Dr. Francis Baron Nopcsa — British Dinosaurs. 203^ 



II. — Notes on British Dinosaurs. Part I: Syfsilophodon. 



By Dr. Francis Baron Nopcsa. 



(WITH A PAGE-ILLUSTRATION.) 



DURING a recent stay in London the kindness of Dr. A. S. 

 Woodward enabled me to study some of the splendid Dinosaurian 

 remains in the British Museum. 



Having principally occupied myself till now with Ornithopodous- 

 Dinosaurs, first of all Eypsilophodon attracted my attention, and' 

 my expectation that this type would prove to be the clue for the 

 understanding of all the other Orthopoda has been perfectly fulfilled. 



Eypsilophodon was described and figured at various times by 

 Owen, Huxley, and Hulke ; a restoration of this animal was given 

 by Marsh in the Geological Magazine for 1896 (p. 6, Fig. 2), 

 and the complete bibliographical list concerning this Dinosaur is 

 compiled in my paper "Synopsis und Abstammung der Dinosaurier" 

 {Foldtani Kozlony, 1901, Budapest). 



In consequence of our more recent knowledge of Dinosaurs m 

 general I managed to detect some new points of remarkable interest. 



Mandible. What Hulke, in describing the Eypsilophodon skull. 

 No. 110, supposed to be the parietal, frontal, and post-frontal bones 

 (Phil. Trans., 1882, pi. Ixxi, fig. 1, pa., fr., ps.f.), turned out to b© 

 the outer view of a complete right mandibular ramus, so that the 

 parietal changes into an articular, the frontal becomes the dentary, 

 and the post-frontal the coronoid bone. This piece (p. 207, Fig. 4) is, 

 in fact, the finest mandibulum of Hypsilophodon I have seen in the 

 whole collection, and as such worthy to be refigured. 



The general outline of the mandibulum, with its strongly ab- 

 breviated post-coronoidal part and its blunt processus coronoideum, 

 reminds one somewhat of the under jaw of Placodus gigas, though 

 it differs of course in nearly every detail, being built up after the 

 Iguanodon type. The comparatively very slight elevation of the' 

 blunt coronoideum, a feature in which Hypsilophodon difi"ers from 

 Iguanodon and the Hadrosauridse, is to be met with in the Upper 

 Cretaceous Mochlodon, while the abbreviation of the post-coronoidal 

 part of the lower jaw is a character which among all Dinosaurs is 

 only known in the Iguanodon type. 



So-called sclei-otic plates. After fixing former difi'erences of inter- 

 pretation Hulke's so-called sclerotic plates were closely examined^ 

 and proved to be nothing else but the teeth belonging to the 

 very same mandible, showing each a nicely polished masticating 

 surface ; the pointed projection on each of these so-called sclerotic 

 plates being simply due to the median ridge projecting on the inner 

 enamelled surface of each tooth (compare my similar figui'e of the 

 masticating surface in Mochlodon teeth figured in my paper on 

 Mochlodon in the Denkschr. d. k. Akad. Wiss., Vienna, 1901, pi. ii,. 

 fig. 11). 



Basi-occipital bone. Another point of great interest not yet duly 

 noticed in the skull of Hypsilophodon is the shape of the bird-like 

 basi-occipital bone (Fig. 1, bo.). It is utterly unlike the same 



