoration of the skeleton of Scelidosaurus by Dr. Henry Wood-
ward will be found in the British Museum Guide to Geology and
Palzontology, 1890, p.19. The missing parts are restored from Iguano-
don, and the animal is represented as bipedal, as in that genus.

1The remains of the embryo within the skeleton of Compsognathus, first detected by the writer
in 1881 while examining the type specimen, is not represented in the presentrestoration. Thisunique
fossil affords the only conclusive evidence that dinosaurs were viviparous.

2 The generic name Omosaurus was preoccupied by Leidy in 1856.

230 DINOSAURS OF NORTH AMERICA.

In the present outline restoration of Scelidosaurus the writer has
endeavored merely to place on record his idea of the form and position
of the skeleton when the animal was alive, based on the remains he
has himself examined. In case of doubt, as, for example, in regard to
the front of the skull, which is wanting in the type specimen, a dotted
outline is used, based on the nearest allied form. Of the dermal armor,
only the row of plates best known is indicated. The position chosen in
this figure (Pl. LX XXIII) is one that would be assumed by the animal
in walking on all four feet, and this is believed to have been its natural
mode of progression.

HY PSILOPHODON.
PLATE LXXXIV.

The third of these restorations, that of Hypsilophodon Foxit Huxley,
1870, given in outline one-eighth natural size on Pl. LX XXIV, has
been made with much care, partly from the type specimen, and in part
from other material mostly now in the British Museum. The figures
and description by the late Dr. Hulke! were of special value, although
the conclusions of the writer as to the natural position of the animal
when alive do not coincide with those of his honored friend, who did so
much to make this genus of dinosaurs, and others, known to science.
The restoration by Dr. Hulke represented the animal as quadrupedal.

In the case of Hypsilophodon a number of specimens are available
instead of only one. This makes the problem of its restoration a
simpler matter than in Scelidosaurus. Moreover, there is in America
a closely allied form, Laosaurus, of which several species are known.
A study of the genus Laosaurus, and the restoration of one species
given on Pl. LVII, will clear up several points long in doubt.

Huxley and Hulke both shed much light on this interesting genus,
Hypsilophodon; indeed, on many of the Dinosauria. The mystery of
the dinosaurian pelvis, which baffled Cuvier, Mantell, and Owen, was
mainly solved by them, the ilium and ischium by Huxley, and the pubis
by Hulke. The more perfect American specimens have demonstrated
the correctness of nearly all their conclusions.

IGUANODON.
PLATE LXXXV.

The fourth restoration here given, that of Iguanodon Bernissartensis
Boulenger, 1881, one-fortieth natural size, has been made in outline for
comparison with American forms. It is based mainly on photographs of
the well-known Belgian specimens, the originals of which the writer has
studied with considerable care during several visits to Brussels. The
descriptions and figures of Dollo? have also been used in the prepara-
tion of this restoration. A few changes ouly have been introduced in

1 Philosophical Transactions, 1882. 2 Bulletin Royal Museum of Belgium, 1882-88.

MARSH. ] AFFINITIES OF DINOSAURS. Zoi

the accompanying plate, based mainly upon a study of the original
specimens.

Besides the four genera here represented, no other European dinosaurs
at present known are sufliciently well preserved to admit of accurate
restorations of the skeleton. This is true, moreover, of the dinosaurian
remains from other parts of the world outside of North America.

AFFINITIES OF DINOSAURS.

The extinct reptiles known as dinosaurs were for a long time
regarded as a peculiar order, having, indeed, certain relations to
birds, but without being closely allied to any of the groups of known
reptiles. Megalosaurus and Iguanodon, the first dinosaurian genera
described, were justly considered as representing two distinct families,
one including the carnivores, and the other the herbivorous forms.

With the discovery and investigation of Cardiodon (Cetiosaurus) and
its allies in Europe, and especially of the gigantic forms with similar
characters in America, it became evident that these reptiles could not
be placed in the same families with Megalosaurus or Iguanodon, but
constituted a well-marked group by themselves. It was this new order,
the Sauropoda, as the writer has named them, that first showed definite

Fic. 56.—Restoration of Aétosaurus ferratus Fraas; with dermalarmor of the limbs removed. One-
eighth natural size.
characters allying them with other known groups of reptiles. In 1878
he pointed out that the Sauropoda were the least specialized of the
dinosaurs, and gave a list of characters in which they showed such an
approach to the Mesozoic crocodiles as to suggest a common ancestry
at no very remote period.!

AFFINITIES WITH AETOSAURIA.

Again, in 1884, the writer called attention to the same point, and
also to the relationship of dinosaurs with the Aétosauria, as he has
named them, a group of small reptiles from the Triassic of Germany
showing strong affinities with crocodilians.? A restoration of one of
these small animals is shown in fig. 56. In the same communication
he compared with dinosaurs another allied group, the Hallopoda, which
he described from the lower Jurassic of America, but had not then fully
investigated. Subsequent researches proved the latter group to be of
the first importance in estimating the affinities of dinosaurs, and in
figs. 59 and 60 are restorations of the fore and hind limbs of the type
species (Hallopus victor).

! American Journal of Science, Vol. XVI, p. 412, November, 1878.
? Report British Association, Montreal Meeting, 1884, p. 765.

*

232 DINOSAURS OF NORTH AMERICA.

AFFINITIES WITH BELODONTIA.

Another group of extinct reptiles, which may be termed the Belo-
dontia, were considered in the same paper as allies of the Dinosauvria.
They are known from the Trias of Europe and America, and the type
genus, Belodon, has been investigated by many anatomists, who all
appear to have regarded it as a crocodilian, an opinion that in the
light of our present knowledge may fairly be questioned.

58

Fic. 57.—Diagram of left hind limb of Alligator mississippiensis G ray; seen from the Jeft; in position
for comparison with dinosaurs. One-fourth natural size.
Fic. 58.—Diagram of left hind limb of Aétosaurus ferratus; insame position. One-half natural size.

AFFINITIES WITH CROCODILIA.

The relations of these various groups to the true crocodiles on the
one hand and to dinosaurs on the other is much too broad a subject to
be introduced here, but attention may at least be called to some points
of resemblance between the dinosaurs and these supposed crocodilian
forms that seem to indicate genetic affinities.

MARSH. ] AFFINITIES WITH CROCODILIA. 233

If some of the characteristic parts of the skeletons of these groups
are compared, e. g., of the true Crocodilia as existing to-day, the Belo-
dontia, the Aétosauria, and the Hallopoda, and all with the correspond-
ing portions of the more typical dinosaurs, the result may indicate in
some measure the relationship between them. Taking first the pelvis
and hind limb, as being especially characteristic. it will be seen in

61

Fic. 59.—Diagram of left fore limb of Hallopus victor Marsh; seen from the left.

Fic. 60.—Diagram of left hind limb of same individual. Both figures are one-half natural size.

Fic. 61.—Left hind leg of Laosaurus consors Marsh; outside view. One-sixth natural size.

a,astragalus; c, caleanenm; f, femur; f’, fibula; il, ilium- is, ischium; p, pubis; p’, postpubis;
t, tibia; I, IV,V, first, fourth, and fifth digits.

the existing alligator, as represented in fig. 57, that the pubie bone is
excluded from the acetabulum, articulating with the ischium only, and
not at all with the ilium. The calcaneum, moreover, has a posterior
extension. In Aétosaurus, as shown in fig. 58, the pubic bone forms
part of the acetabulum, as in dinosaurs and birds, and this is a note-

234 DINOSAURS OF NORTH AMERICA.

worthy difference from all the existing crocodiles. The hind foot, how-
ever, is of the crocodilian type, with the caleaneum showing a posterior
projection.

In Belodon, only the pelvis of which is here represented (fig. 62),
the pubis contributes a very important part to the formation of the
acetabulum, and to the entire pelvic arch. The latter differs from the
pelvis of a typical dinosaur mainly in the absence of an open acetabu-
lum, but a moderate enlargement of the fontanelle at the junction of
the three pelvic elements would practically remove this difference. A
more erect position of the limb, leading to a more distinct head on the
femur, might possibly bring about such a result. The feet and limbs
of Belodon are crocodilian in type.

Bearing these facts in mind, the diagram representing the restored
fore and hind limbs of the diminutive Hallonus (figs. 59-60) shows first

Fic. 62.—Diagram of pelvis of Belodon Kapfi von Meyer; seen from the left. One-fourth natural

§1ze.

a, acetabular surface within dotted line; il, ilium; is, ischium; p, pubis.

of all the true dinosaurian pelvis, with the pubic bone taking part
in the open acetabulum, and forming an important and distinctive
element of the pelvic arch. The delicate posterior limb and foot,
evidently adapted mainly for leaping, as the generic name suggests,
are quite unique among the Reptilia, but the tarsus, especially the
calcaneum, recalls strongly the same region in the orders already
passed in review.

Just what this posterior extension of the caleaneum signifies in this
case it is difficult to decide from the evidence now known. It may be
merely an adaptive character, as Hallopus appears in nearly every
other respect to be a true carnivorous dinosaur. It may, however, be
an inheritance from a crocodilian ancestry, preserved by a peculiar
mode of life. Whatever its origin may have been, it was certainly,

MARSH] PLATEOSAURID ®. 2a)

during the life of the animal, an essential part of the remarkable leap-
ing foot to which it belonged, and in which it has since kept its posi-
tion undisturbed. The presence of such an element in the foot of this
diminutive dinosaur certainly suggests that the group Hallopoda,
which the writer has here considered a suborder, stands somewhat apart
from the typical Theropoda, but not far enough away to be excluded
from the subclass Dinosauria, as defined in the present paper.

The genus Plateosaurus (Zanclodon), which is from essentially the

Fic. 63.—Pelvis of Morosaurus lentus Marsh; seen from the left. One-eighth natural size.
a, acetabular opening; other letters as in fig. 62.

same geological horizon in Germany as Aétosaurus and Belodon, is one
of the oldest true dinosaurs known, and a typical member of the order
Theropoda. In the pelvic arch of this reptile the ilium and ischium are
in type quite characteristic of the group to which it belongs, but the
pubic elements are unique. They consist of a pair of broad, thin
plates united together so as to form an apron-like shield in front, quite
unlike anything known in other dinosaurs. The wide pubic bones of
Belodon, and the corresponding plates in some of the Sauropoda (Moro-
saurus, fig. 63), indicate that this feature of the reptilian pelvis may

236 DINOSAURS OF NORTH AMERICA.

have been derived from some common ancestor of a generalized primi-
tive type. The known transformations of this same pelvic element in
one other order of dinosaurs (the Predentata) show that the modifica-
tions here suggested: are well within the limits of probability. The hind
limb of one genus of this order is shown in fig. 61 (p. 233).

Fic. 64.—Pelvis of Ceratosaurus nasicornis Marsh; seen from the left. One-twelfth natural size.
Letters as in fig. 63. x

Fic. 65.—United metatarsal bones of Ceratosaurus nasicornis; left foot; front view. One-fourth
natural size.

Fig. 66.—United metatarsal bones of great penguin (Aptenodites Pennantii G R.Gr.); left foot;
front view. Natural size.

MARSH.] CLASSIFICATION OF DINOSAURIA. 237

The skulls of Aé€tosaurus and Belodon both show features character-
istic of some of the dinosaurs, especially of the Sauropoda, but these
features need not be discussed here.

AFFINITIES WITH BIRDS.

The relation of dinosaurs to birds, a subject of importance, must
also be postponed for another occasion. One point, however, may be
mentioned in this connection. The pelvic bones of all known birds,
living and extinct, except the genus Archeopteryx, are coossified,
while in all the known dinosaurs they are separate, excepting Cerato-
saurus (fig. 64) and Ornithomimus. Again, all known adult birds, liv-
ing and extinct, with possibly the single exception of Archzopteryx,
have the metatarsal bones firmly united (fig. 66), while all the Dino-
sauria, except Ceratosaurus (fig. 65), have these bones separate. The
exception in each case brings the two classes near together at this point,
and their close aftinity is thus rendered more than probable.

These few facts will throw some light on the affinities of the reptiles
known as the Dinosauria. The problem is certainly one of much diffi-
culty, and the writer hopes soon to discuss it more fully elsewhere.

IRIN Wg
CLASSIFICATION OF DINOSAURIA.

In the present review of the dinosaurs the writer has confined him-
self mainly to the type specimens which he has described, but has
included with them other important remains where these were available
for investigation. The extensive collections in the museum of Yale
University contain so many of the important type specimens now known
from America that they alone furnish an admirable basis for classifi-
cation, and it was mainly upon these that he first established the pres-
ent system, which has since been found to hold equally good for the
dinosaurs discovered elsewhere. In the further study of these reptiles
it was also necessary to examine both the European forms and those
from other parts of the world, and he has now studied nearly every
known specimen of importance. These investigations have enabled
lim to make this classification more complete, and to bring it down to
the present time.

Many attempts have been made to classify the dinosaurs, the first
being that of Hermann von Meyer in 1830. The name Dinosauria,
proposed for the group by Owen in 1839, has been generally accepted,
although not without opposition. Heckel, Cope, and Huxley followed,
the last in 1869 proposing the name Ornithoscelida for the order, and
giving an admirable synopsis of what was then known of these strange
reptiles and their affinities. Since then, Hulke, Seeley, Lydekker,
Gaudry, Dollo, Baur, and others have added much to our knowledge
of these interesting animals.

238 DINOSAURS OF NORTH AMERICA.

The remarkable discoveries in North America, however, have changed
the whole subject, and in place of fragmentary specimens many entire
skeletons of dinosaurian reptiles have been brought to ight, and thus
definite information has replaced uncertainty and rendered a compre-
hensive classification for the first time possible.

The system of classification first proposed by the writer in 1881 has
been very generally approved, but a few modifications have been sug-
gested by others that will doubtless be adopted. This will hardly be
the case with several radical changes recently advocated, based mainly
upon certain theories of the origin of dinosaurs. At present these
theories are not supported by a sufficient number of facts to entitle
them to the serious consideration of those who have made a careful
study of these reptiles, especially the wonderful variety of forms recently
made known from America.

Further discoveries may in time solve the problem of the origin of
all the reptiles now called dinosaurs, but the arguments hitherto
advanced against their being a natural group are far from conclusive.
The idea that the Dinosauria beloug to two or more distinct groups,
each of independent origin, can at present only claim equal probability
with a similar suggestion recently made in regard to mammals. This
subject of the origin of the dinosaurs and the relation of their divi-
sions to each other will be more fully treated by the writer elsewhere.

A classification of any series of extinct animals is of necessity, as the
writer has previously said, merely a temporary convenience, like the
bookshelves in a library, for the arrangement of present knowledge.
In view of this fact and of the very limited information in regard to so
many dinosaurs known only from fragmentary remains, it will suffice
for the present, or until further evidence is fortheoming, to still con-
sider the Dinosauria as a subclass of the great group of Reptilia.

Regarding, then, the dinosaurs as a subclass of the Reptilia, the forms
best known at present may be classified as follows:

Subclass DINOSAURIA Owen.

