Different Biological/Evolutionary Eras

Question 1

What are 3 famous eras in order?

Answer 1

1. paleozoic era (paleo = old)
2. Mesozoic era (meso = middle)
3. Cenozoic Era (ceno = new)

Question 2

What occurred in the paleozoic era?

Answer 2

• the cambrian explosion occurred in the paleozoic era, which the earliest fossil appearance of many major groups of living animals occured
• complex life started to form and many skeletons such as arthropods and sponges
• most of the major phyla occured
• land vertebrates started t show up
• colonization of land (fungi, plants and animals) resulted from this cambrian explosion

Question 3

What occured in the mesozoic era

Answer 3

• dinosaurs were dominant terrestrial vertebrates at this time
• the first mammals emerged! (they were small and rodent-like)
• flowering plants and insects began to diversify (took place in co-evolution, the insects provided flowers with a reproductive advantage of carrying their pollen and flowers provided food for the insects, therefore they evolved side by side)

Question 4

What occured in the cenozoic Era?

Answer 4

• this era followed mass extinctions of both terrestrial and marine animals (mainly non-avian dinosaurs)
• mammals increased in size and exploited vacated ecological niches because the dinosaurs were gone
• the global climate cooled down which resulted in new organisms arising/diversifying

Question 5

What is so special about the group of invertebrates in the animalia tree?

Answer 5

it is paraphyletic (therefore missing some species)
- 95% of animal species are invertebrates and we were all invertebrates until chordata clade broke off into a group of invertebrates that turned into verebtrates, and this makes the group paraphyletic because its also composed of species that don’t have a vertebrate but aren’t included