''Mariella'' is an

ammonoid 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 cuttlefish) ...

genus, named by Nowak (1916) from the upper

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0.9 M ...

and

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...

stages of the mid

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 th ...

, included in the

Turrilitidae Turrilitidae is a family of extinct heteromorph ammonite cephalopods. All members had shells that coiled helically that tended to resemble auger shells. The ecological roles turrilitids played is largely unknown, as experts are still speculati ...

. Its type is ''Turrilites bergeri''

Description

''Mariella'' resembles ''

Turrilites ''Turrilites'' is a genus of helically coiled ammonoid cephalopods from the lower part of the Upper Cretaceous (Cenomanian and Turonian); generally included in the Ancyloceratina. Previously (Arkell, 1957) it was included in the ammonoid suborder ...

'' in general form. The shell is asymmetric, closely wound in a long expanding trochoidal spire. Ribs are slightly oblique and are rather feeble, each with 4 more or less equally spaced tubercles. ''Turrilites'' differs primarily in being more strongly ribbed and in having a more oval aperture.

Distribution

Fossils of ''Mariella'' have been found in Angola, Antarctica, Australia, Brazil, Canada (British Columbia), Colombia (

Hiló Formation The Hiló Formation ( es, Formación Hiló, Kih) is a geological formation of the Altiplano Cundiboyacense, Eastern Ranges of the Colombian Andes. The predominantly shale formation dates to the Middle Cretaceous period; Late Albian to Early Cenom ...

), France, Germany, Iran, Japan, Kazakhstan, Madagascar, Mexico, Mozambique, New Zealand, South Africa, Spain, Switzerland, Turkmenistan, Ukraine, the United Kingdom, and the United States (California, Texas, Oregon).''Mariella''
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org

Description

Distribution

References

Further reading