Premaxillary bones separate; upper and lower temporal arches; no
teeth on palate; rami of lower jaw united in front by cartilage only.
Neural arches of vertebrie joined to centra by suture; cervical and
thoracic ribs double-headed; ribs without uncinate processes; sacral
vertebree united; caudal vertebree numerous; chevrons articulated
imtervertebrally. Scapula elongate; no precoracoid; clavicles wanting.
Ilium prolonged in front of the acetabulum; acetabulum formed in part
by pubis; ischia meet distally on median line. Fore and hind limbs »
present, the latter ambulatory, and larger than those in front; head of
femur at right angles to condyles; tibia with procnemial crest; fibula
complete; first row of tarsals composed of astragalus and caleaneum
only, which together form the upper portion of ankle joint; reduction
in number of digits begins with the fifth.

MARSH. ] THEROPODA. 239

Order THEROPODA (Beast foot). Carnivorous.

Skull with external narial openings lateral; large antorbital vacuity ;
brain case incompletely ossified; no pineal foramen; premaxillaries with
teeth; no predentary bone; dentary without coronoid process; teeth
with smooth compressed crowns and crenulated edges. Vertebrae more
or less cavernous; posterior trunk vertebre united by diplosphenal
articulation. Neural canal in sacrum of moderate size. Each sacral rib
supported by two vertebr; diapophyses distinct from sacral ribs. Ster-
num unossified. Pubes projecting downward, and united distally; no
postpubis. Fore limbs small: limb bones hollow; astragalus closely
applied to tibia; feet digitigrade; digits with prehensile claws; locomo-
tion mainly bipedal.

(1) Family Megalosauridie. Lower jaws with teethin front. Anterior
vertebre convexo-concave; remaining vertebrae biconcave; five sacral
vertebre. Abdominalribs. Lium expanded in front of acetabulum;
pubes slender, and distally coossified. Femur longer than tibia; astrag-
alus with ascending process; five digits in manus and four in pes.

Genus Megalosaurus (Poikilopleuron). Jurassic and Cretaceous.
Known forms, European.

(2) Family Dryptosauride. Lower jaws with teeth in front. Cervi-
cal vertebrie opisthocelian; remaining vertebrie biconcave; sacral ver-
tebrie less than five. Ilium expanded in front of acetabulum; distal ends
of pubes coossified and much expanded; an interpubic bone. Femur
longer than tibia; astragalus with ascending process; fore limbs very
small, with compressed prehensile claws. (Pls. X-XII.)

Genera Dryptosaurus (Lelaps), Allosaurus, Coelosaurus, Creosaurus.
Jurassic and Cretaceous. All from North America.

(5) Family Labrosauride. Lower jaws edentulous in front. Cervi-
cal and dorsal vertebre convexo-concave; centra cavernous or hollow.
Pubes robust, with anterior margins united; aninterpubic bone. Femur
longer than tibia; astragalus with ascending process. (Pl. XIII.)

Genus Labrosaurus. Jurassic, North America.

(4) Family Plateosauride (Zanclodontide). Vertebrae biconcave;
two sacral vertebre. Ilium expanded behind acetabulum; pubes
broad, elongate plates, with anterior margins united; no interpubic
bone; ischia united at distal ends. Femur longer than tibia; astrag-
alus without ascending process; five digits in anus and pes.

Genera Plateosaurus (Zanclodon), Teratosaurus (?), Dimodosaurus.
Triassic. Known forms, European.

(5) Family Anchisauride. Skull light in structure, with recurved,
cutting teeth. Vertebre plane or biconcave. Bones hollow. [ium
expanded behind acetabulum; pubes rod-like and not coossified dis-
tally; no interpubic bone. Fore limbs well developed; femur longer
than tibia; astragalus without ascending process; five digits in manus
and in pes. (Pls. II-IV.)

Genera Anchisaurus (Megadactylus), Ammosaurus, Arctosaurus (7),

240 DINOSAURS OF NORTH AMERICA.

Bathygnathus, aud Clepsysaurus, in North America; and in Europe,
Paleosaurus. Thecodontosaurus. All known forms, Triassic.

Suborder CazLurtiA (Hollow tail).

(6) Family Coeluride. Teeth uch compressed. Vertebra and bones
of skeleton very hollow or pneumatic; neural canal much expanded;
anterior cervical vertebrie convexo-concave; remaining vertebrae bicon-
cave; anterior cervical ribs coossified with vertebree; pubes slender
and distally coossified; an interpubic bone. Femur shorter than tibia;
metatarsals very long and slender. (PI. VII.)

Genera Ccelurus in North America, and Aristosuchus in Europe.
Jurassic.

Suborder COMPSOGNATHA.

(7) Family Compsognathidie. Skull elongate, with slender jaws and
pointed teeth. Cervical vertebree convexo-concave, with free ribs;
remaining vertebrie biconcave. Ischia with long symphysis on median
line. Bones very hollow; femur shorter than tibia; astragalus with
long ascending process; three functional digits in manus and in pes.
(Pl. LX XXII.)

Genus Compsognathus. Jurassic. Only known specimen, European.

Suborder CERA'TOSAURIA (Horned saurians).

(8) Family Ceratosauridee. Horn on skull; teeth large and trenchant.
Cervical vertebrae plano-concave; remaining vertebre biconcave. Ribs
free. Pelvic bones coossified; ilium expanded in front of acetabulum;
pubes slender; an interpubic bone; sacral vertebrie five; ischia slender,
with distal ends coossified. Limb bones hollow; manus with four digits;
femur longer than tibia; astragalus with ascending process; metatar-
sals coossified; three digits only in pes. Osseous dermal plates. (Pls.
VILI-X, XIV.)

Genus Ceratosaurus. Jurassic, North America.

(9) Family Ornithomimide. Pelvic bones coossified with each other
and with sacrum; ilium expanded in front of acetabulum. Limb bones
very hollow; fore limbs very small; digits with very long, pointed
claws; hind limbs of true avian type; femur longer than tibia; astrag-
alus with long ascending process; feet with three functional digits,
digitigrade and unguiculate. (Pl. LVIII.)

Genus Ornithomimus. Cretaceous, North America.

Suborder HALLOPODA (Leaping foot).

(10) family Hallopide. Vertebrie and limb bones hollow; vertebrie
biconcave; two vertebre in sacrum. Acetabulum formed by ilium,
pubis, and ischium; pubes rod-like, projecting downward, but not coos-
sified distally; no postpubis; ischia with distal ends expanded, meeting
below on median line. Fore limbs very small, with four digits in

MARSH.) SAUROPODA. 241

manus; femur shorter than tibia; hind limbs very long, with three
functional digits in pes, and metatarsals greatly elongated; astragalus
without ascending process; calcaneum much produced backward; feet
digitigrade, unguiculate. (Pl. VI.)

Genus Hallopus. Jurassic, North America.

Order SAUROPODA (Lizard foot).'- Herbivorous.

External nares at apex of skull; premaxillary bones with teeth;
teeth with rugose crowns more or less spoon-shaped; large antorbital
openings; no pineal foramen; alisphenoid bones; brain case ossified; no
columell; postoccipital bones; no predentary bone; dentary without
coronoid process. Cervical ribs coossified with vertebrae; anterior ver-
tebrze opisthoccelian, with neural spines bifid; posterior trunk vertebree
united by diplosphenal articulation; presacral vertebrie hollow; each
sacral vertebra supports it own transverse process, or sacral rib; no
diapophyses on sacral vertebrie; neural canal much expanded in
sacrum; first caudal vertebre proceelian. Sternal bones parial; ster-
nal ribs ossified. Ilium expanded in front of acetabulum; pubes pro-
jecting in front, and united distally by cartilage; no postpubis. Limb
bones solid; fore and hind limbs nearly equal; metacarpals longer than
metatarsals; femur longer than tibia; astragalus not fitted to end of
tibia; feet plantigrade, ungulate; five digits in manus and pes; second
row of carpal and tarsal bones unossified; locomotion quadrupedal.

(1) Family Atlantosauride. <A pituitary canal; large fossa for nasal
gland. Distal end of scapula not expanded. Sacrum hollow; ischia
directed downward, with expanded extremities meeting on median
line. Anterior caudal vertebre with lateral cavities; remaining cau-
dals solid. (Pls. XV-X XIV, and XLII.)

Genera Atlantosaurus, Apatosaurus, Barosaurus, Brontosaurus.
Include the largest known land animals. Jurassic, North America.

(2) Family Diplodocide. External nares superior; no depression
for nasal gland; two antorbital openings; large pituitary fossa; denti-
tion weak, and in front of jaws only; brain inclined backward; dentary
bone narrow infront. Ischia with shaft not expanded distally, directed
downward and backward, with sides meeting on median lines. Sacrum
hollow, with three vertebre. Caudal vertebrie deeply excavated below;
chevrons with both anterior and posterior branches. (Pls. XX V—
X XIX.)

Genus Diplodocus. Jurassic, North America.

(3) Family Morosauride. External nares lateral; large fossa for
nasal gland; small pituitary fossa; dentary bone massive in front;
teeth very large. Shaft of scapula expanded at distal end. Sacral ver-
tebre four in number, and nearly solid; ischia slender, with twisted
shaft directed backward, and sides meeting on median line. Anterior
caudals solid. (Pls. XXIX-XXXVIII.)

Genera Morosaurus, Camarasaurus(?) (Amphicelias). Jurassic,
North America.

16 GEOL, PT 1——16

242 DINOSAURS OF NORTH AMERICA.

(4) Family Pleurocelide. Dentition weak; teeth resembling those
of Diplodocus. Cervical vertebre elongated; centrum hollow, with
large lateral openings; sacral vertebrz solid, with lateral depressions
in centra; caudal vertebrie solid; anterior caudals with flat articular
faces and transversely compressed neural spines; middle caudal verte-
bree with neural arch on front half of centrum. Ischia with compressed
distal ends, meeting on median line. (Pls. XL and XUI.)

Genera Pleurocelus, Astrodon (?). Potomac, North America.

(5) Family Titanosauride. Fore limbs elongate; coracoid quadri-
lateral. Presacral vertebre opisthocelian; first caudal vertebra bicon-
vex; remaining caudals procelian; chevrons open above.

Genera Titanosaurus and Argyrosaurus. Cretaceous (?), India and
Patagonia.

(6) Family Cardiodontidse. Teeth of moderate size. Upper end of
scapula expanded; humerus elongate; fore limbs near equaling hind
limbs in length. Sacrum solid; ischia with wide distal ends meeting
on median line. Caudal vertebre biconcave.

Genera Cardiodon (Cetiosaurus), Bothriospondylus, Ornithopsis, and
Pelorosaurus. European, and probably all Jurassic. !

Order PREDENTATA. Herbivorous.

Narial opening lateral; no antorbital foramen; brain case ossified ;
supraorbital bones; teeth with sculptured crowns; maxillary teeth with
crowns grooved on outside; lower teeth with grooves on inside of crown ;
apredentary bone; dentary with coronoid process. Cervical ribs articu-
lating with vertebrae; each sacralrib supported by two vertebra. Ilum
elongated in front of acetabulum; prepubic bones free in front; post-
pubic bones present; ischia slender, directed backward, with distal
ends meeting side to side. Astragalus without ascending process.

Suborder STEGOSAURIA (Plated lizard).

Skull without horns; no teeth in premaxillaries; teeth with distinct
compressed crowns and serrated edges. Vertebra and limb bones
solid. Pubes projecting free in front; postpubis present. Fore limbs
small; femur longer than tibia; feet plantigrade, ungulate; five
digits in manus and four in pes; second row of carpals and tarsals
unossified; locomotion mainly quadrupedal. Osseous dermal armor.

(1) Family Stegosauride. Vertebre biconcave. Neural canal in
sacrum expanded into large chamber; ischia directed backward, with
sides meeting on median line. Dorsal ribs T-shaped in cross section.
Astragalus coossified with tibia; metapodials very short. Back sur-
mounted by a crest of vertical plates; tail armed with large spines.
(Pls. XLITI-LI1.)

Genera Stegosaurus (Hypsirhophus), Diracodon, Paleoscincus, Pri-
conodon, all from North America; and in Europe, Omosaurus, Owen.
Jurassic and Cretaceous.

1The Wealden is here regarded as upper Jurassic, and not Cretaceous. See American Journal of
Science, Vol. L, p. 412, November, 1895.

MARSH. ] PREDENTATA. 243

(2) Family Scelidosauride. Neural canal narrow; diapophyses of
dorsal vertebr supporting head and tubercle of ribs. Astragalus not
coossified with tibia; metatarsals elongated; three functional digits in
pes.

Genera Scelidosaurus, Acanthopholis, Hyleosaurus, Polacanthus.
Jurassic and Cretaceous. Known forms, all European. (PI. LX XXIII.)

(3) Family Nodosauride. Heavy dermalarmor. Bones solid. Fore
limbs large; five digits in manus; feet ungulate.

Genus Nodosaurus. Cretaceous, North America.

Suborder CERATOPSIA (Horned face).

Premaxillaries edentulous; teeth with two distinct roots; skull sur-
mounted by massive horn cores; a rostral bone, forming a sharp, cutting
beak; expanded parietal crest, with marginal armature; a pineal fora-
men(?). Vertebrie and limb bones solid; fore limbs large; femur longer
_ than tibia; feet ungulate; locomotion quadrupedal. Dermal armor.

(4) Family Ceratopside. Anterior cervical vertebra coossified with
each other; posterior dorsal vertebrie supporting on the diapophysis
both the head and tubercle of the rib; lumbar vertebre wanting;
sacralvertebre with both diapophyses and ribs. Neural canalinsacrum
without marked enlargement. Pubes projecting in front, with distal end
expanded; postpnbic bonerudimentary or wanting. (Pls. LIX-LX XI.)

Genera Ceratops, Agathaumas, Monoclonius, Polyonax, Sterrholo-
phus, Torosaurus, Triceratops, in North America; and in Europe, Stru-
thiosaurus (Cratzeomus). All are Cretaceous.

Suborder ORNITHOPODA (Bird foot).

Skull without horns; premaxillaries edentulous in front. Vertebree
solid. Fore limbs small. Pubes projecting free in front; postpubis
present. Astragalus closely fitting to end of tibia; feet digitigrade;
three to five functional digits in manus and three to four in pes; loco;
motion mainly bipedal. No dermal armor.

(5) Family Camptosauridie (Camptonotide). Premaxillaries edentu-
lous; teeth in single row; a supraorbital fossa. Anterior vertebrie
opisthocelian; sacral vertebree five, not coossified, with peg-and-notch
articulation. Sternum unossified. Limb bones hollow; fore limbs
small; five digits in manus. Postpubis reaching to the distal end of
ischium. Femur longer than tibia, and with pendent fourth trochan-
ter; hind feet with three functional digits. (Pls. LITI-LVI.)

Genus Camptosaurus (Camptonotus). Jurassic, North America.

