New Mexico Geological Society Annual Spring Meeting — Abstracts

Together with numerous ammonites, only one specimen of the extremely rare (in North America) nautiloid Angulithes fleuriausianus (d’Orbigny, 1840) was recovered from the basal part of the Upper Cretaceous (Cenomanian) Paguate Sandstone southeast of Mesa Prieta, in Sandoval County, New Mexico. Ammonites collected from this interval include Acanthoceras amphibolum, Tarrantoceras sellardsi, and Desmoceras aff. D. japonicum. This places A. fleuriausianus from the Paguate in the study area in the A. amphibolum Zone, which is of middle Cenomanian age.

The shell of this nautiloid specimen has a rounded venter, a small umbilicus, very involute coiling, and a compressed and subtrigonal whorl section, as in Angulithes fleuriausianus (Cobban and Kennedy, 1993, p. E2). The slightly sinuous suture extends from the umbilicus, and crosses the flanks with a slight concavity, forming a broad, shallow lobe that then curves forward across the venter to form a shallow ventral saddle.

Cenomanian nautiloids are rare in the Western Interior of the United States. Here, Angulithes fleuriausianus is only known from the Acanthoceras amphibolum Zone in the Paguate Sandstone. Previous records (three specimens) of A. fleuriausianus are from the Paguate Sandstone in Cibola and McKinley counties, New Mexico (Cobban and Kennedy, 1993, p. E1-E2). This is the first report of this nautiloid from Sandoval County. A. fleuriausianus has also been reported from the Cenomanian of England, France, Germany, Tunisia and southern India.

References:

1. Cobban, W. A. and Kennedy, W. J., 1993, Cenomanian (Upper Cretaceous) nautiloids from New Mexico: in Shorter Contributions to Paleontology and Stratigraphy 1993: U. S. Geological Survey Bulletin 2073, p. E1-E3, 2 pls.
2. Orbigny, A., d’, 1840-1842, Paléontologie française: Terrains crétacés, v. 1, Céphalopodes: Paris, Masson, p. 1-120 (1840), p. 121-430 (1841), p. 431-662 (1842).