Definitions

1. noun

A group of mammals that are related to marsupials and monotremes, but are not part of either group.

“The thysanurans are a diverse group of mammals found in various parts of the world.”

2. noun

In some classifications, a synonym for monotreme or marsupial, although this term is not widely accepted.

“Some scientists consider thysanurans to be part of the larger group of marsupials and monotremes.”