Claude Spinosa

Nautilus movement and distribution in palau, Western caroline islands.

Long-term movement of up to 150 kilometers in 332 days by tagged, living Nautilus, and postmortem shell drift of 1000 kilometers in 138 days, corroborate and explain the cosmopolitan distribution of many fossil shelled cephalopods.

Sexual dimorphism in Nautilus from Palau

Shells of 375 sexed specimens of Nautilus cf. N. pompilius trapped at 300-700 ft (90-215 m) depth off Mutremdiu Point and Ngemelis Island, Palau, exhibit distinctive dimorphism in shell proportion and overall size. Of 221 mature animals, males have larger shells (mean diameter _ 209 mm), a broader aperture (mean maximum width - 99 mm; mean width at apertural salient = 92 mm) and greater weight (mean shell + body weight = 1426 gmi). Female shells are smaller (mean diameter = 198 mm), narrower (mean maximum width = 91 mm; mean apertural salient width = 81 mm) and the overall weight is less (mean = 1157 gm). Dimorphic differences are not apparent in young shells (less than 180 mm diameter), but develop during the final 1/2 to 1/4 whorl. This is accompanied by development of the spadix in males, indicating that shell dimorphism reflects sexual maturity. Of 375 animals trapped, 28%o were female; no depth segregation was apparent. Traditional identification of larger fossil dimorphic cephalopods as females and smaller forms as males is the reverse of observed dimorphism in Nautilus and should be discontinued in favor of macroconch and microconch designations.

Predation on Nautilus

Little has been written regarding predation on Nautilus, because information on the subject has largely been limited to inferences based on indirect evidence, such as healed injuries, shell breaks, and borings. For example, Willey (1902) remarked on the presence of healed severe injuries to the hoods of several males and speculated that they might be due either to attacks by fishes or to fighting between sexes. Haven (1972) regarded shell breakage and hood injuries in N. pompilius as a fairly common product of fighting within the species and demonstrated that the distinctive, V-shaped breaks so common in Nautilus shells are a product of biting (Haven, 1972, Figs. 4 and 5). Arnold (1985) described and categorized a wide variety of shell abnormalities in N. pompilius from the same region. In addition, evidence indicates that Nautilus is regularly preyed upon by Octopus, and attacks on Nautilus by fishes have now been documented. This chapter briefly summarizes the results of previous studies and presents new information regarding predation on Nautilus.

Permian of the Western United States

The former Antler orogenic belt divides Permian of displaced terranes to the west from Permian continental margin miogeoelinal deposits to the east. We will refer to this important structural feature as the Antler belt. The structural setting of the Permian of the displaced terranes accreted to the North American continent is complex and a subject of much active research. The structural setting of the Permian rocks of the miogeocline is becoming well known and will be briefly elucidated here.

Mississippian Through Permian Orogenesis in Eastern Nevada: Post-Antler, Pre-Sonoma Tectonics of the Western Cordillera

Mississippian through Permian strata in eastern Nevada, and related strata in southern Nevada and southern Idaho, document a series of tectonic episodes that are either generally unrecognized, or assigned to the Antler or Sonoma orogenies. Some of these were local and others were regional in scale, and none fit either the Antler or Sonoma orogenies as normally defined. They are listed below, along with the last phase of the Antler and the first phase of the Somoma orogenies:

Petroleum Geology of the Southern Pre-Uralian Foredeep with Reference to the Northeastern Pre-Caspian Basin

The southern Pre-Uralian Foredeep and the northeastern Pre-Caspian Basin of southern Russia and Kazakhstan are at the juncture of two major oil-producing regions, the Volga-Ural Basin and the new fields of the Northern Caspian Basin (e.g., Tengiz). The southern Pre-Uralian Foredeep has produced little oil; nevertheless, the Permian-Carboniferous stratigraphy and the general fold-thrust structure of the Pre- Uralian Foredeep, and adjacent Pre-Caspian Basin, afford the possibility for classic and largely untested sub-salt and sub-thrust plays. Prior to the onset of Uralian orogenic activity, Late Devonian-Early Carboniferous rifting disrupted the East European continent, forming a series of rift basins including the Kama-Kinel troughs and the Pre- Caspian Basin. The Middle Carboniferous to Early-Middle Triassic Uralian Orogenic Belt consists of a complicated series of lower Paleozoic continental margin sequences, basement nappes, and accreted terranes, structurally interleaved via large-scale folding and th...

The Permian ammonoid Demarezites Ruzhencev from the Phosphoria Formation, Idaho

Representatives of the ancestral cyclolobin ammonoid Demarezites Ruzhencev (Cyclolobidae) are known from only a few localities in North America where they occur as rare faunal elements. Demarezites furnishi n. sp. is based on a single specimen from “Middle” Permian (Roadian) strata in the Meade Peak Member of the Phosphoria Formation in eastern Idaho. Several specimens of the closely comparable Demarezites n. sp., described herein, are known from the Pipeline Shale Member of the Brushy Canyon Formation in West Texas.

CISURALIAN AMMONOID GENUS URALOCERAS IN NORTH AMERICA

Abstract In North America, the ammonoid Uraloceras Ruzhentsev occurs in Cisuralian (Lower Permian) strata of the northern Yukon Territory, eastern Alaska, Ellesmere Island, southern British Columbia, and Nevada. From Sakmarian to Kungurian, species of Uraloceras occupied a narrow belt in the Northern Hemisphere (Boreal paleogeographical realm) that extended from the northern and northwestern margin of the Pangaean supercontinent southward to regions of present-day Siberia, the Ural Mountains, as well as Nei Monggol and Tibet. In the Yukon Territory, Nevada, Nei Monggol, and possibly Tibet, the association of Uraloceras with typically equatorial perrinitid ammonoids may represent a transition from “Boreal” occurrences in high latitudes to “Tethyan” of lower latitudes. Uraloceras nevadense n. sp. is described herein from Nevada and eastern Alaska.

A Small, Closed Aquarium System for Nautilus

As described in Chapter 35, aquarium displays of living Nautilus are now featured at numerous public aquaria. Although the number of such exhibits has increased in recent years, they are limited primarily to large public institutions, where professional staffing and facilities are possible; these necessities are not available at smaller institutions with limited budgets. The experience at Boise State University has demonstrated that a small, closed-circulation aquarium, customized to specific needs, can be constructed to accommodate long-term maintenance of Nautilus, with relatively small expenditure and investment of time. The system described in this chapter was designed and used primarily for educational and display purposes; it has proven worthwhile and easy to construct and maintain.