Is Nanotyrannus A Separate Species Or Is It A Juvenile T Rex?

[Troodon]

A note on Sue rex; she was correctly and professionally collected, with all data recorded. The fact that she was sold commercially should not impugn her scientific value.

Sue was collected by Pete Larsen of the Black Hills Institute who consulted closely with the finder of the Dueling Dinosaurs and in my discussions with him was very happy with the process. I cannot speak to what data was or was not collected it would pure speculation. Museums were interested in the specimen so it was not a deal breaker just a pure money issue. The seller wanted a big numbers for the two specimens and it never got there.

Edit: let me add that the finder was an experienced collector, not a professional and has sold many specimens to museums.

Edited August 11, 2015 by Troodon

[starman]

paleontologists believe that T. bataar was extremely closely-related to T. rex (so much so some consider them to be both Tyrannosaurus genus).

As I posted before, the proposed synonomy was debunked. I don't think anyone thinks they're the same genus anymore. T. bataar and T. rex were sister taxa not ancestor-descendant.

[Troodon]

As I posted before, the proposed synonomy was debunked. I don't think anyone thinks they're the same genus anymore. T. bataar and T. rex were sister taxa not ancestor-descendant.

Agreed and one can see the relationship in the attached clad.

[-Andy-]

As I posted before, the proposed synonomy was debunked. I don't think anyone thinks they're the same genus anymore. T. bataar and T. rex were sister taxa not ancestor-descendant.

So are we still able to use the observation of juvenile Tarbo having the same tooth count as adult Tarbo to infer that juvenile Rex most likely had the same tooth count as adult Rex?

[Troodon]

Good question and I would lean toward supporting that observation. Makes sense unless you are on the other side of the argument.

Edit: Although a more distant relative but still a tyrannosaurid I believe there is a similar relationship between adult and juvenile Albertosaurs with the mass mortality bonebed found in Alberta.

Edited August 11, 2015 by Troodon

[Ridgehiker]

Good question and I would lean toward supporting that observation. Makes sense unless you are on the other side of the argument.

Edit: Although a more distant relative but still a tyrannosaurid I believe there is a similar relationship between adult and juvenile Albertosaurs with the mass mortality bonebed found in Alberta.

Odd you mentioned that bonebed, I walked by it this past Friday on my way through Dry Island island to an area north of the park. Small world.

[Troodon]

Odd you mentioned that bonebed, I walked by it this past Friday on my way through Dry Island island to an area north of the park. Small world.

I've found that at least in the dinosaur world its a very small world. It's a pretty cool site, demonstrated a possible family relationship in tyrannosaurs.

[starman]

Agreed and one can see the relationship in the attached clad.

20150811_070118-1_20150811071153512_20150811071336733.jpg

Is the Dinosaur Park tyrannosaur the big fragment found by Phil Currie and mentioned in GSP's PDW?

Edited August 12, 2015 by starman

[starman]

It's a pretty cool site, demonstrated a possible family relationship in tyrannosaurs.

Even without it there's now virtual proof of gregarious behavior in tyrannosaurs.

[Troodon]

Is the Dinosaur Park tyrannosaur the big fragment found by Phil Currie and mentioned in GSP's PDW?

I don't know and was asking myself the same question.

[starman]

Too bad tyrannosaur material from the DPF is so scanty, despite good ankylosaur, ceratopsid and hadrosaur material. I don't know what other tyrannosaur remains are known from the unit other than that big specimen.

[-Andy-]

Bumping this post again. (and because Fossil News section don't get much attention)

I was just talking to Dr. Thomas Holtz, and he said that the arms of the Dueling Dinosaur specimen does not have larger arms than all known T-Rex specimens; they are only larger proportionally.

Do we have any good data on the size of the Dueling Dinosaur arms?

[jpc]

Has Tom seen the specimens? I have not, but I have seen Pete Larson's comparative drawings of the arms, and according to him, theybare indeed physically bigger.

[Troodon]

Agree they are bigger. I held an adult nanotyrannus hand claw today in the ballroom of the show and it was huge when I compared it to Stan's (big adult rex). Very different morphology. I did take a picture of the claw and will post it when I get back on my computer

Edited January 29, 2016 by Troodon

[Troodon]

In my opinion one just needs to look at the hand claws to see the difference. The Nanotyrannus Claw that I just added to my collection appears to be from an adult (biggest I've seen) and measure 5" straight across. The T-rex Claw is a replica from an adult Rex from the Black Hills Institute and measures 4" and is typical of others I've seen. The differences other than the obvious length is that the Nano is much more slender and not has re-curved and it's double the width. The proximal end on the Rex claws are also wider and more compressed and overall its a more compact claw. The argument that I've heard is that the claws get smaller as the animal gets older. I think that's weak, one just needs to look at what happens in other tyrannosaurs or theropods, they get larger with age. Andy I do not have measurements on the arms.

