| Nautiloids Fossil range: Late Cambrian - Recent |
||||||||
|---|---|---|---|---|---|---|---|---|
 |
||||||||
| Scientific classification | ||||||||
|
||||||||
| Orders | ||||||||
|
Palcephalopoda
Neocephalopoda (in part) |
Nautiloids are a group of marine mollusks in the subclass Nautiloidea, which all possess an external shell, the best-known example being the modern nautiluses. The Furongian (which represented approximately the old notions of Late Cambrian, Merioneth, Croixian, or Potsdamian) is the third and final Molluscs are animals belonging to the phylum Mollusca. There are around 250000 extant Species within the phylum with an estimated 70000 The cephalopods ( Greek plural (kephalópoda "head-feet" are the Mollusc class Cephalopoda characterized by Jean Louis Rodolphe Agassiz ( May 28 1807 — December 14 1873) was a Swiss - American Zoologist, Glaciologist Year 1847 ( MDCCCXLVII) was a Common year starting on Friday (link will display the full calendar of the Gregorian Calendar (or a Common This article is about the taxonomic rank for the sequence of species in a taxonomic list see Taxonomic order In scientific classification used The primitive and ancestral Plectronoceratidae are included in the suborder Plectronoceratina (Flower R The Ellesmerocerida comprise early Nautiloid cephalopods from the late Upper Cambrian (Trempealeauan and Ordovician that are typically rather small with close The endocerids were a diverse group of Cephalopods that lived from the Early Ordovician possibly to the Late Silurian. The Oncocerida comprise a diverse group of generally small nautiloid cephalopods known from the Middle Ordovician to the Mississippian (early Carboniferous) united by Discosorida is a unique order of Cephalopods that lived from the beginning of the Middle Ordovician, through the Silurian, and into the Devonian Nautilida is an order of mostly prehistoric Cephalopods that includes the modern Nautiluses and their immediate ancestors and relatives Neocephalopods are a group of Cephalopod Mollusks that include the Coleoids and all extinct species that are more closely related to extant Orthocerida are an order of extinct Nautiloid Cephalopods that lived from the Early Ordovician (about 500 million years ago to the Late Permian Ascocerida is an order of extinct Nautiloid Cephalopods The shell slightly exogastrical is morphologically very reduced The Bactritida form a small order of more or less straight-shelled (orthoconic Cephalopods that first appeared during the Emsian Stage of the Devonian Molluscs are animals belonging to the phylum Mollusca. There are around 250000 extant Species within the phylum with an estimated 70000 Nautilus (from Greek ναυτίλος, 'sailor' is the common name of any marine creatures of the Cephalopod family Nautilidae, the sole They flourished during the early Paleozoic era, where they constituted the main predatory animals, and developed an extraordinary diversity of shell shapes and forms. The Paleozoic or Palaeozoic Era (from the Greek palaio (παλαιο "old" and zoe (ζωη "life" meaning "ancient life" Some 2,500 species of fossil nautiloids are known, but only a handful of species survive to the present day. FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system.
Contents |
Taxonomic relationships
The nautiloids are among the group of animals called the cephalopods (class Cephalopoda), which also includes ammonoids, belemnites and modern coleoids such as octopus and squid. The cephalopods ( Greek plural (kephalópoda "head-feet" are the Mollusc class Cephalopoda characterized by Ammonites are an extinct group of marine animals of the subclass Ammonoidea in the class Cephalopoda phylum Belemnites (or belemnoids are an extinct group of marine Cephalopod, very similar in many ways to the modern Squid and closely related to the modern Cuttlefish Subclass Coleoidea is the grouping of Cephalopods containing all the primarily soft-bodied creatures The cephalopods are an advanced class of a larger group of animals called the mollusks (phylum Mollusca), which includes gastropods and bivalves. The class Gastropoda or the gastropods, also previously known as gasteropods, or univalves, and more commonly known as Snails Bivalves are Molluscs belonging to the class Bivalvia. They have two-part shells and typically both valves are symmetrical along the hinge line
Traditionally, the most common classification of the cephalopods has been a three-fold division (by Bather, 1888), into the nautiloids, ammonoids, and coleoids. Ammonites are an extinct group of marine animals of the subclass Ammonoidea in the class Cephalopoda phylum Subclass Coleoidea is the grouping of Cephalopods containing all the primarily soft-bodied creatures This article is about nautiloids in that broad sense, sometimes called Nautiloidea sensu lato.
