Bob the Baby T-rex

[Troodon]

Bob, the Baby T-rex was presented to the public at the Tucson Gem and Mineral Show on Thursday. I did not know very much about the discovery and now have a little more knowledge since I've had the opportunity to talk to a few individuals and see Baby Bob, so this is what I have learned.

Who is Baby Bob?

Bob is a partial T-rex skeleton, approximately 4 years old that was found on July 7, 2013 by Bob Detrich. Fortunately the skull was the major portion of the discovery and said to be approximately 75% complete. A 25” femur was also found with a tibia, hip bone, few vertebrae and ribs. It will take another year to finish the cleaning and the bones presented at the show were those completed or in some jackets.

I spoke with Pete Larsen and he had an opportunity to examine a section of the jaw and said there were features that were diagnostic to T rex. Bob also indicated that Robert Bakker and others also confirmed the ID. Photos of the reconstructed skull and cervical column is attached. The real bones have only been cleaned and stabilized to preserve the scientific integrity.

Where was it found?

Baby Bob was discovered on a ranch (deeded property) in Jordan Montana, actually not far from where the Nanotyrannus dueling dinosaurs were uncovered. It was found in a flood plain so it was probably not the actual location of where it fossilized. Bob said he first saw a rib, started to dig, saw teeth and bones but the bones were scattered throughout the flood plain. He tried to find the rest of the animal and said they sifted an area as large as a football field. Unfortunately there are no photos of the dig site.

Bob Detrich in the middle with the ranch owner and son.

Where is Baby Bob going?

Bob Detrich is a commercial fossil digger, owns a fossil company, and is going to sell Baby Bob. He told me he has no intentions of selling it to a private collector or even contacting one. The good news is that most of his finds have wound up in Museums. He knows what happened to the Dueling Dino’s and has no intention of repeating that mistake. He understands the scientific value of the discovery and wants to put it in the right hands. He already has had discussions with a private individual who would donate it to a major Museum in the States. Bob has been sharing his finds with the scientific community including the Smithsonian Institution. Hopefully it will wind up in the right hands.

Is this the Smoking Gun?

Andy raised this question in a post a week or so ago on Nanotyrannus vs Rex. I asked that question to Bob and he said YES is clearly a miniature version of the adult skull but quickly said that it’s going to be up to the scientific community to make that call. I also addressed the same question to Pete Larsen, earlier in the week, and he chuckled. One key argument used to support a Juvenile Rex is that the jaw of Nanotyrannus with around 17 teeth looses some positions has it ages to what we see in an adult T rex’s jaw. Baby Bob lower jaw has 12 tooth sockets more typical of what you would find in an adult Rex.

Reconstructed Jaw

Photos

Some of the photos of the bones/teeth are awful. They had a display case laying flat on the floor so it was very hard to take crisp pictures due to the ceiling lights and glass .

So I used both photos from the show and online sites.

I also had an opportunity to hold one of the teeth, well actually held the riker mount with the tooth in it, very cool. Think it would go well in my collection, now how to convince Bob to let one of many go

The smallest tooth in the jaw was about 1" crown with root. Never asked about the largest but he's holding a big one in his hands.

Edited February 12, 2016 by Troodon

[Troodon]

Photos of the skull elements were to bad to show but they had about 10.

Hopefully the final chapter of this book reads that the debate over these two dinosaurs has finally been answered.

Edited February 12, 2016 by Troodon

[LordTrilobite]

Good stuff. Now lets hope it gets properly described.

I used to be in the camp of Nanotyrannus being a juvenile T. rex. Now I'm not so sure. This specimen does not look like a Nano. Though until we see more it's hard to tell how much of the skull was actuall found and how much of that reconstruction is accurate.

I guess we'll see.

Edited February 12, 2016 by LordTrilobite

[jpc]

Wow.. this is pretty cool. I also hope it goes to a good home and gets some good science done on it. Thanks for the update.

[Carcharodontosaurus]

I am very glad this will not be sold to a private collector. This specimen is very important and must be studied by the right people.

I used to be in the Nanotyrannus as a juvenile T. rex camp as well, but this could change that.

[bcfossilcollector]

Great information!

[sandgroper]

Fantastic photos of a great discovery. I agree, something as important as this belongs in a museum where everyone can appreciate it and it can be studied in a professional and scientific environment. thanks for posting these great pics.

[Killclaw]

It seems pretty fragmentary based on the original material displayed, if that skull reconstruction is accurate it does look more like a miniaturised adult Rex than Jane would appear but with practically no upper maxilla material on view its quite hard to judge.

