paper suggests Tyrannosaurus to be split into 3 species

[Rhiguita]

https://www.nationalgeographic.com/science/article/call-to-split-tyrannosaurus-rex-into-3-species-sparks-fierce-debate

https://www.nytimes.com/2022/02/28/science/tyrannosaurus-rex-three-species.html?smid=tw-share

Gregory S Paul new paper has just dropped with an interesting hypothesis to say the least. I for one think it is worth considereing.

Edited March 1, 2022 by Rhiguita

[Troodon]

Tom Holts warned his twitter followers earlier today that there would be blockbuster news today but no one anticipated this.   Will be interesting to see the paper tomorrow. 

Wow Tyrannosaurus rex, Tyrannosaurus regina and Tyrannosaurus imperator.

 

This will rock the paleo community and Tyranno experts like Thomas Carr are already calls it "vanishingly weak" that evidence exists.   Will see where this goes and will be exciting to see which side the key players fall.

   

 

Paper is PAYWALLED  

https://link.springer.com/article/10.1007/s11692-022-09561-5#citeas

[Troodon]

Michael Greshko posted this:

The proposed species breakdowns, based on the paper's three morphotypes versus the existing specimens in museums.  It also list the key diagnostic features identifying each species

Sue is considered the Holotype for T. imperator 

Stan is considered T. regina

Wankel  is considered the Holotype for T. regina

Pecks Rex is considered the Holotype for T. rex

Scotty (Saskatchewan) is considerd  T. rex

 

 

Noteworthy that Jane, BMRP 2002.4.1 the Juvie Trex but really a Nanotyrannus is not on the list..  

[Nanotyrannus35]

Does this mean that isolated tyrannosaurus teeth will have to be identified as Tyrannosaurus sp.?

[Troodon]

Based on this paper yes.  However, I would not do anything right now since since its yet to get much traction from key theropod paleontologists.    Their diagnosis of the differences are based on limited material.

[Praefectus]

I don’t buy it. Extraordinary claims require extraordinary evidence. The burden of proof is on the authors to justify their naming of new species of Tyrannosaurus. A scant 2 diagnostic features (generally robust femur, usually one incisiform tooth) that are generally and usually observable, is not sufficient to support their argument.

 

There may very well be several tyrannosaurids present in the Late Maastrichtian of North America, but this paper does not provide sufficient stratigraphic, morphologic, or paleoecologic evidence to support this. 

 

 

 

As a slight aside, this may be tin-foil-hattery, but I wonder if the lead author is just publishing a controversial Tyrannosaurus paper in order to get free advertising for his new book that recently published. 

[Troodon]

14 minutes ago, Praefectus said:

There may very well be several tyrannosaurids present in the Late Maastrichtian of North America, but this paper does not provide sufficient stratigraphic, morphologic, or paleoecologic evidence to support this. 

I would agree with this, we are just not there yet since the number of available specimens to adequately diagnose the differences dont exist. 

[pachy-pleuro-whatnot-odon]

21 minutes ago, Praefectus said:

A scant 2 diagnostic features (generally robust femur, usually one incisiform tooth) that are generally and usually observable, is not sufficient to support their argument.

 

I agree. Considering ontogenetic changes and sexual dimorphism - as is already suggested by the proposed names T. rex [king] and T. regina [queen] - I think the diagnostic features are simply too weak and too undifferentiated to warrant species differentiation. From what I understand about phylogenetic analysis, moreover, more then two characters are usually used to define one species from the other, with there being significant overlap between the proposed species in this case.

[Troodon]

I would like to read the paper, if I can get a hold of it,  to see the specifics and get a feel of the authors positions.  

[jpc]

14 hours ago, Troodon said:

Tom Holts warned his twitter followers earlier today that there would be blockbuster news today but no one anticipated this.   Will be interesting to see the paper tomorrow. 

Wow Tyrannosaurus rex, Tyrannosaurus regina and Tyrannosaurus imperator.

 

This will rock the paleo community and Tyranno experts like Thomas Carr are already calls it "vanishingly weak" that evidence exists.   Will see where this goes and will be exciting to see which side the key players fall.

   

 

Paper is PAYWALLED  

https://link.springer.com/article/10.1007/s11692-022-09561-5#citeas

Holtz (Note... with a z) did the same on facebook.  

[jpc]

 

34 minutes ago, Praefectus said:

I don’t buy it. Extraordinary claims require extraordinary evidence. The burden of proof is on the authors to justify their naming of new species of Tyrannosaurus. A scant 2 diagnostic features (generally robust femur, usually one incisiform tooth) that are generally and usually observable, is not sufficient to support their argument.

 

There may very well be several tyrannosaurids present in the Late Maastrichtian of North America, but this paper does not provide sufficient stratigraphic, morphologic, or paleoecologic evidence to support this. 

 

 

 

As a slight aside, this may be tin-foil-hattery, but I wonder if the lead author is just publishing a controversial Tyrannosaurus paper in order to get free advertising for his new book that recently published. 