Cladistically speaking, nautiloids are a paraphyletic assemblage united only by shared primitive (plesiomorphic) features that are not found in other cephalopods. Cladistics is the hierarchical classification of Species based on evolutionary ancestry In Phylogenetics, a group of organisms is said to be paraphyletic if the group contains its most recent common ancestor but does not contain all Cladistics is the hierarchical classification of Species based on evolutionary ancestry In other words, they are a grade group that gave rise to both ammonoids and coleoids, and are defined by the exclusion of both those descendent groups. In Alpha taxonomy, a grade refers to a level of morphological and/or Physiological complexity Both ammonoids and coleoids are thought to be descended from the bactritids, which in turn arose from straight-shelled orthocerid nautiloids. The Bactritida form a small order of more or less straight-shelled (orthoconic Cephalopods that first appeared during the Emsian Stage of the Devonian An orthocone is a usually long straight shell of a Nautiloid Cephalopod. Orthocerida are an order of extinct Nautiloid Cephalopods that lived from the Early Ordovician (about 500 million years ago to the Late Permian
The ammonoids (a group which includes the ammonites and the goniatites) are extinct cousins of the nautiloids that evolved early in the Devonian period, some 400 million years ago. Ammonites are an extinct group of marine animals of the subclass Ammonoidea in the class Cephalopoda phylum Ammonites are an extinct group of marine animals of the subclass Ammonoidea in the class Cephalopoda phylum Goniatites are an extinct group of ammonoid, which are shelled Cephalopods related to Squids Belemnites Octopuses The Devonian is a geologic period and system of the Paleozoic era spanning from to million years ago. Also in the Devonian or Early Carboniferous, the bactritids separately gave rise to the first coleoids, in the form of early belemnoids. The Carboniferous is a geologic period and system that extends from the end of the Devonian period about 359 Belemnites (or belemnoids are an extinct group of marine Cephalopod, very similar in many ways to the modern Squid and closely related to the modern Cuttlefish Hence, all cephalopods living today are descended from Paleozoic nautiloids. The Paleozoic or Palaeozoic Era (from the Greek palaio (παλαιο "old" and zoe (ζωη "life" meaning "ancient life"
Some workers apply the name Nautiloidea to a more exclusive group, called Nautiloidea sensu stricto. This taxon consists only of those orders that are clearly related to the modern nautilus. The membership assigned varies somewhat from author to author, but usually includes Tarphycerida, Oncocerida, and Nautilida.
Characteristics
There are three key features which are common to the shells of the nautiloids. These are the internal chambers, the siphuncle and the sutures of the shell, features that are also found in the shells of all ammonoids. The siphuncle is a strand of tissue passing longitudinally through the shell of a Cephalopod Mollusk.
The thin walls between the internal chambers (camerae) of the shell are called the septa. In Biology, Camera can refer to Camera (anatomy, spaces or chambers enclosed between two adjacent septa in the Phragmocone Septa (singular septum) are thin walls or partitions between the internal chambers ( Camerae) of the shell of a Cephalopod, namely Nautiloids As the nautiloid grew, it would detach its body from the walls of the shell, move forward, and secrete a new septum behind it. Each septum added created a new camera in the shell. The body of the animal itself occupied the last chamber of the shell - the living chamber. The body chamber, also called the living chamber, is the outermost or last chamber in the shell of a Nautiloid or ammonoid Cephalopod
The septa were perforated by the siphuncle, which ran through each of the internal chambers of the shell. Surrounding the fleshy tube of the siphuncle were structures made of Aragonite (a polymorph of Calcium Carbonate - which during fossilisation was converted to Calcite): septal necks and connecting rings. Some of the earlier nautiloids deposited calcium carbonate in the empty chambers (called cameral deposits) or within the siphuncle (endosiphuncular deposits), a process which may have been connected with controlling buoyancy. In Physics, buoyancy ( BrE IPA: /ˈbɔɪənsi/ is the upward Force on an object produced by the surrounding liquid or gas in which it is The nature of the siphuncle and its position within the shell are important in classifying nautiloids.