(6) Family Laosauride. Premaxillaries edentulous; teeth in single
row. Anterior vertebre with plane articular faces; sacral vertebre
coossified. Sternum unossified. Postpubis reaching to distal end of
ischium. Limb and foot bones hollow; fore limbs very small; five digits
in manus; femur shorter than tibia; metatarsals elongate; four digits
in pes. (Pls. LV and LVIL.)

244 DINOSAURS OF NORTH AMERICA.

Genera Laosaurus and Dryosaurus. Jurassic, North America.

(7) Family Hypsilophodontide. Premaxillaries with teeth; teeth in
single row; sclerotic bony plates. Anterior vertebre opisthocelian;
sacral vertebrie coossified. Sternum ossified. Postpubis extending to
end of ischium. Limb bones hollow; five digits in manus; femur
shorter than tibia; hind feet with four digits. (Pl. LX XXIV.)

Genus Hypsilophodon. Wealden, England.

(8) Family Iguanodontide. Premaxillaries edentulous; teeth in sin-
gle row. Anterior vertebre opisthoccelian. Manus with five digits;
pollex spine-like. Sternal bones ossified. Postpubis incomplete.
Femur longer than tibia; three functional digits in pes. (Pl. LXXXYV.)

Genera Iguanodon, Vectisaurus. Jurassic and Cretaceous. Known
forms, all European.

(9) Family Trachodontidx (Hadrosauride). Premaxillaries edentu-
lous; teeth in several rows, forming with use a tessellated grinding
surface. Cervical vertebre opisthoccelian. Limb bones hollow; fore
limbs small; femur longer than tibia.

Genera Trachodon (Hadrosaurus, Diclonius), Cionodon, and Orni-
thotarsus. Cretaceous, North America.

(10) Family Claosauride. Premaxillaries edentulous; teeth in sey-
eral rows, but a single row only in use. Cervical vertebree opisthoce-
lian. Limb bones solid; fore limbs small. Sternal bones parial.
Postpubis incomplete. Sacral vertebrie nine. Femur longer than tibia;
feetungulate; three functional digits in manusand pes. (Pls. LX XII-
LXXIV.)

Genus Claosaurus. Cretaceous, North America.

(11) Family Nanosauride. Teeth compressed and pointed, and in a
single uniform row. Cervicaland dorsal vertebrie short and biconcave;
sacral vertebrie three. Ilium with very short pointed front and narrow
posterior end. Limb bones and others very hollow; fore limbs of
moderate size; humerus with strong radial crest; femur curved, and
shorter than tibia; fibula pointed below; metatarsals very long and
slender. Anterior caudals short.

Genus Nanosaurus. Jurassic, North America. Includes the most
diminutive of known dinosaurs.

POSTSCRIPT.

The accompanying plates, as well as the figures in the text, are all
from original drawings made to illustrate the writer’s investigations on
the early vertebrate life of North America. Many of these illustrations
were designed especially for the monographs on dinosaurian reptiles
now in preparation for the United States Geological Survey, and are
here used, with the approval of the Director, to give the general reader
aclear idea of some of the type specimens of one great group of extinet
animals that were long the dominant forms of life on this continent. —

YALE UNIVERSITY, June 15, 1895.

JP iL IS:

Je dbus Ie), JUL.

247

PLATE IL.

TRIASSIC DINOSAURS.—THEROPODA.

ANCHISAURID.E.

Fic. 1. Skull of Anchisaurus colurus Marsh; side view; one-half natural size-
a, nasal opening; b, antorbital opening; c, lower temporal fossa; d, upper
temporal fossa; 0, orbit; g, quadrate.
Fic. 2. Bones of left fore leg of same individual; outside view; one-fourth
MAGUTAL SI ZO = a2iste cameo eisisiesisle wine oes espe ree taeimeie ce clciae aeieist ere ee eee eee
c, coracoid; h, humerus; 7, radius; s, scapula; u,ulna; J, first digit; V,
fifth digit.
Fic. 3. Bones of left hind leg of same individual; outside view; one-fourth
NATUTAU SIZE RAS ee os tae ete aero are eee aoe a eee alesis ae eee ener
a, astragalus; c, caleaneum; f, femur; /f, fibula; i/, ilium; is, ischium; p,
pubis; f, tibia; J, first digit; V, fifth digit.
248

Paga
148

149

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2
o

ANCHISAURUS COLURUS Marsh,

Triassic.

PGA; - UE

PLATE III.

TRIASSIC DINOSAURS.—THEROPODA.

ANCHISAURIDA.

Fic. 1. Skull of Anchisaurus colurus Marsh; top view; one-half natural size-.
Fic. 2. Base of same skull; back view; one-half natural size.........-.-.---.
a, nasal opening; bp, bas pterygoid process; d, upper temporal fossa; f,
frontal; j, jugal; n, nasal; 0, orbit; oc, occipital condyle; p, parietal;
p', parocecipital process; pf, prefrontal; pm, premaxillary.
Fic. 3. Sacrum and ilia of Ammosaurus major Marsh; seen from below; one-
fourth naturalisize--ss-selcsees sem eee ae eee eel eeeeereee ease =P eee eee
Fic. 4. Ischia of Anchisaurus polyzelus Hitchcock, sp.; seen from above; one-
half maturalssizetsor cer -sni- aaces Aes oie alee ee eee eae eee eee eee
a, posterior view of distal ends; ac, acetabular surface; il, face for ilium;
is, face for ischium; p, distal end; pb, face for pubis; s, symphysis; 7, 2,
8, sacral vertebra.
Fic. 5. Left fore foot of Anchisaurus polyzelus; back view; one-half natural
BIZO) oS ere e a lowe ecto on see el nice seein s eee eee Ree aes sae eee aan
c, centrale; 7, radiale; R, radius; U, ulna; J, first digit; V, fifth digit.
Fic. 6. Right hind foot of Ammosaurus major; front view; one-fourth natural
C1, hee Ree Ceara ar eeraa6 Lmao OA OOn ANA Mb aaaa ceesanseaans Bie Taree tae
a, astragalus; c, caleaneum; F, fibula; 7, tibia; 12, t3, t4, tarsal bones; J,
first digit; V, fifth digit.

250

Page.
148
148

150

150

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SIXTEENTH ANNUAL REPORT PARTI PL. Ill

ANCHISAURUS AND AMMOSAURUS.
Triassic,

ON CR

Tee IE JOY

PLATE IV.

TRIASSIC DINOSAURS.—THEROPODA.
: |

ANCHISAURIDE.

Page.
Restoration of Anchisaurus colurus Marsh ..---...------- Geancccensogusocsacas = id)
One-twelfth natural size. : ;
Connecticut River sandstone, Connecticut.
yi

U. S, GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PART! PL, Iv

RESTORATION OF ANCHISAURUS COLURUS Marsh

Ono-twelft

JE Ibe, We

253

RICA Ve;

TRIASSIC DINOSAURS.—FOOTPRINTS.

Fic. 1. Footprints of small dinosaur (Ammopus); showing impressions of both
fore and hind feet; one-twelfth natural size

Fic, 2. Footprints of bipedal dinosaur (Anomcepus); showing where the ani-
mal sat down; one-twelfth natural size

Fia. 3. Moonprints of large bipedal dinosaur (Brontozoum)) ; one-twentieth
Matra S1Z0 = sce se clee= c re sem eee oslo eters oe ee a eee eee aee eee

Fic. 4. Footprints of large dinosaur (Otozoum); showing impressions of hind
feet alone; one-twentieth natural size.---.---- 2 -- 2-22.25 eos anes

Fic. 5. Footprints of bipedal dinosaur; one-twelfth natural size

The specimens represented in figs. 1-4 are from the Connecticut River sand-

stone of Massachusetts, and the one shown in fig. 5 is from nearly the
same horizon in Arizona.

254

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. V

FOOTPRINTS OF TRIASSIC DINOSAURS.

eer WE

PLATE VI.

JURASSIC DINOSAURS.—THEROPODA.

HALLOPID.

Fic. 1. Outline rstoration of left fore leg of Hallopus victor Marsh; outer view.

Fic. 2. Outline restoration of left hind leg of same individual; outer view. -.
Both figures are natural size. :

256

HALLOPUS VICTOR Marsh.
Jurassic

SIXTEENTH ANNUAL REPORT PART! PL. VI

Bag
the oe

on tM

or

JPG WOE

16 GEOL, PT 1——17

PLATE VII.

JURASSIC DINOSAURS.—THEROPODA.

Ca@LURID&.

Fic. 1. Tooth of Celurus fragilis Marsh; twice natural size. ..--..-..--..-----

a, outer view; 6, front view; c, inner view.

Fic. 2. Cervical vertebra of Celurus fragilis; front view ..---..-.---.-------
2a, side view; 2b, transverse section of same vertebra.

FiG. 3. Dorsal vertebra of Calurus fragilis; front view .--.--- A ee ot
3a, side view ; 3b, transverse section of same.

Fig. 4. Caudal vertebra of Calurus fragilis; front view -...-..---------------
4a, side view; 4b, transverse section of same.

4, anterior end; ¢, cavity; d, diapophysis; jf, lateral foramen; nc, neural
canal; p, posterior end; 7, coossified rib; s, neural spine; 2, anterior
zygapophysis; 2’, posterior zygapophysis.

All the figures of vertebre are natural size.

258

Page.
155

156

156

156

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. Vil

a b c

CCELURUS FRAGILIS Marsh.

Jurassic.

PLAINS, WOU.

PLATE VIII.

JURASSIC DINOSAURS.—THEROPODA.

CERATOSAURID,

Page.
Fic. 1. Skull of Ceratosaurus nasicornis Marsh; side view.......---.-.--------- 157
Ere: 2. The same skull; frontiview <--.-- ---6-- - 2-42-2422 ses eee eee eee 157
Fic. 3. The same skull, with brain cast; seen from above ...-....- wo balers ete 159

a, nasal opening; b, horn core; c, antorbital opening; c’, cerebral hemi-
spheres; d, orbit; ¢, lower temporal fossa; /, frontal bone; f’, foramenin
lower jaw; h, supratemporal fossa; j, jugal; m, maxillary bone; m’,
medulla; n, nasal bone; oc, occipital condyle; ol, olfactory lobes; pf,
prefrontal bone; pm, premaxillary bone; q, quadrate bone; qj, quadrato-
jugal bone; ¢t, transverse hone.

All the figures are one-sixth natural size.

260

uu.

S. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT

PART |

PL. Vill

CERATOSAURUS NASICORNIS Marsh.

Jurassic.

Z

Yj

JP eve)

PLATE IX.

JURASSIC DINOSAURS.—THEROPODA.

CERATOSAURIDE.

Fic.1. Atlas of Ceratosaurus nasicornis Marsh..........--..------------------
HNG.25 Axisiof same individual .).0s2e-e-- eee eee scene ete eee eee eee
Hie:3. Third‘ vertebra of same.s. 2: 5 <20s.---eree secs hice oe eee eater eee

a, side view; b, front view; c, posterior view; d, top view; e, inferior view.
Fic. 4. Sixth vertebra of same; side view - ---- Weiss ac ee sls ziete\Sele Sale eise eee ee
Fie.5. Dorsal vertebra‘of same; side view ..----=-.- <2. 2222 s2e- ss ose senses

Fic. 6, Fifth caudal] vertebra of same, with chevron in natural position; side
VIOW coe man cel- ese ens earns JobeeeGaceiestieneeccs Css merase eee ee ereeeere

All the figures are one-sixth natural size.
262

haan

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PART! PL. IX

CERATOSAURUS NASICORNIS.

Jurassic.

JEAN), OSS

263

PLATE X.

JURASSIC DINOSAURS.—THEROPODA.,

CERATOSAURID®, DRYPTOSAURID®H, AND C@@LURIDE.

Page.
Fic. 1. Pelvis of Ceratosaurus nasicornis Marsh; side view; seen from the left;
one-twelfth natural) size. oe cacsarias ele se ieee sees ate all eee ee eee eee 161
The three pelvic bones are coossified.
Fig. 2. Pelvis of Allosaurus fragilis Marsh; the same view; one-twelfth nat-
UPA \SIZO ss oce seis ce ye se oe e ck Swale Se eis eet tere te eee ene eer 163
a, acetabulum; il, ilium; is, ischium; p, pubis.
Fic. 3. Pubes of Calurus agilis Marsh; one-fourth natural size .......-.-.---- 156
Fic. 4. The same bones; one-fourth natural size...--.. .-.-.----.------------ 156
a, side view; b, front view; c, foot, or distal end.
264

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. X

CERATOSAURUS, ALLOSAURUS, AND CCELURUS.

Jurassic.

JP bye Ma OE

PLATE XI.

JURASSIC DINOSAURS.—THEROPODA.

DRYPTOSAURIDE.

Fic. 1. Bones of left fore leg of Allosaurus fragilis Marsh; outer view
Fic. 2. Bones of left hind leg of Allosaurus fragilis; outer view
Both figures are one-twelfth natural size, :

266

U. S. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PART |

PL. XI

ALLOSAURUS FRAGILIS Marsh.

Jurassic,

JedwaI0ID) 20L

PLATE XII.

JURASSIC DINOSAURS.—THEROPODA.

DRYPTOSAURID®.

Fic. 1. Right premaxillary bone of Creosaurus atroc Marsh; one-sixth natural
a, front view; b, lateral view, showing outer side; c, lateral view, showing
inner surface.
Fic. 2. Left ilium of Creosaurus atroz; seen from the left; one-tenth natural
Fic. 3. The same; seen from below; one-tenth natural size .......----.------
a, anterior, or pubic, articulation; b, posterior, or ischiadic, articulation.
Fic. 4. Pubes of Creosaurus atrox; front view; one-twelfth natural size...---
a, acetabular surface; b, face for ilium; c, distal end.
Fic. 5. Lumbar vertebra of Creosaurus atrox; tront view; one-sixth natural
Fic. 6. The same; side view; seen from the left; one-sixth natural size..---.
a, anterior articular face; d, diapophysis; p, posterior articular face; s,
neural spine; 2, anterior zygapophysis; 2’, posterior zygapophysis.
268

160
160

—

. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT

PART |

PL.

xii

CREOSAURUS ATROX Marsh.

Jurassic.

IPL AS 08k

J
:

PLATE XIII.

JURASSIC DINOSAURS.—THEROPODA.

LABROSAURIDE.
Page.
Fic. 1. Tooth of Labrosaurus sulcatus Marsh; natural size..... .----.-------- 163
a, outer view; b, back view; c, inner view. :
Fic. 2. Left dentary bone of Labrosaurus ferox Marsh; superior view....-.-. 163

Fic. 3. The same bone; lateral view; outer side 163
Fic. 4. The same bone; lateral view; inner side 163
All three figures are one-sixth natural size.
Fic. 5. Pelvis of Labrosaurus fragilis Marsh; seen from the left; one-twelfth
natural size (outline of ilium from Creosaurus atroc Marsh)...--.-.---------- Gonos

a, acetabulum; il, ilium; is, ischium; p, pubis.
270

~ GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PART |

PL. Xill

LABROSAURUS.

Jurassic.

Je JL ae, 2D.