Without reading the actual paper, I tend to agree wholeheartedly with Praefectus here.  Esp the last line.  Paul is known to be a lumper more than a splitter, as seen in his Princeton Guide to Dinos.  But even in that book clams three species of Tyrannosaurus in the Lance/Hell Creek etc.   

 

("foil-hattery"... can I use that word in future discourses?)

 

[Praefectus]

12 minutes ago, Troodon said:

I would like to read the paper, if I can get a hold of it,  to see the specifics and get a feel of the authors positions.  

PM sent. If anyone else wants it, let me know. 

 

2 minutes ago, jpc said:

Paul is known to be a lumper more than a splitter, as seen in his Princeton Guide to Dinos.  But even in that book clams three species of Tyrannosaurus in the Lance/Hell Creek etc. 

I think some of his other theories include lumping Carcharodontosaurus and Giganotosaurus together and Velociraptor and Deinonychus. These theories were similarly lacking in paleontological justification. 

 

4 minutes ago, jpc said:

("foil-hattery"... can I use that word in future discourses?)

[Auspex]

With a 74 million 2.4* million year run, I might expect to see some speciation in the line.

*(correcting a typo)

 

https://www.cnn.com/2022/02/28/world/t-rex-three-different-dinosaurs-scn/index.html?fbclid=IwAR2lVehqFoqbXGAd1lWZX3QIBuRGcHcqiQQsh96hMPnONs0ObqgT3-ME1Hg

[dinosaur man]

Well this is interesting news, first thing I seen when I woke up this morning.  Pretty controversial subject and for a good reason, after finishing the paper here’s my two cents.  I don’t think these species should be considered valid even though I’d love to see more Tyrannosaurus species and I can confidently bet they are out there but I don’t think this is the paper.  Paul makes some big assumptions out of the little he was working with, the evidence sketchy to confirm his hypothesis at best.  I personally think it’s wishful thinking, with the evidence he has and the belief that he’s had on more Tyrannosaurus species existing for over a decade I’m pretty sure that this type of thinking played a huge role in his research, I have personal experience in the affects of wishful thinking, your beliefs have habits of affecting the results no matter what the evidence says. 

[jpc]

2 hours ago, Auspex said:

With a 74 million year run, I might expect to see some speciation in the line.

 

https://www.cnn.com/2022/02/28/world/t-rex-three-different-dinosaurs-scn/index.html?fbclid=IwAR2lVehqFoqbXGAd1lWZX3QIBuRGcHcqiQQsh96hMPnONs0ObqgT3-ME1Hg

74 million year run?  Did I miss something?

 

[Rhiguita]

From what I have been able to see so far Paul has not made that convincing an argument for 3 species, although the idea of 2 species of tyrannosaurus in hell creek makes sense to me if there are chrono species, like there are with triceratops, although he didn't have the data to support that one, but I hope future studies including stratigraphy show that to be the case.

[Troodon]

Excellent Podcast

 

Tom Holtz and Dave Hone reaction to paper

 

[Kikokuryu]

11 hours ago, Troodon said:

 

Tom Holtz and Dave Hone reaction to paper

So from what I understand, the paper is mostly to establish, or reserve the species names Tyrannosaurus imperator and Tyrannosaurus regina.

 

If I am interpreting what I listened to correctly, even if the 2 supposed diagnostic differences are indeed just expected variations within a single species, if a different set of data shows that there is indeed a chronospecies similar to genera like Triceratops, Otodus, Allosaurus, etc, and if Sue does fit within that ancestral species, then T. imperator will become valid, even though the original diagnostic characters were wrong. This could be 10, 50, 100, 200 years down the road.

 

I guess it makes sense that, if your goal is to preemptively establish a name of what is hypothetically, you choose the specimens that have any form of variation as the holotype to give it the best possible chance.

[pachy-pleuro-whatnot-odon]

15 minutes ago, Kikokuryu said:

So from what I understand, the paper is mostly to establish, or reserve the species names Tyrannosaurus imperator and Tyrannosaurus regina.

 

If I am interpreting what I listened to correctly, even if the 2 supposed diagnostic differences are indeed just expected variations within a single species, if a different set of data shows that there is indeed a chronospecies similar to genera like Triceratops, Otodus, Allosaurus, etc, and if Sue does fit within that ancestral species, then T. imperator will become valid, even though the original diagnostic characters were wrong. This could be 10, 50, 100, 200 years down the road.

 

I guess it makes sense that, if your goal is to preemptively establish a name of what is hypothetically, you choose the specimens that have any form of variation as the holotype to give it the best possible chance.

 

Yeah, that's the same thing I get from it all. But I'd say that's a rather dirty trick!

[Troodon]

They did say that it certainly raised awareness around T rex chronospeices which most seem to agree exist to some degree.   They added that future research and discoveries will be looking for diagnostic features to fit these three individuals.   So regardless of the motive of the paper some positive will come out of its being published.   