Sutures (or suture lines) are visible as a series of narrow wavy lines on the surface of the shell, and they appear where each septa contacts the wall of the outer shell. The sutures of the nautiloids are simple in shape, being either straight or slightly curved. This is different from the "zigzag" sutures of the goniatites and the highly complex sutures of the ammonites.
Modern nautiloids
Much of what is known about the extinct nautiloids is based on what we know about the modern nautiluses, such as the Chambered Nautilus which is found in the south west Pacific Ocean, from Samoa to the Philippines, and the in the Indian Ocean off of the coast of Australia. The Palau Nautilus ( Nautilus belauensis) is a species of Nautilus native to the waters around the Pacific Island nation of Palau The Pacific Ocean is the largest of the Earth 's Oceanic divisions Samoa, officially the Independent State of Samoa, is a country governing the western part of the Samoan Islands Archipelago in the South Pacific Ocean The Philippines ( Filipino: Pilipinas, officially known as the Republic of the Philippines (fil ''Republika ng Pilipinas'' RP The Indian Ocean is the third largest of the world's Oceanic divisions covering about 20% of the water on the Earth 's surface For a topic outline on this subject see List of basic Australia topics. It is not usually found in waters less than 100 meters deep and may be found as far down as 500 to 700 meters (2,300 feet).
Nautiluses are free swimming animals that possess a head with two simple lens-free eyes, arms (or tentacles). The evolution of the eye has been a subject of significant study as a distinctive example of a homologous organ present in a wide variety of taxa They each have a smooth shell, with a large body chamber, which is divided into chambers that are filled with an inert gas (similar to air but with more nitrogen and less oxygen) making the animal buoyant in the water. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the As many as 90 tentacles are arranged in two circles around their mouth. Tentacles can refer to the elongated flexible organs that are present in some animals especially Invertebrates and sometimes to the hairs of the leaves of some insectivorous The animal has jaws which are horny and beak-like, and it is a predator, feeding mainly on crustaceans. Structure of crustaceans As Arthropods crustaceans have a stiff Exoskeleton, which must be shed to allow the animal to grow ( Ecdysis or molting
Empty nautilus shells may drift a considerable distance and have been reported from Japan, India and Africa. For a topic outline on this subject see List of basic Japan topics. India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country Undoubtedy the same applies to the shells of fossil nautiloids, the gas inside the shell keeping it buoyant for some time after the animal's death so that the empty shell was carried some distance from where the animal lived before it finally sank to the sea-floor. FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system.
Nautiluses propel themselves by jet propulsion, expelling water from an elongated funnel called the hyponome, which can be pointed in different directions to control their movement. The hyponome or siphon is the organ used by Cephalopods for locomotion They do not have an ink sac like that found in belemnites and some of the other cephalopods, and there is no evidence to suggest that the extinct forms possessed an ink sac either. Unlike the extinct ammonoids, the modern nautiluses lack any sort of plate for closing their shell. With one exception, no such plate has been found in any of the extinct nautiloids either.
The coloration of the shell of the modern nautiluses is quite prominent, and, although it is somewhat rare, the shell coloration has been known to be preserved in fossil nautiloids. They often show color patterns on the dorsal side only, which suggests the living animals swam horizontally. In Anatomy, the dorsum is the upper side of animals that typically run fly or swim in a horizontal position and the back side of animals (like humans that walk upright
Fossil record
Nautiloids are often found as fossils in early Palaeozoic rocks (less so in more recent strata). FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system. The Paleozoic or Palaeozoic Era (from the Greek palaio (παλαιο "old" and zoe (ζωη "life" meaning "ancient life" The shells of fossil nautiloids may be either straight (i. e. , orthoconic as in Orthoceras and Rayonnoceras), curved (as in Cyrtoceras) coiled (as in Cenoceras), or rarely a hellical coil (as in Lorieroceras). An orthocone is a usually long straight shell of a Nautiloid Cephalopod. Orthoceras ("straight horn" is a Genus of extinct Nautiloid Cephalopod. Rayonnoceras is a Genus of extinct Cephalopod of the order Actinoceratida and that lived around 325 million years ago during Ordovician to Cyrtoceras is an Extinct Genus of Oncoceridan Nautiloid that lived from the middle Ordovician to the middle Devonian Some species' shells -- especially in the late Paleozoic and early Mesozoic -- are ornamented with spines and ribs, but most have a smooth shell.
