''Phylloceras'' is an extinct genus of

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) ...

cephalopods 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, an ...

belonging to the family Phylloceratidae. These nektonic carnivores lived from Early Jurassic (

Hettangian The Hettangian is the earliest age and lowest stage of the Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (My ...

age) to Late Cretaceous ( Maastrichtian age) (from 201.30 to 66.043 Ma).

Description

Shells of ''Phylloceras'' can reach a diameter of about , with a maximum of about . These primitive

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 cuttlefish) ...

s had an involute, laterally flattened shell with a regular shell opening. They were almost smooth and the ornamentation was virtually absent or, at most, represented by simple growth lines barely visible. The striking sinuous suture lines were characteristic of this genus. They are reminiscent, in some ways, of the leaves of plants (hence the name ''Phylloceras'', which means " leaf-horn").

Distribution

Fossils of species within this genus have been found all over the world, particularly in Western Europe.

References

* Cyril Walker & David Ward (1993) - Fossielen: Sesam Natuur Handboeken, Bosch & Keuning, Baarn. Jurassic ammonites Cretaceous ammonites Ammonites of Europe Hettangian genus first appearances Sinemurian genera Pliensbachian genera Toarcian genera Aalenian genera Bajocian genera Bathonian genera Callovian genera Oxfordian genera Kimmeridgian genera Tithonian genera Berriasian genera Valanginian genera Hauterivian genera Barremian genera Aptian genera Albian genera Cenomanian genera Turonian genera Coniacian genera Santonian genera Campanian genera Maastrichtian genus extinctions Ammonites of South America Paja Formation Hasle Formation {{ammonite-stub