Fruitland Formation

Fruitland Formation Stratigraphic range: Campanian[1] ~75.5–74.5 Ma PreЄ Є O S D C P T J K Pg N ↓
Type	Geological formation
Sub-units	Fossil Forrest Member Ne-nah-ne-zad Member
Underlies	Kirtland Formation
Overlies	Pictured Cliffs Sandstone
Lithology
Primary	Sandstone
Other	Shale, coal
Location
Region	New Mexico  Colorado
Country	USA

The Fruitland Formation is a sedimentary geological formation containing layers of sandstone, shale, and coal. It was laid down in marshy delta conditions, with poor drainage and frequent flooding, under a warm, humid and seasonal climate. It is found in the San Juan Basin in the states of New Mexico and Colorado, in the United States of America. The Fruitland Formation contains beds of bituminous coal that are mined in places along the outcrop. Since the 1980s, the coal beds of the Fruitland Formation have yielded large quantities of coalbed methane. The productive area for coalbed methane straddles the Colorado-New Mexico state line, and is one of the most productive areas for coalbed methane in the United States.

Description

The Fruitland is underlain by the Pictured Cliffs Sandstone, and overlain by the more recent Kirtland Formation. The sequence of rocks represents the final filling of the Cretaceous seaway. The underlying Pictured Cliffs is a marginal marine sandstone, deposited in an environment similar to offshore barrier islands of the southeast United States. As the seaway retreated, the Pictured Cliffs was covered by the Fruitland Formation, which was deposited in near-shore swampy lowlands. The formation is dated to the late Campanian (part of the Cretaceous period), and was deposited over a period of about a million years. Radiometric dating from just below the base of the formation has yielded an age of 75.56 ± 0.41 Ma ago. An ash bed lying below the upper boundary with the Kirtland Formation has been dated to 74.55 ± 0.29 Ma ago.^[1]

The formation is subdivided into the upper Fossil Forrest Member (deposited between about 75-74.5 million years ago) and the lower Ne-nah-ne-zad Member (deposited from 75.5-75 million years ago).^[1] The Fossil Forrest member is considered to be part of the Hunter Wash, fauna shared with the overlying lower Kirtland Formation.^[1]

Paleofauna

Ornithischians

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Ornithischians of the Fruitland Formation
Genus	Species	Location	Member	Abundance	Notes	Images
Hadrosauridae indet.[2]	Intermediate[2]		Fossil Forest[2]	One print.[2]	Giant hadrosaur track, indicating an individual larger than Shantungosaurus, the largest known hadrosaur known.[2]	Parasaurolophus cyrtocristatus Pentaceratops
Parasaurolophus[3]	P. cyrtocristatus[3]		Fossil Forest[4]	One specimen, holotype
Pentaceratops[3]	P. fenestratus[3]				A jr. synonym of P. sternbergii.[3]
	P. stenbergii[3]		Fossil Forest[5]	Specimens including holotype	Also found in the Kirtland Formation.
Stegoceras[6]	S. novomexicanum[6]		Fossil Forest[6]	"(holotype) NMMNH P-33898, nearly complete frontoparietal" and "SMP VP-2555, greater posterior part of left frontal and anterior-most portions of left and right frontals"[6]	Also found in the lower Kirtland Formation.

See also

• List of stratigraphic units with dinosaur body fossils

References