271

PLATE XIV.

JURASSIC DINOSAURS.—THEROPODA.

CERATOSAURIDE.

Restoration of Ceratosaurus nasicornis Marsh
One-thirtieth natural size.
Jurassic, Colorado.
979 ;

U. S. GEOLOGICAL SURVEY \ SIXTEENTH ANNUAL REPORT PARTI PL. XIV

RESTORATION OF CERATOSAURUS NASICORNIS Marsh,

Ono-thirtloth natural size, Jurassic, Colorado,

Ae, OV

16 GEOL, PT 1——18

273

PLATE XV.

JURASSIC DINOSAURS.—SAUROPODA.

i ATLANTOSAURID.
Page.
Fic. 1. Back of skull of Atlantosaurus montanus Marsh.......---.------ scenes lO
Fic. 2. The same specimen; inferior view ....--...---- Gasosstesabeascass ae oeeLOG,

bp, basioccipital process; c’, pituitary canal; f, foramen magnum; h, pos-
terior fossa; i, internal carotid foramen; oc, occipital condyle; p, par-
occipital process; pr, parietal; s, suture; so, supraoccipital. :

Both figures are one-half natural size.

274

u.

Ss

GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT

PART |

PL. XV

ATLANTOSAURUS MONTANUS Marsh.

Jurassic

Tedby IN OW IL

275

PLATE XVI.

JURASSIC DINOSAURS.—SAUROPODA.

ATLANTOSAURIDE.
. Page.
Fic. 1. Left pubis and ischium of dtlantosaurus immanis Marsh; outer view;
one-twentieth natural 8iz0 ~~ 2-22. 2 ane ee eee a= cae eee eae eee eee
f, foramen in pubis; is, ischium; p, pubis.
Fic. 2. Left femurof Atlantosaurus immanis; inner view; one-sixteenth natu-

2a, proximal end.
Fic. 3. The same bone; front view; one-sixteenth natural size. ..--..--.-----
3a, distal end.

c, inner condyle; c’, outer condyle; f, groove for fibula; h, head; t, tro-
chanter; t’, inner trochanter. ;

276

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PART! PL. XVI

ATLANTOSAURUS IMMANIS Marsh.

Jurassic.

PIGS 2 WOE

277

PLATE XVII.

JURASSIC DINOSAURS.—SAUROPODA.

ATLANTOSAURIDA.
Page.
Fic. 1. Sacrum of Atlantosaurus montanus Marsh; seen from below. ......--- 166
Fic. 2. Sacrum of Apatosaurus ajax Marsh; seen from below...-.-.-.----.------ 166

a, first sacral vertebra; b, transverse process of first vertebra; c, trans-
verse process of second vertebra; d, transverse process of third vertebra;
e, transverse process of fourth vertebra; f, f’, f'’, foramina between trans-
verse processes; g, surface for union with ilium; p, last sacral vertebra,
Both figures are one-tenth natural sme.

278

-« GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PART 1

PL. XVII

ATLANTOSAURUS AND APATOSAURUS.

Jurassic.

Pile Ia 2OVIOEE

PLATE XVIII.

JURASSIC DINOSAURS.—SAUROPODA.

ATLANTOSAURID.

Fic. 1. Cervical vertebra of Apatosaurus laticollis Marsh; back view; one-
sixteenth natural’size me 25 - sco sesn eeu s omer ene sone ee ee eee a namieeneee
Fic. 2. Dorsal vertebra of Apatosaurus ajax Marsh; front view; one-eighth
MERKEL YAs s56ncq so Scoma6 CCbSOD BEERen Eos ness Cosa dsooosen scognasa tease
a, metapophysis; b, ball; c, cup; d, diapophysis; jf’, lateral foramen; h,
hatchet bone; n, neural canal; p, parapophysis; z, anterior zygapophy-
sis; 2’, posterior zygapophysis.

Fic. 3. Cast of sacral cavity of Apatosaurus ajax; top view; one-fourth nat-
Tal SiZ6:2 =~ loca, scisin sw ater sie es aero see eiaein os isieleyate este c= = eee eee eee
Jf, foramen; v, cast of cavity in first true sacral vertebra; v', cast of cavity

in second sacral vertebra; v’’, cast of cavity in third vertebra.

280

166

:
{

SIXTEENTH ANNUAL REPORT PARTI PL. XVIII

APATOSAURUS.

Jurassic

Ie iba deh. DI

281

PLATE XIX.

JURASSIC DINOSAURS.—SAUROPODA.

ATLANTOSAURIDA AND MOROSAURIDZ.

Fic. 1. Left scapula and coracoid of Apatosaurus ajax Marsh; side view; one-
fourteenth natural size.......-..-.-....-- Sonic eine Sets a eee
Fic. 2, Left scapula and coracoid of Morosaurus grandis Marsh; side view;
one-tenth natural size
a, scapular face of glenoid cavity; a’, coracoidean part of glenoid cavity;
b, rugose surface for union with coracoid; f, foramen in coracoid,

282 e

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. XIX

NN

‘ << i i

SN
ii 7 A <f

>

APATOSAURUS AND MOROSAURUS
Jurassic.

JP Ibu IIB) OX

PLATE XX.

JURASSIC DINOSAURS.—SAUROPUDA.

ATLANTOSAURIDZ.

Fic. 1. Tooth of Brontosaurus excelsus Marsh; natural size .......-..--.------ 168
a, outer view; b, posterior view; c, inner view; d, front view.
Fic. 2. Left dentary bone of Brontosaurus excelsus; outer view; one-third
MAGULAl SIZE. Ane ce miee o a ele ease ane oma ee eee nse te ae ee eee eee 168
a, edentulous margin; 8, symphysis; s7, face for surangular.
Fic. 3. Sixth cervical vertebra of Brontosaurus excelsus; side view; one-twelfth
maturalisize. pees ees pa lene Ree ane ae neem en eee ese ai eee 169
Fic. 4. The same vertebra; back view; one-twelfth natural size..-...---.---- 169
b, ball; ec, cup; d, diapophysis; f, lateral foramen; n, neural canal; p,
parapophysis; 7, cervical rib; z, anterior zygapophysis; z’, posterior
zy gapophysis.
284

U.S

. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PARTI PL. XX

BRONTOSAURUS EXCELSUS Marsh.

Jurassic.

Lae 2X IL,

285

PLATE XXI.

JURASSIC DINOSAURS.—SAUROPODA.

ATLANTOSAURIDA.
Page.
Fic. 1. Posterior cervical vertebra of Brontosaurus excelsus Marsh; front view. 169
Fic. 2. Dorsal vertebra of Brontosaurus excelsus; side view..-----.----..----- 169
Fic: '3:, Thesame'vertebra;s backviews--s-2-cienecesee oon see eee eee eee 169

b, ball; c, cup; d, diapophysis; f, foramen in centrum; f’, lateral fora-
men; n, neural canal; p, parapophysis; r, rib; 8, neural spine; z, anterior
zygapophysis; 2’, posterior zygapophysis.

All the figures are one-twelfth natural size.
286

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. XXI

BRONTOSAURUS EXCELSUS.

Jurassic.

JEL AUIS 2Os00E

PLATE, XXII.

JURASSIC DINOSAURS.—SAUROPODA.

ATLANTOSAURID&.
Page.
Fic. 1. Seapular arch of Brontosaurus excelsus Marsh; front view; one-sixteenth
Natural! SiZO es scsse ee ee mee eae ee a ee eee eee 168
c, coracoid; ct, cartilage; g, glenoid cavity; 0s, right sternal bone; 0s’,
left sternal bone; s, scapula.
Fic. 2. Left sternal bone of same individual; one-eighth natural size-......- 168
a, superior view; 6, inferior view; c, face for coracoid; d, margin next to
median line; e, inner front margin; p, posterior end.
Fic. 3. Sternal plates of young ostrich (Siruthio camelus Linn.); seen from
below. two-thirds naturalisizey sas see s=- eee eee ee eae ee eee ee eee 169
ce, coracoid; ct, sternal cartilage; 08, ossified sternal bone; sr, sternal rib.

288

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. XXil

STERNAL PLATES OF BRONTOSAURUS AND YOUNG STRUTHIO,

(PP ins) es

JE JbveviE ls) 2O300L

16/GHOL, Pr 1——19

PLATE XXIIL

JURASSIC DINOSAURS.—SAUROPODA.
ATLANTOSAURIDE Z

Fig. 1. Sacrum of Brontosaurus excelsus Marsh; seen from below
a, first sacral vertebra; b, transverse process of first vertebra; c, transverse
process of second vertebra; d, transverse process of third vertebra; e,
transverse process of fourth vertebra; f, f', f’’, f'’, foramina between

processes of sacral vertebre; g, surface for union with ilium; J, last
lumbar vertebra; p, last sacral vertebra. :
Fic. 2. Section through second vertebra of sacrum of Brontosaurus excelsus -...
e, cavity; g, face for union with ilium; ne, neural canal.
Both figures are one-tenth natural size.

290

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. XXill

BRONTOSAURUS EXCELSUS.

Jurassic

291

_— <4

ai

PLATE XXIV.

JURASSIC DINOSAURS.—SAUROPODA.

rs ATLANTOSAURID ©.

Fic. 1, Ischia of Brontosaurus excelsus Marsh; seen from above; one-twelfth
* Matmiral S126: cv. enctetne coe keen eee ee ees oes coe et rer en ee TOR
la, distal ends.
a, acetabular surface; e, extremity; il, face for ilium; pb, face for pubis;
8, symphysis. :
Fig. 2. Fourth caudal vertebra of Brontosaurus excelsus; side view. .....-----

Pig. 3. The'same vertebra stronti views. - sc 22-502 22 oe eee eae eee
Fic. 4. Chevron of Brontosaurus excelsus; side view... -..----.----------+----
FiG..5..Dhe same; (front views. -2-s-ese oe oe cee oe Sane ee See ee eee é

C
Last four figures are one-eighth natural size.

ce, face for chevron; h, hemal orifice; n, neural canal; s, neural spine; t,
transverse process; z, anterior zygapophysis; 2’, posterior zygapophysis.
292

U. S. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PART 1

PL. XXIV

BRONTOSAURUS EXCELSUS.

Jurassic.

TEAL, DXOKOV:

PLATE XXV.

JURASSIC DINOSAURS.—SAUROPODA,

DipPLopocip2&.

Fic. 1. Skull of Diplodocus longus Marsh; side view....- ------- wacetcocmeese
Fic. 2. The same skull; front view
Fic. 3. The same skull; top view

All the figures are one-sixth natural size.

294

U. S. GEOLOGICAL SURVEY > SIXTEENTH ANNUAL REPORT PARTI PL. XXV

UT
Lily

My
Dipyfts Wis

— = = ——

DIPLODOCUS LONGUS Marsh

Jurassic.

ae
‘

Jebel

ROGvalr

295

PLATE XXVI.

JURASSIC DINOSAURS.—SAUROPODA. : aa

DipLopocip.2«®.
Page. 6
Fig. 1. Maxillary teeth of Diplodocus longus Marsh; side view; one-half natural =
UAH BS estan ae Eno RPcen Seabees Decae 7 She ces Dann DeSa A SUSASEA obempSacgbaonsacc. 179

Fig. 2. Section of maxillary bone of Diplodocus longus; showing functional
tooth (fourth) in position and five successional teeth (2-6) in dental cavity ;
one-half natural Size scot eee see oe eea ei cee ee conte Sete eee eee 179 ie

a, outer wall; b, inner wall; c, cavity; e, enamel; f, foramen; 7, root.

Fic. 3. Cervical vertebra, with rib, of Diplodocus longus; side view; one-eighth

MaburalsiZer<c 2 cypscioSe oe iiseetisioe crete eee eine eas Somes Sista eee eee 180 ~ ee
a,metapophysis; b, ball; c,cup; f, foramen in centrum; 7, rib; 2, anterior eh
zygapophysis; 2’, posterior zygapophysis. hat
Fic. 4. Twelfth caudal vertebra of Diplodocus longus; side view; one-sixth Vr
MabUral/ SiZO: essence ce sneer Ce eer a 2 ee ee a 180 ae
Fic. 5. The same vertebra; bottom view; one-sixth natural size.....--..---. 1803.)

ce, anterior face for chevron; c’, posterior face for chevron; s, neural spine;
2, anterior zygapophysis; 2’, posterior zygapophysis.
Fic. 6. Cheyron found attached to tenth and eleventh vertebrae of Diplodocus

longus; top and side views; one-tenth natural size........--...---..--.---- 180
Fic. 7. Chevron of another individual; top and side views; one-tenth natural 1.
BIZOs.22.(n)s apse ops 2% ed aleicie dieroessleiaets Se Fre elec vee Be MSEE Ee eee ee eee eee 180 |

a, anterior end; p, posterior end; 1, faces for articulation with vertebra.
296

u.

- GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PART |

PL. XXVI

DIPLODOCUS LONGUS.

Jurassic.

Fett

TELA ROOT

297

PLATE XXVII.

JURASSIC DINOSAURS.—SAUROPODA,

DIPLopocID.©.

Fic. 1. Atlas of Diplodocus longus Marsh; side view; one-half natural size--..
Fig. 2. The same; front view; one-half natural size.........--..------------
a, artienlar face for axis; ¢,cup; n, neural canal; 0, cavity for odontoid
process of axis; 1, face for rib; 2’, posterior zygapophysis.

Fic. 3. Cervical vertebra of Diplodocus longus; front view; one-eighth natural

Fic. 4. Dorsal vertebra of Diplodocus longus; back view; one-eighth natural
BI ZO oo c.csce cinneblace=s ate sleeleetocie sree aie pe Renae seh eee Cee e eee eee eee
a, metapophysis; b, ball; c,eup; d, diapophysis; /’, lateral foramen; n,
neural canal; 7, rib; 2, anterior zygapophysis; 2’, posterior zyga-
pophysis.

298

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. XXVII

qu

| < eA ) Au

DIPLODOCUS LONGUS

Jurassic.

TILA, SOOVINGL

299

PLATE XXVIII.

JURASSIC DINOSAURS.—SAUROPODA,

DIPLODOCIDE.

Fic. 1. Sacrum and ilium of Diplodocus longus Marsh; seen from below; one-
tenth'natural size: - 22. 25252 ss enec cece o= (eee ee job atseten = eee 180
la, transverse section through second vertebra; c, cavity.
a, first sacral vertebra; ac, acetabular surface; b, transverse process of
first vertebra; c, transverse process of second vertebra; d, transverse
process of third vertebra; f, f, foramina between sacral vertebre; g,
face for ilium; il, ilium; is, face for ischium; p, last sacral vertebra; pb,
face for pubis.
Fic. 2. Right foot of Diplodocus longus; front view; one-eighth natural size.. 180
a, astragalus; c, place for caleaneum; d, distal phalanx; f, fibula; ¢, tibia;
JI-V, metatarsals; i-iii, ungual phalanges.
Fic. 3. Ischia of Diplodocus longus; inferior view; one-eighth natural size.... 180
e, distal ends; il, face for ilium; p, distal extremity; pb, face for pubis;
8, symphysis.
300 ,

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. XXVIII

DIPLODOCUS LONGUS

Jurassic.

