Name GEOL 104 Dinosaurs A Natural History Homework 6 The Cretaceous Tertiary Extinction DUE Fri Dec 8 Part I Victims and Survivors Below is a list of various taxa Indicate by letter if the taxon A Was already extinct by the Cretaceous Tertiary Boundary X Died out at the Cretaceous Tertiary Boundary S Survived the Cretaceous Tertiary Boundary although it may have died out subsequently 1 Inoceramids 2 Ammonoids 3 Plesiosaurs 4 Ichthyosaurs 5 Placentals 6 Rudists 7 Multituberculates 8 Champsosaurs 9 Coccolithophorids 10 Pterosaurs 11 Ornithischia Extra Credit Saurischia Part II Causal Agents and Physical Evidence There are three environmental changes at or near the K T boundary that might have had the potential to produce the extinction events These three potential causal agents were introduced in class but here they are again Chicxulub Impact collision of a 10 15 km asteroid with the Earth at 65 5 Ma blasting an enormous volume of ash and dust into the atmosphere Expected effects o Blotted out sunlight stopping photosynthesis on land and sea causing starvation of herbivores causing starvation of carnivores o Possibly other short term effects blast wave increased acid rain wildfires etc o Immediate effects would be very intense but very short term 1 day to a year or less Deccan Traps Volcanism eruption of vast lava fields in western India starting around 66 Ma and lasting for a million years or less sending huge amounts of ash and dust into atmosphere Expected effects o Blotted out sunlight stopping photosynthesis on land and sea causing starvation of herbivores causing starvation of carnivores o Possibly also increased amounts of various pollutants into atmosphere o Immediate effects would be intense and extend over hundreds of thousands of years prior to K T boundary Maastrichtian Regression huge drop in global sea levels exposing large areas of land previously submerged starting around 69 Ma and ending around 65 Ma Expected effects o Change planetary albedo reflectivity changing both amount of heat absorbed by Earth and that heat s distribution o Change in oceanic circulation patterns o Decrease in oceanic productivity how much nutrients are produced because of loss of warm shallow seas o Increase in continentality of climate more intense summers and winters o Immediate effects would be gradual and extend over millions of years 1 Name These different causal agents would leave different types of records in the rocks For each of the questions below circle the appropriate answer as to which causal agent s Asteroid Impact Deccan Traps Volcanism or Maastrichtian Regression would leave such a record 12 Ash from very short term but global forest fires A Asteroid Impact B Deccan Traps Volcanism D A B but not C E A B C C Maastrichtian Regression 13 Replacement of one set of plant fossils over the last several million years of the Cretaceous A Asteroid Impact B Deccan Traps Volcanism D A B but not C E A B C C Maastrichtian Regression 14 Iridium spike A Asteroid Impact B Deccan Traps Volcanism D A B but not C E A B C C Maastrichtian Regression 15 Chemical evidence for decreased amount of photosynthetic activity indicating reduction in sunlight A Asteroid Impact B Deccan Traps Volcanism D A B but not C E A B C C Maastrichtian Regression 16 Tsunami deposits on the Atlantic Gulf Coasts of the Americas A Asteroid Impact B Deccan Traps Volcanism D A B but not C E A B C C Maastrichtian Regression 17 Extensive lava flows in India A Asteroid Impact B Deccan Traps Volcanism D A B but not C E A B C C Maastrichtian Regression 18 Shocked quartz A Asteroid Impact B Deccan Traps Volcanism D A B but not C E A B C C Maastrichtian Regression Extra Credit All of these three agents would have had global effects However two of them would have DIRECT evidence over much of the world while one would have direct physical evidence that was much more limited in its coverage Which one would have the most restricted coverage Asteroid Impact Deccan Traps Maastrichtian Regression Circle 2 Name Part III K T Extinction Patterns in the Terrestrial Realm Let s look at the patterns of extinctions at the K T boundary for major clades of terrestrial vertebrates with emphasis on dinosaurian clades For each taxon the diet the adult size and the likely physiology warm or cold blooded are listed Note that sizes of the late Maastrichtian representatives are shown earlier or later representatives may have been larger Survivors Taxon Habitat Adult Size kg Physiology Aves various lineages Flying 1 5 most 1 Warm Crocodilians various lineages Semi aquatic 10 50 Cold Champsosaurs Semi aquatic 10 25 Cold Lepidosaurs lizards and snakes Land 1 10 most 1 Cold Turtles Land semi aquatic 1 10 Cold Mammals various lineages Land 1 5 most 1 Warm Amphibians Semi aquatic 1 Cold Victims Taxon Habitat Adult Size kg Physiology Ichthyornithiform birds Flying 1 3 most 1 Warm Enantiornithine birds Flying 1 5 most 1 Warm Deinonychosauria Land 10 Warm Oviraptorosauria Land 10 175 Warm Therizinosauroidea Land 500 3000 Warm Alvarezsauridae Land 1 5 Warm Ornithomimosauria Land 175 Warm Tyrannosauridae Land 6000 Warm Abelisauroidea Land 5 3000 Warm Titanosauria Land 30 000 Warm Ceratopsidae Land 6000 Warm Leptoceratopsidae ceratopsians Land 100 Warm Pachycephalosauria Land 200 Warm Hadrosauridae Land 6000 Warm Thescelosauridae ornithopods Land 90 Warm Rhabdodontidae ornithopods Land 150 Warm Ankylosauridae Land 3000 Warm Nodosauridae Land 2500 Warm Pterosauria Flying 5 200 Warm 3 Name 19 Many scientists have said that there is a strong size bias in survivors vs victims in the K T boundary on land Look at the data on the previous page In general the majority of the survivor groups are smaller the same size larger than the majority of the victims 20 Semi aquatic animals mostly became extinct mostly survived the K T extinction 21 Compare the list of survivors and victims Warm blooded Cold blooded animals tended to survive better than the others 22 Overall circle which of the following types of animals had the worst survivorship i e most likely to die out at the extinction A Small semi aquatic cold blooded B Small terrestrial or flying warm blooded C Large semi aquatic cold blooded D Large terrestrial or flying warm blooded 23 Small animals need less total amount of food than large ones Cold blooded animals need less total amount of food than warm blooded ones of the same size Given this information and your answer to question 23 what might this indicate about