Charles H. Sternberg's "hoodoo" site, Ah-shi-sle-pah Wash, San Juan Basin, New Mexico, in 1921 (left); same site in 2003 (right).
Yours truly with a cervical vertebra of Alamosaurus sanjuanensis, Willow Wash, San Juan Basin, New Mexico (left) fossil log (right) in the Fruitland Formation, Fossil Forest Research Study Area, San Juan Basin, New Mexico.
Ceratopsid rigft lower jaw (left) from the Ojo Alamo Formation (Naashoibito Member) and ceratopsid pelvis (right) from the Kirtland Formation (De-na-zin Member), San Juan Basin, New Mexico
LATE CRETACEOUS VERTEBRATE FAUNAS FROM
THE SAN JUAN BASIN
Two vertebrate faunas (local faunas) are presently recognized in the upper Fruitland and Kirtland Formations, San Juan Basin, New Mexico. They are: the Hunter Wash local fauna, from the upper Fruitand and lower Kirtland formations; the other is the Willow Wash local fauna from the upper Kirtland Formation. A third local fauna is the Alamo Wash local fauna from the unconformable overlying Ojo Alamo Formation (Naashoibito Member). The first two are late Campanian age; the latter is probably early Maastrichtain age.
The taxonomic composition of the first two local faunas differs (so far as known), but they share some taxa in common, most notably Pentaceratops sternbergii. The lambeosaurine dinosaur Parasaurolophus is known from both local faunas, but is represented by different species: P. cyrtocristatus is known only from the Hunter Wash local fauna, while P. tubicen is known solely from the Willow Wash local fauna.
Our understanding of the taxonomic diversity of the Alamo Wash local fauna is very poor. Only one dinosaur taxon is identifiable at the genus level or below, the titanosaurid Alamosaurus sanjuanensis. Other dinosaurs are present including a large carnosaur, ceratopsids, ankylosaurs, hadrosaurids and ornithomimids. Turtles, crocodylians and mammals are also known, but this material is very incomplete.
South side of Ah-shi-sle-pah Wash (formerly Meyers Creek). This is one of the collecting areas prospected by Charles H. Sternberg in the early 1920's.