Ammonitida or "True ammonites" are an order of ammonoid cephalopods that lived from the Jurassic through Paleocene time periods, commonly with intricate ammonitic sutures.
Euhoplites is an extinct ammonoid cephalopod from the Lower Cretaceous, characterized by strongly ribbed, more or less evolute, compressed to inflated shells with flat or concave ribs, typically with a deep narrow groove running down the middle. In some, ribs seem to zigzag between umbilical tubercles and parallel ventrolateral clavi. In others the ribs are flexuous and curve forward from the umbilical shoulder and lap onto either side of the venter.
Acanthohoplites is an extinct genus of ammonites in the family Parahoplitidae that lived in the Aptian and Early Albian stages of the Early Cretaceous.
Aconeceras is an early Cretaceous ammonite included in the oppeliid subfamily Aconeceratidae, characterized by an involute, high-whorled, flat-sided shell that bears a finely serrate keel along the venter. Sutures have narrower and deeper elements than in Protaconeceras. Aconeceras has been found in western Europe, South Africa, and eastern Australia. Its stratigraphic range is from the Upper Barramian to the Lower Albian.
Parahoplitidae is an extinct family of Cretaceous ammonites with stoutly ribbed, compressed, generally involute shells lacking or with only minor tubercles included in the Deshayestoidea, a superfamily now separated from the Hoplitacaceae.
Lytoceratina is a suborder of Jurassic and Cretaceous ammonites that produced loosely coiled, evolute and gyroconic shells in which the sutural element are said to have complex moss-like endings.
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.
Heteroceras is a genus of Lower Cretaceous heteromorph ammonites belonging to the ancyloceratoidean family, Heteroceratidae.
Ancyloceratoidea, formerly Ancylocerataceae, is a superfamily of typically uncoiled and loosely coiled heteromorph ammonoids established by Alpheus Hyatt in 1900, that may contain as many as 11 families, depending on the classification accepted.
Collignoniceratidae is a family of Upper Cretaceous ammonites characterized by typically more or less evolute shells with compressed, oval, or square whorl sections; serrate or entire keels; and dense ribs with one to 5 tubercles.
Oxynoticeratidae is a family of true ammonites included in the superfamily Psiloceratoidea.
Stoycho Vassilev Breskovski was a Bulgarian paleontologist.
Macroscaphites is an extinct cephalopod genus included in the Ammonoidea that lived during the Barremian and Aptian stages of the Early Cretaceous. Its fossils have been found throughout most of Europe and North Africa.
The family Dactylioceratidae comprises Early Jurassic ammonite genera with ribbed and commonly tuberculate shells that resembled later Middle Jurassic stephanoceratids and Upper Jurassic perisphinctids. Shells may be either evolute or involute.
Pseudothurmannia is a genus of extinct cephalopods belonging to the subclass Ammonoidea and included in the family Crioceratitidae of the ammonitid superfamily Ancylocerataceae. These fast-moving nektonic carnivores lived in the Cretaceous period, from Hauterivian age to Barremian age.
Acanthoptychoceras is an extinct genus of ammonites belonging to the family Ancyloceratidae.
Otohoplites is a genus of ammonite that lived in the Early Albian age and whose fossils were found in Svalbard, Denmark, England, France, Austria, Poland, Russia and Kazakhstan. It has evolved from Hemisonneratia and gave rise to the genus Hoplites. Shells belonging to this genera are rather inflated to compressed and have zigzagging, or looped ribs that end in oblique ventrolateral clavi. Usually, ribs are zigzagging through venter. Macroconchs have a smooth body chamber and rounded venter.
Leyvachelys is an extinct genus of turtles in the family Sandownidae from the Early Cretaceous of the present-day Altiplano Cundiboyacense, Eastern Ranges, Colombian Andes. The genus is known only from its type species, Leyvachelys cipadi, described in 2015 by Colombian paleontologist Edwin Cadena. Fossils of Leyvachelys have been found in the fossiliferous Paja Formation, close to Villa de Leyva, Boyacá, after which the genus is named. The holotype specimen is the oldest and most complete sandownid turtle found to date.
Antarcticoceras is a genus of crioconic ammonites in the family Shasticrioceratidae. It lived during the Early Cretaceous Period. Antarcticioceras fossils can be found in the Cretaceous rocks of Antarctica and South America.
Macroscaphitidae is an extinct family of ptychoceratoid cephalopods from the subclass Ammonoidea that lived from the Lower Barremian to the Lower Cenomanian stages of the Cretaceous. Fossils of Macroscaphitidae were found all around the world although the abundance of found fossils is rather limited. Known fossils from collections were found largely in Europe, South America and Africa. It is known for some species of which complete specimens were found that these animals developed a hetermorphic shell, i.e. the coiling of the shell was not regular, such that the first whirls formed a planispirally coiled evolute section as seen in homomorphic ammonites, but had an additional straight middle part and a presumably upwards facing aperture. Due to their odd morphology the taxonomic classification of Macroscaphitidae changed often over time since their discovery and may not be finally settled even now.
