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Re: Fwd: Are dinosaurs really reptiles? (2)
I have probably explained this ten times now, spread over the last two or
three years, and so have others, but you still don't get it.
To quote-mine Oliver Cromwell, I BESEECH YOU IN THE BOWELS OF CHRIST to open
your mind and let the following two points sink in _at long last_.
=== 1) Tree-thinking ===
The tree of life is just that -- a tree --, not a pole.
Branching points on a cladogram are just that: branching points. Points
where a _population_ splits into _two_. "Sister" really does mean "sister"
and not "mother".
The terminal taxa in a cladogram are just that: terminal. They sit at the
_end_ of branches, not at nodes. The nodes are occupied by _reconstructed_
_hypothetical ancestors_, and so is the entire length of all internodes.
=== 2) The nature of the fossil record ===
You know how matter consists almost entirely, _way_ over 99 %, of vacuum,
with an atomic nucleus here and there, and with a few electrons thinly
smeared all over the place? That's a good metaphor for the fossil record.
The fossil record doesn't have a terribly strong systematic bias (within
terrestrial tetrapods, that is!!!) -- I've published on this --, but it
still consists mostly of absence. _Fossils are extremely rare._ Or rather,
fossiliferous sites are extremely rare and much, much poorer than you seem
It follows logically that we will more or less _never_ find a direct
ancestor of any known species of terrestrial tetrapod older than Miocene
perhaps. (To really find ancestors, you have to look at Pliocene _diatoms_
and the like, in other words, at rocks that consist entirely of fossils.)
You keep asking for ancestors, and you keep interpreting known taxa as
ancestors. Have you still not grasped how naïve this is?!?
Got that at last? Now to details.
This list, if it is a good one, should follow a gradual evolutionary path
with regard to morphology.
Yes, _if_ we had a fossil record that were 25 % complete, as opposed to 0.25
%. (This number comes off the top of my head and may well be several orders
of magnitude too _high_.)
okay. good start. Somewhere outside of Amniota. But where are
Utaherpeton? They're a little more plain and ordinary. Have they
Perhaps surprisingly, I agree. The seymouriamorphs are quite far away from
Amniota. The lepospondyls are more closely related to the amniotes than the
seymouriamorphs are, and so is *Solenodonsaurus*. You'll probably have to
wait for my thesis.
I'm seeing a pattern here: Small, flat-headed and short-toed gives
rise to big,
and short-toed. There's some logic to it. The intertemporal is gone.
So this must be an
amniote.Or is it? A fat, slow, plant-eater is the father of us all?
Doesn't *Tseajaia* have an intertemporal? I'll check in a few hours. But
anyway, your ignorance shines through. By default ( = by plesiomorphy),
diadectomorphs are rather crocodilelike critters, with *Limnoscelis*,
*Limnostygis* and *Tseajaia* having conical teeth, and pretty impressive
fangs in the maxilla (caniniform teeth!) and premaxilla. Only within
Diadectidae we have the very kind of Hennig comb you are looking for: the
more closely related to *Diadectes*, the more adaptations to omni- and then
herbivory and graviportality.
Things like the astragalus of *Diadectes* are convergent to the amniote
condition. *Tseajaia* retains separate tibiale and intermedium.
The pattern of giant, weird, plant-eaters continues. So it must be
No doubt this is an amniote [representing the Synapsida?].
Yes, it represents Theropsida. It's not a bad choice: Caseidae +
Eothyrididae together are the sister-group of all other theropsids; the
eothyridids are known from a grand total of two isolated skulls, one of
which (*Oedalops*) is quite incomplete and the other (*Eothyris*) is not
well reconstructed in the literature (I hear work on it is going on right
now), while we have fairly complete skeletons of several caseids.
Of course, it would still be better to add ophiacodontids and varanopids. A
manuscript that more or less does that (with all varanopids except the most
pathetic crumbs) will, hopefully, be submitted soon; I'm its third author.
Where are the plain little insect and meat eaters, like
Helosuchus and Westlothiana?
Are we ignoring them because they're not intriguing?
Do you mean *Heleosuchus*? It's a varanopid. That's not just obvious from
its recent redescription, but... W4tP. :-) *Westlothiana* is a lepospondyl.
Yes, it was reconstructed with diapsid-like peg-shaped supratemporals, but
look at the specimen drawing in the same paper: those are ordinary
At least the tail is long here. Didn't early reptiles have long
Suddenly we're aquatic! With a decidely long premaxilla! And long
And a long tail. And a long neck. And long toes! So derived! So
This one seems misplaced.
