Synonymous Synonyms and Dubious Dubiums

[PaleoMatt]

A thread on Synonymous Dinosaurs and Possible Synonyms. Oh and Nodem Dubiums.

Lets kick things off with Triceratops/Torosaurus!

Jack Horner believes that when Triceratops got older there frills opened and elongated, these "adult" Triceratops were once known as Torosaurus.

Maybe this theory will be debunked when we find young torosaurus or bigger trikes.

Personally I believe this theory because of another genus. Nedoceratops. This dinosaur is about the size of Triceratops but has its frill beginning to open into a pair of holes.

Are we looking at the transition between Triceratops and Torosaurus or a Ceratopsian hybrid??

I want to know your thoughts on synonyms and nodem dubiums

[MLMjp]

I believe this matter ended quite time ago.

While the theory is not completely denied, the majority´s consense is that Horner´s theory is unprovable

With that said, Triceratops is still Triceratops, and Torosaurus is still Torosaurus

If some member could explain this better and with more fact I would be very greatfull

[PaleoMatt]

I believe this matter ended quite time ago.

While the theory is not completely denied, the majority´s consense is that Horner´s theory is unprovable

With that said, Triceratops is still Triceratops, and Torosaurus is still Torosaurus

If some member could explain this better and with more fact I would be very greatfull

Interesting

[stargatedalek]

It has been disproved (completely) by the presence of Torosaurus remains smaller than Triceratops remains.

[MLMjp]

It has been disproved (completely) by the presence of Torosaurus remains smaller than Triceratops remains.

I kinda know it but I wasn't sure, so thanks

[Dinoguy2]

It has been disproved (completely) by the presence of Torosaurus remains smaller than Triceratops remains.

Nonsense. Maximum adult size is highly variable, especially in dinosaurs. This is like saying Danny DeVito must be a different species because he's shorter than Arnold Schwarzenegger despite being older.

The Triceratops/Torosaurus hypothesis has a long way to go to be proved, but size isn't one of the factors to consider.

Factors that DO need to be considered before Horner's idea is to be accepted are: which species of Triceratops is Torosaurus a synonym of? Are all Torosaurus specimens coeval with Triceratops, or could we be looking at evolutionary change rather than change during growth? Are there any juvenile Torosaurus skulls that have open fenestrae? What the heck is Tatankaceratops? Etc.

[stargatedalek]

Fair enough, but wouldn't the presence of significant variances in adult size also indicate multiple species? For example did some species of Triceratops develop Torosaurus features earlier than others? I think there just isn't enough evidence to conclusively paint it as any more than a novelty hypothesis, the kind of thing that gets low budget documentaries made of it but doesn't have any real proof behind it. It would be silly at this point to claim Torosaurus as a nomen dubium, but I suppose I shouldn't dismiss the possibility outright like that.

What about Spinosaurus? That recent paper that was so long and wordy made an awful big fuss about the possible validity of Sigilmassasaurus and more pertinently that our current Spinosaurus remains are not synonymous with the original holotype. In my opinion even if that paper is correct it doesn't make a difference because the new neotype is now recognized by the name. Just as we aren't going to remain Tyrannosaurus as Manospondylus I don't think we should rename Spinosaurus as Sigilmassasaurus. Doing so would serve no purpose other than to pander to those who refuse to give up the old idea of Spinosaurus. And that is of course also ignoring the elephant in the room, that being that even if it's not the same species it's almost certainly similar enough to be in the same genus as Spinosaurus aegyptiacus.

On that note I have a less philosophical question. If Sigilmassasaurus is in fact valid as a species and not a genus and the remains are applicable to it and not aegyptiacus, would the new species be dubbed Spinosaurus maroccanus or Spinosaurus brevicollis? Would brevicollis take precedence?

[PaleoMatt]

Anyones opinions on Saurophaganax?

[Dinoguy2]

Anyones opinions on Saurophaganax?

Saurophaganax is apparently from the highest Morrison strata. I wouldn't be surprised if it were a chronospecies (i.e. a direct descendant of earlier, smaller Allosaurus). Whether to make this its own species or not is a big philosophical question. Same with Centrosaurus and Styracosaurs. One clearly evolved directly from the other without any other splitting.