The rocks of the Ordovician period in the Baltic coast and parts of the United States contain a variety of nautiloid fossils, and specimens such as Discitoceras and Rayonnoceras may be found in the limestones of the Carboniferous period in Ireland. The Ordovician is a geologic period and system, the second of six of the Paleozoic era, and covers the time between 488 The Baltic Sea is a Brackish inland sea located in Northern Europe, from 53°N to 66°N Latitude and from 20°E to 26°E Longitude. Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3 The Carboniferous is a geologic period and system that extends from the end of the Devonian period about 359 Ireland ( Irish: Éire, ˈeːrʲə is a country in north-western Europe. The marine rocks of the Jurassic period in Britain often yield specimens of Cenoceras, and nautiloids such as Eutrephoceras are also found in the Pierre Shale formation of the Cretaceous period in the north-central United States. The Jurassic is a geologic period and system that extends from about Ma (million years ago to Ma that is from the end of the Triassic to the beginning The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located The Cretaceous (kriːˈteɪʃəs, usually abbreviated 'K' for its German translation "Kreide" is a geologic period and system, reaching from the end of
Specimens of the Ordovician nautiloid Endoceras have been recorded measuring up to 3. The Ordovician is a geologic period and system, the second of six of the Paleozoic era, and covers the time between 488 The endocerids were a diverse group of Cephalopods that lived from the Early Ordovician possibly to the Late Silurian. 5 meters (13 feet) in length, and Cameroceras is (somewhat doubtfully) estimated to have reached 11 meters (36 feet). Cameroceras ("chambered horn" was a genus of giant Orthocone Cephalopod that lived in the Ordovician period These large nautiloids must have been formidable predators of other marine animals at the time they lived.
In some localities, such as Scandinavia and Morocco, the fossils of orthoconic nautiloids accumulated in such large numbers that they form Orthoceras limestones. Terminology and usage As a cultural term "Scandinavia" has no official definition and is subject to usage by those who identify with the culture in question as well Morocco (المغرب "al-Maghrib" officially the Kingdom of Morocco (المملكة المغربية is a country located in North Africa FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system. An orthocone is a usually long straight shell of a Nautiloid Cephalopod. Although the term Orthoceras now only refers to a Baltic coast Ordovician genus, in prior times it was employed as a general name given to all straight-shelled nautiloids that lived from the Ordovician to the Triassic periods (but were most common in the early Paleozoic era. Orthoceras ("straight horn" is a Genus of extinct Nautiloid Cephalopod. The Baltic Sea is a Brackish inland sea located in Northern Europe, from 53°N to 66°N Latitude and from 20°E to 26°E Longitude. The Ordovician is a geologic period and system, the second of six of the Paleozoic era, and covers the time between 488 An orthocone is a usually long straight shell of a Nautiloid Cephalopod. The Triassic is a geologic period and system that extends from about 251 to 199 Ma (million years ago The Paleozoic or Palaeozoic Era (from the Greek palaio (παλαιο "old" and zoe (ζωη "life" meaning "ancient life"
Evolutionary history
Nautiloids are first known from the late Cambrian Fengshan Formation of northeastern China, where they seem to have been quite diverse (at the time this was a warm shallow sea rich in marine life). China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National However, although four orders have been proposed from the 131 species named, there is no certainty that all of these are valid, and indeed it is likely that these taxa are seriously oversplit. In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank.
Most of these early forms died out, but a single family, the Ellesmeroceratidae, survived to the early Ordovician, where it ultimately gave rise to all subsequent cephalopods. The Ordovician is a geologic period and system, the second of six of the Paleozoic era, and covers the time between 488 In the Early and Middle Ordovician the nautiloids underwent an evolutionary radiation, perhaps due to the new ecological niches made available by the extinction of anomalocarids at the end of the Cambrian. Anomalocaris ("Anomalous shrimp" is an extinct genus of Anomalocarids which are in turn thought to be closely related to the Arthropods The Some eight new orders appeared at this time, covering a great diversity of shell types and structure, and ecological lifestyles.
