Nautilo ideas

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Nautilo ideas
Live reconstruction of extinct nautiloids

Live reconstruction of extinct nautilo ideas

Temporal occurrence
Upper Cambrian to date
approx. 495 to 0 million years
Locations
  • Worldwide
Systematics
Multicellular animals (Metazoa)
Primordial mouths (protostomia)
Lophotrochozoa (Lophotrochozoa)
Molluscs (mollusca)
Cephalopods (cephalopoda)
Nautilo ideas
Scientific name
Nautiloidea
Agassiz , 1847

The nautiloids (Nautiloidea) are a subgroup of the cephalopods (Cephalopoda, Mollusca ), which are extinct except for a family that survives today, the pearl boats (Nautilidae). This taxon was with about 800 known species very rich in forms. 90% of them lived in the era of the Paleozoic , in the Triassic came a little more than 30 species, about 26 in Jungmesozoikum ( Jurassic and Cretaceous ), 9 in the Paleogene and 3 in the Neogene . Two genera still live today, Nautilus with four species and Allonautilus with one species. Both occur in the central Indo-Pacific from the Philippines to Samoa .

In the classical rank-based systematics , the Nautiloidea have the position of a subclass within the cephalopods (Cephalopoda).

features

casing

Housing shapes. The living chambers are dotted.
Treptoceras from the Upper Ordovician of North America. Stone core , length 4.8 cm

All nautilo ideas have an outer housing, which can be of very different shape, an often highly specialized siphon and concave, in most cases unfolded chamber partitions. The smallest housings are just over a centimeter long, the largest achieved lengths of almost ten meters, with a maximum diameter of over 30 cm. The housing could be elongated and straight (orthocon) or curved (cyrtocon), barrel-shaped (brevicon) or rolled up (gyrocon). In the case of the latter, one can distinguish between those rolled up in one plane (plane spiral ) and those rolled up like a snail shell (torticon). In some genera, the housing shapes changed in the course of their ontogeny . The cross-sections of the housings are round or oval, with rolled-up housings mostly high - in rare cases also transversely oval. The mouth of the case is usually not completely rimmed. Often there is a sinusoidal recess for the funnel (funnel bay). Inwardly bending housing projections can narrow the mouth, but it can also expand like a trumpet. With elongated housings, the expansion of the living chamber is variable; it can take up most of the housing or only a small part. When the case is rolled up, it usually comprises half a handle, sometimes a little less. In the case of very tight housings, it can also take up an entire turn. Adjacent to the living chamber is the phragmocone , the rear buoyancy body chambered by septa (chamber partition walls). The septa divide the interior of the case across or diagonally. They can be narrow, which results in small chamber lumens , or wide with large chamber lumens. Towards the mouth they are concave and follow the inner wall for a while. The free part of the septum has a pearly surface. The line at which the septa meet the inside of the housing and grow together is called the suture. The support ring with which the sutures have grown together with the interior of the housing is called a mural strip. The mural strip, which separates the living chamber from the phragmocone, also serves as a point of attachment for the adhesive and retractor muscles of the viscera of the nautiloids.

The chambers of the phragmocon are connected by the siphon . This can run through the chambers more or less centrally (through the middle of the septa) or have a dorsal upper ventral edge position. At the points of passage through the septa, these are tubular, extended by siphon nuts pointing away from the living chamber, the morphology of which is very varied. The Sipho can reach a thickness of almost half the casing tube diameter or, as with the Nautilus , be very thin. In genera with a thick sipho it is assumed that he also took up part of the intestines.

In addition to the cases, the calcite jaws of the nautiloids have been handed down in fossil form, especially from the Triassic and more rarely from the Paleozoic . Mostly they are so-called rhychotheuts, upper jaws, which are divided into three or four sections by edges. Calcified upper jaw tips (rhychocholites), which resemble those of today's Nautilus, are rarer . Lower jaws (Conchorhynchen) are even rarer. From the carbon there is a single find of a nautiloid radula , which is quite similar to that of the recent nautilus .

The nautiloids can be distinguished from the ammonites (Ammonoidea) primarily on the basis of the externally smoother housing, the simple sutures and the complex siphon. With the ammonites, the outer surface of the casing is often more or less ribbed, the sutures are complex and the siphon simple.

Soft tissues

Soft tissues are not preserved in fossil form. It is generally believed that the bodies of the extinct nautiloids were similar to that of Nautilus . Early forms that had barrel-shaped, vertically aligned housings may still have had a snail-like creeper.

