Sample Problems for Mesozoic Earth
1. Both reptiles and seed plants arose to dominate the land community during the upper Paleozoic (before the beginning of the Mesozoic). This change from the earlier amphibian- and spore plant-dominated community was most likely a result of:
- A dramatic shift to cooler climates that favored seed plants and reptiles.
- Reptile herbivores were more efficient than the earlier amphibians at eating land plants.
- A dramatic shift to warmer climates that favored seed plants and reptiles.
- Amphibians were unable to digest the new tougher seed plants.
- The consolidation of continental masses to form a single, larger, dryer landmass.
2. How did the breakup of Pangea affect dinosaur diversity through time?
- Diversity decreased because their ranges were reduced as continents broke off from Pangea.
- Diversity increased as separated communities evolved independently of one another.
- Diversity decreased as some continents drifted into inhospitable climates.
- Diversity increased as the breakup indirectly led to global warming and more hospitable climates.
- Overall, there was little change in diversity as losses on some continents were balanced by gains on others.
3. During the Middle Cretaceous, angiosperms (flowering plants) largely replace the gymnosperms (conifers, cycads and gingkoes) that had dominated much of the Mesozoic. All of the following probably played a role in this dramatic change EXCEPT:
- Angiosperms tend to be more efficient at photosynthesis than gymnosperms.
- Angiosperms reproduce more quickly than gymnosperms.
- Mammals first evolved in the Cretaceous, allowing angiosperms to use their fur coats to disperse seeds.
- Unlike angiosperms, gymnosperms tend to rely on wind dispersal of seeds.
- A shift in dinosaur communities towards low browsing forms may have tipped the balance in favor of angiosperms.
4. Which is TRUE concerning the age and order of the periods that make up the Mesozoic Era?
- Of the three periods, the Triassic covered the longest interval of time.
- Of the three periods, the Jurassic covered the longest interval of time.
- All three periods were of roughly equal duration, with each period being much shorter than the time between the last dinosaurs and us.
- All three periods were of roughly equal duration, with each period being longer than the time between the last dinosaurs and us.
- There was more than twice as much time between the first and last dinosaurs, than between the last dinosaurs and us.
5. During the Triassic, the continents had only just begun to rift apart, but none of them had separated yet. So why were these rifts important?
- This early rifting led to changes in atmosphere circulation patterns that made the Mesozoic world a warmer place.
- This early rifting led to changes in ocean circulation patterns that made the Mesozoic a warmer place.
- Volcanism associated with rifting put tremendous amounts of ash into the air, making the start of the Mesozoic cooler than its end.
- These early rift valley sediments provide an unusually good record of land sediments and the earliest dinosaur fossils.
- These early rift valleys were the sites of lakes, which were the only source of water in the otherwise dry Pangea supercontinent.
6. All of the following are TRUE statements concerning the climate during the Cretaceous and Triassic periods, EXCEPT:
- Cretaceous dinosaur communities were less diverse, because there was less variation in climate between areas at that time.
- Decreased ocean overturn during the Cretaceous led to the formation of many of our society’s present oil resources.
- Increased CO2 production associated with the Cretaceous climate may have helped angiosperms become the dominant land plants.
- Despite being cooler, the Triassic land area was actually drier, because the continents were still connected as Pangea.
- During the Cretaceous, tropical plants and reef communities occurred as far north as the present Twin Cities’ latitude.
7. Some people have argued that since elephants are very susceptible to heat, then sauropods (long-necked dinos) could not have had a warm-blooded physiology because of their much greater size. Which of the following is the best evidence to counter or support this argument?
- Since dinosaurs are reptiles they must have been cold-blooded anyway, which supports their argument.
- The climate was cooler during the Mesozoic than it is now, so heat would not have been as much of a problems for sauropods.
- The climate was warmer during the Mesozoic, so the problems would have been even worse for sauropods, so they are correct.
- The body design of the sauropods is much more efficient for shedding heat than the elephants’ body design, so the argument is flawed.
- Since large animals handle heat better than small animals, the greater size of the sauropods would make them less susceptible to heat.
8. Plate tectonic processes may have contributed to a warmer Cretaceous Earth in all of the following ways, EXCEPT:
- Higher sea levels due to faster plate spreading increased the amount of water-covered areas, increasing the absorption of sun light.
- Changes in the shape of ocean basins, altered ocean current patterns, resulting in a higher rate of heat transfer to polar areas.
- Increased rates of volcanism led to higher levels of CO2 in the atmosphere, contributing to a higher level of greenhouse warming.\
- At the time Antarctica was still connected to South America and warmed by tropical currents so it was not an ice-covered continent.
- During the Cretaceous more of the continents were located in tropical areas than now, so the world was a warmer place then than now.
9. Which of the following is the most likely reason why some dinosaurs were so much larger than modern land animals.
- Big size and bulk feeding were one approach to deal with the problems of eating land plants.
- The Earth was smaller then and had less mass, so gravity was not as great a factor then as now.
- Mesozoic gymnosperms were much more nutritious than modern angiosperm plants.
- The lack of efficient modern predators meant that there was no size limit on Mesozoic herbivores.
- Big animals do not have to worry about heat loss as much as small animals so increased size reduces heat stress.
10. How might the rise of angiosperms (flowering plants) over gymnosperms (pine trees and kin) be linked to a change in dinosaur communities?
- Angiosperms are all short plants, so dinosaurs evolved into smaller sizes in order to take advantage of these new shorter plants.
- Angiosperms were less nutritious than gymnosperms, so dinosaurs could not be as large when angiosperms arose.
- A shift from high-browsing dinosaurs to low browsers favored the rise of fast growing angiosperms over slower growing gymnosperms.
- Angiosperms are more nutritious than gymnosperms, so dinosaurs could be much larger after angiosperms arose than before.
- Since dinosaurs preferred the taste of gymnosperms, they preferentially fed on those, allowing angiosperms to grow unmolested.