JP bv IB OCI,

PLATE XXIX.

JURASSIC DINOSAURS.—SAUROPODA. y

DiIPLopocipz. a

Page.

Fic. 1, Leftmetacarpals of Diplodocus longus Marsh, with first phalanx of first f
digitin positions: front) wiew poo. ----s= = see eee eee eee eee 189
Fic. 2. Left metatarsals of Morosaurus grandis Marsh; front view..-.-...----- 183

Both figures are one-fourth natural size. ; ;
302

U. S. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PART |

PL. XXIX

DIPLODOCUS AND MOROSAURUS.

Jurassic

303

PLATE XXX.

JURASSIC DINOSAURS.—SAUROPODA.

MornosauRID.z.

Fic. 1. Skull of Morosaurus agilis Marsh; posterior view; one-half natural size. 181
a, postoceipital bone; b, lateral plate of atlas; c, odontoid process, or cen
trum, of same; co, exoccipital; i, inferior portion of atlas; m, neural
canal; p, parietal; po, postorbital; 8, squamosal; so, supraoccipital.
Fic, 2. Portion of skull, with brain cast, of Morosaurus grandis HAEESINS top
view; one-fourth natural size ....--..--.------------ See eee
(i combed hemispheres; cb, cerebellum; fp, mos conta Jr, frontal; ol,
olfactory lobe; on, optic nerve; op, optic lobe; p, paroceipital process;

pr, parietal; q, quadrate; s, squamosal.
Fic.3. Left dentary bone of Morosaurus grandis; outer view; one- -third natural
81200522 socites so viose hee «cee neon eee eieebecese pace cee eres ee aa
a, edentulous margin; s, symphysis; s7, face for surangular.

304

U. S. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PARTI PL. XXX

MOROSAURUS.

Jurassic,

JP Jbua ID, 2x

16 GEOL, PT 1——20

PLATE XXXI.

JURASSIC DINOSAURS.—SAUROPODA.

MOROSAURID.E.

Fic. 1. Tooth of Morosaurus grandis Marsh; outer view; one-half natural size.
Fic. 2. The same tooth; front view; one-half natural size....-..--..---.----
Fic. 8, Axis and part of atlas of Morosaurus grandis; side view; one-eighth
Matural SiZ0s- mio nests a eee oie sis ae as = See a
Fic. 4. The same; front view; one-eighth natural size....-.........---..--- e
a, odontoid process; ax, centrum of axis; d, diapophysis; f, foramen in
centrum; s, neural spine; 2, auterior zygapophysis.

Fic. 5. Fourth cervical vertebra of Morosaurus grandis; side view; one-eighth
natural size..-.--- auo.ain ete S Seve tejemne are eee al ea Seis e See eee eee ee
Fic. 6. The saine vertebra; back view; one-eighth natural size.......-..---.
b, ball; ec, cup; d, diapophysis; e, parapophysis; f, foramen in centrum;

z, anterior zygapophysis; 2, posterior zygapophysis.
Fic. 7. Pelvie arch of Morosaurus grandis; seen from in front; one-sixteenth
natural size

a, first sacral vertebra; b, transverse process of first vertebra; c, transverse
process of second vertebra; d, transverse process of third vertebra;
é, transverse process of last sacral vertebra; f, /’, f, foramina between
processes of sacral vertebriv; g,g, surfaces for union with iia; i, lium;
is, ischium; ne, neural canal; p, last sacral vertebra; pb, pubis.

306

183

183

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. XXXI

MOROSAURUS GRANDIS Marsh.

Jurassic

PLATE XXXII.

JURASSIC DINOSAURS.—SAUROPODA.

: 3 MorosavuRiD.e (a
Page.
Fig. 1. Anterior dorsal vertebra of Morosaurus lentus Marsh; posterior view-. 182°
Fic. 2. Posterior dorsal vertebra of Morosaurus lentus; side view...--..----- 182
2a, transverse section through centrum of same. ; i
Fic. 3. The same vertebra; posterior view.......---..---------------------- 182
All three figures are one-fifth natural size. Pane
Fic. 4. Caudal vertebra of Morosaurus grandis Marsh; side view- . 182
Fic. 5. The same vertebra; front view 182 hehe,
HiG./6; Lhe same;vertebra; posterior views .---- -s2462 © -1se ee eee eee eee 182 ‘OR ks
Last three figures are one-half natural size. ;
b, ball; ec, eup; d, diapophysis; f, foramen in centrum; m, metapophysis; 2
n, neural canal; ns, nenral suture; s, nenral spine; x2, hyposphene; ;
. 2, anterior zygapophysis; 2’, posterior zygapophysis.
is
i 308
e
'
Ri 7
:
n
1 .

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. XXXII

MOROSAURUS.

Jurassic.

PALS, 2x OxOxUOE

309

PLATE XXXII.

JURASSIC DINOSAURS.—SAUROPODA.

MoROSAURID.

Fic. 1. Sacrum of Morosaurus lentus Marsh; seen from above....-....---. .--
Fig. 2. Last sacral vertebra of Morosaurus lentus; posterior view.-.-.--.------
a, anterior face of centrum of first sacral vertebra; b, transverse process
of first vertebra; ¢c, transverse process of second vertebra; d, transverse
process of third vertebra; e, transverse process of last sacral vertebra;
t,f',f', foramina between transverse processes of sacral vertebra; g,
surface for union with ilium; m, neural canal; ns, neural spine; p, pos-
terior face of centrum of last sacral vertebra; 8s, suture; 2’, posterior
zygapophysis. 7
Both figures are one-tifth natural size.
310

OLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT “PART |

2

MOROSAURUS LENTUS Marsh.

Jurassic.

IEICE, DOOD

311

PLATE XXXIV.

JURASSIC DINOSAURS.—SAUROPODA.

MOROSAURID®.

Fic. 1. Anterior caudal vertebra of Morosaurus grandis Marsh; side view; one-
eighth naturalsizetjon-2ic sone ee os shade n tee eee cee eee ee ee
Fic. 2. The same vertebra; front view; one-eighth natural size..-..........-
Fig. 3. Second caudal vertebra of Morosaurus lentus Marsh; side view; one-
fidth naturaliisize 'S.2 - 2 secede ct cence olsen ae, cae See ee ene eee
Fig. 4. The same vertebra; front view; one-fifth natural size..-...--..------
Fic. 5. Distal caudal of Morosaurus grandis; side view. .----...--------------
iG. 6. The same) vertebra; front view, .-2--- -2--2e 2-2 22a =e ee eee
Fic. 7. More distal caudal of same animal; side view..--..----...----.------
Last three figures are natural size.
n, neural canal; ns, neural suture; 8, neural spine; ¢, transverse process;
2, anterior zygapophysis; 2’, posterior zygapophysis.
312

Page.

GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PART |

=

Sy

S

S35

ES

MOROSAURUS.

Jurassic,

JEIb eC) DOW,

313

PLATE XXXV.

ne JURASSIC DINOSAURS.—SAUROPODA. ) aa

, *MOROSAURIDA. i
i Page. {
Fic. 1. Left ium of Morosaurus robustus Marsh; side view; one-tenth natural i ;
WAN oo Sa cesn Ssosase soc Os S22 sSdeoucses teeta Pes tesencados ssopetsccsocces 132
Fic. 2. The same bone; inferior view; one-tenth natural size ........-.-..--- 182 ah
| a, anterior, or pubic, articular surface; ), posterior, or ischiadie, articular '
7 surface.
' : Fic.3. Ischium of Morosaurus grandis Marsh; superior view; one-eighth
natural size ....-... npECeO SoG BEES Uar Asc sua -SanboseonusaEcoosS peeacaes 183
Fic. 4. Ischia of Morosaurus lentus Marsh; inferior view; one-eighth natural —
UGE Seco seme clocme seeder sceo spite s=e essa oe Onan coSbeh ashe c= bacoss choc ee also)
e, distal ends; il, face for ilium; p, posterior extremity; pb, tace tor pubis;
’ 8, symphysis.
, 314
.
€ A
‘

U. S. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PARTI PL. XXXV

MOROSAURUS.

Jurassic,

PILZ IS, ROX OO WAL

PLATE XXXVI.

JURASSIC DINOSAURS.—SAUROPODA.

MOROSAURIDZ AND ATLANTOSAURIDA.

Paga
Fic. 1. Pelvis of Morosaurus lentus Marsh; seen from the left; one-eighth oe
MatuTral SiZ0\-:2 Ae cers sad cee eee e/a Ces mies eee nce eee = RCE Eee eee 183
Fic. 2. Pelvis of Apatosaurus ajax Marsh; seen from the left; one-sixteenth
natural: size: + = 32 2c. cheeses hee eee oe een eee ene eer eee 166

a, acetabulum; /, foramen in pubis; il, ilium; is, ischium; p, pubis.

316

SIXTEENTH ANNUAL REPORT PART 1 PL, XXXVI

U. S. GEOLOGICAL SURVEY

1

f

/

MOROSAURUS AND APATOSAURUS,

Jurassic.

JPL ON ILL,

317

PLATE XXXVIL._ oe

JURASSIC DINOSAURS.—SAUROPODA.

Se nh Be

MOoROSAURID.E.

Fic. 1. Portion of right fore foot ot Morosaurus agilis Marsh; front view; one-—
fonnthwn atu Tal G1 ZO). else et ee eee eet oe ee 182
c, carpal bone; J-l’, metacarpals. *
Fic. 2. Right hind foot of Morosaurus agilis; front view; one- afourth natural
BIZO@: s2 sods oose ss oan Se Se sen ~ sak ete nesses ea ebeeer/ sche sees ess EE eee oom

Fic. 3. Fifth metacarpal of Morosaurus lentus Marsh; front view..----------- 182
hig. 4) (Dhesameyboner, INNER vil Wie ate ee eee ae eee 182,
a, proximal end; e, distal end. Moewid
Fig..5. The same: outer view... -2--<--so- = ses sce loess cea ees eee eee eee «18
Last three figures are one-half natural size. &

318

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. XXXVII

MOROSAURUS.

Jurassic.

JP IAT) OX VIELE

PEATE XexXGy ie

JURASSIC DINOSAURS.—SAUROPODA.

MOROSAURIDE.

Fic. 1. Bones of left fore leg of Morosaurus grandis Marsh; outer view
Fic. 2. Bones of leit hind leg of same individual; outer view
Both figures are one-twentieth natural size.

320 ,

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. XXXVIII

MOROSAURUS GRANDIS.
Jurassic,

EAD END) OOD,

21

16 GEOL, PT 1

321

| PLATE XXXIX.

JURASSIC DINOSAURS.—SAUROPODA.

ATLANTOSAURID.Z, MOROSAURIDE, AND DIPLODOCIDE.

a, front view; a’, anterior end; b, side view; c, back view, d, top view;
h, hwmal orifice; p, posterior end; v, face for vertebra.
‘ 322

U. S. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT

PART |

PL. XXXIX

2

BRONTOSAURUS, APATOSAURUS, MOROSAURUS, AND DIPLODOCUS.

Jurassic,

Jebel) 2CILy

PLATE XL.

JURASSIC DINOSAURS.—SAUROPODA.

PLEUROCELID&.
Page.
Fic. 1. Left dentary none of Pleurocelis nanus Marsh; outer view; one-half
natural ‘size 222 Mec dd e-25- co crde meee ee este nl] io Se Eee Ee eee) Gab
a, edentulous margin; 8s, symphysis.
Fic. 2. Tooth of Pleurocalus nanus; natural size........-..----- .----------- 183
a, outer view; b, front view; c, inner view; d, posterior view.
Fig. 3. Cervical vertebra of same; side view...-<-------2-2- 2-02 oceee eee 183
3a, transverse section of same vertebra.
Fie. 4. Dorsal vertebra of same; sideiview.--.--=.---s.25--. se2= esse ee 184
Fic. 5. The same vertebra; posterior view --.---- -=:---:--- ---22- os=--2 == 184
Era: 62 Sacral vertebraiof same: side wiewss eco - <= ee eee 184
Fic. 7. The same vertebra; posterior view .----- .----- .---- ©2- seem = spines 184
Fug. 8. Caudal yertebrajof same; sidenview =--=--55- 204) sce eee eee eee 184
Fic. 9. The same vertebra; superior view -.-.-------------- ----5- -<=---2==- 184
Fic. 10. Distal caudal vertebra of same; side view ..---------..------------- 184
Fic, 11. The same vertebra; posterior view...---- .---<< eoeese eee seoe ee eee 184

All the figures of vertebre are one-half natural size.

a, anterior end of centrum; c, face for chevron; f, foramen in centrum;
n, neural canal; p, posterior end of centrum; 7, face for rib; s, neural
spine.

Potomac formacion, Maryland.

324

SIXTEENTH ANNUAL REPORT

PART |

PL. XL

PLEUROCCELUS NANUS Marsh.

Jurassic.

PLATE XU.

PLATE XLI.

JURASSIC DINOSAURS.—SAUROPODA.

PLEUROC@LID®.

Fic. 1. Metacarpal of Plewrocelus nanus Marsh; front view ..---.----------- a
a, proximal end of same; b, distal end. ; :
RIG) QNeThojsame bone; siderview,--esse eee eee eetee eee ae eee eee
Fic. 3. Metatarsal of same; front view ..--.-----...-----.------------- oni roel
a, proximal end; b, distal end.

_ Fic. 4. The same bone; side view . ....-----.------------ saeeeesise oe Josnaeane
Fic. 5. Ungual phalanx of same; outer view -.--.-.-------------------------
iG: 6. Lhe'same ‘phalanx; front view-o-o--2-->=-\--5-2-- eee eee eee eee
6a, proximal end of same.
Hic. 7. Theisame bone; inner view: ---------.---2--s---oseee ocdese 008 ae
All the figures are one-half natural size.
Potomac formation, Maryland.

326

U. S. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PART | PL. XLI

PLEUROCCELUS NANUS.

Jurassic,

leis, 2IIOL.

PLATE XLII.

JURASSIC DINOSAURS.—SAUROPODA. F

ATLANTOSAURIDA,

Restoration of Brontosaurus excelsus Marsh ......--.---.-.------- --+--0------

‘ One-ninetieth natural size. tae
Jurassic, Wyoming.
: 328

t
.

U. 8, GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT FART I PL. XLII

—a —_—_—__—_——___,

RESTORATION OF BRONTOSAURUS EXCELSUS Marsh,

One-ninotleth natural size, Jure

lo, Wyoming,

AMID) SGLIUn,

PLATE XLITI.

JURASSIC DINOSAURS.—PREDENTATA.

