Volume 1 Number 2 Single-copy price: $2.50 August 1988

Late Jurassic North American • > Brachiosaurids

AUROPODS were the grand- pod skeleton and thus the likeliest the Uncompahgre Upwarp in wes- Sest animals ever to walk the to be discovered still joined togeth- tern Colorado, and it remained un- earth. Adult specimens of the gi- er - are very thin-walled for their described until last year, in a bra- ant Apatosaurus, Diplodocus, Baro- size, with large internal cavities chiosaur paper by James A. Jen- saurus, and Mamenchisaurus ho- called pleurocoels. This makes sen. In more than two decades of chuanensis were as much as 25 them prone to crushing and there- field work, Jensen could find only meters (over 80 feet) long. A sau- by hampers proper measurement scattered additional bones of Bra- ropod skeleton discovered in and identification. This problem chiosaurus and related sauropods, China in 1987 by the Canada- particularly plagues the brachiosau- but because brachiosaur material China Dinosaur Project has a re- rids, among which are the most of any kind is so scarce, his discov- ported length of about 27 meters massive sauropods known. eries are nevertheless extremely (90 feet). Thus a sauropod 15 me- significant. ters long would be considered ra- Brachiosaurus Our knowledge of Brachiosau- ther small, even though a non-sau- The first Brachiosaurus a/tithor- rus would be terribly incomplete ropod dinosaur this size would be ax specimen was collected in 1900 were it not for the discovery of a giant in its class. from the Late Jurassic Morrison considerable material - including Because they were so big, sauro- Formation (about 140-160 million skulls - in Tendaguru, Tanzania pods make spectacular museum years old) of Grand Junction, Col- by German paleontological expedi- displays that attract crowds of cus- orado by Elmer S. Riggs. It was a tions a few years before World tomers. It is thus quite frustrating quite incomplete skeleton, com- War I. This was described in a se- that sauropod specimens are usual- prising several vertebrae, parts of ries of papers by Werner Jan- ly fragmentary skeletons or isolat- the shoulder and pelvis, an upper ed bones. There is a good anatomi- arm and upper leg, and four ribs, cal reason for this. A close look at that is now stored at the Field Mu- a sauropod skeleton shows that seum in Chicago. Riggs was struck the bones, particularly those in the by the length of the upper arm legs, do not "fit together" very bone and realized that in life the well; there is a lot of space be- animal's chest was as high off the tween them. In the live dinosaur, ground as the hips, and its back this space was taken up by carti- sloped down to the tail. This is lage and ligaments - connective why he named it the "high-chested tissue - that held the skeleton to- arm-lizard." gether. After death, however, the It wasn't until 1943 that another dinosaur's connective tissue would Brachiosaurus skeleton was found decay and the skeleton would fall in North America, by uranium apart; many bones would wash prospectors Vivian and Daniel away before burial. "Eddie" Jones, who donated their As if this weren't bad enough, find to the Smithsonian Institution. sauropod vertebrae - the most This badly eroded specimen was tightly articulated bones in a sauro- from the Potter Creek Quarry on

