END-CRETACEOUS MASS EXTINCTION Flashcards
Hadrosaur teeth vs. Sauropod teeth
Sauropod peg-like teeth were used to nip off vegetation and swallow it
Hadrosaur washboard-like teeth were used to grind and chew vegetation
Coevolution of herbivorous dinosaurs (teeth) and land plants with particular emphasis on the rise of angiosperms
Dinosaurs would eat everything in their path, including all the tall conifers. Over time angiosperms would be favored for their shorter reproductive cycle, while conifers would be overwhelmed by all the dinosaurs
Angiosperms were the dominant large plants in the cenozoic
What are angiosperm land plants? (think about their flowers, reproductive biology, and rapid growth to sexual maturity)
Flowering seed plants
Embryo develops in the protective ovary of the flower
Double fertilization
Angiosperms have a reproductive cycle of a few weeks vs gymnosperms 18-month reproductive cycle
When do angiosperm land plants first appear in the fossil record
Early Cretaceous
What do fossil nest sites and trackways tell us about dinosaur behavior and social structure?
The young are reared in the nest, similar to warm-blooded endotherms like birds
Communal nesting sites suggest seasonal breeding, migration, and birthing
When was the “End-Cretaceous Mass Extinction”?
It took 10,000 years for the marine ecosystems to recover from the meteor
Walter and Luis Alvarez: Gubbio, Italy
Walter - wanted to measure time on the KT (K/Pg) boundary
Louis Alvarez - knew to use the iridium to measure time
Various lines of evidence for extraterrestrial cause of End-Cretaceous Mass Extinction, what are they?
Shocked quartz
Microspherules (tektites)
Iridium anomaly
Yucatan Crater (the circle of potholes)
Do you think a bolide impact, like that at the End-Cretaceous could happen again in the future?
Yes, but maybe not the same extent as the End-Cretaceous meteor
