''Phylloceras'' is an extinct genus of
ammonoid
Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...
cephalopods
A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...
belonging to the family
Phylloceratidae
Phylloceratidae is the predominant family of the Phylloceratina with some 15 or more genera found in rocks ranging from the Lower Jurassic to the Upper Cretaceous. Members of the Phylloceratidae are characterized by smooth, involute shells with v ...
. These
nekton
Nekton or necton (from the ) is any aquatic organism that can actively and persistently propel itself through a water column (i.e. swimming) without touching the bottom. Nektons generally have powerful tails and appendages (e.g. fins, pleopods, ...
ic carnivores lived from Early
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 (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...
(
Hettangian
The Hettangian is the earliest age and lowest stage of the Jurassic Period of the geologic timescale. It spans the time between 201.3 ± 0.2 Ma and 199.3 ± 0.3 Ma (million years ago). The Hettangian follows the Rhaetian (part of the Triass ...
age) to Late
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
(
Maastrichtian
The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...
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 extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...
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
Fossil taxa described in 1865
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