Cephalopoda (Chapter 13) Flashcards
Cephalopoda
head foot; most intelligent
herbivore & carnivores
good fossil record in marine sedimentology
some group w/ short time ranges but cosmopolitan - useful for zonation in biostratigraphy
major categories: nautiloidea, ammonoidea, coleoidea
Cephalopoda (morphology)
Soft tissue:
siphon - evolve for mobility
eye - well developed
tentacles - feet evolve to arm-like structures (8-60)
reproductive, anus, mouth…complex organs
Hard tissue:
radular - beak
siphuncle
thing piece of living material that regulate gas for floating
nautiloid - locate in near center
ammonite - locate near outer edge of shell
suture
featured line that makes contact with the septa and the interior of the aragonitic shell
nautiloid - very simple; single, not as wavelike line
ammonite - complicated suture pattern; especially of late mesozoic
Nautiloid
oldest & best fossil record more abundant in Paleozoic limited record for Mesozoic very limited for Cenozoic have conch - typically planispiral but also heteromorphic
straight & coiled Nautiloid
straight - heteromorph; ex: Bactritoidea
coiled - typical shape; ex: Cymatoceras
Ammonite
Mesozoic marine macrofossil; extinct at end of Mesozoic
zones 250 - 500 Ma
sexual dimorphism - females in certain groups»_space; bigger than males
have shell - typically planispiral but also heteromorphic
coiled Triassic or Jurassic ammonite
triassic - simplest suture
jurassic - more complex
coiled Cretaceous ammonite
most complex suture
many extensions, curves - finger-ilke
taxa of Cretaceous: Ancyloceratida, Ammonitida, & Phylloceratida
heteromorphic ammonite
without typical coiled shell, continous whorls not touched - no planispiral symmetry
ex: Scaphites whitfield - outer whorl unattached to previous shell
Coleoid (Belemnites)
type of mollusca
cuttlefishes, octopuses, & squids
mainly soft-bodied
sporadic fossil record
