Lecture 14 Flashcards
Cephalopoda life modes
Vagile and nektonic; herd behaviour
Cephalopoda stratigraphic range
Cambrian - recent
Cephalopoda basic structure
Single shell with bilateral body symmetry
Mostly external (ectocochlia), sometimes internal (endocochlia)
Internal segmentation (ballast)
Cephalopoda novel/important structures
Large brain, elaborate sensory organs
Arms or tentacles, beak with mandibles
Cephalopoda location of radula
Inside beak or rostrum
Cephalopoda ink sac purpose
Contain a pigmented mucus that they can excrete to confuse predators
Nautilodea basic structure
External shell: Straight, curved, or coiled
Simple sutures
Siphuncle central or subcentral
Nautilodea stratigraphic range
Cambrian - present
Diversity of Nautilodea during the Paleozoic
Broad
Nautilodea composition
Aragonite shell
Nautilodea structures
Septa divide shell into different chambers filled with gas and water, except final chamber, where the organism “resides”
Orthocone
Vertical movement
Crytocone
Horizontal movement
Gyrocone
Convergence between centre of gravity and floatability
Phragmocone
Partitioned (fragmented) into chambers separated by septa secreted by the organism
Living chamber
Where organism resides
Hyponome
Funnel through which water is ejected; locomotion through propulsion; can be directed into different directions
Ammonoidea cardinal features
External shell; Coiled or straight, ribbed
Complex sutures
Siphuncle ventral or nearly dorsal
Ammonoidea stratigraphic range
Devonian - Cretaceous
Are members of Ammonoidea still around today?
No they are extinct
Ammonoidea abundance of fossils
Great
Chemical composition of Ammonoidea external shell
Araoginite
What is special about the external shells of Ammonoidea?
Often ornamented (spines, bumps, undulations…)
4 forms of sutures in Ammonoidea
Clymenid, goniatitic, ceratitic, ammonitic
Coleoidiea shell
Internal shell or shell-less (calcite guard or rostrum)
Straight or coiled
Siphuncle may be absent
Coleoidiea stratigraphic range
Carboniferous - recent
What 2 main species does Coleoidiea contain?
Belemnites, cuttlefish
Coleoidiea phragmocone
Segmented part
Coleoidiea rostrum/guard
Envelopes the phragmocone; often cigar-shaped, composed of lamellar calcite/most easily preserved part