STEGOSAURID.
) Page.
Fic. 1. Skull of Stegosaurus stenops Marsh; side view .--....----------------- 186
iGo) Lhesame soll) fron tiv O Wiss. taal setae ieee ee ee ieee 187
HiG..3. Lhesame;) seen trom) above. s- -ees eee eee sess eee SBua bobs 187

a, anterior nares; an, angular; ar, articular; b, orbit; c, lower temporal
fossa; d, dentary; e, supratemporal fossa; f, frontal; fp, postfrontal;
Jj, jugal; 1, lachrymal; m, maxillary; n, nasal; oc, occipital condyle; os,
supraoccipital; p, parietal; pd, predentary; pf, prefrontal; pm, premax-
illary ; po, postorbital; g, quadrate; s, splenial; sa, surangular; 80,
supraorbital; sq, squamosal.

All the figures are one-fourth natural size.

330

U. S. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PART 1

PL. XLII

STEGOSAURUS STENOPS Marsh.

Jurassic.

TeJbeand, SILI’,

331

PLATE XLIV.

JURASSIC DINOSAURS.—PREDENTATA.

STEGOSAURID.

Fic. 1. Tooth of Stegosaurus ungulatus Marsh; a, natural size; b, c, d, twice
Natural'sizec 22.20 o2..o te emiae one oee Cee otc oe eee eee ee eee eee
b, outer view; c, end view; d, top view.
Fic. 2. Tooth of Priconodon crassus Marsh; twice natural size..-......--.----
a, outer view; b, end view; c, inner view.
Fic. 3. Outline of skull of Stegosaurus ungulatus, with brain cast in position;
seen trom aboves one-halfnatural SiZ6 a=) ses eeee oe = eee ee eee ee ear
Fic. 4. The same brain cast; seen from the left; one-half natural size...--..
c, cerebral hemispheres; cb, cerebellum; f, orbital cavity; f’, temporal
fossa; m, medulla; oc, occipital condyle; ol, olfactory lobes; on, optic
nerve; op, optic lobes. :
332

Page.
187

187

187
187

. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PARTI PL. XLIV

STEGOSAURUS AND PRICONODON.

Jurassic.

eben 2 NW

PLATE XLV.

JURASSIC DINOSAURS.—PREDENTATA.

STEGOSAURID.
Page.
Fic. 1. Cervical vertebra of Stegosaurus ungulatus Marsh; side view..---- ---- 188
HrG. 2; ‘Lhe same vertebrais front view --2-2.--2 =e -s oeees eee eee eraser 188
Fic. 3. Dorsal vertebra of same series; side view. .----....--..----.-------- 188
Hre, 4. The same) vertebra’) trontiview s.----< oe - 4 -ee eee eee eee Eee 188
Fig. 5. First caudal vertebra of same series; front view ..------------------ 189
Fig. 6. Anterior caudal of same series; side view ------.-------------------- 189
HIG.) 7. Lhe same vertebra) tront views ees see eee eee aes oS eee eee eee 189
Fic. 8. Median caudal of same series; side view ...---..----.-----..-------- 1389
Pics 9) The'samevertebrasitrontsviewi-seeeesesoe ene cree eee eee eee eee 189
Fic. 10. Chevron of same; front view -.----- Jeeescecde fs cae Coo eeme eee 189
Fic. 11. The sameibone; posterior view --------=----- -----= -s--=eee sere =e 189
ec, face for chevron; d, diapophysis; n, neural canal; p, parapophysis;
8, neural spine; 2, anterior zygapophysis; 2’, posterior zygapophysis.
All the figures are one-eighth natural size. .

334

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. XLV

STEGOSAURUS UNGULATUS Marsh.

Jurassic.

i Wa ~~ e
r iad” Leh “<a ke

— re 4 . a cee er oN A
° .
= Aw Xe Vale
= > ; ‘
‘ : . 385 . : .
i ; iy ° 7 N
i]

= ’ z 7 r ‘

Beet i

PLATE XLVI.

JURASSIC DINOSAURS.—PREDENTATA.

STEGOSAURID.

Fic. 1. Brain cast of Stegosaurus ungulatus Marsh; seen from above ..---.-.----
ec, cerebral hemispheres; cb, cerebellum; m, medulla; ol, olfactory lobes;
on, optic nerve; op, optic lobes.
Fic. 2. Cast of neural cavity in sacrum of Stegosaurus ungulatus; side view -.
Fig..3. The same cast;/seen from above--- = 22-2). 22. -seeee- ese = eee eee
a, anterior end; f, f’, /’, foramina between sacral vertebrae; p, exit of
neural canal in last sacral vertebra.
Fic. 4, Outlines representing transverse sections through same brain and
sacral cavity. 2ss)2- J. 22. ccs sic ce see ence cetee sees ete o ee eele se Nae ee eee
b, brain; 8, sacral cavity.
All four figures are one-fourth natural size.
Fic. 5. Sacrum and ilia of Stegosaurus ungulatus; seen from below; one-twelfth
natural 8170. <-< 6 <--osc< <2 dose 52 soceeeeeisees cane Sees soe eee bees
a, first sacral vertebra; ac, acetabular surface; b, transverse process of
first sacral vertebra; e, transverse process of last sacral vertebra;
il, ilium; 1, second lumbar vertebra from sacrum; l’, lumbar vertebra
next to sacrum; p, last sacral vertebra. :

336

190

190

U. S. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PART 1

PL. XLVI

9

STEGOSAURUS UNGULATUS.

Jurassic.

JPA, SEV IOL

16 GEOL, PT 1—_22

337

PLATE XLVII.

JURASSIC DINOSAURS.—PREDENTATA.

STEGOSAURID.

Fic. 1. Left femur of Stegosaurus ungulatus Marsh; front view .......-..-----
c, inner condyle; s, shaft, showing absence of third trochanter; t, great.
trochanter.

Fic. 2. Tibia and fibula of same limb; front view -.-----2--2--------.---
a, astragalus; c, caleaneum; /f, fibula; ¢, tibia.
Fic. 3. Humerus of Stegosaurus ungulatus; front view..--....--..------------
Fic. 4. Ulna of another individual; side view.... .--..-...----..:----.-1---- ;
h, head; 0, olecranal process; 7, radial crest.
All four figures are one-twelfth natural size.
Fic. 5. Metapodial bone of same species; one-fourth natural size -.-..-..----
a, side view; b, front view. ;
Fic. 6. Terminal phalanx of same species; one-fourth natural size -
- a, front view; b, side view; c, posterior view.
338

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. XLVII

STEGOSAURUS UNGULATUS

Jurassic

Pb IID SSE YUE.

i

PLATE XLVIIL

JURASSIC DINOSAURS.—PREDENTATA.

STEGOSAURID.

Fic. 1. Left fore leg of Stegosaurus wngulatus Marsh; outer view; one-sixteenth
naturaligize 20-2 se oe obscene eee Toes Sees oo
Fic. 2. Left hind leg of same species; outer view; one-sixteenth natural size.
Fic. 3. Pelvis of Stegosaurus stenops Marsh; side view; one-tenth natural size.
a, acetabulum; c, coracoid; f, femur; f’, fibula; h, humerus; il, ilium; is,
ischium; p, pubis; p', postpubis; 7, radius; s, scapula; t, tibia; u, ulna:
T, first digit; V, fifth digit.

340 ;

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. XLVIII

STEGOSAURUS

Jurassic.

IPI AA SD, OX RID

341

PRE AWE exaiaixe

JURASSIC DINOSAURS.—PREDENTATA,

STEGOSAURIDE.

Fic. 1. Gular plate of Stegosaurus wngulatus Marsh ..........-.-.-.----
a, superior view; b, side view; ¢, inferior view.
Fig. 2. Tubercular spine of same species..-.-..----..--------------=--
a, Superior view; b, inferior view; c, end view. :
Fig. 3. Caudal plate of Stegosaurus wngulatus .......-.---..-------2+---22--
a, side view; b, end view of base; c, view of opposite side; d, thin mar-
gin; e, rugose base; f, f’, surface marked by vascular grooves.

Fic. 4. Dorsal plate of same animal ....-- rae oesacs Rare E ce ae Pe eae an
. 4, superior surface; }, thick basal margin; c, inferior surface; other let-
ters as in fig. 3.

All the figures are one-twelfth natural size.

342

PL. XUIX

SIXTEENTH ANNUAL REPORT PART I

URVEY

EQLOGICAL S!

us.

STEGOSAURUS UNGULATUS

Jurassic.

a

TILING) 1

343

PLATE L.

JURASSIC DINOSAURS.—PREDENTATA.

STEGOSAURIDE.

Fic. 1. Dorsal spine of Stegosaurus ungulatus Marsh.....----..--.----------
Fic. 2. Large caudal spine of same individual.---.....-....---.----.----.-
a, side view; b, front view; c, section; d, inferior view of base.
Fic.3. Smaller/caudal spinetof same ----- 42-6 2 eee eee tees ero eeeeee
b, posterior view; other letters as above.
Fig. 4. Caudal spine of Stegosaurus sulcatus Marsh; side view--...---------
PG: 5» Lhejsame spine; posterior view-----sos- -hee ea] --= eee ee eee eee
(Pig. (6; Whejsamesinver WOW, meee = eee ee eee
a, anterior; b, base; p, posterior; r, ridge; s, face for adjoining spine.
All the figures are one-twelfth natural size.
344

REE

PART |

OLOGICAL SURVEY

GE

S.

SIXTEENTH ANNUAL REPORT

STEGOSAURUS

Jurassic.

EASE Val

PLATE LI.

JURASSIC DINOSAURS.—PREDENTATA.

STEGOSAURID2.

Caudal vertebr, spines, and plate of Diracodon laticeps Marsh; seen from the

left; one-sixth natural size
a, right anterior spine; a’, left anterior spine; b, small caudal plate; c,
chevron bone; p, right posterior spine; p’, left posterior spine; t, ter-
minal vertebra; v, median caudal vertebra. :
The bones represented are essentially in the position in which they
were found. ;

346

‘oIsseine

ysteW SdadILV1 NOGOOVHIG

Aaauns AWOIDOIOAD ‘Ss “1

PRS ers mE I EEE eens

JEIb 24h; IEJOE

PLATE LIL.

JURASSIC DINOSAURS.—PREDENTATA.

STEGOSAURID&.

Restoration of Stegosaurus ungulatus Marsh
One-thirtieth natural size.

Jurassic, Wyoming.
348

U. S, GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PART! PL. LII

CLM

RESTORATION OF STEGOSAURUS UNGULATUS Marsh,

One-thirtieth natural size, Jurassic, Wyoming,

Jb BU

349

PLATE LIII.

JURASSIC DINOSAURS.—-PREDENTATA.

’
CAMPTOSAURIDA.

Page —

Fic. 1. Skull of Camptosaurus medius Marsh; seen from the left side; one-fourth
natural isizes< 3 seen. sees) clsises oe ee epee ise) eos = es eee eee 197
Fic. 2. The same skull, with brain cast in position; seen from above; one-fourth
MEA EN LIST) eae e pees noe BAe chs ob Ssh Soe aea SeBNOS AanSso Saati Scnbaso scot sSse
a, exterior narial opening; an, angular; bo, basioccipital; d, dentary; f,
frontal; fp, postfrontal; if, infraorbital fossa; j, jugal; 1, lachrymal;

m, maxillary; n, nasal; 0, orbit; pd, predentary; pf, prefrontal; pm, pre-
maxillary; q, quadrate; qj, quadratojugal; s, squamosal; sa, surangular;

sf, supratemporal fossa; so, supraorbital bone.

Fic. 3. Tenth upper tooth of Camptosaurus medius; natural size...--.----- hee
Fic. 4. Fifth lower tooth of same species; natural size ....-...---. .---------
a, outer view; b, posterior end view; c, inner view.

350

U. S. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PARTI PL, LIII

CAMPTOSAURUS MEDIUS Marsh,

Jurassic,

LA er

PLATE LIV.

JURASSIC DINOSAURS.—PREDENTATA,

CAMPTOSAURID.

Fic. 1. Left fore leg of Camptosaurus dispar Marsh; outer view; one-twelfth
Natural! SiZ6: . 2) -- seon cafena seco es nessessecesece seins ce ReRee EE tense ee ee
c, coracoid; h, humerus; r, radius; s, scapula; u, ulna; J, first digit; V,
fifth digit.
Fic. 2. Left hind leg of same species; outer view; one-twelfthk natural size --
a, astragalus; c,caleaneum; f,femur; f’, fibula; il, ilium; is, ischium; p,
pubis; p’, postpubis; ¢, tibia; J, first digit; 7Vmt, fourth metatarsal.

Fig. 3. Posterior sacral vertebre of Camptosaurus dispar; showing peg-and-

notch articulation; top view; one-fourth natural size......--.---------

a, anterior end; p, posterior end.
Fic. 4. Sacral vertebra of same individual; seen from the left; one-sixth nat-
TYAL BIZOL coe sean eee oe ote eee nee ee oes foe ns oie

Fic. 5. The same vertebra; front view; one-sixth natural size ...-...-1-.-- :
a, anterior face for transverse process; b, posterior face.

352

Page.

196

199

197

197
197

. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PARTI PL. LIV

\ dt Ss
CR.
RY

CAMPTOSAURUS DISPAR Marsh.

Jurassic.

TANG oe

16 GEOL, PT 1——23 353

PLATE LV.

JURASSIC DINOSAURS.—PREDENTATA.
CAMPTOSAURID-E AND LAOSAURID.

Fic. 1. Lower tooth of Laosaurus consors Marsh; natural size...-....-.--.--- 199
a, outer view; b, posterior end view; c, inner view.
Fic. 2. Left fore leg of Camptosaurus nanus Marsh; outer view; one-fourth
maturalisize~- sass ee ee ees = reece eee == eee ee eee eee eee eee 196
ce, coracoid; h, humerus; 7, radius; s, scapula; u, ulna; J, first digit; V,
fifth digit.
Fic. 3. Left hind leg of Laosaurus consors; outer view; one-sixth natural size. 199
Fic. 4. The same of Dryosaurus altus Marsh; outer view; one-eighth natural
BIZO is Sarclne Soe icielneinin oe ne lenin ttninaie's se nieni= ee Ree Gee ene eee eee eee 5 e198
a, astragalus; c, caleaneum; f, femur; f, fibula; il, ilium; is, ischium;
p, pubis; p’, postpubis; ¢, tibia; J, first digit; ZV, fourth digit; Vmt,
fourth metatarsal; V, fifth metatarsal.

354 .

U. S. CEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PARTI PL. LV

CAMPTOSAURUS, DRYOSAURUS, AND LAOSAURUS.

Jurassic.

Ieee) IE AV IL

355

PLATE LVI

JURASSIC DINOSAURS.—PREDENTATA.

CAMPTOSAURID&.

Restoration of Camptosaurus dispar Marsh
One-thirtieth natural size.
Jurassic, Wyoming.
356

. §, GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PARTI PL, LVI

Ree
QE 6-@ a
NRE ERR RR ee EE eee

RESTORATION OF CAMPTOSAURUS DISPAR Marsh,
One-thirtleth natural size, Jurassic, Wyoming.

eee ae Sle

PLATE LVII.

JURASSIC DINOSAURS.—PREDENTATA.

LAOSAURID.

