It’s commonly said that synapsids were reptiles, but that’s not true. They were synapsids.
See, there’s a fork in land animals (tetrapods): amphibians on the one side, amniotes on the other.* Amniotes then fork again: reptiles on one side, synapsids on the other.
Birds are a kind of reptile. And we mammals are a kindof synapsid!
Take a look in the mirror and admire yourself. You’re looking at one of the last synapsids alive.
*(simplified, not counting all the extinct clades)
