Cambrian Explosion Flashcards
What characteristics do Metazoans share?
1) Multicellular body formed from different kinds of cells
2) The ability to manufacture the protein collagen (binds cells together and allows cells to be mobile)
3) A reproductive cycle with gametes produced by meiosis
4) A nervous system composed of neurons (except sponges)
What technqiues are being used to find the origin of metazoans?
1) New fossil finds
2) Phylogenetic analysis of anatomical and molecualr data
3) Molecualr clock studies
4) Molecualr genetics of animal development (Evo-Devo studies)
How are animals classified early on?
Diploblastic and triploblastic
When was the late precambrian?
630 - 542 million years ago
When was the early cambrian?
542 - 530 million years ago
When was middle cambrian?
530 - 520 million years ago
What are some theories of how Ediacaran organisms fed? (They had no mouth, gut or anus)
1) The compartments contained unicellualr photosynthetic algae (unlikely due to water depth)
2) Took in substance through the body wall (particualrly food and dissolved organic matter)
3) Chemosymbiosis (utilising sulphide oxidising bacteria)
What are some of the ways Edicaran organisms have been interpreted?
1) Simple ancestors of several modern phyla (sponges, jellyfish, sea pens etc)
2) Diploblastic animals showing a range in variation not seen in living examples (MOST LIKELY)
3) An entirely separate attempt at multicellular life that ultimately failed
What did small shelly fossilised organisms likely represent?
1) An extinct phylum close to mollusca
2) Some form of annelid
What did organisms evolve during the Cambrian?
Eyes
What envioronmental reason may have caused the Cambrian Explosion?
Increased oxygen levels may have allowed animals to diversify and allow larger animals to evolve