Restoration of Laosaurus consors Marsh...-.-...-----.--- Geet ee ee

salt One-tenth natural size. : .
Jurassic, Wyoming.

358

U. S. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PART! PL. LVII

ae
Pris Ln

{

4 \ y On
-
(\\ i

<=
lies
URS
asc
MRS
RRS
SS
aw r SR
/ | Ys
| Mi ~s
EP, IG —<—= Se ——
EG

RESTORATION OF LAOSAURUS CONSORS Marsh,

One-tenth natural sizo, Jurassic, Wyoming,

aie GITET sien alata

359

PLATE LVIII.

CRETACEOUS DINOSAURS.—THEROPODA.

ORNITHOMIMID 2.

Fic. 1. Left tibia of Ornithomimus velow Marsh-..--.-.-.--------25------ --=-2-4-
A, front view; B, distal end; C, transverse section.

Fic. 2. Left metatarsals of same specimen....-..--/--. .--------.----.------
A, front view; B, proximal ends; C, transverse section; D, distal ends.
Fic. 3. Phalanges of second digit of same foot; front view........-.-..-----

A, first phalanx; B, second phalanx; C, third, or terminal, phalanx.
Fic. 4. Left metacarpals of same species, perhaps of smaller individual; front

All four figures are one-third natural size.
Fic. 5. Left tibia of young ostrich (Struthio camelus Linn.)...---.--.-.--------
A, front view; B, distal end.
Fic. 6. Left metatarsals of young turkey (Meleagris gallipavo Linn.) ..-...-----
A, front view; B, proximal ends.
Last two figures are one-half natural size.
a, astragalus; as, ascending process of astragalus; c, caleaneum; /f, fibula;
f', face for fibula; JJ, second metatarsal; //J, third metatarsal; IV,
fourth metatarsal.

360

204

. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. LVIII

ORNITHOMIMUS VELOX Marsh.

Cretaceous.

JE Ibe IDI) SEE

361

PLATE LIX.

CRETACEOUS DINOSAURS,—PREDENTATA.

CERATOPSIDE.

Skull and lower jaw of Triceratops prorsus Marsh; seen from the left side...--.
One-ninth natural size. ce
Cretaceous, Wyoming. : ce ay

362

"sNoaseyald

"YSIEI, SNSYOUd SdOLVYSOINL

AF LUV = LHOdaY IVANNY HLNISLXI9,

AaAuNS TvOIpO10aD

S20

JEib aN e Eo,

363

PLATE LX.

CRETACEOUS DINOSAURS.—PREDENTATA.

CERATOPSID®.

Fic. 1. Skull of Sterrholophus flabellatus Marsh; seen from the left side... . ----
a, nasal opening; b, orbit; c, supratemporal fossa; e, epoccipital bone; h,
horn core; h’, nasal horn core; p, predentary ; q, quadrate; 7, rostral bone.
EG. 2; Thesame skull’) seem from behind ps-es eee eee eee eee eee
d, dentary; e, epoccipital; h, horn core; p, parietal; pd, predentary; q,
quadrate; s, squamosal.
Fic. 3. Skull of Triceratops serratus Marsh; diagram; seen from above. ..----
c, supratemporal fossa; d, epijugal bone; e, epoccipital; f, frontal; fp,
postfrontal; hf, horn core; h’, nasal horn core; j, jugal; m, maxillary;
n, nasal; p, parietal; pf, prefrontal; pm, premaxillary; 7, rostral bone;
8, Squamosal; x, pineal foramen (?).
Fic. 4. Skull of Triceratops prorsus Marsh; seen from behind. ..-.---.--------
Letters as in fig. 2.
All the figures are one-twentieth natural size.

364

208

GEOLOGICAL SURVEY

sS.

U.

SIXTEENTH ANNUAL REPORT PARTI PL. LX

STERRHOLOPHUS AND TRICERATOPS.

Cretaceous

led boav Id, Joe

PLATE LX?

CRETACEOUS DINOSAURS.—PREDENTATA,

CERATOPSIDA.

Fic. 1. Anterior part of skull of Triceratops prorsus Marsh; side view
IGS 2a MroOntiview Ol SAM see eae an eet esata nee sae eee eee
Fic.3. The same; seen from below

hl’, nasal horn core; nx, nasal; na, narial aperture; pm, premaxillary; r,

rostral bone. me
Fic. 4. Predentary bone of same individual; side view
BIG) oo Lop view Of same sSpeClMen ees eee se setae ae ee eer
ENYGAG = Bottomyie waO fis ke oe tee ee tee ela te
«, anterior end; b, upper border; d, groove for dentary; s, symphysis.
All the above figures are one-eighth natural size.
Fic. 7. Cast of brain cavity of Triceratops serratus Marsh; side view; one-half
HEH ALENT VA2 emo smc Smonnrinn ano anes See say aan one MRS ROS SD Ate o cote ca Smsecene
c, cerebral hemispheres; cb, cerebellum; m, medulla; ol, olfactory lobe; on,
optic nerve; p, pituitary body; J, fifth nerve: X, XJ, tenth and elev
enth nerves; \JJ, twelfth nerve.
Fic.8. Skullof Triceratops prorsus; seen from in front; one-twentieth natural

, dentary; e, epoceipital; h, horn core; h’, nasal horn core; p, parietal;
pd, predentary ; q, quadrate.
Fic. 9. Maxillary tooth of Triceratops serratus; side view; natural size...---.-
Fic.10. The same tooth; inner view; natural size.._.-...-.--..----.-..-----
366

Page.
209
209
209

211
211
211

211

TRICERATOPS.

i
‘ies t

, ad
‘Sua ia he

iPlbpea ed I becee

Pi
‘

a PLATE, LXIT.

CRETACEOUS DINOSAURS.—PREDENTATA.

_ CERATOPSID®.

Fic..1. Skull of Torosaurus latus Marsh; seen from above...........---------

Fic. 2. Posterior crest of Torosaurus qgladius Marsh; seen from above....------. _
c, supratemporal fossa; c’, anterior temporal foramen; f, parietal fonta-

nelle; h, horn core; h’, nasal horn core; p, parietal; s, squamosal. rae

Both figures are one-twentieth natural size. :

368

*SNOOIB}O1D

SNYNVSOYOL

WRT "Id | LaWe

AQAUNS WOODED "8 A

IPibye dha IEE,

16 GEOL, pT 1——24

369

PLATE LXIII.

CRETACEOUS DINOSAURS.—PREDENTATA.

CERATOPSIDA.

Fic. 1. Horn core of Ceratops montanus Marsh; side view......-.---.--------- 2
Fic. 2. Horn cores of same skull; front view...--....-...--- ---------------
a, right horn core; c, left horn core.
Fic. 3. Basioceipitallofesame skulle =e -opeseee (eee eee eee eee
a, side view; b, posterior view. .
All three figures are one-fourth natural size.
Fic. 4. Right squamosal of Torosaurus gladius Marsh; inner view ...-...-.---
Tic. 5. The same of Sterrholophus flabellatus Marsh.....---..-------------
Fic.6: The'sameiof Geratops montants-------22-- 22 sass os eee eee Eee
Last three figures are one-twentieth natural size. ati
e, epoccipital; g, groove for quadrate; s’, suture for parietal.

370

*

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. LXiil

CERATOPS, STERRHOLOPHUS, AND TOROSAURUS.

Cretaceous.

IPIL ACTIN, JES"

PLATE LXIV.

CRETACEOUS DINOSAURS.—PREDENTATA.
CERATOPSID®.

Fic. 1, Anterior cervical vertebre of Triceratops prorsus Marsh; side view. --
Fic. 2. Fourth cervical vertebra of same series; back view.......-..---.----
a, anterior face of atlas; d, diapophysis; n, neural canal; p, posterior face

of fourth vertebra; r,rib; 8,neural spine of axis; s‘, neural spine of
third vertebra; s’’, neuralspine of fourth vertebra; 2‘, posterior zygapo-

physis.
Fic. 3. Anterior dorsal vertebra of same species; side view .-.---...---.----
Fic. 4. Thesame vertebra; frontiview- 2-2-2. 2-5 === eee aie eee eine
Fic. 5. First caudal vertebra of Triceratops prorsus; side view..----.--------
Fic. 6) 'Theisame vertebra: front views. --020 22s ce ees ce eee eee
Fig. 7: Thesame;: back view: --22....2..-.s5scc0 sss =o os soe eee oes eee
Fic. 8. Median caudal of same species; side view.-....----.--..------------
Fig. 9. The same vertebra; frontiview == --2es-.- = ee a eee eee
Fig. 10: The:sames back-view=.22--.s2s-cs2 + a-s6-em-- 245s oo eee eee eee
Fic. 11. Distal caudal of same species; side view .----.----------------------
Fic. 12. More distal caudal of same species; side view.---.-.-----.-----.----

a, anterior face of centrum; c, face for chevron; h, facet for head of rib; n,
neuralcanal; p, posterior face of centrum; r, rib; s, neural spine; t, facet
for tubercle of rib; z, anterior zygapophysis; 2’, posterior zygapophysis.

All the figures are one-eighth natural size.

372

Page.
212

212

212
212
212
212
212
212
212
212
212
212

SIXTEENTH ANNUAL REPORT

PART |

PL. LXiv

TRICERATOPS PRORSUS

Cretaceous,

JeAbveNIEI, ILO

PLATE LXV.

CRETACEOUS DINOSAURS.—PREDENTATA.

CERATOPSIDA. :
7 Page.
Sacrum of Triceratops prorsus Marsh; seen from below; one-eighth natural size. 212
a, anterior face of first sacral vertebra; p, posterior face of last sacral ver-
tebra; s, neural spine of last vertebra; z, anterior zygapophysis of first
vertebra; J-10, transverse processes, left side. 1

374

U. S. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PART 1 PL. LXV

TRICERATOPS PRORSUS.

Cretaceous.

JP live eh 1px

PLATE LXVI.

y CRETACEOUS DINOSAURS.—PREDENTATA,
CERATOPSIDA.

Fic. 1. Right scapula and coracoid of Triceratops prorsus Marsh; side view...
Fic. 2. Right humerus of same species; front view ...-..-.--------.----.----
Fic. 3. Left ulna of same individual; front view ...-....-.-..---------------
cr, coracoid, g, glenoid fossa; h, head; 0, olecranon process; 1, radial crest;

7’, face for radius; s, suture; sc, scapula.

All the figures are one-eighth natural size.

376

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. LXVI

TRICERATOPS PRORSUS.

Cretaceous.

JP IAIN, JODO W IDL

377

PLATE LXVII.

: CRETACEOUS DINOSAURS.—PREDENTATA.

CERATOPSID&.

Fic. 1, Pelvis of Sterrholophus flabellatus Marsh; side view; one- twelfth natu-
Talisize ce ses) eee ore ceeereee adeeeac Be scee

a, acetabulum; il, ilium; is, ischium; p, pubis.

Fic. 2. Pubis of Triceratops prorsus Marsh; inside view; one-eighth natural

CO RSS Se eR REE SS oER pee Se cos aa aa oaas Haodne shms qdastaheescoseesnocstase
Fic. 3. The same pubis; showing postpubic process; inferior view.-.-...----
Hie.4. The same;soutside View =.= a2 on ene ein ele ile lsioe ieee ete ee

a, proximal end; 6, face for ilinm; ec, postpubic process; d, distal end.
378

U. S$. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT

PART |

PL. LX¥VII

|
|

STERRHOLOPHUS AND TRICERATOPS.

Cretaceous.

Jive Ia) Ibo WOOL,

379

PLATE LXVIII.

CRETACEOUS DINOSAURS.—PREDENTATA.
CERATOPSIDE.

Fic. 1. Left femur of Triceratops prorsus Marsh; front view.--....-----------
Fic. 2. Left tibia of same species; front view .....-.--....---.--------------
Fic. 3. The same tibia; distal end; back view....-.-.....-_-.-.-------------
a, astragalus; c, inner condyle; ec’, cnemial crest; f, face for fibula; h,
head; t, great trochanter.

All the figures are one-eighth natural size.

380

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. LXVIII

TRICERATOPS PRORSUS.

Cretaceous,

Jedbve eh IOI,

381

PLATE LXIX..

CRETACEOUS DINOSAURS.—PREDENTATA.
CERATOPSID..

Fic. 1. Metacarpal of Triceratops prorsus Marsh; front view; one-eighth natu-

TAN WA) qoecenoStaks seat see5 MODs cose detec seeeseds acetace cscs deeebosocots
Bic. -2:, The: same bone; sidbiview- --:% = ------05 2s ees sees coer eee nees
Hig: 3, Tle.same; backiviewJsea> cress. ere tee a eee Renee eee
Fic. 4. Terminal phalanx of manus of Sterrholophus flabellatus Marsh; front

view;, one-fourth natural size ......--..-----.---------------- aodmee iene
HIG? 75.) vhesameyphal ans: yS10 6) yA 0 yj ce sematte = oleee le cn ie eae ees
BiG! 165 Theisames backwiew cee. a-- neonates eee e ae eee eee eeeaes
Fic. 7. Metatarsal of Triceratops prorsus; inner view; one-eighth natural size.
Fic: (8: The:same bones drontiview 22 os=-)-9 = ee eee ene eieeen eee eee
Hie. .9) Theisame ssouternview.--\s-- 5 sos ee eee eats ea ee ep eee eet
Fic. 10, Ungual phalanx of Triceratops horridus Marsh; front view; one-

fourth naturalisize--2- osc -=--5 == ee SRSA aS AARP ERAS SSS Aaebed qeecte
PiGil) Lhe same phalanx: sid ewie wise sate oat meee el Storrs
Fig: 12. The sames; posterior View-c. =. =e = se naar ee eee eee

382

U. S. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PARTI PL. LXIX

STERRHOLOPHUS AND TRICERATOPS.

Cretaceous.

JPG NIE, IUOXOXS

383

PLATE LXX.

CRETACEOUS DINOSAURS.—PREDENTATA. —

CERATOPSIDE.
Page. ;
Fic. 1. Dermal spine of Triceratops Marsh; side view.--.---- S580 00n5c0n0 214
Fic!) 2) Dhe}sanieispines | trontivle wi ss = ane = eet ee ae eee eee » 214
Fig: 3) Cheisamesstopiview---- m6. er a leer ee ese eee eee eee 214
Fig. 4. Dermal plate of Triceratops; top wiew.--.----.-------------.--------- 214
Fic. 5.) The/same plate; bottomiyiewe sess -ess 2 - ee ee eee eee eee 214
Fig..6.; Thesames' sideview -2 2-22 ...25 eect ee eros - oreo ce eee ee nee 214
RIG: 7. Lhe same; end WieWees= aloes asec eee ee ae re seen eee eee 214
Fig. 8. Dermal plate of Triceratops; top view ---.--.------------------------- 214
Fic. 19) Thejsame plate; side view ----5--1-2+----2 ---2o- 2 > oeeeee eee eee 214
Eig: 10) The'same;) bottomiview ---2-2-s-ss-~ => ole ene oe eee 214

All the above figures are one-eighth natural size.
Fic. 11. Dermal ossification of Triceratops; side view; one-half natural size.. 214
Fig..12. The same; front view, -<-.<-22--25 ---se- neem s-seeneeeeeoeesee saneme 214

384

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. LXX

TRICERATOPS.

