New Late Cretaceous gastropods from the Pacific slope of North America

Abstract

Two new genera and ten new species of shallow-marine, warm-water gastropods are reported from several Upper Cretaceous formations found between British Columbia and southern California. The buccinid Zaglenum new genus is represented by two new species and the turbinellid Fimbrivasum new genus is represented by three new species. The nododelphinulid Trochacanthus pacificus new species is the first record of this genus in the Western Hemisphere, and the procerthiid Nudivagus? califus new species could be the first record of this genus on the Pacific slope of North America. The xenophorid Xenophora (Endoptygma) hermax new species is only the second known Cretaceous species of this genus on the Pacific slope of North America, and this species establishes that Endoptygma Gabb, 1877, is a valid taxon. The neritid Otostoma sharonae new species is only the fourth known Cretaceous species of this genus on the Pacific slope of North America. The ringiculid Ringicula? (Ringiculopsis?) hesperiae new species is the first Campanian record of this genus on the Pacific slope of North America and the first recognition of this subgenus in this area.

A comparison of recent and fossil large, high-spired gastropods and their environments: the Nopparat Thara tidal flat in Krabi, South Thailand, versus the Swiss Kimmeridgian carbonate platform

“…Turritellids on the other hand have a homoeostrophic protoconch, do not possess a slitband and only some forms display a siphonal canal (Tichy 1980;Ziegler 1992;Squires and Saul 2007). For a full anatomical description of shapes and characteristics of turritellids and nerineoids, see Wenz (1938) and Moore and Pitrat (1960).…”

The varix: evolution, distribution, and phylogenetic clumping of a repeated gastropod innovation

“…These varices are visible on the internal moulds (steinkerns), with generally two per whorl (Squires & Saul, 2004). Although Bandel (2007) considers them stromboids, Kollmann (2009) rejects this hypothesis on the grounds that a rostrum and an expanded outer lip, both characteristic of Stromboidea, are absent.…”

“…Although Bandel (2007) considers them stromboids, Kollmann (2009) rejects this hypothesis on the grounds that a rostrum and an expanded outer lip, both characteristic of Stromboidea, are absent. Squires & Saul (2004) …”

Northeast Pacific record of the Cretaceous marine gastropodAtiraand a review of its paleobiogeography

“…Current summaries of the geological details of the formations and members containing study area Atira can be found in the following papers (listed in ascending chronostratigraphic order): Hornbrook Formation, Osburger Gulch Member (Squires and Saul, 2003a); Redding Formation, Frazier Siltstone Member (Squires and Saul, 2003b); Ladd Formation, upper Baker Canyon Member (Squires and Saul, 2003c); Ladd Formation, lower and middle Holz Member (Saul, 1982); Chico Formation at Granite Bay [5 Texas Flat 5 Rock Corral] (Squires and Saul, 2009); Cedar District Formation and Chatsworth Formation (Squires and Saul, 2001); upper Tuna Canyon Formation (Squires and Saul, 2009); Chico Formation, Musty Buck Member (Squires and Saul, 2003c); Williams Formation, Pleasants Sandstone Member (Squires and Saul, 2001); El Piojo Formation (Squires and Saul, 2009); Moreno Formation, Tierra Loma Member (Squires and Saul, 2006); Deer Valley Formation (Squires and Saul, 2006); and Panoche Formation near Martinez, California (Squires and Saul, 2006 Remarks.-This subfamily was previously generally believed to be a trochid subfamily (e.g., Fretter and Graham, 1977;Hickman and McLean, 1990), but based on extensive molecular studies of extant taxa by Williams et al (2008), it has been assigned provisionally to the Turbinidae. Atira was traditionally assigned to subfamily Margaritinae (e.g., Keen, 1960) which has been reported previously as ranging from Triassic to Recent (Keen, 1960) or late Eocene to Recent (Hickman and McLean, 1990;Hickman, 1998).…”