p. 267-274, [3] leaves of plates : ill. ; 24 cm.Includes bibliographical references

Brown, Barnum.

Hyde Exploring Expedition.

Pepper, George H. (George Hubbard), 1873-1924.

American Museum of Natural History Scientific Publications

56.81.K(117:78.9)Article XXIV.- THE CRETACEOUS OJO ALAMO BEDS OF NEWMEXICO WITH DESCRIPTION OF THE NEW DINOSAURGENUS KRITOSA URUS.BY BARNUM BROWN.PLATES XXVII-XXIX.A new locality for dinosaurs near Ojo Alamo, in northern New Mexico,was reported to the American Museum by Mr. George H. Pepper, of theHyde Exploring Expedition in 1902.The bones submitted at that time were indeterminate but were said to beso numerous that it was thought advisable to investigate the locality. Ac-cordingly, in 1904, the writer was detailed to that region for a preliminaryreconnaissance, during which a small but interesting collection of fossils wassecured.This collection is of especial interest, as it represents a fauna that isdistinctly older than that of the "Lance Creek Beds or Ceratops Zone"and "Hell Creek beds" o? the Laramie Cretaceous. I am unable to defi-nitely correlate the horizon in which these bones occur but the faunal faciesappears to be even older than that of Black Buttes, Wyoming, and probablyrepresents a period synchronous with the lower part of the Edmonton seriesof Alberta, Canada. The lower Edmonton series has previously been con-sidered equivalant to the Laramie butt its fauna, as determined by the writer,is intermediate in age b3tween the Judith R&ver and the Laramie.Ojo Alamo is an Indian trading post in Chaco Caion, about ninety-fivemiles northwest of Gallup, New Mexico, and twenty miles west of the oldIndian pueblo, Bonito, now known as Putnam. It is situated in the easternedge of the bad land exposures that extend west and south to the ChacoCahion. On the east and north these bad lands flank a mesa that is dissectedon the east by Coal Creek. The escarpments near the head of Coal Creekhave furnished a large part of the lower Puerco or basal Eocene fossils of thesouthwest and may be considered Cope's typical Puerco of 1874. Theknown fossil-bearing Puerco from which many of Cope's types were obtained,was traced by the writer southwest from Coal Creek and identified with theunfossiliferous bad lands at the head of Ojo Alamo Creek where the strataare weathered into a great amphitheater of open terraces. A careful searchthrough these upper clays failed to reveal either vertebrate or invertebrate267Bulletin American Museum of Natural History. [Vol. XXVIII,remains, not even fragments. Near their base sandstones predominate andare characterized by quantities of petrified wood with large logs often form-ing the cap-rock of isolated clay monuments.Less than a mile south of the store at Ojo Alamo the Puerco formationrests unconformably on a conglomerate that is composed of red, gray, yellow,and white pebbles. The position of these beds below what may be calledthe type of the Puerco or basal Eocene and their unconformable relation ishighly significant. The writer is fully aware that the conditions found here,as indicated by the fauna, are not strictly comparable to those of the northernStates, where the Fort Union conformably overlies beds now consideredLaramie, but it is a point of contact between the uppermost Mesozoic and thelowermost Tertiary and marks the termination of the principal Mesozoiclife, the dinosaurs, before the beginning of the Eocene in which no dinosaurshave as yet been found.Below the conglomerate there is a series of shales and sandstones evenlystratified and usually horizontal, in which there is much less cross-beddingthan commonly occurs in the Laramie formation of the northern UnitedStates.The shales below the conglomerate that contain numerous dinosaurand turtle remains I shall designate as the Ojo Alamo Beds. They wereestimated to be about 200 feet thick, but owing to lack of time I was unableto determine their relation to the underlying formations.The vertebrate remains were numerous in several places from thirty toone hundred feet below the conglomerate. They consisted chiefly of limbbones, usually lacking the ends, isolated vertebrae and a few skull fragments.Most of this material was chalcedonized, a condition common in the JudithRiver but never observed in the Laramie. Carnivorous dinosaurs werefar more numerous than in the Laramie of the northern United States. Thefamily Trachodontidee is also well represented, but only a few fragments ofceratopsian reinains were found.The ceratopsian fragments were small sections oF characteristic squa-mosal bones, not collected, and part of a supraorbital horn, No. 5798 of theAmerican Museum collection. Both ends of this specimen are broken butvery little is gone from the upper end. It is 120 mm. long, 180 mm. incircumference at the base, and 90 mm. in circumference at the upper end;subovate in cross-section and strongly decurved near the upper end, havinga greater curve on the convex than on the concave surface. It is muchsmaller and lacks the vascular grooves that characterize