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Re: Synapsids weren't reptiles? I'm confused.
Someone mentioned scales, uric acid and something else
> which escapes me for the moment, though surely these would be speculations
> going that far back in time.
That was me, and yes, they are guesses.
All the living synapsids do not secrete concentrated uric acid, whereas the
diapsids+turtles do (or at least most of them do, there may be exceptions), it
appears to be ancestral for the crown group.
Only reptiles have beta keratin - and scales ("reptile type" scales, not the
"fish type"), don't know when these evolved, but they are currently diagnostic
for synapsids vs sauropsids, and ancestral to the crown group.
Surely when the Synapsid+ Sauropsids initially split, they weren't much
The point is, looking at reptiles today, the synapsids that were called "mammal
like reptiles" must have lacked features one would expect to find in "reptiles"
today, and shouldn't be grouped with today's reptiles, ie lizards, crocodiles,
turtles, all share features those synapsids never would have had