Flashcards
Phanerozoic [Paleozoic cont...] (23)
Flashcards do conjunto (9)
- 1☼What is the Cambrian Explosion?☼-Sudden evolutionary appearance of abundant body fossils, trace fossils, & microfossils near Precambrian - Cambrian boundary.
- 2Why did the Cambrian Explosion occur?We're not sure
- 3What causes have been suggested?-Supercontinent breakup
-End of Snowball Earth glaciations
-"start" of predation & increase in ecosystem complexity
-Increase in atmospheric O2
-Evolution of complex organs (i.e., eyes)
-Sudden increase in body size - 4Cambrian rocks have lots of fossils in them - what kinds of fossils are they?Mostly body fossils of hard parts plus trace fossils/burrows plus microfossils
- 5What is the hypothesized origin of hard parts (hard shells/hard skeletons)? (Biomineralization)-Organisms secrete salts as waste
-A mutation may have prevented efficient excretion of waste salts
-Salts accumulated along the outer edges of the body - 6☼What are the advantages & disadvantages of having hard parts?☼i) Provides mechanical strength
ii) Supports soft tissues
iii) Protection from predators
vi) Continuous external shell & growth?
vii) Continuous external shell & movement? - 7What solutions have evolved in organisms to deal with the disadvantages?-Molting or shedding: grow quick after molt, then form new skeleton.
-Development of joints & many-parted skeletons - 8☼What is the # 1 most common group of fossils in Cambrian rocks?☼Trilobites
-90% of all Cambrian fossils (but not only creature) - 9What other kinds of organisms are found in Cambrian rocks?Brachiopods, molluscs, sponges, hyoliths, weird echinoderms, weird microfossils
Informações
- Descrição
- Test 2 Packet XII
- Criado por
- Jake Fredrickson · mar 2018
- Atualizado
- 25 mar 2018
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- 2
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