Geoscience Reference
In-Depth Information
To be sure, insects—especially pollinators, like bees, wasps, beetles, and oth-
ers—were a big part of this picture, too. But once theropods, both non-avian and
avian, began climbing trees and using powered flight, they must have also sought
food resources in those trees, which surely included fruit. In some of the earliest
studies done of this phenomenon, ecologists estimated that about half to 90% of all
fruitedtreesofmodernforestsareadaptedforbirdsandmammalstoeatthem.Sim-
ilarly, dinosaurs, including birds, must have been powerful change agents, spread-
ing flowering plants to places they never could have reached through other means.
These actions even brought about changes that later benefited the evolution of tree-
dwelling mammals, including thoseinourownlineage. Lookatafriendorrelative,
then yourself, and thank a dinosaur for helping to shape the ecosystems that aided
your shared ecological and evolutionary legacy.
The way Mesozoic non-avian dinosaurs and birds accomplished this moment-
ous task, which was carried on as an evolutionary tradition by birds throughout the
Cenozoic Era, was through their poop. Very simply, flowering plants produce seeds
covered by delicious and nutritious fruit. Birds are among the animals that eat these
fruits, seeds and all, which they carry in their bellies. Birds then later deposit the
seeds somewhere else, while helpfully covering them with a nice mix of nitrogen-
and phosphorus-rich fertilizer.
For an extreme example, recall the previously mentioned cassowaries of Aus-
traliaandNewGuinea,bigflightlessbirdsthateatthefruitsofmorethanahundred
species of flowering plants and later dump the seeds of these plants, which are en-
sconced in voluminous piles of feces. Now apply this same thought to small, flight-
worthy birds that ingest seeds in berries or other fruits, then fly away from those
plants to drop seeds tens of kilometers away. No big deal, you might think: gravity
would have done the same thing, through fruit just falling off plants, rolling a little
bit downhill, or perhaps was aided by wind or water, which, after tens of millions
of years, would have very gradually extended the geographic range of those plants.
