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 Ammosaur us. 



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 

 largeand is bounded below by a slender quadratqjugal. 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 PI. Ill, 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 

 small and oblique. The basipterygoid processes are unusually short. 



The neck vertebras of this skeleton are long and slender and very 

 hollow. Their articular ends appear to be all plane or slightly con- 

 cave. The trunk vertebras are more robust, but their centra are quite 

 long. The sacrals appear to be three in number. 



1 The original descriptions of nearly all the other fossils discussed in the present paper may be found 

 in the same journal. 