What is this talk about "early"? All three mesosaurs are smack dab in the
middle of the Early Permian. Their split from the diapsid line cannot have
happened later than the existence of *Hylonomus*, which is near the
beginning of the Late Carboniferous. We have lots of time here -- compare
whale evolution! Lots of time to acquire autapomorphies, and that's what all
characters you list are: autapomorphies -- derived characters that
Mesosauridae evolved after having split from its sister-group.
The paper has nice trees _with branch lengths_. The cause for branch length
is time. Look at the scale bars.
Oh, yeah, Modesto said it nested with pareaisaurs (not even on the
Wait, wait, wait, wait, wait. It's the sister-group of a clade composed of
Millerettidae, *Eunotosaurus*, Bolosauridae, Lanthanosuchidae, the
"nycteroleters", Procolophonoidea _and_ Pareiasauria.
Oh, man. Now we're back to dull teeth, short tail, short toes and a
Kinda like Dia
Now we're back to long of belly, low to the ground again. With a
skull like Gephyrostegus.
Not at all like Procolophon. Not flat-headed.
You deleted at least one line here before sending. But anyway, forget the
procolophon_id_s for a moment and look at the other procolophon_oid_s
(Owenettidae). Plain vanilla insect eaters all. Herbivorous procolophonoids
(Procolophonidae) are no more spectacular than herbivorous lizards.
`--+--+--Thuringothyris and (Captorhinids)
This one (and its kin) are decidedly flat-headed. Plant eaters.
They all have a fairly strong bite, that's true, but only a part of
Captorhinidae was herbivorous. Just look: *Saurorictus*, *Rhiodenticulatus*,
*Protocaptorhinus*, *Romeria*, *Concordia*... all have ordinary conical
teeth. May have eaten thick-cuticled arthropods.
I'll have to pass on this one. Not yet in my data base. A pdf would
I doubt there is one, it's a paper from the 1970s. That said, it's the same
paper as the descriptions of *Cephalerpeton*, *Coelostegus* and/or
*Anthracodromeus* (I don't quite remember), which you seem to have.
Another close cousin. Say, isn't this fanged taxon getting
uncomfortably close to
No. As mentioned above, I know what I'm talking about, W4tP.
[...] That pelvis only has room for on sacral vertebra.
That's interesting, I'll check.
That means this guy really
belongs way back there near Seymouria. A reptile imposter!
Are we now doing cladistics with one character? You should be ashamed. All
together, *Anthracodromeus* looks just like *Petrolacosaurus*, except for
the fact that its skull is anapsid.
BTW, reversals in the number of sacral vertebrae do happen. We have gone
through one, related to the size squeeze around the origin of Mammalimorpha.
That's why mammalian ilia look so ridiculous.
This guy deserves more respect than he gets. I'm wondering why he
because he's more like Thuringothyris with that flatish head and
those great big dull teeth,
...like, dare I say it... Casea ... way...back...yonder...
Cladistics with _two_ characters now! Woohoo!
It's simply a durophage, with enlarged teeth much like *Araeoscelis*.
Suddenly, after all these 'anapsids' a diapsid!
Two holes at once! Isn't it interesting that he
went straight for two, rather than dawdling about with one or the
other for awhile?
We have no idea whatsoever if Diapsida went straight for anything or if one
of the three* holes came first. That's because of those pesky holes in the
Incidentally, *Spinoaequalis* (described as the third araeoscelidian in
1995) would have made a very nice addition. W4tP.
* The suborbital fenestra in the palate.
And that's not all. Long toes. Long limbs. Long neck. Long tail. Sharp
teeth. The only taxon
on this list, other than Araeoscelis [and Anthracodromeus] who
remotely resembled this one is
Mesosaurus...way... back ...yonder. [shudder]
The mesosaurs are not terribly similar, but *Anthracodromeus* is, and so are
*Protorothyris* and *Cephalerpeton*, and so are to a lesser degree
*Hylonomus* and *Brouffia*, and to an even lesser degree *Paleothyris*, and
to an even lesser degree *Coelostegus*... man, that's precisely what you
were asking for! :-) The best part is that this is described at length in
the paper, and not even in the online appendices (which I hope you have
downloaded and read! -- www.systbiol.org), but in the main text.
this seems to be very scattered famiy tree.
That's because it is. That, in turn, is because of the nature of the fossil
but the change ought to be gradual. Evolutionary. Not like this see-saw.
Here, both of your fundamental errors apply. First, your failure to
appreciate the lack of fossils. Second, you look horizontally across a
treetop and complain that you can't see the trunk anywhere.
Next question: What were the five to ten sister genera leading up to
Herrerrasaurus? No suprageneric taxa please.
Translation: if we tell you that the fossil record isn't complete enough for
that, you will simply refuse to accept that answer. Methinks you haven't
thought things through.