lec 7- fossils and evolution Flashcards
what are fossils?
physical evidence of past life, include original tissue, and evidence of activity like tracks trails and burrows
what preserves organisms that went extinct into fossils?
Amber, frozen sediments, petrification and fine sediments
what are the three types of fossils?
-compressions: flattened fossil that still retains some organic material/ carbon film
-impressions: an imprint that has no organic material/ carbon film
-organic tissue: where the whole organism is perfectly preserved due to slowed decay, occurs in amber and permafrost
of what age is the bedrock under SFU, and what type of fossils are abundant?
Eocene age, has abundant plant fossils
what are some fossils that show behaviour?
fossilized eggs, tracks, mating, live birth, diet
what is the point of the crest on hadrosaurs and where does it connect too?
-it helps communicate and helped with species recognition (sexual selection)
-connects to the nose
what is the earliest known life?
stromatolites which were fossilized cyanobacteria that did photosynthesis
what is the earliest eukaryotic life fossil of?
algae, date was 1.6 Ga
what is the ancestor of all plants?
green algae which first appeared 750 Ma
what is believed to be the first animal?
sponges, don’t have any tissue and are simple with many fossils
what eon did the early sponges live in?
ediacaran (600 Ma, before cambrian explosion)
what was the life during the ediacaran like?
sessile, slow moving, soft shelled, surface feeders on microbial mats
where were the first ediacaran fossils discovered?
Ediacara hills Australia
what was the beginning of the phanerozoic (flowering of animal life)?
the cambrian
what is the cambrian explosion and when did it occur?
it is the rapid diversification of life and it occurred during 542-490 Ma
what is the most famous Lagerstatte and who found it?
The Burgess Shale in B.C. and it was found by Charles Doolittle Walcott
why did fossils get preserved so well in the Burgess Shale?
because the organisms got rapidly buried in fine sediments with low O2 exposure
what was the main apex predator of the Cambrian?
Anomalocaris
what did predators in the Cambrian initiate the co-evolution of?
ways to protect from predators, like spines, shells, scales and behaviours like burrowing
what are the hypotheses behind the rapid diversification during the Cambrian explosion?
-rising oxygen levels (due to photosynthesis) allowed evolution of larger active animals
-predators evolved to eat sessile and slow moving animals which also resulted in the evolution of anti-predator adaptations
-appearance of Hox genes (new body plans)
what did mid-precambrian oxygen form in oceans?
rust deposits (banded iron), oxygen from photosynthesis combines with iron to form iron oxide in oceans and rusts
what phylum are the vertebrates in?
the phylum chordata which are the ancestors of the first vertebrates known as bony fish
what is the notochord?
a part of the backbone seen in all vertebrates
during what time period is the first fossil evidence of chordates?
Cambrian