I personally think this is a good opportunity to make "genus" mean something - lump into the same genus if direct descent is likely. So Allosaurus maximus evolved from Allosaurus fragilis. Centrosaurus albertensis evolved from Centrosaurus apertus. Pachyrhinosaurus pertotorum evolved from P. lakustai evolved from P. canadensis evolved from P. horneri (=Achelousaurus) evolved from P. ovatus (=Rubeosaurus). Etc. But it's a matter of opinion, not science.

[E.D.G.E. (PainterRex)]

Alright everybody! here comes the bigger controversy!

Tyrannosaurus vs. Nanotyrannus
Horner's (and probably other scientists have come up with this hypothesis too) hypothesis that nanotyrannus, a rather small tyrannosaur from the same time and place as Tyrannosaurus Rex, being a juvenile morph of the adult Tyrannosaurus. What do y'all think about this. I recently viewed a documentary by National Geographic (I think) about this, and they provided some good evidence of Nanotyrannus being a separate genus/species to Tyrannosaurus. What is the evidence for this?

[PaleoMatt]

Alright everybody! here comes the bigger controversy!

Tyrannosaurus vs. Nanotyrannus
Horner's (and probably other scientists have come up with this hypothesis too) hypothesis that nanotyrannus, a rather small tyrannosaur from the same time and place as Tyrannosaurus Rex, being a juvenile morph of the adult Tyrannosaurus. What do y'all think about this. I recently viewed a documentary by National Geographic (I think) about this, and they provided some good evidence of Nanotyrannus being a separate genus/species to Tyrannosaurus. What is the evidence for this?

Because of the new evidence I think Nano was just a young deformed t rex. I seen that doc too but the whole teeth thing has been debunked. It's the arms that are causing the controversey. We found sub adult trex with more teeth sockets than adults and youngsters with even more sockets so the answer becomes pretty obvious.

[E.D.G.E. (PainterRex)]

Alright everybody! here comes the bigger controversy!

Tyrannosaurus vs. Nanotyrannus
Horner's (and probably other scientists have come up with this hypothesis too) hypothesis that nanotyrannus, a rather small tyrannosaur from the same time and place as Tyrannosaurus Rex, being a juvenile morph of the adult Tyrannosaurus. What do y'all think about this. I recently viewed a documentary by National Geographic (I think) about this, and they provided some good evidence of Nanotyrannus being a separate genus/species to Tyrannosaurus. What is the evidence for this?

Because of the new evidence I think Nano was just a young deformed t rex. I seen that doc too but the whole teeth thing has been debunked. It's the arms that are causing the controversey. We found sub adult trex with more teeth sockets than adults and youngsters with even more sockets so the answer becomes pretty obvious.

What was up with the arms?

[Simon]

Alright everybody! here comes the bigger controversy!

Tyrannosaurus vs. Nanotyrannus
Horner's (and probably other scientists have come up with this hypothesis too) hypothesis that nanotyrannus, a rather small tyrannosaur from the same time and place as Tyrannosaurus Rex, being a juvenile morph of the adult Tyrannosaurus. What do y'all think about this. I recently viewed a documentary by National Geographic (I think) about this, and they provided some good evidence of Nanotyrannus being a separate genus/species to Tyrannosaurus. What is the evidence for this?

Because of the new evidence I think Nano was just a young deformed t rex. I seen that doc too but the whole teeth thing has been debunked. It's the arms that are causing the controversey. We found sub adult trex with more teeth sockets than adults and youngsters with even more sockets so the answer becomes pretty obvious.

What was up with the arms?

Well, the thought is that the young TRex rapidly grew arms to adult size, which would have given it a raptor-like appearance while young.  Then the arms simply stopped growing at some point as the animal grew larger and the head grew more massive and "took over" all of the predatory functions.

Its a plausible hypothesis.  Based on photos, the arms of the "Dueling Dinosaurs" Nano/TRex (?) are as large as an adult TRex's arms. ("Sue's" arms are about the size of an adult man's arms).  So we have "Sue", at 42 feet long and 7 tons estimated weight having approximately the same size arms as the "Dueling Dinos" Nano/Trex (?) which is less than half its size (and probably much less than half its mass).

Until more complete fossils are found its going to be an open question.  Mis-identifying juvenile animals as a different species is a common problem in paleontology, however.  Let's hope the "Dueling Dinos" tyrannosaurid winds up in a museum and gets a proper study ....

