So, I read in a few sources, all of them sketchy, that there was a species of MAMMAL that existed before the dinosaurs called gorgons. Is this true or not?
They died out 200 MILLION YEARS before the dinosaurs did, said one source. Absolute bull says another. Which is it, and if so, what did they die of?
Not exactly a species of mammal, but before the time of dinosaurs, the dominant large terrestrial vertebrates were Therapsids, of which Gorgonopsia was one, which were the ancestors of mammals. In the Triassic, the larger species were replaced by dinosaurs.
Because I’ve written about that other Gorgon – you know, lady with snakes for hair, nasty habit of turning people into stone – I inevitably got Peter Ward’s book Gorgon about this beast.
http://books.google.com/books?id=s2y64YXfi_0C&printsec=frontcover&hl=en
My recommendation – get the book if you’re interested in the life of a paleontologist. But go somewhere else if you really want to know about the therapsid.
Not. They were mammal-like reptiles (protomammals), and were related to the ancestors of mammals, but were not themselves mammals. You might be more familiar with their earlier relative, Dimetrodon.
Approximately true, give-or-take 10 million years. They died out in the Great Dying.
Thank you, my people. If the gorgonopsia were not ‘true’ mammals, what was the difference between them and ‘real’ mammals?
I was looking at Ward’s book on Amazon, but the reviews were not so hot. I am interested in paleontology, but only in the context of what was found, not what was done in order to find it.
That could get to be a very technical answer, with lots of references to the minutiae
of skull openings and dentition schemes, I’d think - way past my level of expertise. But simplistically, there’s little evidence earlier synapsids had hair (I’ve seen some talk of at least sensory whiskers), they probably laid eggs (but so do monotremes), they hadn’t yet reduced the jaw to just two bones per side (as opposed to the earlier 4), no hard palate (but analogous structures), and they still had a very “primitive” stance - not as horizontally splayed as reptiles in the rear limbs, but not as vertically underslung as true mammals.
It’s generally accepted that mammals developed from the advanced theraspids called cynodonts (cladistically, mammals are cynodonts), and gorgonopsids were a terminated branch.
That could get to be a very technical answer, with lots of references to the minutiae
of skull openings and dentition schemes, I’d think - way past my level of expertise. But simplistically, there’s little evidence earlier synapsids had hair (I’ve seen some talk of at least sensory whiskers), they probably laid eggs (but so do monotremes), they hadn’t yet reduced the jaw to just two bones per side (as opposed to the earlier 4), no hard palate (but analogous structures), and they still had a very “primitive” stance - not as horizontally splayed as reptiles in the rear limbs, but not as vertically underslung as true mammals.
It’s generally accepted that mammals developed from the advanced theraspids called cynodonts (cladistically, mammals are cynodonts), and gorgonopsids were a terminated branch.
Can I just say, I love this bit of accidental poetry? (OK, the first line is a hair long for good rhythm but that’s fixable).
I’m starting on writing the rest of the poem in my head right now. I think it’s contrasting our scientific knowledge of extinct animals, with how little we know about why relationships work or fall apart. Either a guy trying to figure out how to tell his dino-crazy son about why Dad and Mom aren’t living together any more, or a break-up poem.
“The Minutiae of Skull Openings and Dentition Schemes” is the name of my Yes cover band.
I want a copy of their album “Close to the Ear” (Down by the Dentary). 
There’s a fairly easy way to summarize this. Under traditional pre-cladistics taxonomy, “reptile” meant a tetrapod vertebrate reproducing by an amniote (shelled) egg (s opposed to waterborne fish and frog eggs), cold-blooded and with most skin covered by scales, as opposed to warm-blooded feather-bearing birds and warm-blooded fur-bearing modern therian mammals.
Now mammals have a whole .suite of non-reptilian characteristics: fur, milk, warm-bloodedness, differentiated teeth, live birth… The problem is that they picked up these distinctives one at a time. Where then should we draw the line between the extinct synapsids (“mammal-like reptiles”) and “true mammals”, especially remembering that we’re working with fossils, and most of the more obvious characteristics distinguishing mammal from reptile don’t fossilize well if at all.
Now, reach back on the side of your face and feel where your jaw joint is. Notice it’s within a centimeter of the hole leading to your middle and inner ear. The jaws of reptiles, including synapsids, are made up of several bones; the jaws of mammals, in contrast, are a single bone.
As synapsids became more advanced, more mammal-like, the rearmost bones in both jaws, the quadrate and articular, became tiny nubbins of bone right at the joint. At one point about halfway through the evolution of modern mammal characteristics, the point where the jaws articulated shifted over to the big bones in front of them. Remembering these animals are only about mole-sized, it took a shift of on the order of a millimeter to move the no-longer-useful quadrate and articular into the middle ear, where they became the malleus and incus, improving mammal hearing.
Since jawbones and teeth fossilize extremely well, if you have a primitive mammal fossil at all, you most likely have a jawbone at minimum, this provided an excellent arbitrary point to draw the reptile/mammal line. You could be sure whether it was a reptile or a mammal by the presence or absence of the quadrate and articular (finding the malleus and incus is "gravy’ and somewhat rare). And you knew roughly how far along the line from reptile to therian mammal it was by this alone.