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Home , Dry Mesa Quarry, Haplocanthosaurus, Supersaurus, Ultrasaurus

Great Basin Naturalist

Volume 45 Number 4 Article 7

10-31-1985

Three new sauropod from the Upper of Colorado

James A. Jensen Brigham Young University

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Recommended Citation Jensen, James A. (1985) "Three new sauropod dinosaurs from the Upper Jurassic of Colorado," Great Basin Naturalist: Vol. 45 : No. 4 , Article 7. Available at: https://scholarsarchive.byu.edu/gbn/vol45/iss4/7

This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. THREE NEW SAUROPOD DINOSAURS FROM THE UPPER JURASSIC OF COLORADO

James A. Jensen'

Abstract. — From 1972 to 1982 three exceptionally large sauropod scapulocoracoids and other ecjually large sauropod bones were collected from the base of the Brushy Basin Member of the Upper Jurassic, , in western Colorado. Two of the scapulae are conspecific, but the third represents a second and possibly a new family. The two conspecific specimens are described here as; vivianae, the second genus is described as

Ultrasaurtis mcintoshi, and a large, robust anterior dorsal vertebra of unique form is described as Dystylosaitrus edwini. Various miscellaneous elements are referred to the three genera.

Historical tively new fauna, described as the Uncompahgre fauna (Jensen, in preparation). The genus , named by The author later returned to Potter Creek and E. S. Riggs (1903), was part of an articulated collected additional brachiosaur material (be- skeleton the Upper Jurassic Morrison from ing described elsewhere). Formation within the present city limits of Grand Junction in western Colorado. Riggs believed the genus represented a land- dwelling , rather than one preferring an aquatic habitat. Three large sauropod scapulocoracoids No one took him seriously at the time, but were collected from one of the Jones localities modern interpretations of sauropod habits near Dry Mesa, Mesa County, 35 miles west and paleoenvironments agree with him. The of Delta, Colorado. Over a period of 10 years brachiosaurs are now considered to be the the site proved to be very productive, yield- largest terrestrial to have lived on ing many tons of field blocks and packages of earth. dinosaur material. It was named after Dry The first uranium boom during World War Mesa and is located near the base of the II triggered the discovery of the second Brushy Basin member of the Morrison For-

known North American brachiosaur; it was mation and, consequently, is not easily con- found by prospectors Eddie and Vivian Jones fused with the overlying Lower , who were looking for uranium, circa 1943, Cedar Mountain Formation when making when they collected a brachiosaur humerus simple stratigraphic determinations. The top from the Uncompahgre Upwarp and donated of the Morrison Formation is easy to follow

it to the Smithsonian Institution, where it was cross-country because the superior Cedar put on display. However, no credit was given Mountain sediments are set-back above it, to the collectors. forming a prominent shoulder from 100 to 500 That display led to the discovery of the m wide. Sag-ponds are a characteristic feature Uncompahgre fauna and the materials des- of this shoulder, being produced by land-flow cribed herein. The author saw the Jones and slumping that crush and mutilate humerus in 1958 and later in Colorado found contained in the moving sediments. Its ben- the Jones family, who took him to the location tonitic clays and mudstones, interbedded on Potter Creek. They also took him to three with soft sandstones, grits, and fine gravels, other major localities on the Uncompah- respond actively to cyclic wet/dry stressing, gre Upwarp that together produced a rela- accelerating the deterioration rate of fossil

Earth Science Museum, Brigham Young University. Provo, Utah 84602. Present address: 2821 North 700 East, Provo, Utah 84604.

697 posterior dodorsal vertebra, BYU B, Holotype, Ultm.saurus nmcintoshintoshi , F ig 1 A Brac/iK««,iru.ssp., dorsal vertebra. phalanges. anterior dorsal vertebra, BYU 5750. D, El, unidentified manual 50003. C, Holotype, Di/.s^r/Z.^n/n/scf/a/rH-, New Sauhopod Dinosaurs 699 )ctober 1985 JENSEN;

anterior view. E, posterior view. .