the horns of thegenus Triceratops and, judging by the form and size, approaches nearestMonoclonius recurvicornis of the Judith River formation from which, how-ever, it is distinct. M. recurvicornis is proportionately shorter and more268Brown, The Ojo Alamo Beds of New Mexico.robust. The squamosal fragments of another inidividual observed in thefield were much thinner than that bone in the genus Triceratops but similarlymarked by deep vascular grooves. The horn and other skull fragmentswere apparently from a mature animal representing a ceratopsian genussmaller than either Triceratops or Torosaurts, but the remains are toofragmentary for characteriza ion.Little can be said of the carnvorous dinosaurs.The remains were numerous; chiefly disassociated /limb bones, lacking articular ends but character- /ized by hollow shafts, and vertebrae representinga dinosaur as large as A.bertosaurus of the lowerEdmonton series. The single tooth preserved inthe collection is not diagnostic.In the Cope collection obtained from thisregion, there are several carnivorous dinosaur /iteeth and a few separate upper teeth of a largeTrachodont dinosaur. As these lower Puercofossils were collected largely from the Coal Creeklocality the dinosaur teeth probably came from theOjo Alamo beds.Turtle bones were frequently found with thoseFig. 1. Ceratopsian horn,of dinosaurs. They were especially numerous No 5798 A. M. N. H X Ljust be'ow the conglomerate. A new species,Thescelus repiens Hay, No. 6066, American Museum collection, is foundedon the greater part of a carapace closely related to T. insiliens Hay, fromthe Lance Creek beds of Converse County, Wyoming. The genus is nearlyrelated to the Baenidae.The most important fossil from this locality is a skull, lower jaws, andatlas, of a hitherto undescribed genus of the family Trachodontidae:Kritosaurus navajovius gen. et sp. nov.Type of species No. 5799, American Museum collection.Generic characters. Skull deep; muzzle narrow; frontals short, orbital portionreduced, barely coming to the border of the orbit; nasals and premaxillaries verylong, quadrate elongate; quadrato-jugal short antero-posteriorly, completely sepa-rating quadrate and quadrato-jugal. Mandibular rami massive; edentulous portiondecurved. Teeth spatulate in lower jaw.Specific characters. Maxillary teeth smooth on borders. Mandibular teethpapillate on borders, median carina low, predentary deep and massive. Free elenti-lous portion of dentary not coverel by predentary, short.The skull is that of an old individual and most of the sutures are obliter-1910.] 269Bulletin American Museum of Natural History. [Vol. XXVIII,ated by exfoliation. When found it was almost completely weathered outand the anterior end was in a very fragmentary condition. It was impossibleto place many of these fragments in the restoration and where there was nocontact the bones were left out. The dentary and predentary, were perfectlypreserved, thus determ:ning the length of the skull. The nasals wererestored after the skull of Trachodon (Diclonius) Cope and the premaxil-laries according to the relative size between the predentary and premaxillarvin that species which necessarily made the rostrum much deeper.SKULL.The skull is very deep and more massive than in any heretofore describedspecies of the family and its elements in general follow the Trachodon form,but with the following distinct modifications.Premaxillaries and rostrum proportionately shorter than in Trachodon(Diclonius) mirabilis or Claosaurus annectens Marsh. Frontal short antero-posteriorly, prefrontal and postfrontal almost excluding it from the borderof the orbit. Paroccipital process of exoccipital actually and relativelylonger than in Trachodon. Orbital opening proportionately smaller andlaterotemporal fenestra proportionately larger than in Trachodon. Quadrateand jugal completely separated by quadrato-jugal, the exposed part of whichis short antero-posteriorly and vertically high. Ectopterygoid extendingforward to the union of the maxillary and the jugal.LOWER JAW.The lower jaw in form reseinbles more closely Judith River than Laramiespecies. Its edentulous portion not covered by predentary is shorter thanin any Laramie form.Predentary. The two predentaries are firmly coossified forming a singleelement but clearly show their union in the median line. Its lateral bordersare massive and nearly vertical, forming a powerful clipping instrument,whereas in all Laramie forms they are delicate and conform to the shape ofthe rostral bones. The anterior upper border is very rugose and is perfor-ated by two parallel series of vascular foramina, resembling alveoli but whichpass obliquely downward and open on the outer surface. Each arm of then terminates in a short rounded inner and a longer outer process. On theposterior lower border in the center there are two processes, an inner short,free, tongue-like process which separates the upper anterior ends of thedentaries and a longer, wider process which underlies the symphysis. Thelatter process is broken near its origin and shows no indication of bifurcation.270Fa:wi,K2Iu'.2vFig 3XFig. 2. 