Title
Lower jaw of Spathites (Ammonoidea, Acanthoceratoidea) from the Upper Cretaceous (Turonian) of New Mexico
Title Variants
Alternative:
Lower jaws of Spathites
Related Titles
Series:
American Museum novitates, number 3925
By
Landman, Neil H.
, author
Foley, Michael P.,
, author
Lucas, Spencer G.
, author
Sealey, Paul L.,
, author
Type
Book
Material
Published material
Publication info
New York, NY, American Museum of Natural History, [2019]
Notes
Caption title.
"April 24, 2019."
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A lower jaw was recently discovered in a limestone concretion in association with the Late Cretaceous (Turonian) ammonite Spathites puercoensis (Herrick and Johnson, 1900) from the Carlile Member of the Mancos Shale in Sandoval County, New Mexico. It is nearly complete and comprises the aptychus with a hinge along the midline. The better-preserved plate, the left (according to its position in life), is roughly triangular in shape with a broadly rounded lateral margin, a narrowly rounded posterior margin, and a weakly concave anterior margin. It is 26.2 mm wide and 33.0 mm long. Together, the left and right plates form an escutcheonlike shape that projects slightly forward at the apex. The ratio of jaw width to length (26.2 mm x 2 / 33.0 mm) equals 1.59. The aptychus consists of yellow-orange calcite and is covered with comarginal ribs that parallel the lateral and posterior margins and become more prominent toward the posterior end. It is likely that this jaw belongs to the associated ammonite and would have comfortably fit inside the body chamber, based on a comparison of the length of the jaw and the whorl height, suggesting that it functioned as a jaw, rather than as an operculum. It is the first report of an ammonite jaw in the genus Spathites and the first reported occurrence of an ammonite jaw from New Mexico.
Subjects
Ammonoidea
,
Anatomy
,
Cretaceous
,
Mancos Shale
,
mandible
,
Mollusks, Fossil
,
New Mexico
,
Paleontology
,
Sandoval County
,
Spathites puercoensis
Call Number
QL1 .A436 no.3925 2019
Language
English
Identifiers
DOI:
https://doi.org/10.1206/3925.1
OCLC:
1098215478
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