700 Great Basin Naturalist Vol. 45, No.

view^'c; "''''"^'' ''"'^^^''"'- Jt;^i ^^^--^^J vertel,ra: SS";p!!;rr • A left /W later .1 km .

October 1985 JENSEN: New Sauropod Dinosauks 701 materials beyond that of calcified sandstone or "glenoid process"; ridge separating the two limestone preservations. muscular fossae and running on a curved diag- One of the most important problems yet to be onal line up from the glenoid process to the solved is that of the exact age of the Dry Mesa maximum scapidar width is the "transverse sediments. It is mapped as Morrison Formation, ridge." This ridge and the shaft-axis form an but the fauna does not match taxa of classical angle that varies in different sauropod genera. Morrison localities. The assemblage is not only The great depressions to the left (above) and verv diverse but contains many taxa previously right unknown in the Upper Jurassic of North Amer- (below) of the transverse ridge are the ica. "superior fossa" and "inferior fossa," respec- The author believes the Morrison sediments tively. exposed along the eastern monocline of the Un- Description.— (Holotype BYU 5500; right compahgre Upwarp are younger than the Mor- scapulocoracoid) long but not robust; rison in previously described localities, and that distal end expanding moderately; shaft not the Uncompahgre fauna may represent the last severely constricted in midsection. expression of Jurassic dinosaur evolution. A shallow outward curve in inferior border slightly proximad to greatest width of scapula, at Class Reptilia top of transverse ridge, indicates origin of a liga- Order ment, possibly M. scapulohumeralis. This pro-

Suborder cess also present on Diplodociis , occurring con- Infraorder siderably higher up on and most

Family indeterminate prominently developed on , but ab- Supersauriis vivianae, n. gen., n. sp. sent or insignificant in Brachiosaunis, Ap- atosanrus, and . Inferior border Etymology. — Supersaurus , internationally of scapula forming a gentle curve from glenoid published vernacular name; vivianae, after Vi- process to distal end, resembling Apatosaunis vian Jones, co-discoverer of all the important and Diplodociis rather than Brachiosaunis or fossil localities on the Uncompah- Camarasaurus. Inferior fossa not broadly ex- gre Upwarp. panded as in Brachiosanrus and longer than 5500, scapulocoracoid HOLOTYPE. —BYU wide, contrasting with opposite design in Ap- 2.44 m (8') long. atosaurus and Camarasaurus . Coracoid with a Referred material. —BYU 5501, scapuloco- subrectangular profile. racoid 2.70 m (8,10") long; BYU 5502, ischium; Referred material. — BYU 5501, scapu- BYU 5503, medial caudal vertebra; BYU 5504, locoracoid 2.70m (8' 10") long. Description vertebrae. 12 articulated caudal same as Holotype, BYU 5500. locality. — Drv Mesa quarry; E 1/2, BYU 5502, 12 articulated caudal vertebrae: Section 23: T50N, R 14W, NMPM. each approximately 30 cm long, collected but Horizon. — Near the base of the Brushy Basin not yet prepared for study. They were exam- Member of the Upper Jurassic Morrison Forma- ined closely in the field by the author, and a tion, Mesa County, Colorado. decision was made to refer them to Supersau- Collector. —James A. Jensen 1979. rus on the basis of their massive size and Clarification. — Sauropod scapular termi- general morphology. They were found paral- scapula; how- nology in the literature is not uniform (Hatcher lel to, and near the Supersaurus 1903, Mook 1921, Gilmore 1936), resulting in ever, location is not a criterion for association some confusion. This paper describes the in the Dry Mesa cjuarry because of the exten- to scapula in a somewhat normal orientation; using sive fluvial transport of all elements prior an external view with the glenoid cavity down final burial. and the coracoid on the right end, the right BYU 5503, ischium (Fig. 7A): straight shaft, ex- scapula will be described. Descriptive terminol- more robust than ; distal end ventrally. Very ogy used: narrow midsection is the "shaft"; left panded dorsally, truncated end is the "distal" end; upper edge is the similar to Diplodocus

