Generic and specific variation (incomplete)

["Jaime Headden" <jaemei@hotmail.com>]

I need some input from all you guys (and gals) on the list.

I've been involved with all the dino-groups for a long time now, being 
particularly fascinated by each equally, even the ankylosaurs, but I can 
say that the best work-out I've gotten among these wonderful fossils 
were the theropods and sauropods, and of course the protodinosaurs, as 
Greg Paul calls 'em (and me, too). But my input is on the theropods, or 
more correctly, on the tyrannosaurids.

1.
Frankly, I believe the multi-genera thing is not the way to go . . . I 
feel it is unscientific. This does not allow such variation to exist as 
being specific variation, or individual variation, as once seen in 
*Triceratops* skulls. Plus, I don't believe multi-species are the thing 
as well. This has gotten on my nerves, but taking a look at Glut's old 
Dinosaur Dictionary (the first version) I saw all the various 
*Corythosauri,* *Lambeosauri,* and the defunct *Procheneosauri* species, 
all based on the above-mention individuality factor.

OTOH, dropping all the species in a genera, as was done to *Triceratops* 
and Greg Paul's clumping of ornithomimids into *Ornithomimus* is 
unscientific (no insult to you, Greg) in that it too readily 
multispeciates a group, or underspeciates it. There are four species of 
the genus *Homo,* and we are a subspecies (*H. sapiens sapiens*), and 
this is the source of my query to you all.

2.
*Tyrannosaurus* is distinct from Asia to North America, one of our 
Asiamericanan dinosaurs. There is sufficient difference between the dead 
(no pun intended) *Tarbosaurus efremovi* and his senior synonym *T. 
bataar* to *Tyrannosaurus rex* that I feel we have a single species on 
our hands, but two subspecies, *Tyrannosaurus rex rex* and *T. r. 
bataar,* the last synonymizing *Tarbosaurus,* *Jenghizkhan,* and 
*Maleevosaurus* as age-particular individuals. This I feel is a much 
safer (and more scientifically based) dinstinction to make than any 
other I've seen on the subject, and I don't recall ever seeing it 
discussed on the list before.

*Albertosaurus* represents a genus with a subspecies, as well. Instead 
of assigning new genera to the several species now accepted under the 
name of this tyrant, a better approach would be to subspeciate a few of 
them, and group them accordingly. So, 1.) *Albertosaurus sarcophagus* 
should stand alone, pending more complete material to work with
2.) *A. libratus* is sufficiently complete and distinct to base a 
species on, not to rename it *Albertogorgon* or resurrect *Gorgosaurus* 
for it.
3.) I think *A. arctunguis* could do as a subspecies, but this is 
hesitant, for while the angular foramen is separated from the shelf of 
the surangular, the jaws being deeper, and the postorbital more 
processed, I feel some slight individualization is going on here, but 
none of us can be sure. *A. libratus arctunguis* is my suggestion.
4.) *A. megagracilis* should remain a distinct species, and not a new 
genus (*Dinotyrannus* I believe it was called).

Should I go into the groupings of *Aublysodon,* who is based on a tooth 
and is therefore a nomen dubium? I will state that I don't think 
*Alectrosaurus* is a shanshanosaurid (aublysodontid), as based on 
characters that separate Alectro from Shanshan.

*Triceratops* posed me a major headache about three years ago when I 
picked up Glut's second version of the _Dinosaur Dictionary_ and I began 
to set up a character map for all those species, which have now been 
placed in two species, with one turned into a new genus. I disagree. *T. 
horridus* has junior synonyms: *T. calicornis,* *T. eurycephalus,* *T. 
sulcatus,* and *T. albertensis.* *T. prorsus* has the following junior 
synonyms: *T. alticornis* and *T. serratus.* The two T's I left out were 
*T. flabellatus* and *T. obtusus,* which I believe are subspecies of T. 
prorsus, so *T. prorsus flabellatus* and *T. prosus obtusus.* As for 
*Diceratops hatcheri,* I believe the species is correct, but the genus 
is not, and thus revive it as *T. hatcheri.* Such similar forms as 
*Ugrosaurus* and the enigmatic *Agathaumus* should be allocated to new 
species, not genera, so *T. olsoni* and *T. sylvestris* should not be 
ignored as possibilities.

I will not get into hadrosaurs now. I await the results of my studies, 
when I get around to doing them.

But finally, I have this to say: what of the twenty or so genera under 
the heading Titanosauridae? Not even the hadrosaurs have such variation, 
and we are talking about titanic (pun intended) dinosaurs, who specific 
variation would be more easily come upon evolution-wise than generic 
variation. Some of the newer genera I feel should be re-examined for any 
possibility of shorting out this poorly-known group of dinosaurs where 
every new skeleton found gets a new name.

I would greatly appreciate any and all criticism (positive or negative) 
to my suggestions made here-in.

Jaime A. Headden

P.S. Sorry about the last message, I forgot to put a subject header on 
it.

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