284 



NA TURE 



[January 18, 1906 



and Prof. William Hallock, of the physical department of 

 Columbia University, the Brontosaurus displaced 34J tons 

 of water. If the animal was slightly heavier than the 

 water which it displaced, say 10 per cent., it would weigh 

 38 tons. Prof. Hallock thinks that an estimate of from 

 35 tons to 40 tons would be very near the truth, even 

 allowing for errors of restoration. 



Skull of Morosaurus. 

 Before the British Association .it the Cambridge meeting 

 the remarkable deposit of dinosaur remains known as tin- 



Model, 



" Bone Cabin Ouarry " was described. The quarry, which 

 lies about nine miles north of the Como Bluffs, west ot 

 the Rockies in south-central Wyoming, is believed to 

 represent a delta or mud and sand bar formation, in which 

 were accumulated more or less complete remains of all the 

 dinosaurs of the period. 



One of the most rare and welcome products of this 

 quarry in the continuous workings which began in 1897 

 and were recently completed have been 

 the series of skulls, because the skull is 

 the rarest and most fragmentary part of 

 any of the Jurassic dinosaurs. They in- 

 clude one complete and two incomplete 

 skulls of Diplodocus, two complete skulls 

 of the carnivorous AUosaurus, one of 

 Ornitholestes, the supposed bird-catching 

 dinosaur, one of Laosaurus, a primitive 

 iguanodont, one complete skull and por- 

 tions of two other skulls of Morosaurus. 

 This last is herewith described and illus- 

 ti.it 1 < 1 for the first time. It was found 

 at the end of a series of cervical vertebra; 

 by Dr. W. D. Matthew in an extremely 

 crushed condition, and its restoration re- 

 quired great skill and care. 



Hitherto our knowledge of the skull of 

 the Sauropoda has been limited to the 

 single complete skull of Diplodocus and 

 to the posterior portion of the cranium 

 of "lie specimen of Morosaurus, both de- 

 scribed by Marsh. These new materials, 

 therefore, greatly expand our knowledge. 



The most important point brought out 

 is that all three skulls exhibit a wi II 

 denned tubular opening on top of the 

 skull at the junction of the parietals and paroccipitals. 

 This foramen is smoothly lined with bone, and leads directly 

 down into the cerebral cavity. It is thus probable that it 

 lodged a large pineal eye, an organ the existence of which 

 was left problematical by Marsh, as shown in the following 

 passage : — 



" I here is no true pineal foramen, but in the skull here 

 figured (Plate ii.) there is the small unossified tract men- 

 tioned above. In one specimen of Morosaurus a similar 

 opening has been observed, but in other Sauropoda the 

 parietal bones, even if thin, are complete." In Marsh's 

 drawing the parietal opening is indicated rather as a 

 fontanelle than as a foramen. While this opening is 



NO. 189O, VOL. 73] 



observed in the form of a bony tube in three skulls, it is 

 of course possible that it was not invariably present in the 

 Sauropoda, and that in some forms the foramen was 

 partially or completely roofed over. 



It will be recalled that the skull of Diplodocus has a 

 long snout or antorbital extension supporting a series of 

 slender, pencil-like teeth. The skull of Morosaurus differs 

 widely from this type, first in the highly convex forehead 

 or antorbital region, which is undoubtedly correlated with 

 the presence of the great spoon-shaped cropping teeth, 

 which wire comparatively powerful and presented con- 

 siderable resistance. Above, there are 

 four premaxillary and eight maxillarv 

 teeth, (lei leasing in size as they extend 

 toward the hack of the jaw. From 

 twelve to thirteen teeth are preserved in 

 the mandible. The deep, massive pro- 

 portions of the premaxillaries, mam- 

 illaries, and mandibular rami are also 

 mechanically correlated with the inser- 

 tion and powerful function- of these 

 large teeth. It is evident, however, that 

 as in Diplodocus the animal had no 

 power of masticating its food, and that 

 these anterior teeth served simply for 

 prehensile purposes. 



The anterior narial or respiratory- 

 openings are very large, facing forward 

 rather than more directly upward, as 

 in Diplodoi lis, while the openings in 

 front of the orbits are correspondingly 

 reduced. As restored in this specimen, 

 the orbits are of enormous size, but 

 considerable restoration was necessary in 

 the bone surrounding this region, so that the con- 

 tours of the orbits cannot be certainly ascertained. In 

 the superior aspect of the skull it is evident that the 

 frontal and nasal bones were much longer than in Diplo- 

 docus. It is noteworthy that the occiput or back part 

 of the skull has practically the same composition as in tin- 

 carnivorous Dinosaurs, namely, the parietals hardly enter 

 at all into the top of the cranial roof except to bound the 



parietal or pineal foramen at the sides; this foramen, 

 which is absent in the carnivorous dinosaurs, is bounded 

 posteriorly by the supraoccipitals. The squamosals form 

 the infralateral portions of the occiput. These resemblances 

 tend, so far as they are of value, to sustain Prof. Seeley's 

 view that the Sauropoda and Theropoda, or carnivorous 

 dinosaurs, are more nearly related to each other (Saur- 

 isi hia, Seeli j 1 than either are to the Predentata (Ornith- 

 ischia, Seeley) ; in fact, it is possible to derive the sauropod 

 type from a primitive quadrupedal theropod type, but not 

 to derive either from an iguanodont type. 



IIenrv Fairfield Osbork. 

 American Museum of Natural History, October 5, 1905. 



