Sue’s claw (manual ungual)

[BirdsAreDinosaurs]

Hi all! I am a bit confused about the manual ungual of Sue that Longrich and Saitta refer to in their recent Nanotyrannus paper (https://www.mdpi.com/2813-6284/2/1/1?trk=public_post_main-feed-card-text)

 

In the paper, they compare a complete manual ungual of FMNH PR 2081, the T. rex knows as Sue, to manual unguals of supposed Nanotyrannus specimens. But  I remember reading (I might be wrong though) that no complete manual ungual was found associated with Sue, although an undetermined claw was found near Sue.

 

Looking at pictures of Sue’s right arm, I see two incomplete claws, one of which (I think the one Longrich used) has a very different preservation than Sue’s other bones (see here: https://news.uchicago.edu/story/sue-t-rexs-right-arm-undergoes-ct-scan-uchicago-medicine).

 

 

Can someone explain to me what is going on here?

 

 

 

 

 

 

[BirdsAreDinosaurs]

Here are two images from The Sue Exhibition Educators Guide of the Field Museum from 2000. The first one suggest no manual unguals were found associated with Sue. But perhaps undetermined claws were later assigned to Sue after all?

 

[rocket]

as far as I know no handclaws were found

[BirdsAreDinosaurs]

Thanks, @rocket That is what I thought. So what are we looking at here? (this is the figure from the Longrich and Saitta paper):

 

 

[Kikokuryu]

On 8/17/2024 at 11:26 AM, BirdsAreDinosaurs said:

That is what I thought. So what are we looking at here? (this is the figure from the Longrich and Saitta paper):

 

Weird. Maybe it's previously undescribed material which is why it seemingly comes out of nowhere, or the specimen ID is wrong, and this is not Sue's claw, but from a different T. rex.

 

You could probably ask Longrich himself about it on one of his social media accounts whenever he makes a Nanotyrannus post. He seems relatively responsive.

[rocket]

On 8/17/2024 at 8:26 PM, BirdsAreDinosaurs said:

Thanks, @rocket That is what I thought. So what are we looking at here? (this is the figure from the Longrich and Saitta paper):

 

 

 

Do not know..., I will ask Nick about it. He should know :-)

As far as I know there was one handclaw found near the skeleton. But (I cannot really remember all, talked about it with Larson in perhaps 2000 in Tucson and perhaps I am wrong with that I write now) remember that there was an overall meaning this claw does not belong to SUE.

[BirdsAreDinosaurs]

Hi @rocket! Did you find the time to ask Nick about the claw?

[rocket]

11 hours ago, BirdsAreDinosaurs said:

Hi @rocket! Did you find the time to ask Nick about the claw?

Yes, I asked him about it and sent a mail. But, he did not answer... So, I have my personel thougths about the situation. I know there was no attached claw found and not arms. Only a claw not so far away from the skeleton.

[Kikokuryu]

At least according to Pete Larson, this is "Sue's" claw along with BMRP 2006.4.4 which was also used by Longrich.

 

https://x.com/PeteLarsonTrex/status/770672506340605961

 

I don't think other paleontologists will be much help, and they don't seem to have really commented on it either. At best, they talk about claws in private collections. This is sort of the similar case with the juvenile T. rex frontal bones UCMP V84133.

 

All of this skirting around these specimens is likely because of the Dueling Dinosaurs (Bloody Mary) paper in the horizon, I don't think a lot of professional can really comment on these other specimens without potentially leaking research done on the DD specimen or accidentally risk saying things they shouldn't.

[BirdsAreDinosaurs]

The claw size argument is potentially one of the most convincing arguments in favour of the existence of Nanotyrannus, but all I ever see is people (even renowned paleontologists) sharing pictures of T. rex claws that are casts and/or of a vague origine that cannot be validated. To see this particular claw (which also looks like a cast to me) published in a peer-reviewed scientific paper without any reliable reference towards its validity, is something I find quite shocking.

 

Anyway, I am really looking forward towards the Dueling Dinosaur reveal! 

[Kikokuryu]

1 hour ago, BirdsAreDinosaurs said:

The claw size argument is potentially one of the most convincing arguments in favour of the existence of Nanotyrannus

The issue with the claws (other than the undescribed specimens like the Dueling Dinosaurs) is that most are all loosely associated or isolated specimens.

 

As of right now, the UCMP V84133 juvenile frontal bone that is diagnostically Tyrannosaurus is the strongest piece of evidence that is described. This specimen should not exist if the current ontogeny theory is true and fits more in line with what we see in Tarbosaurus. It could I suppose belong to an undescribed small bodied tyrannosaurid similar in size/niche to the recently described Asiatyrannus, but it's most likely Tyrannosaurus.

 

Nanotyrannus is not diagnostically a Tyrannosaurus rex as far as I recall, and the apomorphies that linked it to Tyrannosaurus I think were not actually present as originally proposed. This has been passed off more recently as juvenile animals appearing more basal in the tree than adults. However, a big caveat is that other tyrannosaurids which we have juvenile specimens do share apomorphies with their adult counterparts. As far as we have been shown with studies, we can distinguish a juvenile Tarbosaurus from Alioramus, Raptorex, and possibly Bagaraatan, the first two genera are also only described from immature specimens but distinct from juvenile Tarbosaurus. If the recently described Asiatyrannus also turns out to be an immature specimen, it also suggests these deep-snouted tyrannosaurids are recognizable from a young age. I think the reasoning behind Asiatyrannus being an almost mature specimen is not far off from what the Longrich paper proposes for Nanotyrannus.

 

There's a lot of weird things going on here which the Dueling Dinosaurs should clear up to a great extent. It could very well be that there are multiple taxa, not just two, being lumped into Tyrannosaurus which is causing the odd results compared to every other tyrannosaurid. It could also be that Tyrannosaurus is simply unlike any other theropod to ever exist due to its sheer mass difference to any other terrestrial predator.

 

Here's a little snippet from Tom Holtz on his Facebook page... sort of talking about the frontals, but not really. In other words, most paleontologists are not going to talk about this subject with any significance until the Dueling Dinosaur paper comes out. Nanotyrannus being included in the Asiatyrannus paper was also met with relative silence from academics, granted, they noted its status as contentious in that paper despite plugging it into their phylogeny.

 

Edited August 26 by Kikokuryu

[BirdsAreDinosaurs]

7 hours ago, Kikokuryu said:

The issue with the claws (other than the undescribed specimens like the Dueling Dinosaurs) is that most are all loosely associated or isolated specimens.

My main problem here is that the authors present the claw as SUE’s claw, while it might not be that at all. They do not even mention that it was loosely associated (if it indeed is the claw that was found near Sue). Honestly, I think this is misleading and not very scientific. I also do not understand that the reviewers did not comment on it.

 

The frontal is interesting, but I cannot really judge its significance. But I am sure we will hear more about this discussion soon.