"superior border"; lower edge is the "inferior BYU 5504, two medial caudal vertebrae border"; ventral projection of glenoid area is the (Figs. 7C, D, Dl). C, double-keeled, diplo- 702 Great Basin Naturalist Vol. 45, No. 4 October 1985 JENSEN: New Sauropod Dinosau

,5 m ,

704 Great Basin Naturalist Vol. 45, No. 4 coid caudal with broad ventral channel; D, preparation by the author) appears to be al- Dl, double-keeled diplocoid caudal with tithorax (see Figs. lA, B; 3A-D). transveisely thick neural spine that is ex- Figure 3C is a detail of the base of the panded dorsoventrally at its summit. The cau- neural spine and postzygapophyses of BYU dal neural spines oi Diplodociis are thin, nar- 5000. The form of the suprapostzygapophysal row, and unexpanded at the summit; caudal laminae is greatly altered by assymetry, with rib missing, no pleurocoel but a short channel the right side being more robust than the left. exists below base of caudal rib. Proportion of The vertebra is crushed transversely, making diameter-to-length would place the specimen an anterior view nearly useless. The neural as number 12 in a Diplodociis caudal series, spine is tall and buttressed posteriorly by but the reduction of the neural arch would suprapostzygapophysal laminae 2/3 the height place it much further back in the same series. of the spine (Fig. 3B). In contrast, the supraprezygapophysal laminae are almost Order Saurischia nonexistent. The general structure of the neu-

Suborder Sauropodomorpha ral spine is fragile compared to the Potter Infraorder Sauropoda Creek specimen (Fig. lA) and altithorax Family (Riggs 1903). Pleurocoels are present, their Ultrasaurus macintoshi, n. gen., n. sp. length being less than twice their height. Referred material. — BYU 5001, scapu- Etymology. — Ultrasaurus , internation- locoradoid. The inferior fossa is broader than ally published vernacular name; macintoshi, in Supersaurus (Figs. 4A, B); glenoid process in honor of John S. Mcintosh, an enthusiastic, projects beyond the inferior border of the indefatigable student of sauropods who en- shaft as in Brachiosaurus; overall length ap- courages everyone to greater effort in their proximately 2.70 m (8' 10"); dorsoventrally, behalf midshaft is constricted to 23 cm (9"). A tabular HOLOTYPE. — BYU 5000, posterior dorsal process occurs on the inferior border, slightly vertebra. above the transverse ridge and slightly below material. 5001, scapu- Referred — BYU the minimum dorsoventral diameter of the locoracoid; BYU 5002, anterior caudal verte- flattened shaft (Fig. 4A). The function of this bra; BYU 5003, medial cervical vertebra; tabular process is unknown but appears to Type LOCALm.—E 1/2 Section 23, T 50N, support the origin of an intercostal muscle or R 14W, NMPM, Mesa County, Colorado. possibly an m. humeroscapularis. The process

