FOSSIL FOOTPRINTS OF THE JURA-TRIAS 499 



Selenichnus breviusculus E. Hitchcock. 

 Selenichnus hreviusmlus E. Hitchcock, '58, p. 134, pi. 23, fig. 9 ; pi. 6(1, fig. 7. 

 Specific characters. Pes : length of foot, .(I4G m. ; length of step, .058 m. Width of 



trackway, .038 m. -,.^.71 



This form is found at Turner's Falls, Massachusetts, associated with \ Jahatm and as 



Hitchcock says, " may be the young of that species." 



Type, no. % of the Hitchcock cabinet, a beautiful slab of twenty-three tracks passing 



in a curved line across the surface. 



Order ORTHOPODA Cope. {Fredentata Marsh.) 



Ordimd characters. Bipedal dinosaurs, with a mesaxonic, generally digitigrade, 

 tetradactyl or tridactyl foot, armed with more or less blunted claws. The foot ranges 

 from the plantigrade, functionally tetradactyl type of Otozoum, through the digitigrade 

 (occasionally calcigrade while resting) and functionally tridactyl pes of Anomoepus, to the 

 Litigrade, probably structurally tridactyl pes of Eubrontes. The manus is pentadactyl 

 wilh blunt claws and, while occasionally touching the ground in the resting position, is 

 never used for locomotion ; it is considerably smaller than the pes. A caudal trace is 

 occasionally present in some genera. 



Family ANOMOEPODIDAE 



Faraily characters. Bipedal in gait, the manus impressing only when resting. Pes 

 tetradactyl, digitigrade with elongate metatarsal segment upon which the animal sits (cal- 

 cigrade) while at rest. Hallux half rotated, insistent, and subfunctional, but rarely 



impressing. Pes ornithoid. „ ^, , , . 



Manus pentadactyl, the digits ranging through an angle of 180 . Phalangeal for- 

 mula: 2. 3. 4. 3. 2. Claws bluntly rounded. _ 



The proportions, except for the elongated metatarsals, and the conformation of the 

 feet and claws, seem to correlate this group with the Wealden predentate dinosaur 

 Hvpsilophodon, which, because of 'its toothed premaxiUary, the generalized character of 

 the teeth and other reasons, Osborn^ believes to represent the Triassic Orthopoda more 

 nearly than any other known form. There are at least two genera which exhibit uU of 

 the family characters and others which are e^'idently nearly related. Genera: Anomoe- 

 pus, Fulicopus, Apatichnus; possibly Corvipes, and others. 



'OsUorn, Culumbia university lectures, 1903. 