August 1988 9 ensch, starting III 1914, and it individual, and all the brachiosaur second brachiosaurid genus to be proved possible to construct a material from Tendaguru is now described from North America. complete skeleton from the re- considered to belong to just the The story of Ultrasaurus has re- mains of several individuals. This species B. brancai. cently taken a couple of unexpect- skeleton, rescued from destruction In a recent paper, Gregory S. ed twists. In the early 1980s - be- during the air raids of World War Paul of Baltimore, Maryland, sum- fore Jensen formally published II, now stands, nearly 12 meters marized what is known of both the Ultrasaurus macintoshi - a Kore- (40 feet) tall and 23 meters (75 North American and African spe- an paleontologist named Haang feet) long, in the Humboldt Muse- cies of Brachiosaurus, corrected a Mook Kim published a series of um fur Naturkunde in East Berlin. few errors that seemingly crept in- short papers describing dinosaurs Representing an animal with an es- to Janensch's descriptions, and from South Korea, including ma- timated body weight of almost 50 produced a new reconstruction of terial that he also called "Ultrasau- tons, it is still the largest mounted B. brancai, the side view of which rus," thinking that it came from a dinosaur skeleton in the world. is reproduced here as Figure 6. dinosaur larger than "Supers au- Janensch discerned the similari- Paul considered B. brancai differ- rus." In 1983, he formally named ty of the Tendaguru brachiosaurs ent enough from B. altithorax that his dinosaur Ultrasaurus tabriensis. to Riggs's specimen and named he placed it into its own subgenus, Unfortunately, the remains of Ul- them Brachiosaurus brancai and Giraffatitan ("big giraffe"). The trasaurus tabriensis seem to have Brachiosaurus fraasi - two new full name of the American species been misidentified, and the dino- species of the same genus as thus became Brachiosaurus (Bra- saur is considerably smaller than Riggs's dinosaur - after the Ger- chiosaurus) altithorax, and of the Kim believed. But even more un- man paleontologists Wilhelm Bran- African species Brachiosaurus (Gi- fortunately, the name Ultrasaurus ca and Eberhard Fraas. It soon be- raffatitan) brancai. B. (B.) altithor- was preempted for the Korean di- came apparent that B. fraasi actu- ax has longer dorsal vertebrae and nosaur, and Jensen's giant dino- ally represents a smaller B. brancai relatively longer ribs than B. (G.) saur had to be rechristened. brancai, so it had a longer, deeper, Then, in the Brachiosaurus and presumably heavier body. study noted above, Paul examined Jensen's figures of Ultrasaurus and Ultrasaurus concluded that Ultrasaurus macin- In 1972 at the Dry Mesa Quar- toshi is simply a large Brachiosau- ry in Colorado, Jensen discovered lUS altithorax. If this is indeed true, two shoulder blades (scapulacora- then it is not necessary to rename coids) and a few other fossilized Jensen's dinosaur; it can simply be bones of a very large dinosaur that called Brachiosaurus. But Jensen, he nicknamed "Supersaurus." In who has collected material of both 1979, also at Dry Mesa, a third Brachiosaurus and Ultrasaurus, dis- scapulacoracoid was found during agrees with Paul's interpretation, filming for a Japanese television and the question of what Ultrasau- show. Since it was a bit larger than lUS really is remains open. the "Supersaurus" shoulder blades Paul's paper also discussed skel- and evidently belonged to a differ- etal material from other gigantic ent kind of dinosaur, Jensen nick- sauropods, to see how it compared named that dinosaur "Ultrasau- with what is known of Brachiosau- rus." Both names remained infor- lUS. It is too bad that practically all mal until Jensen published the di- of it is so scrappy - a femur here, nosaurs' descriptions, in 1985, un- a vertebra there - so that much der the names Supersaurus vivian- guesswork was involved in Paul's ae (named after Vivian Jones) and estimates. Paul concluded that Jen- Ultrasaurus macintoshi (after John sen's Ultrasaurus specimens repre- S. McIntosh, a noted student of sent an animal not too much larg- the sauropods). According to Jen- er than the largest known Brachio- sen, Supersaurus is probably a di- saurus individual, weighing about plodocid sauropod, similar to but 55 tons. Supersaurus, on the other larger than Apatosaurus, Diplodo- hand, could well have been 42 cus; and Barosaurus, while Ultra- meters (140 feet) long, if it had a saurus is a brachiosaurid - the whiplash taillike that of its smaller

10 Archosaurian Articulations relative Diplodocus. But because about as large as the biggest Bra- Sauropod Dinosaurs from the diplodocids had smaller and slen- chiosaurus and probably also Upper Jurassic of Colorado," derer bodies than brachiosaurids, weighed about 50 tons. None of Great Basin Naturalist 45(4): at 50 tons Supersaurus would not the sauropods listed in Paul's pa- 697-709. have outweighed Ultrasaurus. per was conclusively shown to be Jensen, J. A., 1985b. "Uncompah- heavier than Jensen's giant. Of the giant sauropods report- gre Dinosaur Fauna: A Prelimi- ed from South America, Paul be- The last word in giant dinosaurs nary Report," ibid.: 710-720. lieved Antarctosaurus giganteus, may reside in an enormous brachi- known from a thigh bone 2.31 me- osaurid femur from the Recapture Jensen, J. A., 1987. "New Brachio- ters (nearly 7.7 feet) long, was Member of the Morrison Forma- saur Material from the Late Ju- tion, only a third of which was pre- rassic of Utah and Colorado," served. Illustrated in Jensen's 1987 ibid. 47(4): 592-608. paper, this fragment is over a me- Kim, H. M., 1983. "Cretaceous Di- ter long and is 1:67 meters around, nosaurs from Korea," Journal of and the bone itself may have been the Geological Society of Korea nearly 3 meters (10 feet) long in 19(3): 115--126. [Two versions life - representing an animal with of this paper exist, one, appar- a possible body weight of as much ently an offprint, that does not as 70 tons. contain the specific name Ultra- saurus tabriensis, and another, Recent References apparently the published ver- Anonymous, 1988. "In Search of sion, that does. In Chinese.] Ancient Dragons," Alberta Re- Paul, G. S., 1988. "The Brachio- pori, January 4, 1988 issue, pp. saur Giants of the Morrison 28-32. [Currently the most com- and Tendaguru with a Descrip- prehensive available report on tion of a New Subgenus, Giraffa- the discoveries of the Canada- titan, and a Comparison of the China Dinosaur Project.] World's Largest Dinosaurs," Jensen, J. A., 1985a. "Three New Hunteria 2(3): 1-14.

Figure 6 Skeleton of Brachiosaurus (Giraffatitan) brancai as restored by Paul, 1988. Based on the composite mounted specimen on display at the Humboldt Museum In East Berlin and various other specimens referred to that species. Height after several corrections (including the addition of a twelfth dorsal vertebra) about 16 meters, length about 25 meters (a somewhat larger individual than the Humboldt skeleton).

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