A: Bears Ears was 1.35 million acres. Trump sliced it into two national monuments totaling just under 229,000 acres.
Grand Staircase-Escalante was 1.9 million acres. Trump split it into three national monuments totaling just over 1 million acres.
Q: Is it just scenic lands that could now be developed?
A: No. Much of the mesas, canyons and mountains of Bears Ears are sacred to Native American tribes, including the Navajo, Zuni, Ute Mountain and Hopi. Its archaeological treasures include rock art, ancient cliff dwellings and ceremonial sites.
Grand Staircase-Escalante is one of the world's premier sites for paleontological discoveries. More than two dozen new species of dinosaurs have been discovered there in the 21 years since Clinton preserved it as a national monument.
Fossils preserved from the Late Cretaceous period, from 100 million to 66 million years ago, have given scientists an unparalleled view of life on Earth in an era when the climate was hotter, the air contained a lot more carbon dioxide and the sea level was extremely high.
Q: Do the boundary changes jeopardize any of the research?
A: The Society of Vertebrate Paleontology, a nonpartisan group of scientists, says the removal of national monument protections is a serious setback.
"Trump's claim that the new boundaries protect the resources named in the original proclamations is simply untrue," said P. David Polly, an Indiana University professor who serves as the group's president.
"Almost all of the Triassic period, the time when dinosaurs originated, has been purged from Grand Staircase-Escalante, as have the unique Cretaceous mammals and the amazing marine reptiles from the Tropic Shale that justified founding the monument in 1996."