15-500: Eoderoceratoidea is a superfamily of true ammonites (suborder Ammonitina ) from the Lower Jurassic , comprising seven phylogenetically related families, characterized in general by having ribbed evolute shells that commonly bear spines or tubercles. Adult shell size ranges from 2 or 3 cm to giants reaching 50 cm in such genera as Apoderoceras , Epideroceras , and Liparoceras . The earliest known eodoceroceratoidean
30-671: A dominant 1st lateral lobe and a well-developed umbilical lobe. (Arkell et al. 1957) Stephanoceratoidea contains five families according to Donovan et al. (1981), a reduction from the 11 listed in the Treatise on Invertebrate Paleontology , 1957 Part L. They are the: The Pachyceratidae and Tulitidae included in the Stephanoceratoidea in the Treatise (1957) are reassigned to the Perisphinctoidea . The Macrocephalotidae and Mayaitidae of
45-518: A single plane and symmetrical from side to side. They come in various forms, including evolute shells where all whorls are exposed, and strongly involute shells with only the outer whorl visible. Shells may be heavily ribbed, with some featuring nodes and spines, while others are completely smooth. Some shells have broad, rounded venters (the outer rim), while others have a sharp, keel-like venter. Sutures are generally ammonitic, characterized by complex saddle and lobe patterns. However, in some derived forms,
60-540: Is a stub . You can help Misplaced Pages by expanding it . Ammonitina Ammonitina comprises a diverse suborder of ammonite cephalopods that lived during the Jurassic and Cretaceous periods of the Mesozoic Era. They are excellent index fossils , and it is often possible to link the rock layer in which they are found to specific geological time periods . The shells of Ammonitina are typically planospiral, coiled in
75-412: Is a stub . You can help Misplaced Pages by expanding it . Stephanoceratoidea See text Stephanoceratoidea , formerly Stephanocerataceae , is a superfamily of middle- upper Jurassic ammonoid cephalopods within the order Ammonitida containing diverse forms, generally with sharp ribbing and complex suture lines. Aptychi are believed to be mostly granular (Granulaptycus) or concentrically ribbed on
90-514: Is the eoderoceratid genus Microderoceras . Although its origin is uncertain, it is likely that it is derived from the Psiloceratoidea . It has also been proposed, with some imagination, that Microderoceas has its origin some earlier Jurassic lytoceratid such as Analytoceras . Seven families are included, beginning with the Eoceroceratidae, which gave rise at about the same time to
105-709: The Psiloceratoidea , Eoceroceratoidea, and Hildoceratoidea , which is in part Middle Jurassic. Superfamilies from the Middle and Upper Jurassic include the Stephanoceratoidea, Perisphinctoidea, and Haploceratoidea; the Perisphinctoidea and Haploceratoidea continued well into the Cretaceous. Exclusively Cretaceous superfamilies include the Desmoceratacea, Hoplitoidea , and the Acanthoceratoidea . The Eoderoceratoidea of
120-868: The Lower Jurassic gave rise in the middle of the epoch to the Hilderceratidae, which in turn gave rise early in the Middle Jurassic to the Stephanoceratoidea , Perisphinctoidea, and Haploceratoidea. The Psiloceratoidea from the Lower Jurassic stands alone. The Cretaceous Desmoceratoidea are derived from the Phylloceratina separately from Jurassic forms and give rise to the Hoplitoidea and to the Acanthoceratoidea. This Ammonitida -related article
135-798: The Phricodoceratidae, Coeloceratidae, Liparoceratidae, and Polyhmorphitidae. The Phricodoceratidae left no descendants but the Coeloceratidae later gave rise to the Dactylioceratidae and the Liparoceratidae to the Amaltheidae. The Polymorphitidae became the source for the superfamilies Hildocerataceae beginning with the Hildoceratidae. The more recent taxonomy of Donovan et al. (1981) with seven families, differs from that of Arkell, et al. in
150-883: The Sphaeroceratidae which gave rise to the Cardioceraticae, the Stephanoceratidae to the Kosmoceratidae, all within the Stephanoceratoidea. The Stephanoceratidae, accordingly, also gave rise to the Perisphinctidae, root stock of the Perisphictoidea. This differs from the older phylogeny of the Treatise Part L the Stephanoceratoidea are thought to be derived from the Hammatoceratidae ( Hildoceratoidea ) through
165-580: The Treatise (1957) which included just five families. The phricodoceratids and coeoloceratids were then considered as subfamilies (Phricodoceratinae and Coeloceratinae, respectively) of the Eoderoceratidae. As later (1981) the Liparoceratidae and Polyhmorphitidae were derived from the Eoderoceratidae but the Dactylioceratidae were derived separately (1957) from the Lytoceratidae - a source since then largely rejected. This Ammonitina -related article
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#1733092360916180-669: The Treatise are reduced to subfamilies within the Sphaeroceratidae, Macrocephalitinae and Mayaitinae, but still in the Stephanoceratoidea. The Clydoniceratidae and Thamboceratidae are combined as the Clydoniceratinae within the Hildoceratoid family Oppeliidae. According to Donovan et al (1981) the Stephanoceratidae and Otoitdae both have their origin in the Hildoceratoidea, in the Phymatoceratidae . The Otoitidae gave rise to
195-748: The ancestral family, the Otoitidae which gave rise in the early Middle Jurassic to the Stephanoceratidae and Sphaeroceratidae, forming two main lineages. The Stephanoceratidae gave rise to the Thamboceratidae which in turn gave rise to the Clydoniceratidae. The Sphaeroceratidae gave rise to the Tulitidae which is the source for both the Macrocephalitidae and the Pachyceratidae. The Pachyceratidae lead to
210-477: The surface (Praestriaptychus) (Arkell et al. 1957) The shells of the Stephanoceratoidea, which determine the different included families, are highly variable in form. They are discoidal and evolute with all whorls exposed, spheroidal and involute with only the outer whorl showing, cadiconic with a deep umbilicus and broad ventral margin, and oxiconic with the ventral margin sharp. They are united by being generally sharply ribbed and by their complex suture lines with
225-649: The suture pattern becomes simplified, appearing ceratitic or even goniatitic. The Ammonitina are derived from the Phylloceratina, another ammonitid suborder which has its origin in the Ceratitida of the Triassic . As with the subclass, the closest living relatives of the Ammonitina are the Coleoidea ( octopus , squid , and cuttlefish ) and not the superficially similar modern Nautilus . Lower Jurassic superfamilies include
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