Sunday, May 18, 2008

Gastropoda - Caenogastropoda

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The Caenogastropoda are one of the most diverse sub-class of Gastropoda and include a wide range of shell shapes, habitats and uses for facies reconstruction. A short description of the most useful orders will be presented.

Architaeniglossa

Viviparus
  • shell shapes gyrocscopic to speroidal
  • worldwide in freshwater
  • Jura - today (species since Carboniferous)
  • drainage lakes, rivers
  • shell primarily organic, mineralisation in the uterus
Ampullaria
  • Apple Snail
  • today: South America, Asia, Africa
  • Cretaceous - today
  • shell sinistral, slightly asymmetric
  • forms clutch
  • subtropical - tropical
  • can withstand droughts
  • terrestrial
Cerithimorpha

Cerithium
  • perhaps oldest Caenogastropoda
  • Aperture not holostome
  • Trias - today
  • warm lakes, also marine
  • photic zone, Mangroves
  • herbivor, detritus
  • soft grounds
  • may cement itself to surface
Melanoides
  • marine - brackish
  • worldwide in tropics
  • Miocene - today
  • Parthenogenesis
  • high resistance
  • rhipidogloss
Melanopsis
  • today: mainly in New Zealand
  • typical for Paratethys
  • eggs in estuary conditions, adults in freshwater
Littorinimorpha

Littorina
  • marine
  • tidal zone and rocky shores
  • herbivor
  • since Triassic/Palaeocene?
  • vivipar
  • thick shell, gyroscopic shape
  • Apex blunt
  • Aperture askew
  • important for Holocene Baltic Sea stratigraphy
Hydrobia
  • small, long-cone-shaped
  • mainly freshwater but also marine-brackish
  • gigantism
  • Jurassic - today
  • decoiled forms
  • herbivor
  • wide suture
Strombimorpha
  • low to high-trochispiral shell
  • Aperture with channe or newel
  • Ordovician??? Triassic - today
Strombus
  • Bahamas
  • Jurassic - today
  • giant forms
  • epibenthic
  • shelf, sublittoral to littoral and soft substrates
  • subtropic - tropical
  • "fighting conch"
Tibia
  • deep sea
  • soft substrates, cannot move in sediment
  • long siphonal tube
  • carnivor?
Heteropoda
  • shell mainly reduced
  • foot changed to fins
  • carnivor
  • trunk-like head
  • lower Jurassic - today
  • endoplanctonic
  • facies independent
Atlanta
  • planispiral and keel
  • Jurassic/Palaeocene??? - today
  • mm - cm size
  • Protoconch always varied
  • Teleconch planispiral
  • in all oceans
Ptenoglossa
  • named after ptenogloss Radula
Janthina
  • purple - blueish color
  • Cenozoic
  • foam raft
  • carnivor (jellyfish)
Epitonium
  • tropics
  • benthic
  • carnivor
  • Triassic - today
  • cone-shaped, coiled
  • near-by algae or sea anemones
To be continued...

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