Nanotyrannus 5" hand claw

T-rex replica hand claw 4"

Here is a photo I took of the arm from the Dueling Dino Nanotyrannus (Left) and the T-rex arm from Sue. The bones are different.

Edited January 30, 2016 by Troodon

[-Andy-]

In my opinion one just needs to look at the hand claws to see the difference. The Nanotyrannus Claw that I just added to my collection appears to be from an adult (biggest I've seen) and measure 5" straight across. The T-rex Claw is a replica from an adult Rex from the Black Hills Institute and measures 4" and is typical of others I've seen. The differences other than the obvious length is that the Nano is much more slender and not has re-curved and it's double the width. The proximal end on the Rex claws are also wider and more compressed and overall its a more compact claw. The argument that I've heard is that the claws get smaller as the animal gets older. I think that's weak, one just needs to look at what happens in other tyrannosaurs or theropods, they get larger with age. Andy I do not have measurements on the arms.

Nanotyrannus 5" hand claw

NanoClaw_edited-1.jpg

T-rex replica hand claw 4"

rexmanusclaw_004.jpg

Here is a photo I took of the arm from the Dueling Dino Nanotyrannus (Left) and the T-rex arm from Sue. The bones are different.

Dulers Arm.jpgRexarm.jpg

Great info, Frank.

Do you know if the Nanotyrannus and BHI T-Rex claw were from digit 1 or 2? Thomas Holtz said that different digit claws would've had different sizes (though he didn't address the morphological difference).

[Carcharodontosaurus]

The only studied "Nanotyrannus" individual, Jane, was found through histology to be a juvenile. Where are the adult nanos?

[Troodon]

Great info, Frank.

Do you know if the Nanotyrannus and BHI T-Rex claw were from digit 1 or 2? Thomas Holtz said that different digit claws would've had different sizes (though he didn't address the morphological difference).

Do not have an answer to your question since the nano claw was an isolated find in a channel deposit and dont know on the Rex. Yes digit 1 and 2 are different in size in Rex's but not that much. Here is a close up of Jane and the adult male at the BHI Stan, you be the judge. Also a close up of the claws in the Duelers and again different but not that much.

Stan

Sue

Duelers

Edited January 31, 2016 by Troodon

[Troodon]

The only studied "Nanotyrannus" individual, Jane, was found through histology to be a juvenile. Where are the adult nanos?

Both Pete Larsen and Robert Bakkar believe the Dueler Nanotyrannus is adult and they had an extensive look at it. I may be wrong but I believe they would argue the findings on Jane.

Edited January 31, 2016 by Troodon

[-Andy-]

Do not have an answer to your question since the nano claw was an isolated find in a channel deposit and dont know on the Rex. Yes digit 1 and 2 are different in size in Rex's but not that much. Here is a close up of Jane and the adult male at the BHI Stan, you be the judge. Also a close up of the claws in the Duelers and again different but not that much.

Stan

IMG_1595.jpg

Sue

IMG_1594.jpg

Duelers

IMG_0307_edited-1.jpg

I've been trying to find out if Stan and Sue have both arm claws preserved. Before I use Bloody Mary's claws as a comparison, I must first make sure there's a T-Rex that has both hand claws preserved.

It seems that Stan wasn't found with his hand, and Sue was missing a hand claw.

[Troodon]

Good point but the replicas used by the Field Museum and BHI were based on comparative specimens and cannot be far off.

Edit: One thing we know for sure is that the Duelers specimen is 99% complete and all 4 hand claws are there.

Edited January 31, 2016 by Troodon

[-Andy-]

Good point but the replicas used by the Field Museum and BHI were based on comparative specimens and cannot be far off.

Edit: One thing we know for sure is that the Duelers specimen is 99% complete and all 4 hand claws are there.

I am playing devil's advocate here. What if all current restorations of T-Rex hand claws were wrong? What if they had one claw bigger than the other? Seems that CM 9380 was used as the type specimen to fill in on other missing T-Rexes. But he's missing his hands too.

(ignore the part about Jane being a young T-Rex)

[Troodon]

I've gotta to believe that an associated set of rex claws exists and just may not be tied to a skeleton. If nothing exists all you have to go with is the family lineage of Tyrannosaurs including Nano which points to digit I & 2 claws that are not that dissimilar in length.

There is a dealers at the show working on Rex skeleton that is 50% complete will see if it has hand claws. I'll also ask the folks at the BHI they are here but have not seen Pete.

[Raggedy Man]

Until more specimens can be observed and studied, it will be a mystery.

[Auspex]

A larger sample size will focus our understanding; go out and find more!