'Left quadrato-jugal of Krito8aurus navajoviu. XiFig. 3. Left quadrate of Kritosaurus navajovius, type. Rear view. X i.)Il 4.4.Fig. 5.Fig. 4. Predentary of Kritosaurus navajovius, type. Top view. Abo-it i nat. size.Fig. 5. Predentary of Kritosaurus navajovius, type. Side view. About j nat. size.BULLETIN A. M. N. H. VOL. XXVIII, PLATE XXVII.r -- --:, -' ':: -: ' ., . . ' .- .. ' . ,- - .-- - . - . ....... E - e . .: : , :. . , -" ' - ' ' ' ' - '' -25 ' ' ', ' , i i ''::: - " =, ' ' ';": ' ', ' ' , ' i :, -: ,:':_' ,' ' ,';,'' i':Z - , . :: . .... : .' ':: - .'. : .' ' .' ' ' :. .' ':. ' .' ':: .:: .: .' ' :: ' ' . ': ': : . ' : . : . ' '. .- . . - . - -- f - - . -- - .: - .: -: . .- - .- - . .- - - .- - . - E : : - - - - . . . : -':. ".', S 'SA_,_' :'<< '-; .',' ',: ', ir : < l + - f - ' ' ' ' ' k - ' - v; - i. . . - - | . . rif < K R -- - i - .; -. t-0k<< < djEv ; 000E CC f;Z nCS ff < SS-< -''XHt; X <_ . . - - - - - . . . , - - - - . _ - ,- - . . - i-- - - - E <- _ _ . r ' f . . . !;Cretaceous, near Ojo Alamo, New Mexico..-4X,X,wH4P-4xx.-i0.zi.gzE-4w"I40pqN00r12~40xpq0-*-4.430"*e*~0000..IQR0C)00.C.0)I "OD1*;H:zr-iBrown, The Ojo Alamo Beds of New Mexico.Dentary. This element is very massive. The edentulous portion isabout one fourth of its entire length, is strongly decurved and near thesymphysis curves inward. The coronoid process rises opposite the last rowDeft. SFig. 6. Inferior view of lower jaw of Kritosaurus navajovius.of teeth as in the genus Trachodon, but the backward prolongation of thesurangular gives it the appearance of being further forward. It is inter-mediate in position, in relation to the complete mandible, between Trachodonand the European genus Hecatasaurus.'Surangular. The surangular is proportionately longer than in Tracho-don. Its anterior vertical process is truncated obliquely and expanded tocontinue the posterior lower border of the coronoid process. Posteriorly itbroadens and furnishes four fifths of the articular surface for the quadrate.Articular. The articular forms the extreme end of the jaw and is wedgedin between the posterior ends of the surangular, angular and splenial. Itfurnishes about one fifth of the articular surface for the quadrate, in front ofwhich it contracts to a thin wedge but does not reach forward to the end ofthe dentary process.Splenial. The splenial follows the usual Trachodon form.Angular. The angular is very long and narrow. Posteriorly its lowerborder is visible on the outside of the jaw. Anteriorly it forms the lower.border of the Meckelian groove and extends nearly to the middle of thedentary.TEETH.Two distinct types of teeth appear in the family Trachodontidie. In theearliest representatives known, Claosaurus agil8 Marsh from the Niobrara,and species from the Judith River beds that have been referred to Trachodon,the enamel face of mandibular teeth is spatulate in form and papillate on theborders. In the later Laramie Cretaceous species the enamel face ofmandibular teeth is diamond-shaped with smooth borders.'To replace Limnosaurus Nopcsa, 1900; preoccupied by Limnosaurus ziphodon Marsh,1871, Proc. Acad. Nat. Sci. Phila., Vol. XXIII, p. 104.Type, Limnosaurus transsYlvanicus Nopcsa, Denk. Ak. Wien, Vol. LXVIII, 1900, pp.555-591.1910.] 273Bulletin American Museum of Natural History. [Vol. XXVIII.The teeth of K. navajovius are of the primitive form. Both upper andlower series respectively are larger than in any described species of the family.In the mandibular series there are 42 vertical rowsof teeth. On the triturating surface one tooth,enamel bearing, a half worn tooth, and an indefiniteAnumber of worn roots appear in each row. Theenamel face of each tooth is spatulate and rathersharply pointed at the simimit; median carina low;lateral surface flat; borders not raised above the flatI9- . \ surface and sparsely studded with enamel papillethat apparently lack definite arrangement.In the maxillary series there are 47 vertical rows,/}2 and never more than two enamel bearing teethappear on the triturating surface in each row. Theyare smooth on the borders, and strongly curvedtransversely; median carina verv high.Fig. 7. Lingual surfaceAleasuremen ts.SKULL.of a lower tooth of Krito- Lenigth, as restoredsaurus navajovius, type. Width across frontal above orb tsX 3. Width across proximal ends of quadrateWidth across distal ends of quadrateFrontal, length ant-ro-po3teriorlyParietal, lengthSupratemporal vacuity, lengthSupratcmporal vacuity, widthQuadrate, heighLitQuacJrato-jugal, exposel, length anteroposteriorlyQuadrato-jugal, exposed, heightEctopterygoid, lengthL.oWER JAWLength withm-t predentaryPredentary, lengthAngular, lengthSplen-al, lengthArticular, lengthmm.995. . 22050490198113140'. . 100516*. 42160ico775240250r 6395Denta' series, upper jaw, lengthTooth, mid-section lower jaw, lengthTooth, n-.id-section lower jaw, width41045. 15274TE El 1-1

Ojo Alamo beds of New Mexico

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