''Mucrodactylites'', which is sometimes considered to be a synonym of ''
Collina'',
[M. K. Howarth 2013. Treatise on Invertebrate Paleontology, Part L, Revised, Volume 3B, Chapter 4: Psiloceratoidea, Eoderoceratoidea, Hildoceratoidea.] is genus of
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) ...
that lived during middle to late
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 (Bifrons Subzone to lower Variabilis ammonite Zone) of
early Jurassic. Their fossils were found in Europe, northern Africa and South America. Species belonging to this genus were probably microconchs of ''
Catacoeloceras
''Catacoeloceras'' is a genus of ammonite that lived during Middle Toarcian stage of early Jurassic
The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earl ...
''. As macroconch of ''M. mucronatus'' is considered to be ''Catacoeloceras raquinianum''.
[
]
Description
Ammonites belonging to this genus have small, evolute and compressed shells with suboval to subquadrate whorl section. Primary ribs are strong, simple and bifurcating. Secondary ribs are projected.[Kovács, Z. (2014). Toarcian Dactylioceratidae (Ammonitina) from the Gerecse Mts (Hungary). Hantkeniana, 9, 45-77.]
References
Ammonitida
Toarcian life
Early Jurassic ammonites of Europe
Ammonites of Africa
Ammonites of South America
Ammonite genera
{{Ammonite-stub