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1. What were some of the landmarks which occurred during the Mesozoic Era?

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Mesozoic Era

1. What were some of the landmarks which occurred during the Mesozoic Era?

  • 245 MYA (Mesozoic Era: Triassic Period)-Reptiles diversify, first dinosaurs, gymnosperms dominate plants, cycads, first mammals

  • 200 MYA (Mesozoic Era: Jurassic Period)- Age of dinosaurs, first birds, first angiosperms

  • 145 MYA (Mesozoic Era: Cretaceous Period)- Angiosperms diversify, dinosaurs diversify through  Period, followed by mass extinction event at end of Period (.65 MYA)

See for all the landmarks in each era.
Time of the Dinosaurs

1. What evolutionary line did mammals evolve from?

The synapsids (see
2. What is convergent evolution? Give an example

This is when two evolutionary unrelated species develop common characteristics such as in the case of whales (mammals) developing fins that resemble fish (Osteichthyes). See for other examples.

3. What was the first bird? It has characteristics of birds and dinosaurs; what are they?

Archaeopteryx lithographica has been identified as the first bird. “Archaeopteryx had a full set of teeth, a rather flat sternum ("breastbone"), a long, bony tail, gastralia ("belly ribs"), and three claws on the wing which could have still been used to grasp prey (or maybe trees). However, its feathers, wings, furcula ("wishbone") and reduced fingers are all characteristics of modern birds.”

See for more information
4. What evidence is there for dinosaurs being warm-blooded?

The evidence for dinosaurs being warm-blooded includes tomography scans that conclude that dinosaurs had hearts and a faster metabolism that more closely resemble mammals and birds than reptiles, the fact that they were top-predators (today there is only one cold-blooded top predator, the crocodile who is primarily a water-dweller), bone structure and histology, growth rates, predator/prey ratios, speed and agility, rate of evolution, similarities with birds, parental Care, bone isotope composition, insulation and arctic faunas (see the second website if you need more detailed information).

5. Describe one non-flowering plant seen before 130mya.

Ferns are an example of a non-flowering plant seen before 130mya that have fronds divided into leaflets.

6. What advantages do flowering plants have over non-flowering plants?

Advantages include having a fleshy fruit protecting the seeds, their leaves and petals are adapted to attract pollinators, they have specialized seed and pollen producing structure, more dispersal mechanisms and exhibit great variety.


7. What caused the K-T extinction of the dinosaurs?

There are many extinction theories to account for the disappearance of the dinosaurs at the K-T (Cretaceous period toTertiary period) boundary. These theories revolve around a global climate change though the cause is hotly debated and some theories include:


-Tectonic plate movement

-Meteor impact

See and

Cenozoic Era

What are the highlights from this era?

  • 65 MYA (Cenozoic Era: Paleocene Epoch)- modern fauna and flora begins to take shape

  • 40 MYA (Cenozoic Era: Eocene-Oligocene Epoch)- Radiation of mammals, eutherian and marsupial in parallel

  • 5 MYA (Cenozoic Era: Pliocene Epoch)- Earliest hominid fossils in Africa, Australopithecines

  • 2 MYA (Cenozoic Era: Pleistocene Epoch)- First members genus Homo

  • 1.5 MYA (Cenozoic Era: Pleistocene Epoch)- Homo erectus

  • 0.4-0.1 MYA (Cenozoic Era: Holocene Epoch)- Homo neanderthalensis

  • 0.01 MYA (Cenozoic Era: Holocene Epoch)- Humans migrate to western hemisphere

Tropical Rockies

1. How are fossils identified as mammals?

Fossils are identified as mammals based on skeletal (number of bones in skull is smaller than reptiles, lower jaw is composed of one bone, three middle ear bones as opposed to one found in reptiles, no hole in top of skull as in reptiles for pineal gland and skull is attached to spine by two points instead of one) and dental patterns (mammals have several different types of teeth).


2. What groups of organisms survived the KT extinction?

Mammals survived the extinction because they could live off of plant debris, insects and eventually other mammals.

3. What affect did the demise of the dinosaurs have for current plants and animals?

The mass extinction of the dinosaurs and many other species led to a massive radiation of biodiversity. The top predators were lost allowing divergence and competition among surviving species and offered new niches to be occupied.

4. What characteristics did primitive primates show which are similar to humans?

Similar characteristics include fingernails, opposable thumbs, dental pattern, five-fingered hand and forward facing binocular vison.


Expanding Grasslands

1. What are some new animal behaviors and what are their advantages?

New behaviors included foraging and herbivore to carnivore transitions.
2. Name three animals that were present 50mya and can still be found today?


-Army ants


See for a complete list
3. What are two ways of life were established as climate warmed and dried?

The water column ecology diversified with a reliance on phytoplankton and warm-blooded animals flourished.

4. Ancestors of whales lived on land. Why did they take to the water?

It is believed that they took to the water to fill an ecological niche left vacant after the K-T extinction. Competition for resources on land was intense and so the whales adapted to a specialized niche, the ocean.

5. What scientific evidence is human evolution based on?

Evidence for human evolution consists of fossil comparisons and mitochondrial DNA evidence of relatedness.

6. Are humans more closely related to orangutans or monkeys?


8. What types of changes occurred in humans evolution from the time of Lucy until current man?

-Adaptation to diverse food sources (3mya)

-Adaptation in chewing (2.7mya)

-Increased height (2.4mya)

-Diet shifted to more meat, loss of specialized herbivore structures (2.3mya)

-Increased brain size and development (2.3mya)

-Use of tools (2mya)

-Body heat regulation through sweating and loss of hair covered skin (1.9mya)

-Narrowing of pelvic bone and ribs (1.9mya)

-Opening of female’s pelvic to birth babies with bigger brains (1.9mya)

-Many social changes also occurred


(if you press on last link on the page it will take you to the next stage in evolution)

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