''Calycoceras'' is an extinct genus of

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

s belonging to the subclass

Ammonoidea 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 cuttle ...

and

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Acanthoceratidae Acanthoceratidae is an extinct family of acanthoceratoid cephalopods in the order Ammonitida, known from the Upper Cretaceous. The type genus is '' Acanthoceras''. Diagnosis Acanthoceratidae species are strongly tuberculate with at least umbil ...

that lived during the

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 ...

stage of the Late

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 ...

, 100-94 Mya. Their shells had ornate ribs.

Species

*''C. algeriense'' Kennedy & Gale, 2017 *''C. annulatum'' Collignon, 1964 *''C. asiaticum'' (Jimbo, 1894)William James Kennedy, Herbert Christian Klinger (2010
Cretaceous faunas from Zululand and Natal, South Africa. The ammonite subfamily Acanthoceratinae de Grossouvre, 1894
/ref> **''C. a. asiaticum'' (Jimbo, 1894) **''C. a. spinosum'' (Kossmat, 1897) *''C. besairieri'' Collignon, 1937 *''C. boreale'' Kennedy, Cobban & Landman, 1996 *''C. dromense'' (Thomel, 1972) *''C. cenomanense'' (d’Archiac, 1846) *''C. navicularis'' Mantell, 1822 *''C. orientale'' Matsumoto, Saito & Fukada *''C. paucinodatum'' (Crick) *''C. tarrantense''The Paleobiology Database
/ref>

Distribution

''Calycoceras'' species may be found in the Cretaceous of Angola, Antarctica, Canada (British Columbia), France, Germany, Japan, Nigeria, Oman, Russia, the United Kingdom, United States (Alaska, Arizona, Kansas, New Mexico, South Dakota, Utah) ''C. asiaticum'' may be found in the

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

, Southern

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

, northern and southern

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

Romania Romania ( ; ro, România ) is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern, and Southeast Europe, Southeastern Europe. It borders Bulgaria to the south, Ukraine to the north, Hungary to the west, S ...

Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedon ...

Tunisia ) , image_map = Tunisia location (orthographic projection).svg , map_caption = Location of Tunisia in northern Africa , image_map2 = , capital = Tunis , largest_city = capital , ...

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

, south

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

and

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

.Paleobiology Database
/ref> ''C. cenomanense'' may be found in the Cenomanian of United Kingdom, France and Madagascar. Calycoceras orientale

Description

Shells of ''Calycoceras asiaticum'' may reach a diameter of about . The larger

phragmocone The phragmocone is the chambered portion of the shell of a cephalopod. It is divided by septa into camerae. In most nautiloids and ammonoids, the phragmocone is a long, straight, curved, or coiled structure, in which the camarae are linked by a ...

s may reach in diameter. Coiling is moderately involute. All ribs show strong subspinose tubercles. ''C. asiaticum asiaticum'' and ''C. asiaticum spinosum'' are very similar, the latter has much more robust tuberculation.Ammonites
/ref>

References

Acanthoceratidae Ammonitida genera Cretaceous ammonites Late Cretaceous ammonites of North America Late Cretaceous cephalopods of North America Late Cretaceous animals of Africa Cenomanian life {{Cretaceous-animal-stub