''Collina'' is genus of
ammonite that lived during lower to upper
Toarcian
The Toarcian is, in the ICS' geologic timescale, an age and stage in the Early or Lower Jurassic. It spans the time between 182.7 Ma (million years ago) and 174.1 Ma. It follows the Pliensbachian and is followed by the Aalenian.
The Toarcian ...
stage of
early Jurassic
The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...
. Members of this genus existed from Braunianus Subzone to Variabilis Zone. Their fossils were found in Europe, Asia, North America and South America.
It has evolved from ''
Mesodactylites''.
[Kovács, Z. (2014). Toarcian Dactylioceratidae (Ammonitina) from the Gerecse Mts (Hungary). Hantkeniana, 9, 45-77.]
Description
Whorl section is angular quadrate. Distant ribs can be bifurcating or trifurcating on the place of high ventrolateral tubercules. Secondary ribs are bent strongly forward and raised in the middle part of the venter. Size dimorphism is present in the case of this genus.
References
Dactylioceratidae
Toarcian life
Early Jurassic ammonites of Europe
Ammonites of Asia
Ammonites of North America
Ammonites of South America
Ammonitida genera
{{Ammonitina-stub