Topic
Nautilida
About: Nautilida is a research topic. Over the lifetime, 35 publications have been published within this topic receiving 472 citations.
Papers
TL;DR: Westermann et al. as mentioned in this paper measured the tensile strength of concave septa in the shells of all Endocer-oidea, Actinoceroidea and Bactritoidea.
Abstract: Westermann, G. E. G.: Strength of concave septa and depth limits of fossil cephalopods.
Simple septa with spherical curvature are present in the shells of all Endocer-oidea, Actinoceroidea, Bactritoidea, and most Nautiloidea and Coleoidea. Such septa act as quasi-hemispherical concave membranes when subjected to hydrostatic pressure. Since the tensile strength of a spherical membrane is directly proportional to the ratio of its thickness and radius of curvature, measurements of these parameters on polished and thin sections of septa can be used to obtain strength of the septum against implosion. Depth limits of fossil cephalopods can be made by calibrating these measurements in terms of recent implosion data on ‘living’Spirula and Nautilus. Estimates of septal strength are augmented by strength estimates for long septal necks and cylindrical to globular connecting rings.
Assuming that actual habitats ranged to approximately two-thirds of the mechanical limits of the shells, the following maximum depth ranges are indicated from this preliminary survey: Endoceroidea 100–450 m; Actinoceroidea 50–150 m; Nautiloidea, Ellesmerocerida 50–200 m, Orthocerida 150–500 m, Oncocer-ida <150, Discosorida <100 m, Tarphycerida <150 m, Nautilida 200–600 m; Bactritoidea c. 400 m; Coleoidea, Aulacocerida 200–900 m, Sepiida 200–1000 m, Belemnitida 50–200 exceptionally 350 m.
115 citations
TL;DR: It is surmised that Allonautilus is a descendent of Nautilus, that the latter is paraphyletic, and first evolved in the Mesozoic, rather than in the late Cenozoics, as has been previously suggested.
Abstract: Living ectocochliate cephalopods have long been thought to be restricted to a single genus, Nautilus Linnaeus, 1758, comprising five or six extant species. The shells of two species, N. scrobiculatus Lightfoot, 1786, and N. perforatus Conrad, 1847, are quite distinct, but no soft-parts were known until 1984, when N. scrobiculatus was seen alive for the first time. Dissections show that significant anatomical differences exist between N. scrobiculatus and other Nautilus species, including differences in gill morphology and details of the male reproductive system. These differences, along with phylogenetic analysis of extant and selected fossil nautiloid species, indicate that N. scrobiculatus, and N. perforatus should be distinguished from Nautilus as a newly defined genus, Allonautilus. This analysis contradicts previous phylogenies proposed for the Nautilida, which placed Nautilus as the last-evolved member of the order. We surmise that Allonautilus is a descendent of Nautilus, that the latter is paraphyletic, and first evolved in the Mesozoic, rather than in the late Cenozoic, as has been previously suggested.
63 citations
TL;DR: In this article, a systematic revision of Aturia is called for, based on the singular morphology of the siphuncle, in a dorsal position, which represents a unique morphological feature among the post-Triassic Nautilida.
37 citations
TL;DR: In this paper, the authors considered the origin of the nautiloid cephalopods from the Monoplacophora and the evolution of the coiled Nautilida.
Abstract: The origin of the cephalopods from the Monoplacophora is briefly considered. The first rare Upper Cambrian Plectronoceras are now known to be succeeded by a later Cambrian radiation involving the Plectronoceratida, Ellesmeroceratida, and two other orders, all well documented from Chinese occurrences. The greatest success of the nautiloid cephalopods came in the Ordovician Period with three evolutionary pulses in the Tremadoc, Arenig, and later Ordovician. Three particular Palaeozoic problems are treated: gigantism in cephalopods, the orthocone operculum Aptychopsis, and the Chinese Pagoda Limestone as an example of an 9Orthoceras9 limestone. Devonian developments included the origin of the ammonoids through their first suborder, the Bactritina; the origin of the coleoids; and the beginning of the long history of the coiled Nautilida. After a brief aside on the classification of the cephalopods, the Nautilida are treated in terms of their survival after the extinction of the ammonoids. Finally, there are comments on the living Nautilus.
36 citations
TL;DR: Anomalies of embryonic shell growth, described for the first time in several Mesozoic Nautilida, provide important clues on morphology, structure, and size of their egg capsules; on the physical characteristics where egg laying occurred; and on the hatching processes.
Abstract: No egg of any fossil nautiloid has yet been discovered. However, anomalies of embryonic shell growth, described for the first time in several Mesozoic Nautilida, provide important clues on morphology, structure, and size of their egg capsules; on the physical characteristics where egg laying occurred; and on the hatching processes. Roughness inside the inner egg capsule—caused by hard and uneven egg-laying substrate, locally and temporarily slowing down or stopping the apertural shell growth—could cause temporary deformations of growth lines. Such roughness, caused by stone, is described inside an egg capsule of Nautilus, which was fixed obliquely relative to the egg-laying substrate. This reduced the space between the inner and outer capsules, which locally fused together. The lateral-umbilical grooves, furrows, and deformations of growth lines were probably caused by the inner egg capsule during the prehatching stage. In fossil Nautilida, as in Nautilus, the size of this capsule was relatively ...
24 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2020 | 2 |
| 2019 | 2 |
| 2018 | 3 |
| 2017 | 5 |
| 2013 | 1 |
| 2010 | 1 |