Cephalopods Flashcards
What are Cephalopods?
phylum: Mollusca
Class: cephlapod
–> Sub-class
*Exclusively marine
-Bilateral body symmetry
-Temporal range: late Cambrian to present
-Became dominant in the Ordivician
Cephalopod sub-classes
Coleoids (squids, internal skeleton if any) and Nautiloids (external shell/skeleton)
What are nautiloids?
External shell/skeleton
What are Coleoids?
Internal skeleton (if any)
When have nautiloids exited?
Cambrian to recent
Give an example of a Coleoids
Belemnites
Temporal range: Devonian to Cretaceous.
Most abundant: Jurassic and Cretaceous
Give an example of a nautiloid?
Orthocone, Nautilus
Basic morphology of an Orthocone
Camerae
Septa
Septal necks
phragmocone
body chamber
growth lines
hyponomic sinus
Nautilus
Whorls
Camerae
Septa
Septal necks
Phragmocone
Body chambre
(These are related to ammonoids but are not ammonoids)
The name 3 types of ammonoids and give their age ranges (age ranges and diagnostic features)
gonotites, ceriotites and ammonites
Temporal range of gonotites
Devonian to Permian
Temporal range of Ceriotites
Late Permian to Triassic
Temporal range of Ammonites
Jurassic to Cretaceous
Temporal range of Nautiloid
Cambrian to recent
How to tell the difference between a Nautiloid and Ammonoids?
Position of the siphuncle
For a nautiloid: siphuncle ran through the middle of the septa, the chamber walls.
For Ammonoid: ventral siphuncle (meaning it is at the side of the chamber)
