OJO ALAMO BEDS 379 



Iguanodontia : Ornitliopoda Rhynchocephalia 



Kritosaurus (Qryposawus) nota- Champsosaurus profundus Cope 



Mlis Lambe " annectens 



Hypacrosaurus altispinus Brown " hrevicollis Cope 



Trachodon selwyni Lambe Mammalia: 



marginatus Lambe Ptilodus primwvus Lambe 



altidens Lambe Boreodon matiitinus Lambe 



The Ojo Alamo Beds 



This name was proposed by the writer (Bulletin of the American Mu- 

 seum of Natural Histoiy, volume xxviii, article xxiv, pages 267-274, 

 1910) for the upjjer part of the Cretaceous series which unconformably 

 underlies the Puerco formation at Ojo Alamo in New Mexico. 



The Puerco is a clay formation, approximately 250 feet thick in the 

 Ojo Alamo section, probably of fluviatile origin. It contains an exten- 

 sive and varied mammalian fauna of Pal eocene age. The reptilian fauna, 

 which is limited, embraces several genera and species of turtles, several 

 undescribed species of crocodiles, three species of the Ehynocephalian 

 CImmpsQsaurus, and a single species of the Ophidia, Dinosaurs are 

 notably absent. ' 



Invertebrates are not abundant and all are land and fresh water types. 

 A small collection of plant remains has been identified by Doctor Knowl- 

 ton, who states that "the age indicated is that of the Denver or perhaps 

 as late as Fort Union. ^^ 



On Coal Creek, in the immediate vicinity of Ojo Alamo, the Puerco 

 clays rest on massive sandstones which mark the top of a distinct series 

 of sediments. At the point of contact Messrs. Granger and Sinclair have 

 noted a distinct erosional unconformity, and 30 to 70 feet below this 

 point another discordance ai)pears where the sandstones rest on a thick 

 bed of conglomerates. Tlie underlying shales and sandstones, more than 

 200 feet thick, are lithologically distinct from the clays of the Puerco 

 and the fauna is totally different. 



No mammals have been recorded from this horizon, but reptilian re- 

 mains, chiefly dinosaurs, are abundant. 



Most of this material is poorly preserved and bones are rarely asso- 

 ciated. 



;_^The Ceratopsian genera Triceratops said Torosaurus, which are charac- 

 teristic of the Lance, do not occur in these, beds',, feut the known 'frag- 

 mentary remains pertain to a more primitive smaller foriii comparable to 

 M one clonius or Ceratops. 