 

 

[pachy-pleuro-whatnot-odon]

14 minutes ago, Troodon said:

They did say that it certainly raised awareness around T rex chronospeices which most seem to agree exist to some degree.   They added that future research and discoveries will be looking for diagnostic features to fit these three individuals.   So regardless of the motive of the paper some positive will come out of its being published.

 

Yeah, in a way it forces the research community to now look into the matter of Tyrannosaur anagenesis - which, I guess, is not a bad thing

[Troodon]

Denver Fowlers comments on this paper from Twitter.  He was a co-author on the evolution of Triceratops

 

"1st impression of #rexit is that the incisiform dentary tooth data is interesting & makes sense... although I would like to see full stratigraphic justifications beyond what's in Supp. Contrary to what some commentators say, anagenetic change would not necessarily be clear cut.  Study desperately needs histology as bodysize is quite variable especially in predatory dinosaurs . I think it is a great talking point / jumpoff for future research, and color me intrigued, esp on those anterior teeth.  Also worth mentioning that lower parts of Lance might/probably are older than lowermost Hell Creek, or at least are not demonstrably same age. This needs work, but it would explain some faunal patterns."

[Troodon]

More reactions from notable paleontologists Dr Andrea Cau

from his blog Theropoda

 

"In yesterday's post , I anticipated the article by Paul et al. (2022), but I hadn't been able to read it yet.  In that post, I pointed out that a critical evaluation of the hypothesis that North American Tyrannosaurus were distinguishable into 3 species ( T. rex , T. imperator , T. regina ) was only up to North American tyrannosaurid experts, since I believed that the hypothesis of Paul et al. (2022) was based on a detailed comparison of numerous skeletal elements distributed throughout the various Tyrannosaurus specimens , and therefore required a weighted critique based on detailed anatomical evidence.  I was wrong. I had overestimated the scientific depth of that article. Sorry to be direct, but after reading the article, I must conclude that the hypothesis proposed by Paul et al. (2022) is very weak indeed and immediately rejected, even without being a Tyrannosaurus expert .  The hypothesis of Paul et al. (2022), in fact, is based only on two alleged anatomical elements:  - the strength of the bones of the limbs, which the authors believe demonstrates the existence of two morphotypes ("puny" and "robust") in the sample they analyzed (about thirty specimens);  - the number of incisiviform rostral teeth in the dental (two or one) in the sample analyzed by them.  In practice, the authors believe that the three species are definable by these combinations of the two characters:

T. imperator : robust shape with two incisive teeth.

T. rex : strong shape with an incisive tooth.

T. regina : gracile shape (and with an incisive tooth).

Furthermore, the authors argue that the three species are stratigraphically segregated along the terminal part of the North American Maastrichtian, with  T. imperator older and the other two contemporary and more recent. Unfortunately, the stratigraphy of the majority of Tyrannosaurus specimens is not so accurate as to allow for such a segregation for the alleged species.

A similar tripartite division of the specimens on the basis of only 2 characters (one of which, moreover, an alleged morphometric dimorphism in the strength of the bones) is unsustainable. It is not realistic to separate three species on the basis of these two anatomical elements alone. In the first place, because with that sample of only about thirty specimens there is no clear differentiation between "frail" and "robust". I have plotted the measurements reported by the authors, but I cannot identify a clear distinction between those two morphologies, and this, in the first place, because the statistical sample is too small to be able to rigorously separate any morphotypes.

Furthermore, separating dinosaur species on the basis of the shape of the first two teeth of the dental is a very weak criterion, since dinosaurs have a great variability in adult teeth (also linked to the fact that during life they reciprocated their teeth in alternating waves) , far greater than that observed in mammals. Therefore, distinguishing two or more dinosaur species only on the basis of the shape of the first two teeth of the dental, and without being able to consider other elements of the morphology, is unsustainable.

In summary, T. imperator and T. regina are just two junior synonyms of T. rex ."

[Auspex]

20 hours ago, jpc said:

74 million year run?  Did I miss something?

 

Sorry: typo. 2.4 million years is what I meant to say. I'll edit the original so as not to spread misinformation.

[DD1991]

On 3/1/2022 at 8:11 AM, jpc said:

 

Without reading the actual paper, I tend to agree wholeheartedly with Praefectus here.  Esp the last line.  Paul is known to be a lumper more than a splitter, as seen in his Princeton Guide to Dinos.  But even in that book clams three species of Tyrannosaurus in the Lance/Hell Creek etc.   

 

("foil-hattery"... can I use that word in future discourses?)

 

Gregory Paul suggested in his books Predatory Dinosaurs of the World and The Princeton Field Guide to Dinosaurs that some Allosaurus fragilis material constitutes a distinct species from the topotype of A. fragilis based on snout proportions, but it is clear that the supposed shorter snout of USNM 4734 relative to the snout length of AMNH 600 and 666 was based on a reconstruction of the skull by Gilmore (1920).