SYSTEMATIC SYNOPSIS OF FOSSIL BIRDS. 109i 



C. — Jurassic Birds, 



The single representative of birds at present known from this formation is odontornithic. 

 LAOPTERYX PRISCUS. 



Laopteryx priscus Marsh, Am. Journ. Sci. xxi, Apr. 1881, p. 341. 



From the upper Jurassic beds of Wyoming. The known remains are deposited in the 

 Museum of Yale College. 



The interest attaching to this fossil induces me to transcribe the original description: — 



" The type specimen of the present species is the posterior portion of the skull, which 

 indicates a bird rather larger than a Blue Heron {Ardea Herodias). The braincase is so 

 broken that its inner surface is disclosed, and in other respects the skull is distorted, but it 

 shows characteristic features. The bones of the skull are pneumatic. The occipital condyle 

 is sessile, hemispherical in form, flattened and slightly grooved above. There is no trace of a 

 posterior groove. The foramen magnum is nearly circular, and small in proportion to the con- 

 dyle. Its plane coincides with tliat of tlie occiput, which is slightly inclined forward. The 

 bones around the foramen are firmly co-ossified, but the supra-occipital has separated some- 

 what from the squamosals and parietals. Other sutures are more or less open. On each side 

 of the condyle, and somewhat below its lower margin, there is a deep, rounded cavity, perfo- 

 rated by a pneumatic foramen. 



" The cavity for the reception of the head of the quadrate is oval in outline, and its longer 

 axis, if continued backward, would touch the outer margin of the occipital condyle. This 

 cavity indicates that the quadrate had an undivided head. The braincase was comparatively 

 small, but the hemispheres were well developed. They were separated above by a sharp 

 mesial crest of bone. A low ridge divided the hemis])heres from the optic lobes, which were 

 prominent. 



" The following measurements indicate the size of the specimen : — 



Width of skull across occiput (approximate) ... 24 mm. 



Transverse diameter of occipital condyle 5 '• 



Vertical diameter 4 " 



Width of foramen magnum 5 " 



Height G >• 



Distance from occipital condyle to top of supra-occipital 11 '• 



" In its main features, the present specimen resembles the skull of the HatitcE, more than 

 that of any existing birds. Other parts of the skeleton will doubtless show still stronger rep- 

 tilian characters. 



" In the matrix attached to this skull, a single tooth was found, which most resembles the 

 teeth of birds, especially those of Ichthyornis. It is probable that Laopteryx possessed teeth, 

 and also biconcave vertebrae. 



" The specimen here described, and others apparently of the same species, were found iu 

 tlic up])('r .Jurassic of Wyoming Territory, iu the horizon of the Atlantosaurus beds." 