Horizon. — Base of Brushy Basin Member is not a gentle convexity below the inferior of the Upper Jurassic, Morrison Formation. border, as in Supersaurus, but instead is a Collector. —James A. Jensen 1979. distinct tab erupting from the inferior border Diagnosis. —A sauropod diflFering from with a base approximately 100 mm in length, other brachiosaur genera in having a scapula extending approximately 50 mm ventrally with a moderately expanded distal end; dorsal from the edge of the scapula (Fig. 4B). vertebrae with anteroposteriorly narrow neu- BYU 5002, anterior caudal vertebra (Figs. ral spines; midcervical vertebrae lacking 2D, E, 3E). pleurocoels; posterior dorsal vertebrae with This is probably No. 3 caudal with a spine high neural spines; anterior caudal vertebrae taller than those on anterior brachiosaur cau- with high neural spines. dals. All zygapophyses are damaged by crush- Description. — Posterior dorsal vertebra ing, but two infraprezygapophxsal laminae (Figs. IB; 3A, B, C). A long centrum charac- support the anterior pair. The suprapostzx ga- teristic of brachiosaurs: ratio of length to di- pophysal laminae diverge about midway up ameter, 1.2; Potter C^reek brachiosaur, 1.3; the spine, expanding to expose a broad, Brachiosaurus altitlwrax (Riggs 1903), 1.07. rugose development of the postspinal lamina. Ultrasaurus shares the family characteristic of Viewed anteriorly the upper hallOf the spine a long dorsal centrum with Brachiosaurus presents a modified rectangular profile. Like but in other features it has no parallel with BYU 5000 dorsal vertebra, there are no that genus. The Potter Creek Brachiosaurus, supraprezygapophysal laminae. The supradi- collected by Jones and Jensen (description in apophysal laminae ibrm a wide border enclos- 705 October 1985 JENSEN; New Sauropod Dinosaurs

A. Jensen. B, The author, e'a" scapulocoracoid. D. E., Vivian Jones; J. Fig. 6. A, Measuring Supersaurus vivianae

tall beside Supersaurus vivianae scapulocoracoid. 706 Great Basin Naturalist Vol. 45, No. 4

' Supersaurus ^P^^^""^^". vivianac ischium. B, Ultrasaurus caudal vertebra. C BYl' 5503,5503 SupersaurussL^;,^ vtvtanae, f referred specimen, i.schiuu,. I). 1)1. BVU .5504. ,- Suprrsaurus vivianae referredleterred sjxsnc c men, ' caudal vertebra. E, unidentified caudal vertebra October 1985 JENSEN: New Sauropod Dinosaurs 707 ing a narrow, liut prominent, prespinal lam- vertebrae; lower half of neural arch massive, ina. A small pleurocoel is present and the the neurocentral suture occupying nearly 7/8 centrum is not procoelous but both ends are the length of the centrum; neural spine nearly flat. fragile, being transversely broad but antero- BYU 5003, medial cervical Vertebra (Fig. posteriorly thin; supraprezygapophysal lami- 2A, B, C). The original referred specimen is nae not convergent at midshaft as in Bra- not illustrated. What is seen is a life-sized chiosaiirus; neural arches of dorsal vertebrae model of BYU 5003, constructed from careful completely pneumatic, including spine, measurements taken from the crushed origi- transverse processes, and zygapophyses. nal. All brachiosaur cervical vertebrae are ex- Description. —The location of the parapo- tremely fragile in construction and generally physes at the neurocentral suture and the found badly crushed. The cervical rib is arbi- presence of a strongly developed hyposphen/ trary, but the vertebra was modeled as care- hypantrum articulation locates the vertebra fully as possible from the original. One re- anterior to No. 3. Lower half of neural arch markable feature is the absence of pleur- massive, being characterized on its anterior ocoels, so radically developed in some face by four diagonal infraprezygapophysal sauropod families, such as that of the Diplodo- laminae, two below each zygapophyses. Each cidae . Also, the postdiapophysal, or horizon- pair of these diagonal supports are spaced well tal, laminae are missing. The spine is single, apart and more or less parallel, supporting the being slightly lower than the summit of the hypantrozygapophysal arch on each side (Fig. supraprezygapophysal laminae, which align 5A). The hypantrum consists of two opposing with the elevated suprapostzygapophysal articular faces formed by the down-turned, laminae to provide a channel for the long cer- medial edges of the prezygapophyses. Each vical flexor muscles. The anterior convexity is zygapophysis thus specialized forms an arch exaggerated approximately 5%, and the termed a hypantrozygapophysal arch. The postzygapophysal articular facets were not ventral ends of these four laminae rise from modeled. the anterior surface of the parapophyses; in- ternal lamina of each pair supports the ventral Order Sauri.schia end of the hypantrum; external pair supports Suborder Sauropodomorpha the prezygapophyses. No other sauropod fam- Infraorder Sauropoda ily displays such a well-designed mechanical indeterminate Family arrangement for supporting the hypantrozy- Dijstylosatiriis edwini, n. gen., n. sp. gapophysal arches. Thin supradiapophysal laminae rise to the lateral spur near the sum- Etymology. — Greek: di, two; stylos, neural spine, making the spine beam; sauros, lizard; edwini, in honor of the mit of the transversely (5A). However, viewed late Daniel Edwin (Eddie) Jones, who, with broad (5E), the spine is very slender and his wife, Vivian, brought more new dinosaur laterally to the lower half of the taxa to science than any other two amateurs fragile when compared the neural spine while providing 20 years of logistic support for neural arch. By comparison is robust fieldwork on the Uncompahgre "Plateau." oi Brachiosaurtis (5F, E) deep and neural HoLOTYPE. —BYU 5750, anterior dorsal anteroposteriorly, but the base of the the length of vertebra. arch occupies no more than 2/3 the centrum; the neurocentral suture on Su- Type locality.— E 1/2, Section 23; T 50N, R14W, NMPM. persaurus extends approximately 7/8 the the The zygapophyses are Horizon. —Near the base of the Brushy length of centrum. weak, but the hyposphen/hy- Basin Member of the Upper Jurassic Mor- small and structure is as strongly developed as rison Formation. pantrum it is anterior dorsal vertebrae of Collector. —James A. Jensen 1972. in the Barosauriis (Lull 1919). Diagnosis. —A sauropod differing from all described North American sauropod genera This vertebra bears little resemblance to in having two parallel, diagonal infraprezyga- any described genus and no doubt represents pophysal laminae supporting each hy- a new sauropod family. Many elements be- pantrozygapophysal arch in anterior dorsal longing to it were probably collected from the Great Basin Naturalist

