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Palaeoteuthomorpha
Palaeoteuthomorpha is a superorder of primitive coleoid cephalopods, containing the Boletzkyida, characterized by an orthoceroid-like phragmocone early in ontogeny Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the stu ... and a teuthid living chamber later in ontogeny. This contrasts with the later Teuthida which have a reduced living chamber (gladius) throughout. References *Klaus Bandel, J Reitner, and W Sturmer, 1983. Coleoids from the Lower Devonian Black Slate (Hunstruck-Shiefer) of the Hunsruck (West Germany) N Jb Geol Paliont Abh 165(3) 397-414 Stuttgart, Apr 1983. Coleoidea Protostome superorders {{Cephalopod-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coleoidea
Subclass (biology), Subclass Coleoidea, or Dibranchiata, is the grouping of cephalopods containing all the various taxa popularly thought of as "soft-bodied" or "shell-less" (i.e., octopuses, squid and cuttlefish). Unlike its extant sister group, Nautiloidea, whose members have a rigid outer shell for protection, the coleoids have at most an internal cuttlebone, gladius (cephalopod), gladius, or shell that is used for buoyancy or support. Some species have lost their cuttlebone altogether, while in some it has been replaced by a chitinous support structure. A unique trait of the group is the ability to edit their own RNA. The major divisions of Coleoidea are based upon the number of cephalopod limb, arms or tentacles and their structure. The extinct and most primitive form, the Belemnoidea, presumably had ten equally-sized arms in five pairs numbered Dorsum (biology), dorsal to ventral as I, II, III, IV and V. More modern species either modified or lost a pair of arms. The superor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, where rocks from this period were first studied. The first significant adaptive radiation of life on dry land occurred during the Devonian. Free-sporing vascular plants began to spread across dry land, forming extensive forests which covered the continents. By the middle of the Devonian, several groups of plants had evolved leaves and true roots, and by the end of the period the first seed-bearing plants appeared. The arthropod groups of myriapods, arachnids and hexapods also became well-established early in this period, after starting their expansion to land at least from the Ordovician period. Fish reached substantial diversity during this time, leading the Devonian to often be dubbed the Age of Fishes. The placoderms began dominating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boletzkyida
Boletzkyida is a primitive order (biology), order of teuthid coleoidea, coleoid cephalopoda, cephalopod: the boletzkyids are thought to be the earliest forms of coleoid cephalopods, and appear to form a link between nautiloidea, nautiloid orthocerida, orthocerids and more advanced coleoids. Boletzkyida was named and described by Bandel, Reitner, and Sturmer in 1983 (B.R.&S) from specimens found in the Lower Devonian black slate ("Hunsrück Slate") in Germany. Taxonomy Bandel, ''et al'' (1983) divided the Boletzkyida into two, not too dissimilar families, each based on a single genus. They are the Boletzkyidae based on the genus ''Boletzkya'' and the Naefiteuthidae based on the genus ''Naefiteuthis''. The main difference between ''Boletzkya'' and ''Naefiteuthis'' is the length of the phragmocone at which time the living chamber becomes gladius-like and dominates the shell. Ontogeny Boletzkyd shells grew to as long as 16 cm. The juvenile portion is a phragmocone that close ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthocerida
Orthocerida is an order of extinct Orthoceratoid cephalopods also known as the Michelinocerida that lived from the Early Ordovician () possibly to the Late Triassic (). A fossil found in the Caucasus suggests they may even have survived until the Early Cretaceous (). They were most common however from the Ordovician to the Devonian. Shell form The shell is usually long, and may be straight ("orthoconic") or gently curved. In life, these animals may have been similar to the modern squid, except for the long shell. The internal structure of the shell consists of concavo-convex chambers linked by a centrally-placed tube called a siphuncle. There is a tendency for the chambers to develop cameral deposits, which were used as ballast to balance the long gas-filled shell. Depending on the family, the siphuncle has orthochoanitic (short and straight) or cyrtochoanitic (outwardly curved) septal necks, which protrude from the septa. The shell surface may be (depending on the specie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ontogeny
Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the study of the entirety of an organism's lifespan. Ontogeny is the developmental history of an organism within its own lifetime, as distinct from phylogeny, which refers to the evolutionary history of a species. Another way to think of ontogeny is that it is the process of an organism going through all of the developmental stages over its lifetime. The developmental history includes all the developmental events that occur during the existence of an organism, beginning with the changes in the egg at the time of fertilization and events from the time of birth or hatching and afterward (i.e., growth, remolding of body shape, development of secondary sexual characteristics, etc.). While developmental (i.e., ontogenetic) processes can influence sub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
