Part II - State of New Jersey

CRETACEOUS NAUTILOIDS OF XEX' JERSEYIIn North America Late Mesozoic nautiloids are of \\ridespread occurrence,are not particularly rare, and are locally rather abundant,.However, their variety is limited, and only five genera arc knomn tobe represented in our Cretaceous strata: Cymatocerm, Paracj~n~atoceras,Eleminautilus, Auplithes, and Eutrephoceras. The first tmo ofthese belong in the family Cymatoceratidae, which in 1945 was treatedin detail by Miller and IIarris', who discussed all of the Americanspecies known at that time; most of them are Lower Cretaceous in age,as are the single knomn representatives of Hominat~tilus and Angulathes.Eutrephoceras is therefore the only genus that has been foundto occur in any abundance in the North American Upper Cretaceous.It is known to he of widespread distribution in those strata, and altogetherwe have been able to assemble almost a hundred specimens fromsix states. In addition, the literature contains data in regard to formsfrom these and ten other states and from one of the provinces of Canada.1 Family Eutrephoceratidae MillerIn 1951 Miller ~ointed out that the genus Eut~ephocerm is notparticularly close to Naz~tilus, with which it had previously been classedin the family Nautilidae. He therefore established the monogenericfamily Eutrephoceratidae. Typical representatires of it have globnlaror subglobular nautiliconic conchs, small umbilici, relatively smootl~testsa, more or less straight and directly transverse external sutures,and small central or subcentral orthochoanitic siphuncles. The internalsutures form a broad shallow rounded dorsal lobe which is due to theinvolution of the conch and not to an inflection of the septa. Annularlobes are present in some forms and absent in others-they are mostprobably of little taxonomic significance.Geographically this family seems to be of world-wide distribution.Stratigraphically it ranges from the Cretaceous to the Oligocene, inclusive,and it may be represented also in the Jurassic and the Miocene.In North America it is most abundant in the Upper Cretaceous and theEocene.Genus Eutrephoceras HyattThe original description of this genus, which was published in 1804,contains the statement "type Ez~trepllocerns Deliayi." Its author,1 Miller. A. X.. and Harris. Robert A,. North American Cymatoceratidse (Mesozoic Nautilotdea):lour. Paleant., vol. 19, pp. 1-13, pls. 1-5, 1915. See also Psracgmatoecras milleriHumphrey (Gcol. Soc. Am., Bull.. vol. 60. P. 119. 1 1. fig. I: pl. 5. 6ga. 1, 2. 1919).However. Eutrcphoeerar? hutonenre (Martin) Pr~m near the Oligocene-Miocene bovndaryan the island of Butvng IButonI Indoneria bears prominent lon~ifvdinal rib-see LeidscheGcol. Mrded.. d. 6, efl. I, pp. 30h, PI. 5. 6;s. 31, 31a.NEW JERSEY GEOLOGICAL SURVEY