Fig. 8. For comparison only; not to scale. Profiles of various sainopod scapulae and scapulocoracoidae: A, C, E, G, scapulae; B, U, F, I, H, .scapulocoracoidae. A, Haploratithosaurus sp. B, Supersaurus vivianae , first specimen. C, Cetiosatirussp. D, Diplodocus . loitaus F. Cavuirasaunis sti))n'mus . F, Apato.saunt.slotii.sae . C, Supersaurus vivianae second specimen. H, Brachiosaurus . I, hrancai Vltrasaurus macintoshi . B is 2.44 m (8) long; G is 2.74 m (S'lO") long. October 1985 JENSEN: New Sauropod Dinosaurs 709

Dry Mesa quarry, but correct associatiou is many of the elements into generic sets. One difficult wheu dealing with masses of" disartic- paper including a faunal list is in press, and a ulated elements belonging to undescribed second much larger paper is in preparation genera. illustrating most of the prepared material and giving some brief descriptions. Discussion. — In 1983 the unprepared di- nosaur materials collected by the author for Literature Cited the Earth Science Museum at Brigham Young GiLMORE, C. W. 1936. Osteology oi with University amounted to appro.ximately 100 special reference to specimens in the Carnegie tons. This mass of material will require many Museum. Memoirs Carnegie Museum 11(4): 17,5-276. years of careful preparation and, as of this Hatcher, J. B. 1903. Osteology of part it writing, only a very small of had been with additional remarks on Diplodocus. Memoirs prepared for study. The Uncompahgre fauna Carnegie Museum 1(2): 1-75. came from massive deposits of disarticulated Mock, C. C. 1921. Camarasaurus, Amphicoelous and other sauropods of Cope. Memoirs American bones, except two more or less complete Mus. Nat. Hist. (3)3: 247-387. articulated sauropod skeletons from the RiGGS, E. S. 1903. Brachiosaurus altithorax , the largest Dominguez/Jones quarry, and it will be diffi- dinosaur known. American Journal of Science cult, if not impossible, to properly associate (4)15: 299-306.