The Chicxulub fireball impacted Earth 66 million long time ago with the force of 10 teratons of TNT , taking out all the non - avian dinosaur and about one-half of all North American plant species . Now , researchers studying foliage fossil reveal that the dino - booming fireball eradicate evergreen plant far more than their deciduous peers – the latter were able to respond more rapidly to disorderly , post - apocalyptical weather . Sometimes the “ live tight , die unseasoned ” strategy beats out the “ wearisome but steady ” one . Theirfindingsare published inPLOS Biologythis week .
" When you appear at timber around the world today , you do n’t see many forests dominated by evergreen plant flowering plants,“Benjamin Blonder from the University of Arizonasays in anews release . " alternatively , they are dominated by deciduous species , plants that lose their leaf at some stage during the year . "
To determine whether plant specie went extinct at random or non - randomly with respect to their trait , Blonder and colleagues see about 1,000 fossil leaves of angiosperms ( flowering plants , excluding conifers ) from the Hell Creek Formation of southerly North Dakota . These couple across a 2.2 - million - yr full point bracketing the Cretaceous - Paleogene ( K - Pg ) boundary mass defunctness event .
The team measure two central trait : leaf peck per area ( LMA ) , which indicates the amount of carbon invested per foliage area , and leaf pocket-sized vein tightness ( VD ) , which signifies the ability to move carbon and H2O in and out of leaves . These traits help researchers read flora survival strategies and suss out where finical species return along the " leaf political economy spectrum . " In other words , were the leaves chunky and expensive or were they thin and cheap ?
leave of absence that are “ fast return ” ( low LMA , high VD ) are comparatively cheap to make and allow for plant to take up resource quickly under favorably warm and wet conditions ; but they ’re lost when conditions are less prosperous . Deciduous species acquiring resources in varying environments exemplify this scheme . On the other hand , allow that are “ dull return ” ( high LMA , low VD ) are more costly to make but longer populate . metal money on this remnant of the spectrum incline to live in less variable environment , and they ’re usually evergreen , like holly and English ivy .
The researchers come up that Cretaceous species with particularly high-pitched LMA mostly disappeared in the Paleogene , together with Cretaceous plant life species with low VD . An impact winter with humble light levels and in high spirits climatical variability would have selected against slow - growing evergreen species , favoring immobile strategies – which might explicate why gamy - productiveness , deciduous angiosperm woodland dominate today .
" If you think about a mass extinction triggered by a catastrophic event such as a meteorite bear upon Earth , you might reckon all species are equally likely to die,“Blonder says . " The wallop is like a reset release . The alternative hypothesis , however , is that some coinage had prop that enable them to hold up . "
