350 



NATURE 



[August 7, 1890 



account of their gigantic dimensions, but as being the 

 most bizarre and uncouth-looking forms which palae- 

 ontology has yet brought to our notice. These are tlic 

 so-called horned Dinosaurs of the Laramie, in regard to 

 which several important memoirs have been published 

 both by Prof. Cope and Prof. Marsh. There is, however, 

 unfortunately some difference of opinion between these 

 two eminent palaeontologists as to the comparatively 

 trivial point of the proper nomenclature to be applied to 

 the various genera ; and we must not be supposed to 

 prejudge this question if we adopt the names employed 

 by Prof. Marsh, to whom we are indebted for our 

 illustrations. 



As their name implies, one of the most striking features 

 in the organization of these uncouth monsters is the pre- 

 sence of large horn-cores on the skull, as shown in Fig. i. 



Fig. I. — Left lateral and superior aspects of the 

 the Cretaceous of the United ~ 



skull of Trkeratops JlabellaUis 



approach to these dimensions ; that of the huge Bronto- 

 saurus being very small in comparison with the bulk of 

 its owner. The skull of Triceratops is remarkable for 

 its wedge-like form when viewed from above, and carries 

 a pair of large horn-cores immediately over the eyes, and 

 a short and single core above the nose. During life it may 

 be inferred with a high degree of probability that these 

 cores were sheathed with horn, like those of oxen, and 

 that they proved equally effective weapons of defence. 

 Equally remarkable is the huge flange-like expansion of 

 the posterior region of the skull, evidently necessary for 

 the attachment of muscles sufficiently powerful to support 

 such a ponderous structure; and it is also peculiar for the 

 presence of an epoccipital howQ {e), which is quite unknown 

 in all other animals. The structure of the teeth is some- 

 what similar to that obtaining in Iguanodon, but each 

 tooth has two distinct roots. As in the latter, 

 the extremity of the lower jaw is devoid of 

 teeth, and likewise has a separate predentary 

 bone at its extremity. The upper jaw is, how- 

 ever, quite peculiar in having a distinct toothless 

 rostral bone at the extremity of the premaxilloe. 

 It would thus seem probable that the mouth 

 of these reptiles formed a kind of beak sheathed 

 in horn like that of a tortoise. In young in- 

 dividuals the nasal horn-core is a separate 

 ossification, but in the adult it becomes firmly 

 anchylosed to the underlying bones ; so that 

 in this respect we have a precise analogy with 

 the horn-cores of the giraffe. The brain of the 

 creature is very minute— relatively smaller, in- 

 deed, than in any known vertebrate ; this, how- 

 ever, might have been expected from the size of 

 the brain in other Dinosaurs, since, in the same 

 groups, large animals always have relatively 

 smaller brains than their smaller allies. 



Besides mentioning that the limb-bones re- 

 semble those of the armed Dinosaurs known as 

 Stegosaurus, the only other portion of the skele- 

 ton to which we shall allude is the pelvis, of 

 which a representation is given in Fig. 2. In 

 this portion of the skeleton the haunch-bone or 

 ilium (//) is remarkable for its great extension 

 both in front of and behind the cavity, or aceta- 

 bulum («), for the head of the thigh-bone ; and 

 also for its horizontal or roof-like expansion, 

 which is in marked contrast to the vertical 

 plate-like form which is assumed by this bone 

 in most other members of the order. With one 

 important exception, the general contour of the 

 pubis and ischium also comes nearest to that 

 found in Stegosaurus ; this being especially 

 shown in the relation of the former bone to the 

 ilium, and in the shape of the plate which it 

 gives off to form the inner wall of the aceta- 

 from" bulum. The remarkable exception is, however, 



These horn-cores are so like those of the oxen that some 

 detached specimens found lying on the surface of the 

 ground were actually described as belonging to an extinct 

 bison. 



The type of skull of which we give a figure belongs to 

 the best known genus, for which Prof. Marsh proposes the 

 name of Triceratops. It is remarkable not only for its 

 gigantic size — the length of the figured specimen, which 

 is said to indicate an immature individual, being about 

 six feet — but also for its peculiar armature and structure. 

 An imperfect skull of another species exceeds these 

 dimensions, huge as they are, and is estimated when 

 entire to have had a length of over eight feet. No other 

 known animals, except whales, have a skull making any 



NO. 1084 VOL, 42] 



,V nat. size, a, nostril ; b, eye ; c, suprate'mporal ' that whercas in Stegosaurus, Iguanodofi, and all 



fossa ; ^, epoccipital bone ; /^ frontal and y, nasal horn-core ; /, predentary bone ;] Q^j^gj. allied formS the pubis giveS off a long 

 «f, quadrate bone ; r, rostral bone. (After Marsh.) uni^^ ^.l^^^^ ^ t, o 



backwardly projectmg process running parallel 

 with the ischium, in the present form there is no trace of 

 any such process. 



Mainly from the absence of this postacetabular process 

 of the pubis, Prof. Marsh is disposed to regard the 

 horned Dinosaurs as constituting a distinct primary group 

 of the order ; equivalent to those generally known as 

 Sauropoda, Theropoda, and Ornithopoda. The resem- 

 blance in the structure of the limb-bones, and in a 

 less degree that of the pelvis, to the loricated forms 

 known as Stegosaurus, together with the nature of the 

 dentition, render it, however, far more probable that we 

 should regard these strange reptiles as peculiarly modi- 

 fied forms referable to the sub-order Ornithopoda— the 

 group which includes Iguanodon and Stegosaurus. In the 