[PaleoMatt]

Ah, Thanks for clearing the arms up

[Loxodon]

Okay, let's do a rundown.

Nanotyrannus/Tyrannosaurus: At this point the great majority of researchers are convinced that Nanotyrannus is just a young T. rex. All supposed Nannotyrannus individuals are obviously juveniles, meaning that, if the Nanotyrannus hypothesis is correct, we have two species of large tyrannosaurs in Hell Creek, of which one is only represented by juveniles and the other only by adults. This does not seem all that plausible, does it? On top of that, pretty much all of the features supposedly showing N. lancensis to be a distinct taxon have been pretty much refuted. The most obvious of these is the size of the arms, already mentioned earlier in this thread. Nanotyrannus arms are the same size as those of some(but not all) adult Tyrannosaurus arms, and this allegedly shows that they are distinct taxon. The problem with this is that it actually does no such thing. It is completely possible for certain limbs to simply stop growing at a certain stage, thus become proportionally smaller as the animal grows. In fact, one possible explanation for why T. rex had such useless arms as an adult is that they served a function in juveniles, when they were still proportionally large, but then became increasingly less important as the animal grew, eventually becoming essentially vestigial.

Triceratops/Torosaurus: This issue is more complex than one might expect. Often overlooked is the fact is that Torosaurus remains only occur in the lower Hell Creek formation, and have completely vanished by the impact event. Triceratops individuals from the lower formation show signs of a gradual thinning in the frill, while later individuals merely have thin spots. On top of this, several skull features are shared between Torosaurus and Triceratops from the lower Hell Creek, but not the upper Hell Creek. In fact, while earlier Triceratops show signs of developing holes in their frills, this is not the case in later individuals. This opens up the possibility that Torosaurus is a synonym of Triceratops, but only T. horridus. This would mean that "Torosaurus" is essentially the adult form of Triceratops, but that the later species of Triceratops, T. prorsus, had undergone a process known as neoteny, causing it to retain juvenile features through adulthood. And yes, I essentially stole all of that information from the Saurian blog.

Now onto a more clear-cut case - Dracorex/Stygimoloch/Pachycephalosaurus: Pretty much all that needs to be said here is that there are skulls of Dracorex with small domes beginning to develop, conclusively showing that at least that "species" is in fact a juvenile. As for Stygimoloch/Pachycephalosaurus, I don't think it is conclusive yet, but if I was a betting man I would venture a guess and say that they are also both the same. Likewise, it has also been suggested that Homalocephale may be a juvenile of Prenocephale, which also seems quite well supported.

[Dinoguy2]

Okay, let's do a rundown.

Nanotyrannus/Tyrannosaurus: At this point the great majority of researchers are convinced that Nanotyrannus is just a young T. rex. All supposed Nannotyrannus individuals are obviously juveniles, meaning that, if the Nanotyrannus hypothesis is correct, we have two species of large tyrannosaurs in Hell Creek, of which one is only represented by juveniles and the other only by adults. This does not seem all that plausible, does it? On top of that, pretty much all of the features supposedly showing N. lancensis to be a distinct taxon have been pretty much refuted. The most obvious of these is the size of the arms, already mentioned earlier in this thread. Nanotyrannus arms are the same size as those of some(but not all) adult Tyrannosaurus arms, and this allegedly shows that they are distinct taxon. The problem with this is that it actually does no such thing. It is completely possible for certain limbs to simply stop growing at a certain stage, thus become proportionally smaller as the animal grows. In fact, one possible explanation for why T. rex had such useless arms as an adult is that they served a function in juveniles, when they were still proportionally large, but then became increasingly less important as the animal grew, eventually becoming essentially vestigial.

Triceratops/Torosaurus: This issue is more complex than one might expect. Often overlooked is the fact is that Torosaurus remains only occur in the lower Hell Creek formation, and have completely vanished by the impact event. Triceratops individuals from the lower formation show signs of a gradual thinning in the frill, while later individuals merely have thin spots. On top of this, several skull features are shared between Torosaurus and Triceratops from the lower Hell Creek, but not the upper Hell Creek. In fact, while earlier Triceratops show signs of developing holes in their frills, this is not the case in later individuals. This opens up the possibility that Torosaurus is a synonym of Triceratops, but only T. horridus. This would mean that "Torosaurus" is essentially the adult form of Triceratops, but that the later species of Triceratops, T. prorsus, had undergone a process known as neoteny, causing it to retain juvenile features through adulthood. And yes, I essentially stole all of that information from the Saurian blog.