Nautiloids remained at the height of their range of adaptations and variety of forms throughout the Ordovician, Silurian, and Devonian periods, with various straight, curved and coiled shell forms coexisting at the same time. The Silurian is a geologic period and system that extends from the end of the Ordovician period about 443 The Devonian is a geologic period and system of the Paleozoic era spanning from to million years ago. Several of the early orders became extinct over that interval, but others rose to prominence.
Nautiloids began to decline in the Devonian, perhaps due to competition with their descendants and relatives the Ammonoids and Coleoids, with only the Nautilida holding their own (and indeed increasing in diversity). Subclass Coleoidea is the grouping of Cephalopods containing all the primarily soft-bodied creatures Nautilida is an order of mostly prehistoric Cephalopods that includes the modern Nautiluses and their immediate ancestors and relatives Their shells became increasingly tightly coiled, while both numbers and variety of non-Nautilid species continued to decrease throughout the Carboniferous and Permian. The Carboniferous is a geologic period and system that extends from the end of the Devonian period about 359 The Permian is a geologic period and system that extends from 299
The massive extinctions at the end of the Permian were less damaging to nautiloids than to other taxa and a few groups survived into the early Mesozoic, including pseudorthocerids, bactritids, nautilids and possibly orthocerids. A taxon (plural taxa) or taxonomic unit, is a name designating an organism or a group of Organisms In Biological nomenclature according to The Mesozoic Era is one of three geologic eras of the Phanerozoic eon. The Bactritida form a small order of more or less straight-shelled (orthoconic Cephalopods that first appeared during the Emsian Stage of the Devonian Orthocerida are an order of extinct Nautiloid Cephalopods that lived from the Early Ordovician (about 500 million years ago to the Late Permian The last straight-shelled forms were long thought to have disappeared at the end of the Triassic, but a possible orthocerid has been found in Cretaceous rocks. The Triassic is a geologic period and system that extends from about 251 to 199 Ma (million years ago The Cretaceous (kriːˈteɪʃəs, usually abbreviated 'K' for its German translation "Kreide" is a geologic period and system, reaching from the end of Apart from that exception, only a single nautiloid suborder, the Nautilina, continued throughout the Mesozoic, where they co-existed quite happily with their more specialised ammonoid cousins. Nautilus (from Greek ναυτίλος, 'sailor' is the common name of any marine creatures of the Cephalopod family Nautilidae, the sole The Mesozoic Era is one of three geologic eras of the Phanerozoic eon. Most of these forms differed only slightly from the modern nautilus. They had a brief resurgence in the early Tertiary (perhaps filling the niches vacated by the ammonoids in the end Cretaceous extinction), and maintained a worldwide distribution up until the middle of the Cenozoic Era. The chuprichondira geological time interval covers roughly the time span between the demise of the non- avian Dinosaurs and beginning of the most recent Ice Age, approximately The Cretaceous–Tertiary extinction event, which occurred approximately ( Ma) was a large-scale mass extinction of animal and plant species in a geologically The Cenozoic (also Caenozoic or Cainozoic) Era (ˌsiːnəˈzoʊɪk/ /ˌsɛn- (meaning "new life" ( Greek ( kainos) "new" With the global cooling of the Miocene and Pliocene, their geographic distribution shrank and these hardy and long-lived animals declined in diversity again. Global cooling in general can refer to an overall cooling of the Earth. The Miocene is a geological epoch of the Neogene period and extends from about 23 The Pliocene epoch (spelled Pleiocene in some older texts is the period in the Geologic timescale that extends Today there are only six living species, all belonging to two genera, Nautilus (the pearly nautilus), and Allonautilus. Nautilus is a Genus of Cephalopods in the family Nautilidae. Species in this genus differ significantly in terms of The Genus Allonautilus contains two species of Nautiluses which differ significantly in terms of morphology from those placed in the sister Taxon
Classification
- See also: List of nautiloids
The following 1988 classification by Curt Teichert, updates the 1964 version in the Treatise on Invertebrate Paleontology, and is based mostly on shell structure (Teichert 1988, p. This list of nautiloids is a comprehensive listing of all genera that have ever been included in the subclass Nautiloidea excluding purely vernacular terms Year 1988 ( MCMLXXXVIII) was a Leap year starting on Friday (link displays 1988 Gregorian calendar) Year 1964 ( MCMLXIV) was a Leap year starting on Wednesday (link will display full calendar of the 1964 Gregorian calendar. The Treatise on Invertebrate Paleontology (or TIP) published by the Geological Society of America and the University of Kansas Press is a definitive multi-authored 19).