Cretaceous.

Jejbve IU) JEON IE,

16 GEOL, PT 1 25

PLATE LXXI.

CRETACEOUS DINOSAURS.—PREDENTATA,

CERATOPSIDE. ~

Restoration of Triceratops prorsus Marsh......-..--..-----------------+-+---+
One-fortieth natural size.
Cretaceous, \Vyoming.

386

U, 6. GEOLOGICAL BUTVEY BIXTRENTH ANNUAL REPORT PART 1 PL. LXXt

RESTORATION OF TRICERATOPS PRORSUS Marah

Ono-fortloth natural ulze, Cretaceous, Wyoming,

iri Cpadh os bo O.GEE

PLATE. LXXIL.
SRETACEOUS DINOSAURS.—PREDENTATA.

— CLAOSAURID.E.

Fic. 1. Skull of Claosaurus annectens Marsh; seen from the left... ....-...----
Wres2. Mhesame) sin) lstront wenn aseee ae ee eee eae ao ccsosos>

Hic. 3: Theisame!skulll; seen’ fromiaboves----2 a2 eee eee eee
All the figures are one-tenth natural size.

388 ' aol

S. GEOLOGICAL SURVEY

SIXTEENTH ANNUAL REPORT PARTI PL. LXXIl

CLAOSAURUS ANNECTENS Marsh.

Cretaceous.

IAIN TE OSCE.

389

PLATE LXXIII.

CRETACEOUS DINOSAURS.—PREDENTATA.

CLAOSAURIDE.

Fic. 1. Left fore leg of Claosaurus annectens Marsh; outer view; one-twenticth
UapuraliBlZes. <5 «state Seen se haces See eee ee aoe eee es ee ere ees
ce, coracoid; h, humerus; 7, radius; s, scapula; u, ulna; J, first digit;
IV, fourth digit. ;
Fic. 2. Left hind leg of same individual; outer view; one-twentieth nat-
ural SiZ@: = 2.222252 secces scece cosesswsconte so oeneescion cs nee eee eee ere
a, astragalus; ¢c, caleaneum; f, femur; f, fibula; il, ilium; is, ischium;
: Pp, pubis; p', postpubis; ¢, tibia; 7/7, second digit; IV, fourth digit.
Fic. 3. Pelvis of the same individual; seen from the left; one-sixteenth nat-
Ural S126 \ ao6 2 soos ac Seine ceases ae eee eee ae ee eee oS eee eee eee
a, acetabulum; other letters as in fig. 2.

390

SIXTEENTH ANNUAL REPORT PARTI PL. LXxill

CLAOSAURUS ANNECTENS.

Cretaceous,

leita ND IED

391

PLATE DX

CRETACEOUS DINOSAURS.—PREDENTATA.

CLAOSAURIDE.

Restoration of Claosaurus annectens Marsh ......----..--------- po oaasoesasces
One-fortieth natural size.
Cretaceous, Wyoming.

392

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. LXXIV

RESTORATION OF CLAOSAURUS ANNECTENS Marsh,

One-fortioth natural size. Crotacoous, Wyoming,

Jeb LOW,

PLATE LAX,

CRETACEOUS DINOSAURS.—PREDENTATA.

Fic. 1. Portion of right dentary bone of Trachodon breviceps Marsh; inside
Views one-1ourth natural siz sse = seas e eee =e ieee eae ee eee eee
Hic. 2. “Dhe'same; seen’ fromlaboves- ---- s-ce- eae eee eee eee
a, anterior end; b, posterior end. i
Fic. 3. Tooth of Paleoscineus latus Marsh; a, natural size; b, ¢c, d, twice natu-
TASIZ0 ees eens ee ee eens SE CEES SS Eee ee
b, outer view; c, end view; d, inner view.
Fic. 4. Left sternal bone of Claosaurus annectens Marsh; one-eighth natu-
TAS ZO) eee sees Ee ens s tend aeou ope asaacahoscacned
a, seen from above; b, seen from below.
Fic. 5. Dermal ossicles of Nodosaurus textilis Marsh; natural size...........--

394

SIXTEENTH ANNUAL REPORT PARTI PL. LXXV

U. S. GEOLOGICAL SURVEY

CLAOSAURUS, TRACHODON, NODOSAURUS, AND PALAZOSCINCUS.

Cretaceous.

JP ve, IESXOXOW IL

PLATE LXXVI.

DINOSAURIAN SKULLS; SHOWING SIZE OF BRAIN.

Fic. 1. Skull and brain cast of Sterrholophus flabellatus Marsh; seen from
abovesone-bwentieth natural Sizesee se se- eae eaiee eeeeee eeeeee
c, supratemporal fossa; d, epijugal bone; e, epoccipital bone; f, brain
east; h, horn core; hk’, nasal horn core; n, nasal bone; p, parietal; r,
rostral bone; 8, squamosal.
Fic. 2. The same of Claosaurus annectens Marsh; one-tenth natural size... ---
a, nasal opening; ), orbit; c, infratemporal fossa; d, dentary; e, exoccip-
ital; f, frontal; fp, postfrontal; j, jugal; 7, lachrymal; m, maxillary;
n, nasal; pf, prefrontal; pm, premaxillary; q, quadrate; qj, quadra-
tojugal; s, squamosal.
Fic. 3. The same of Camptosaurus medius Marsh; one-fourth natural size ..-..
a, nasal opening; bo, basioccipital; f, frontal; fp, postfrontal; if, infra-
temporal fossa; j,jugal; 1, lachrymal; n, nasal; 0, orbit; pf, prefrontal;
pm, premaxillary; g, quadrate; qj, quadratojugal; s, squamosal; sf,
supratemporal fossa; so, supraorbital bone.
Fic. 4. The same of Diplodocus longus Marsh; one-sixth natural size......----
a, aperture in maxillary; #, antorbital opening; c, nasal opening; c’,
cerebral hemispheres; d, orbit; e, lower temporal fossa; f, frontal bone;
f, fontanelle; m, maxillary bone; m’, medulla; n, nasal bone; oc,
occipital condyle; ol, olfactory lobes; op, optic lobe; p, parietal bone;
pf, prefrontal bone; pm, premaxillary bone; q, quadrate; qj, quadra-
tojugal bone.
396

Page.

211

222

227

178

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. LXXVI

SKULLS OF DINOSAURS, SHOWING SIZE OF BRAIN. CAMPTOSAURUS, CLAOSAURUS, DIPLODOCUS, AND STERRHOLOPHUS.

Jediva die), JUD 2OW AGE

PLATE. LXXVII.

BRAIN CASTS OF DINOSAURS.

Tic. 1. Brain cast of Stegosaurus ungulatus Marsh; side view; one-fourth nat-
UES eatin eens oA REE AMS SSA BSAA Baa SEB a aSc INNES Soto eee Led cone
Fic. 2. Brain cast of Ceratosaurus nasicorris Marsh; side view; one-fourth
natural size; 3455268 oe ance ee ee eee ee ee Cee oe ROG: ee Sees
Fic. 3. The same of Claosaurus anneciens Marsh; side view; one-fourth nat-
nal BiZOr eh ces Sco A Soe eee ee ne ee
Fic. 4. The same of Triceratops serratus Marsh; side view; one-half natural
RIZE) 52. os siaee noe ie Seabees sp See ae Oc Sette See eEE Re ERE aera one
Fic. 5. Brain east of young PUB ENS for comparison; top view; three-
fourths natural size. -2).2 222.5225 s2aosisons elses .c se sjemssrs ete eee se Sepreeraee
c, cerebral hemispheres; ch, cerebellum; m, medulla ol, olfactory lobe;

on, optic nerve; op, optic lobe; p, jetties body; J, fifth nerve;

A, \J, tenth and eleventh nerves; YJ/, twelfth nerve.

398

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. LXXVII

BRAIN CASTS OF DINOSAURS. CERATOSAURUS, CLAOSAURUS, STEGOSAURUS, TRICERATOPS, AND RECENT ALLIGATOR.

IPG AN SD) ILA OOV IEL.

399

,

PLATE LXXVIIL

TEETH OF PREDENTATE DINOSAURS.

Fig. 1. Upper tooth of Camptosaurus medius Marsh; natural SiZ@ ...-.-.------

a, outer view; b, posterior end view; c, inner view.
Fic. 2. Series of five lower teeth of Claosaurus annectens Marsh; one-half nat-
ULAlSIZ6 wee eas 22 sone caret eseeenee Seeeee Slaves ats cece ee eRe eeeeeceees
a, inner view; b, side view; ¢, outer view.
Fic. 8. Tooth of Stegosaurus ungulatus Marsh; a, natural size; b, c, d, twice
natural 8126 %.2.5 -S.sn.\essS se seecw ceric Saco Seles nie Sou estes e Eee eee eee
b, outer view; c, side view; d, seen from above.
Fic. 4. Maxillary tooth of Triceratops serratus Marsh; natural size ..-...-----
a, outer view; b, end view; ¢, inner view, d, seen from below.

400

SIXTEENTH ANNUAL REPORT PART! PL. LXxviil

U. S. GEOLOGICAL SURVEY

STEGOSAURUS, AND TRiCERATOPS,

DINOSAURS, CAMPTOSAURUS, CLAOSAURUS,

=

TEETH OF PREDENTAT

JP LAID eh TEX OXI.

16 GEOL, PT 1——26

PLATE DXXIX:

PUBIC BONES OF PREDENTATE DINOSAURS.

F Page.

Fic. 1. Left pubis of Laosaurus consors Marsh; outer view; one-fourth natural
VES SaGc6q sean aosa atoo aser Shes oad chao cadmetscnadaaotdecsocs St PEE ASSoeeSOS 228
Fic. 2. The same bone of Dryosaurus altus Marsh; one-eighth natural size.... 228

Fic. 3. The same of Camptosaurus dispar Marsh; one-twelfth natural size 228
Fic. 4. The same of Triceratops prorsus Marsh; one-twentieth natural size-... 228
Fic. 5. The same of Claosaurus annectens Marsh; one-sixteenth natural size... 228
Fic. 6. The same of Stegosaurus ungulatus Marsh; one-twelfth natural size.... 228
p, prepubis; p’, postpubis. ;

402 :

vu.

S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PART! PL. LXXIX

7

PUBES OF PREDENTATE DINOSAURS. CAMPTOSAURUS, CLAOSAURUS, DRYOSAURUS, LAOSAURUS, STEGOSAURUS, AND
TRICERATOPS.

Hagler AE OXOXE

. 403

PLATE LXXX.

IscHIA OF PREDENTATE DINOSAURS.

Fic. 1. Ischia of Camptosaurus medius Marsh; superior view; one-eighth nat-
LEN) 01 eee eA oars SO OR AHN Gam ornan Goomoaas mode hoasedeas coacitossaaacce
la, distal ends of same. :
Fic. 2. The same bones of Dryosaurus altus Marsh; superior view; one-fifth
natural sizes. << 2252 ceo. cast cee t cee eases ees nein Sees se Se Eee ee eee
Fic. 3. The same of Claosaurus annectens Marsh; inferior view; one-sixteenth
natural 8120-52 =\-5.02.c5c8 oo> seees te seie cee esooeos occ e eee oe eee nee

Fig. 5. The same bones of Stegosaurus ungulatus Marsh; superior view; one-
tenth natural size. 2.0 1222-32258 ko ce Laren Bee eee ee ee ee eee
5a, distal ends. :

il, face for ilium; pb, face for pubis.

404

U. S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PART 1 PL, LXXX
=

ISCHIA OF PREDENTATE DINOSAURS, CAMPTOSAURUS, CLAOSAURUS, DRYOSAURUS, STEGOSAURUS, AND TRICERATOPS.

IEILASMS, IBXOxOMIL

NIMS LOOSE,

PELVES OF PREDENTATE DINOSAURS.

Fic. 1. Pelvis of Camptosaurus dispar Marsh; seen from the left; one-twelfth
AES ass oreo cee beno Jeon ons dace GSsacnpscd sseenacg Be seastccascs
Fic. 2. Pelvis of Sterrholophus flabellatus Marsh; seen from the left; one-
thy Cbs NEAR EN LSU Ae seo osg oneoeSeS ae aoSo Se Saaens csc So SoasebSseconges eo osan
Fia. 3. The same of Stegosaurus stenops Marsh; seen from the left; one-tenth
natural size.......--- D cjsieccis = cis Saieletieleieieis ea eG ete EEE CS oE eee Seater
a, acetabulum; il, lium; is, ischium; p, pubis; p’, postpubis.

406

vu.

GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PART\ PL. LXXXI

|
|
|
|

ci,
qm
[iN

PELVES OF PREDENTATE DINOSAURS. CAMPTOSAURUS, STEGOSAURUS, AND STERRHOLOPHUS

JP JbVINIE) Ibo OO,

407

PLATE LXXXII.

EUROPEAN DINCSAURS.—THEROPODA.

COMPSOGNATHID&.

Outline restoration of the skeleton of Compsognathus longipes Wagner
One-fourth natural size.
Jurassic, Bavaria.

408

U. &. GEOLOGICAL SURVEY ' SIXTEENTH ANNUAL REPORT PART | PL. LXXxXII

RESTORATION OF COMPSOGNATHUS LONGIPES Wagner.

Ono-fourth natural size, Jurassic, Bavaria,

JP LST, JLAxOx OS IDOL,

409

‘

PLATE LXXXIII.

EUROPEAN DINOSAURS.—PREDENTATA.

SCELIDOSAURID&.

Outline restoration of the skeleton of Scelidosaurus Harrisonit Owen .-.-------
One-eighteenth natural size.
Jurassic, England.

410

U.S. GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL.

i
(y

SS

RESTORATION OF SCELIDOSAURUS HARRISONI! Owen,

One-olghteenth natural size, Jurassic, England,

TAGE eOXOGIING:

PLATE LXXXIV.

EUROPEAN DINOSAURS.— PREDENTATA.

HYPSILOPHODONTID#.

Outline restoration of the skeleton of Hypsilophodon Foxii Huxley
One-eighth natural size.
Wealden, England.

412

U. S, GEOLOGICAL SURVEY SIXTEENTH ANNUAL REPORT PARTI PL. LXXXIV

RESTORATION OF HYPSILOPHODON FOXII Huxley.
Ono-olghth natural size. Wealden, England,

PALMA, WOOO

413

PLATE LXXXV.

EUROPEAN DINOSAURS.—PREDENTATA.

IGUANODONTIDA,

Outline restoration of the skeleton of Iguanodon Bernissartensis Boulenger--..

One-fortieth natural size.
Wealden, Belgium.

414

RESTORATION OF IGUANODON BERNISSARTENSIS Boulenger.

One-fortioth natural sizo, Wealden, Belgium,

SMITHSONIAN INSTITUTION LIBRARIES

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