Ammonoids are extinct spiral shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living coleoids than they are to shelled nautiloids. The earliest ammonoids appeared during the Devonian, with the last species vanishing during or soon after the Cretaceous–Paleogene extinction event. They are often called ammonites, which is most frequently used for members of the order Ammonitida, the only remaining group of ammonoids from the Jurassic up until their extinction.
Dactylioceras was a widespread genus of ammonites from the Lower Jurassic period, approximately 180 million years ago (mya).
Perisphinctes is an extinct genus of ammonite cephalopod. They lived during the Middle to Late Jurassic epochs and serve as an index fossil for that time period. The species P. boweni was named after the English chemist and geologist E. J. Bowen (1898–1980).
Inoceramus is an extinct genus of fossil marine pteriomorphian bivalves that superficially resembled the related winged pearly oysters of the extant genus Pteria. They lived from the Early Jurassic to latest Cretaceous.
Abbasites is an extinct genus of ammonites from the early Middle Jurassic epoch, included in the ammonitid family Erycitidae.
Amoeboceras is an extinct genus of ammonite cephalopod closely related to the genus Cardioceras. Fossils are found in Late Jurassic-aged marine strata of Europe and Russia.
Ataxioceras is an extinct Ammonite cephalopod genus confined to the Upper Jurassic of Europe, included in the superfamily Perisphinctoidea.
Docidoceras is an extinct ammonite genus from the order Ammonitida that lived during the Middle Jurassic. Docidoceras is included in the family Otoitidae which makes up part of the ammonite superfamily Stephanoceratoidea.
Echioceras is an extinct genus of ammonites from the Early Jurassic of Europe and North America.
Cadomites is an extinct ammonite genus from the superfamily Stephanoceratoidea that lived during the Middle Jurassic.
Nannolytoceras is an extinct genus of lytoceratid ammonite, family Lytoceratidae, with a stratigraphic range extending from the Bajocian age to Bathonian age.
Pachycormus is an extinct genus of pachycormiform ray-finned fish known from the Early Jurassic of Europe.
Psiloceras is an extinct genus of ammonite. Psiloceras is among the earliest known Jurassic ammonites, and the appearance of the earliest Psiloceras species form the definition for the base of the Jurassic. Unlike most earlier ammonites, which had complex shell shapes and ornamentation, Psiloceras had a smooth shell.
Kepplerites is a moderately evolute ammonite from the lower Callovian included in the Stephanoceratoidea.
Paleontology in Alaska refers to paleontological research occurring within or conducted by people from the U.S. state of Alaska. During the Late Precambrian, Alaska was covered by a shallow sea that was home to stromatolite-forming bacteria. Alaska remained submerged into the Paleozoic era and the sea came to be home to creatures including ammonites, brachiopods, and reef-forming corals. An island chain formed in the eastern part of the state. Alaska remained covered in seawater during the Triassic and Jurassic. Local wildlife included ammonites, belemnites, bony fish and ichthyosaurs. Alaska was a more terrestrial environment during the Cretaceous, with a rich flora and dinosaur fauna.
Lytoceras is an ammonite genus that was extant during most of the Jurassic and Cretaceous periods, and is the type genus for the family Lytoceratidae. These cephalopods were fast-moving nektonic carnivores.
Harpoceras is an extinct genus of ammonite belonging to the family Hildoceratidae. These cephalopods existed in the Jurassic period, during the Toarcian age from the Falciferum zone to the Commune subzone of the Bifrons zone. They were fast-moving nektonic carnivores.
Lithacoceras is an extinct ammonite cephalopod genus included in the superfamily Perisphinctoidea. These fast-moving nektonic carnivores lived during the Jurassic period, from the Oxfordian age to the Tithonian age.
Parkinsonia is a genus of ammonites belonging to the family Parkinsoniidae.
Cadoceras is an extinct ammonite genus belonging to the Cardioceratidae that lived during the Jurassic period from the late Bajocian to the early Callovian.