Possible evolution of the nautiloids from a single-shell-like , crawling organism to a free-swimming form.

evolution

Apart from Nectocaris from the Middle Cambrian, the nautiloids are the oldest cephalopods. The earliest are dated to the Upper Cambrian. They had conical, relatively wide and short housings, in which the living chamber still took up most of the total housing, and which in the living animal was oriented vertically. Cephalopods probably developed from monkey- like organisms and the first forms probably still had a snail-like creeper. The most important trend in the early evolution of the nautiloids is the acquisition of the ability to swim through the development of the phragmocone into a buoyant body.

In the Ordovician , the diversity of the nautiloids increased sharply and with forms such as Cameroceras , which had a housing nearly ten meters long, the nautiloids were the largest living beings occurring at the time. In the Devonian the Nautilida appeared , the group to which Nautilus belongs and which is the only one to survive to this day. All groups of nautiloids except for the Nautilida and the Orthocerida , which survived until the Triassic, died out at the end of the Devonian and during the Carboniferous. From the Orthocerida the Bactritida probably developed , which in turn became the ancestors of the ammonites and the squid (Coleoidea).

At the end of the Triassic, the Nautilida also died out except for a single genus, which then became the origin of a renewed Nautiloid radiation during the Mesozoic Era.

Systematics

The following cladogram shows the position of the nautiloids as a basal group within the cephalopods:

  Cephalopoda  

 Nautiloidea


  Angusteradulata  

 Orthocerida


   

 Ammonites (ammonoidea)


   

 Bactritida


   

 Belemnites (Belemnoidea)


   

 Octopus (coleoidea)







Template: Klade / Maintenance / Style

Sub-taxa

Diversity of nautical ideas from the Cambrian to the present

The subgroups of the nautiloids, in the classic rank-based systematics in the rank of orders or subordinates, are listed here in the order of their temporal occurrence:

Remarks

  1. ↑ a b The Orthocerida, classically assigned to the nautiloids, belong in the cladistic sense to the sister group of the nautiloids, the Angusteradulata or new cephalopods (Neocephalopoda).

swell

literature

  • Euan NK Clarkson : Invertebrate Palaeontology and Evolution. 4th edition. Blackwell Publishers, Malden MA et al. 1998, ISBN 0-6320-5238-4 .
  • Bernhard Ziegler : Introduction to Paleobiology. Part 2: Special paleontology, protists, sponges and coelenterates, molluscs. 2nd unchanged edition of the 1991 edition. Schweizerbartsche Verlagsbuchhandlung, Stuttgart 2004, ISBN 3-510-65036-0 .

Individual evidence

  1. ^ Ziegler: Introduction to Paleobiology. 2004, p. 247.
  2. ↑ Rosenberg, G. (2013). Nautilus Linnaeus, 1758. World Register of Marine Species, accessed September 12, 2013
  3. ↑ Bouchet, P. (2013). Allonautilus Ward & Saunders, 1997. World Register of Marine Species, accessed September 12, 2013
  4. ^ Ziegler: Introduction to Paleobiology. 2004, p. 234.
  5. ↑ Gofas, S. (2013). Nautiloidea . In: World Register of Marine Species, accessed September 16, 2013
  6. ^ Ziegler: Introduction to Paleobiology. 2004, p. 226.
  7. ^ Ziegler: Introduction to Paleobiology. 2004, p. 235.
  8. ^ Ziegler: Introduction to Paleobiology. 2004, p. 240.
  9. ^ A b Ziegler: Introduction to Paleobiology. 2004, p. 244.
  10. ^ Clarkson: Invertebrate Palaeontology and Evolution. 1998, p. 230.
  11. ^ Ziegler: Introduction to Paleobiology. 2004, p. 250.
  12. ^ Curt Teichert , Bernhard Kummel : Size of endoceroid cephalopods. In: Museum of Comparative Zoology at Harvard College, Cambridge. Breviora. No. 128, 1960, ISSN  0006-9698 , pp. 1-7, digitized .
  13. ^ Ziegler: Introduction to Paleobiology. 2004, p. 247.
  14. ^ Theo Engeser: The Position of the Ammonoidea within the Cephalopoda. In: Neil H. Landman, Kazushige Tanabe, Richard Arnold Davis: Ammonoid Paleobiology (= Topics in Geobiology. Vol. 13). Plenum Press, New York et al. 1996, ISBN 0-30645-222-7 , pp. 7-10.
  15. ^ Ziegler: Introduction to Paleobiology. 2004, pp. 257-258.
  16. ^ Clarkson: Invertebrate Palaeontology and Evolution. 1998, p. 235.

Web links

Commons : Nautiloidea  - collection of images, videos and audio files