Now onto a more clear-cut case - Dracorex/Stygimoloch/Pachycephalosaurus: Pretty much all that needs to be said here is that there are skulls of Dracorex with small domes beginning to develop, conclusively showing that at least that "species" is in fact a juvenile. As for Stygimoloch/Pachycephalosaurus, I don't think it is conclusive yet, but if I was a betting man I would venture a guess and say that they are also both the same. Likewise, it has also been suggested that Homalocephale may be a juvenile of Prenocephale, which also seems quite well supported.

What about other famous synonyms, like Anatotitan copei and Edmontosaurus annectens? These seem to get less attention, I guess because they're boring ornithopods and nobody is nostalgic about Anatotitan being simply a growth stage?

I'm glad to see somebody understands some of the actual nuance to the Triceratops hypothesis. So many people seem to have a very simplistic view of the whole situation. Triceratops HAS to have evolved via neoteny at some point, whether Toro is a synonym or not, because it's the only ceratopsian with a solid frill as an "adult". How exactly this happened is not known, but having a phase where the frill stayed solid until well into adulthood makes sense. When it happened IS known, because its direct ancestor Eotriceratops/Ojoceratops look like Triceratops with holes in their frills, so the solid frill had to evolve in the latest Maastrichtian. A later evolutionary phase would then just have to drop those last few hole-frilled years. It's entirely possible for Torosaurus to be a synonym of Triceratops horridus (solid frill until very late in growth, then Toro-morph) but not T. prorsus (solid frill for entire life, no last-minute perforation of the frill).

[MLMjp]

What about other famous synonyms, like Anatotitan copei and Edmontosaurus annectens? These seem to get less attention, I guess because they're boring ornithopods and nobody is nostalgic about Anatotitan being simply a growth stage?

Yes please!! Altought I get the general idea, I will like to know more about my favorite ornithopod.

[Dinoguy2]

What about other famous synonyms, like Anatotitan copei and Edmontosaurus annectens? These seem to get less attention, I guess because they're boring ornithopods and nobody is nostalgic about Anatotitan being simply a growth stage?

Yes please!! Altought I get the general idea, I will like to know more about my favorite ornithopod.

This one is also less well-known because they were already considered synonyms up until the early '90s when they got split. Researchers back then thought that the famous big, spoonbills specimens were different enough from the smaller type specimen of "Anatosaurus" to get their own genus, hence Anatotitan was born. More recently the case has been made that the flat-bill and large size are simply ontogenetic.

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0025186

Contrary to popular belief, they were never thought to be the same as Trachodon. In the famous American Museum mount they were labelled  "Trachodont dinosaur", the equivalent of labelling them "hadrosaurs" today. Kinda like the new AMNH mount is simply labelled "Titanosaur" pending further study.

[PaleoMatt]

Interesting, Edmontosaurus is my favourite ornithopod.

[MLMjp]

What about other famous synonyms, like Anatotitan copei and Edmontosaurus annectens? These seem to get less attention, I guess because they're boring ornithopods and nobody is nostalgic about Anatotitan being simply a growth stage?

Yes please!! Altought I get the general idea, I will like to know more about my favorite ornithopod.

This one is also less well-known because they were already considered synonyms up until the early '90s when they got split. Researchers back then thought that the famous big, spoonbills specimens were different enough from the smaller type specimen of "Anatosaurus" to get their own genus, hence Anatotitan was born. More recently the case has been made that the flat-bill and large size are simply ontogenetic.

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0025186

Contrary to popular belief, they were never thought to be the same as Trachodon. In the famous American Museum mount they were labelled  "Trachodont dinosaur", the equivalent of labelling them "hadrosaurs" today. Kinda like the new AMNH mount is simply labelled "Titanosaur" pending further study.

So for now Anatotitan is basically a full grown adult Edmontosaurus annectens. That is more or less what I understood the first time I heard about this case. But thanks for the extra info. And the main difference between E.regalis and E. annectens (Apart from other things. This one is the most visible) is the skull, at least in adults, E.annectens had longer and flatter skulls (Anatotitan skull). Still, E.annectens remains as my favorite ornithopod.