Twentieth century, as Martha (probably the last member of the species, although the standard post-extinction cryptic sightings continued into the 1930s) died in 1914.
If anybody wants to read an extremely complete book on the subject, it's hard to do better than A Feathered River Across The Sky[0]. It's well written and the science is sound.
If anybody wants to read an extremely complete book on the subject, it's hard to do better than A Feathered River Across The Sky[0]. It's well written and the science is sound.
[0]: https://www.amazon.com/Feathered-River-Across-Sky-Extinction...