Subclass Orthoceratoidea Kuhn, 1940
- Order Plectronocerida Flower, 1964 (Cambrian)
- Order Yanhecerida Chen & Qi, 1979 (Cambrian)
- ?Order Protactinocerida Chen & Qi, 1979 (Cambrian)
- Order Ellesmerocerida Flower, 1950
- Suborder Ellesmerocerina Flower, 1950 (Cambrian to Ordovician)
- Suborder Cyrtocerina Flower, 1964 (Ordovician)
- Order Orthocerida Kuhn, 1940 (Ordovician to Triassic)
- Order Ascocerida Kuhn, 1949 (Ordovician to Silurian)
Subclass Actinoceratoidea Teichert, 1933
- Order Actinocerida Teichert, 1933 (Ordovician to Carboniferous)
Subclass Endoceratoidea Teichert, 1933
- Order Endocerida Teichert, 1933 (Ordovician to Silurian)
- ?Order Injetocerida Balashov, 1960 (Ordovician)
Subclass Nautiloidea Agassiz, 1847
- Order Tarphycerida Flower, 1950
- Suborder Tarphycerina Flower, 1950 (Ordovician to Silurian)
- Suborder Barrandeocerina Flower (Ordovician to Devonian)
- Order Oncocerida Flower, 1950 (Ordovician to Carboniferous)
- Order Discosorida Flower, 1950 (Ordovician to Devonian)
- Order Nautilida Agassiz, 1847
- Suborder Rutocerina Shimanskiy, 1957 (Devonian to Triassic)
- Suborder Lirocerina Shimanskiy, 1957 (Carboniferous to Triassic)
- Suborder Nautilina Agassiz, 1847 (Triassic to Recent)
A further order, Bactritida, are sometimes considered nautiloids close to the Orthocerida, sometimes very primitive ammonoids, and sometimes placed in a subclass of their own, called Bactritoidea. The Bactritida form a small order of more or less straight-shelled (orthoconic Cephalopods that first appeared during the Emsian Stage of the Devonian Orthocerida are an order of extinct Nautiloid Cephalopods that lived from the Early Ordovician (about 500 million years ago to the Late Permian Ammonites are an extinct group of marine animals of the subclass Ammonoidea in the class Cephalopoda phylum
Since 1988, two other orders have gained recognition by some workers: the Pseudorthocerida and the Dissidocerida, both previously included in the Orthocerida. Year 1988 ( MCMLXXXVIII) was a Leap year starting on Friday (link displays 1988 Gregorian calendar) Orthocerida are an order of extinct Nautiloid Cephalopods that lived from the Early Ordovician (about 500 million years ago to the Late Permian
A more recent interpretation by Theo Engeser (Engeser 1997-1998) suggests that nautiloids, and indeed cephalopods in general, fall into two main groups, the Palcephalopoda (including all the nautiloids except Orthocerida and Ascocerida) and the Neocephalopoda (the rest of the cephalopods). Neocephalopods are a group of Cephalopod Mollusks that include the Coleoids and all extinct species that are more closely related to extant
References
- Doguzhaeva, Larisa. (1994) An Early Cretaceous orthocerid cephalopod from north-western Caucasus. Palaeontology 37(4): 889-899.
- Engeser, T. , (1997-1998) The Palcephalopoda/Neocephalopoda Hypothesis
- Teichert, C. (1988) "Main Features of Cephalopod Evolution", in The Mollusca vol. 12, Paleontology and Neontology of Cephalopods, ed. by M. R. Clarke & E. R. Trueman, Academic Press, Harcourt Brace Jovanovich,
External links
See also
Ammonites are an extinct group of marine animals of the subclass Ammonoidea in the class Cephalopoda phylum Belemnites (or belemnoids are an extinct group of marine Cephalopod, very similar in many ways to the modern Squid and closely related to the modern Cuttlefish Lituites is an extinct Genus of the Nautiloids and is one of the most primitive known Cephalopods It originated in the OrdovicianDapyx Software network: MP3 Explorer | Ebook Manager | Zenithic