The Mesozoic Garden

Question 1

What type of plant evolved during the Mesozoic?

Answer 1

Angiosperms.

Question 2

What plant specifically became really important and prolific during the Mesozoic?

Answer 2

Non flowering seed plants, the gymnosperms.

Question 3

Describe Early Triassic plant communities.

Answer 3

Interior of Pangea was mostly desert, plants grew in places of higher latitude and sources of water. Forests weren’t common and plants would be dominated by herbaceous forms like seed ferns and some conifer.

Question 4

When did gymnosperms start to become more important?

Answer 4

Late Triassic

Question 5

What species is considered a Lazarus Taxon and was found again in 1994?

Answer 5

Wollemi Pine.

Question 6

What were the dominant trees in the Jurassic?

Answer 6

Conifers and cycads (both gymnosperms). Jurassic known as “Age of the Cycads.”

Question 7

What was the dominant gymnosperm during the Early Cretaceous?

Answer 7

Conifer. Ended the “Age of the Cycads.”

Question 8

What plants became increasingly important during the Early Cretaceous?

Answer 8

Angiosperms. By the end of Cretaceous, they were far more abundant and diverse than the conifers.

Question 9

What difference allowed angiosperms to dominate land cropped by dinos?

Answer 9

Angiosperms recovery quickly when cropped and spread quickly.

Question 10

What’s another important development during the Cretaceous?

Answer 10

Evolution of grass.

Question 11

What is coevolution?

Answer 11

When changes in at least two species affect each other’s evolution. Ex. Newt has toxin that discourages snake to eat it. Snake evolves resistance and newts increase potency of toxins.

Question 12

Where do bacteria that produce newt toxins live?

Answer 12

In tiny glands on skin.

Question 13

How does the toxin subdue the predator?

Answer 13

Toxin paralyzes muscles and stops the diaphragm and the heart.

Question 14

Describe the coevolution between the bullhorn acacia tree and the acacia ant.

Answer 14

Queen is enticed by odour of the tree and lays eggs in the tree’s hollow thorns. Acacia provides shelter and nectar from the base of tree leaves. It also provides packets of oil and protein at tips of leaves. Ants attack animals that come by acacia and remove seeds of other plants.

Question 15

Describe the evidence of coevolution in gymnosperms.

Answer 15

Insects called thrips were found in amber with pollen grains stuck to their abdomens. Hairs on abdomen and pollen grains appear to be adapted to carry or be carried.

Question 16

How did coevolution in gymnosperms develop?

Answer 16

Could have come from gingkos. Insects may have collected pollen from a male tree and then brought it to larvae sheltered in female tree ovules.

Question 17

Describe coevolution in angiosperms

Answer 17

Flower traits like colour, odour, flowering time, shape etc. is changed for pollinators. Insect brings pollen from stamen to stigma.

Question 18

What features were coevolved from the relationship between angiosperms and animals?

Answer 18

Scent: to determine how far a flower was or which area had nectar or act as timing mechanism.
Colour: white, blue, purple attracts insects. Red, orange attracts birds.
Nectar: good for animals and placed in place where they get covered in pollen.
Fruit: cue to know when it is ripe and ready to be distributed.
Mimicry: ex. Fly orchid flower looks like the fly orchid and excrete female sex pheromones.

Question 19

What were the first flowers of the Cretaceous?

Answer 19

Probably resembled magnolias and pollinators were probably generalists.

Question 20

More specifically, what are angiosperms?

Answer 20

Plants that produce fruit or flower around their seeds. Seeds contain endosperm that provide nutrients for seedling. Rely on pollinators.

Question 21

Why is the evolution of angiosperms a mystery?

Answer 21

They seem to emerge fully formed in the Cretaceous.

Question 22

What is the most primitive flowering plant?

Answer 22

Amborella. From the Island of Grande Terre of New Caledonia.

Question 23

Describe the Amborella.

Answer 23

Produces either make or female flowers but not at the same time (gymnosperm characteristic). Shows that tropical upland forest setting would be candidate for environment where angiosperms evolved.

Question 24

What’s the other candidate for the environment of first flowering plant?

Answer 24

Aquatic. The Nymphaeales (water lily group) are pretty close to the base of the chart. Aquatic hypothesis is supported by one of oldest flowering plants fossils, Archaefructus from Yixian Formation in NE China.

Question 25

How did we get modern flowers?

Answer 25

Could have evolved from primitive angiosperms with two step process. Stem that holds carpels could have shrunk until close to male stamens and then leaves would have modified to petals.

Question 26

What’s the problem with the aquatic hypothesis?

Answer 26

The rapid emergence of terrestrial plants from aquatic ancestor is concerning.

Question 27

Describe the evolution of grass.

Answer 27

Grasses are angiosperms. It was thought grass emerged after death of Mesozoic creatures until phytoliths (tiny silica structures found in leaves of certain plants including grass. Used as structural support and defense) were found in dino poop.

Question 28

What confirmed Mesozoic grass?

Answer 28

Fossil grass was found in amber dating early-middle Cretaceous.

Question 29

What was found in Myanmar?

Answer 29

Grass specimen with fungus similar to ergot on top of it.

Question 30

How did ergot and grass work together?

Answer 30

Ergot may have repelled herbivores. It’s found in LSD.