On rejection

Early on, a major issue with evolutionary theory was the lack of "early" animal fossils: complex animals, like trilobites, were well known in the Cambrian fossil record, but there was no evidence of their evolutionary precursors.

All this changed in 1946, when geologist Reginald Sprigg made a startling discovery. The New York Times has the story:

Reginald Sprigg, a geologist for the South Australia government, was checking out some old mines in the Ediacaran Hills of the Flinders Range several hundred miles north of Adelaide. Sprigg noticed some striking disc-shaped impressions up to four inches in diameter on the exposed surfaces of rocks nearby. Sprigg interpreted the patterns as the [pre-Cambrian] fossil remains of soft-bodied creatures like jellyfish or their relatives.

The kind of career-making discovery a young scientist could only dream of! But the story goes on (emphasis added):

When Sprigg first showed the imprints to leading authorities, they dismissed them as artifacts made by the weathering of the rocks. ... Later that year, when Sprigg found the frond-like forms he called Dickinsonia, he was certain that such geometrical impressions could have been made only by living creatures. But despite their potential importance, Sprigg’s discoveries were ignored at an international geology meeting and his paper describing the fossils was rejected by the leading journal [Nature]. Sprigg moved on to other, more rewarding pursuits in the oil, gas, and mining industries.

It took another decade for Sprigg's earth-shattering contribution to be widely recognized. Something to keep in mind both as an author and as a reviewer.