Novelty records are whole albums or singles that capitalize on something interesting (novel) or a current fad. Some types of novelty records include sound effects albums, field recordings of cultural or historical import (the moon landing or street scenes in China), or comedy one-offs. They typically do not feature a known celebrity -- although they've created some, like Junior Samples.
When radiation was discovered in 1896, the age of the earth suddenly expanded to support Darwin's belief that far more time was required than Lord Kelvin's estimates (based on the brief time it would take the earth to cool from an original scalding state) giving life enough time for natural selection to operate (Bowler, 1984).
The consistency of the blank areas, in other words the regularity of species appearing in the record with no intermediary fossils between it and its most recent ancestor, suggests a dynamic not evident if natural selection is accepted as the lone selective process.
Female sexual selection is driven by an attraction to novelty (Darwin, 1871), and novelty is characterised by variations in the way things look, sound, smell or feel which can be manifested physiologically and behaviorally.
Novelty music is fine by me. The dark kings are V/VM, who are sound like your average pop novelty spun through a mincer, and then vomited on by Chris Morris.
The root of the word "novelty" is that which is new: but the word "novel" in common parlance refers to something unique, different, or strange: so with noveltyrecords.
Basically, a noveltyrecord is any record that stands out from the pack for reasons other than its own sheer excellence--although novelty alone neither precludes nor guarantees excellence.