Earth's history is long. How do scientists keep track of what happened when?
How do we tell the difference between geologic ages? : Read more
How do we tell the difference between geologic ages? : Read more
Earth's history is long. How do scientists keep track of what happened when?
How do we tell the difference between geologic ages? : Read more
The change was spurred by the asteroid impact that eventually killed the nonavian dinosaurs. -- from the story
I'm sorry but, again, calling birds 'dinosaurs' angers the heck out of me. Birds are NOT dinosaurs in any real sense of the word. Birds evolved FROM dinosaurs and so belong to the same biological clade. But then, mammals evolved from therapsids and belong to that clade but we don't go around calling mammals "therapsids". Calling birds dinosaurs started as a kind of paleontological joke/fad a couple of decades ago when the clade system became widely used because some paleontogist(s) likely thought it was cute and clever. So of course, science journalists took up the fad. But it is misleading and bad biology (as well as bad science journalism).
The oldest method was to note the different stratigraphic layers, e.g. alternating sandstone, limestone, volcanic and plutonic layers. The change in layers represents a change in geological processes. These changes may occur on a regional or global scale. Internal fossils, if any, constrain the age and allow one to tie different regions together. Stable radiometric minerals, if any, allow radiometric dating and correlations across regions.Earth's history is long. How do scientists keep track of what happened when?
How do we tell the difference between geologic ages? : Read more
Science has given way too much energetic credence to the idea of an asteroid impact destroying the dinosaur epoc... an asteroid could not have possibly done as much damage as is reported...if one did possibly hit in the yucatan area as storied.
The first 10% of Earth's history is supposed to be anoxic. The biggest difficulty with the GOE and the anoxic atmosphere-ocean hypothesis is the simple fact that cyanobacteria cannot live and grow (even survive) in an ocean saturated with reduced iron. There have been no successful experiments simulating such conditions. This alone falsifies the GOE and any phylogenetic theories about the LUCA that rely on that.
I'm sorry but, again, calling birds 'dinosaurs' angers the heck out of me. Birds are NOT dinosaurs in any real sense of the word. Birds evolved FROM dinosaurs and so belong to the same biological clade. But then, mammals evolved from therapsids and belong to that clade but we don't go around calling mammals "therapsids". Calling birds dinosaurs started as a kind of paleontological joke/fad a couple of decades ago when the clade system became widely used because some paleontogist(s) likely thought it was cute and clever. So of course, science journalists took up the fad. But it is misleading and bad biology (as well as bad science journalism).