New Mexico Geological Society Annual Spring Meeting — Abstracts

In North America, species of the ammonoid Parapuzosia have previously been reported from the Turonian, Santonian and Campanian (Clark, 1960; Matsumoto, 1988). Parapuzosia (Austiniceras) sealei Clark from the middle Turonian of Texas was the oldest record from North America. A single specimen of a new species of Parapuzosia (Austiniceras) recently recovered from the middle Cenomanian Acanthoceras amphibolum Zone in the upper part of the Paguate Sandstone in Sandoval County, New Mexico, is in the collection of the New Mexico Museum of Natural History (NMMNH P-71327). This is the first record of Parapuzosia (Austiniceras) in the Cenomanian of North America.

The shell of NMMNH P-71327 is moderately involute, with a low, vertical umbilical wall and a fairly narrowly arched and rounded venter, and weak constrictions are replaced by major ribs that approximate on the latter part of the outer whorl, as in Parapuzosia (Wright and Kennedy, 1981). It is compressed and high whorled on the outer whorl, with a convergent whorl section, and has two distinct series of ribbing; long, sinuous primaries and shorter, sinuous intercalatories, as in the type species of Austiniceras (Wright and Kennedy, 1984). The NMMNH specimen differs from other species of Parapuzosia (Austiniceras) in being less involute with a less compressed whorl section, in its smaller size, having coarser ornament, less sinuous ribs with less projection over the venter and substantially fewer intercalated ribs.

Parapuzosia (Austiniceras) has previously been reported from the lower Cenomanian to upper Turonian of Europe, middle Turonian of the USA and Coniacian to Campanian of Madagascar; it has a geographic distribution that includes England, France, Germany, Czechoslovakia, Iran, North Africa, Angola, Madagascar, Japan and Texas (Wright and Kennedy, 1981, 1984). The occurrence of the new species of P. (Austiniceras) in the Paguate Sandstone in Sandoval County, New Mexico, extends the range of the genus Parapuzosia and the subgenus Austiniceras from the middle Turonian back to the middle Cenomanian in North America. It is also the first occurrence of Parapuzosia in New Mexico.

References:

1. Clark, D. L., 1960, Parapuzosia in the north Texas Cretaceous: Journal of Paleontology, v. 34, no. 2, p. 233-236.
2. Matsumoto, T., (compiled) 1988, A monograph of the Puzosiidae (Ammonoidea) from the Cretaceous of Hokkaido: Palaeontological Society of Japan, Special Papers no. 30, p. 1-179.
3. Wright, C. W. and Kennedy, W. J., 1981, The Ammonoidea of the Plenus Marls and the Middle Chalk: Palaeontographical Society Monographs, 148 p.
4. Wright, C. W. and Kennedy, W. J., 1984, The Ammonoidea of the Lower Chalk, Part I: Monograph of the Palaeontographical Society, p. 1-126, pls. 1-40.