''Berriasella'' is a discoidal evolute perisphinctacean

ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefis ...

, and type genus for the neocomitid subfamily

Berriasellinae Berriasellinae is a subfamily of very late Jurassic and very early Cretaceous perisphinctoid ammonites in the family Neocomitidae. Berriasellinae comprises generally compressed, evolute genera, typically with furcated ribbing, and in some a smo ...

. Its ribbing is distinct, consisting of both simple and bifurcated ribs that extend from the umbilical seam across the venter; its whorl section generally compressed, the venter more or less narrowly rounded. The species ''

Berriasella jacobi ''Berriasella jacobi'' is an extinct species of ammonite from the late Jurassic and early Cretaceous. Because of its unique stratigraphic position, it is used as an index fossil to determine the boundary of the Cretaceous and Jurassic periods. The ...

'' traditionally has been regarded an index fossil defining the base of the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

, however since 2016 this had been replaced by the first occurrence of ''

Calpionella alpina ''Calpionella'' is an extinct genus of calpionellid, a group of single celled eukaryotes.

''. Some authors regard ''B. jacobi'' as instead belonging to the genus '' Strambergella.'' ''Berriasella'', named by Uhlig, 1905, is known from the late

Upper Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...

Tithonian In the geological timescale, the Tithonian is the latest age of the Late Jurassic Epoch and the uppermost stage of the Upper Jurassic Series. It spans the time between 152.1 ± 4 Ma and 145.0 ± 4 Ma (million years ago). It is preceded by ...

, to the early

Lower Cretaceous Lower may refer to: * Lower (surname) * Lower Township, New Jersey *Lower Receiver (firearms) * Lower Wick Gloucestershire, England See also *Nizhny Nizhny (russian: Ни́жний; masculine), Nizhnyaya (; feminine), or Nizhneye (russian: Н� ...

Berriasian In the geological timescale, the Berriasian is an age/stage of the Early/Lower Cretaceous. It is the oldest subdivision in the entire Cretaceous. It has been taken to span the time between 145.0 ± 4.0 Ma and 139.8 ± 3.0 Ma (million years ag ...

and has a fairly worldwide distribution.Paleobiology Database - ''Berriasella''
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was crea ...

.org

Distribution

Fossils of ''Berriasella'' have been found in: ;Jurassic * Latady and Himalia Ridge Formations, Antarctica *

Los Molles Formation The Los Molles Formation is a geologic formation of Early to Middle Jurassic age, located at northern and central part of Neuquén Basin at Mendoza Shelf in Argentina. It is overlain by the Niyeu–Lajas Formation.McIlroy et al., 2005 Descrip ...

, Argentina *

Guasasa Formation The Guasasa Formation is a geologic formation in Cuba. It is Tithonian to Early Valanginian in age and contains fossils of ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. ...

, Cuba * Chia Gara Formation, Iraq *

Muktinath Muktinath is a Vishnu temple, sacred to both Hindus and Buddhists. It is located in Muktinath Valley at the foot of the Thorong La mountain pass in Mustang, Nepal. It is one of the world's highest temples (altitude 3,800 m). Within Hinduism, it ...

, Nepal * Punta Moreno Formation, Peru * Hajar Formation, Yemen ;Cretaceous * President Beaches Formation, Antarctica * Guchuochun Formation, China *

Buenavista Breccia Buenavista may refer to: Colombia * Buenavista, Boyacá, a municipality in the department of Boyacá * Buenavista, Córdoba, a municipality in the department of Córdoba * Buenavista, Sucre, a municipality in the department of Sucre * Buenavista ...

, Colombia * Stramberk Formation, Czech Republic * France * Szentivánhegy Limestone, Hungary * Giumal Sandstone, India * Shal Formation, Iran * Chia Gara Formation, Iraq * Carbonera and Taraises Formations, Mexico * Pieniny Limestone and Rogozno Formation, Poland * Chigan Formation, Russia * Tollo and Miravetes Formations, Spain * Dvuyakornaya Formation, Ukraine * Hajar Formation, Yemen

Distribution

References

Further reading