Belemnites Flashcards
What is their phylum and class
Mollusca
Cephalopoda
Is the form extinct or extant
Extinct
What kind of shell do they have and what links them
Chambered shell
Linked by a siphuncle
What is the part that is normally preserved
The guard (a bullet shaped calcite mass)
What is in the anterior of the guard
A chambered phragmocone
What do they chambers of phragmocone represent
The growth stages of the animal with the last body chamber open
What were the chambers used for
Buoyancy
What adjusts the buoyancy
The siphuncle which links all of the tubes up and controlled the amount of gas in each chamber
What is the proostracum
Extension of the guard which may of provided some protection
What is the protoconch
The first chamber
What is their mode of life
Swam just like squid
Nektonic
Could swim both vertically and horizontally
Tentacles used jet propulsion
How do these and animals provide such great evidence for the palaeocurrent
Upon death the guards fell down to the sea floor and aligned up with the current
