K-Pg Extinction Flashcards
mass extinction
global disappearance of large # of species within a short geological time
background extinction
isolated extinction of species
last dinos in north america
ceratopsians
hadrosaurs & tyrannosaurs
pachycephalosaur, ankylosaur, ornithomimid, oviraptorsaurs
dromaesaurs, troodontids
Maatrichtian
last segment of exposed Cretaceous strata
what land animals went extinct?
all non-avian dinos
all pterosaurs (flying reptiles)
mammals that were purely herb/carnivore
terrestrial plants
what marine animals went extinct?
marine reptiles (plesiosaurs, mosasaurs)
invertebrates (ammonoids, rudist bivalves, inoceramid bivalve)
microbiota like phytoplankton and foraminifora
boundary clay
thin layer seen at the K-Pg boundary
contrast strata before and after K-T Boundary
large abundance and variety of foraminifora plankton
large iridium deposits after K-T; boulders dumped all over the place, sediments from other places being torn
Walter Alvarez
geologist who focused on the contrast of strata on either side of boundary
Luiz Alvarez
physicist
tested for rare Earth elements
found large amounts of iridium deposits; not just collection of space dust
tektites
large glass beads
spherules
microtektites that rained down
shocked quartz
deformed quartz grains
crisscrossed with shock lamelle after minerals inside were blown away
tsunami deposits
coastlines near Gulf of Mexico covered in seafloor sediments
backwash; coastal sediments dragged back including glass spherules and vertebrate bones
1991 Chicxulub Crater
bowl shaped structure near Yucatan Peninsula & Gulf of Mexico
raised ridge surrounded collapsed crust
underlying layer of melted rock ~66Ma old, covered in iridium
debris fell into crater, on top of melted rock
shocked quartz grains all over