Why couldn't they find some arms to go with it!

Anyway Troodon having seen the teeth 3 dimensionally would you say they have the hallmarks of rex teeth rather than Nano?

[Troodon]

I really did not handle the teeth and only saw them in 2 dimension in the display case or riker. Since they all had roots it's difficult to make that call. I'll leave this one to the professional. The skull not the arms are the most element to find for a proper ID. If they indeed have 75% they will have answers

[Raptor Lover]

The number of tooth positions was a really important part in indentifying these creatures and luckily Baby Bob has the same number of tooth positions as adult Rexes. I am definitely on the Nano is separate species side. Very convincing evidence. I'm thinknig (and hoping) that this debate will be over soon. Thanks for posting Frank!

[Raptor Lover]

If someone is arguing for Nano as a juvenile Rex, then that would mean that very young ones would have 12 teeth postions, then increase to 17 postions as a teen (as with Jane), then decrease back to 12 as an adult, which sounds very unlikely

[-Andy-]

Thank you for this post, Frank.

I'm glad this precious fossil will be going to a museum instead of a private collection. I'm pleased at the discovery Baby Bob has 12 teeth in his lower jaw. Let's hope this truly is the smoking gun to end the argument!

(Care to smuggle me one of the teeth while you are at it?)

[Troodon]

(Care to smuggle me one of the teeth while you are at it?)

No way going to take care of ME first

[Troodon]

I'm glad this precious fossil will be going to a museum instead of a private collection. I'm pleased at the discovery Baby Bob has 12 teeth in his lower jaw. Let's hope this truly is the smoking gun to end the argument!

Just two cautions, the best intentions are sometimes altered by financial incentives. So let's hope that it finds its way to the right home.

Second even though the lower jaw was pretty intact the reconstruction was Bob's work and not that of a museum. Hopefully it will not change much when it's fully studied.

[Raptor Lover]

Just two cautions, the best intentions are sometimes altered by financial incentives. So let's hope that it finds its way to the right home.

Second even though the lower jaw was pretty intact the reconstruction was Bob's work and not that of a museum. Hopefully it will not change much when it's fully studied.

Hopefully an official reconstruction will stay virtually the same

[Koss1959]

I would love a full scale replica of that skull display. That'd be just about the coolest thing.

[Troodon]

What he has shown is a full scale replica. He has the mold be interesting to see if he sells them. Probably not cheap.

[Paleoworld-101]

Brilliant discovery! Thanks for sharing.

[Killclaw]

Just another query on this. If this is a 4 year old 'baby' surely it would be no more than a quarter of the size of a full grown Tex and yet its femur is already half full grown? The teeth as well, you say the smallest is an inch which you might expect the smallest tooth in an adult jaw to be and others somewhat larger.

Overall the skull just looks a bit too similar to an adult's if you believe the reconstruction.

They found a skull of an estimated 3 year old of its cousin Tarbosaurus and it really did look like a baby, nowhere near this developed.

Anyway looks like an intriguing specimen,I look forward to seeing the remainder. Maybe we can crowdfund a TFF deal and we can all time share it to subject it to our own rigorous scientific analysis

By the way mentioning Mongolian dinosaurs has the parallel been drawn between Nanotyrannus and Alioramus? Assuming both were separate genera from Tyrannosaurus and Tarbosaurus perhaps they are synonymous? I could probably buy T-rex coexisting with a pygmy tyrannosaur if there was a precedent for it, but then you've got the same polemic there really, was Alioramus perhaps a junior Tarb?

Edited February 14, 2016 by Killclaw

[Troodon]

Just another query on this. If this is a 4 year old 'baby' surely it would be no more than a quarter of the size of a full grown Tex and yet its femur is already half full grown?

Not sure I agree with your comment that it's half grown based on the length. When you look at 3 dimensional objects like bones its the mass (volume) that matters. If I look at an adult femur it's diameter is about 20cm at the middle, Bob looks like something less than 7cm. Rough calculation of volume your looking at a bone that is 1/16th the size of an adult. That makes sense since the growth rate on a Rex is not linear.

[Killclaw]

Ok so assuming the femur is proportionate in growth rate the rex reaches half full size lengthwise as a baby but just has real spindly legs? I've seen a graphic for projected growth rates and they have the length more than quadrupling from five year old baby to full size adult. Of course this could all be anyone's guess given the lack of samples to base it on.

Another thing, for a baby, as in Tarbosaurus , you'd expect the skull to be elongated and compressed, more like a stapler, but this guy's head (according to the reconstruction) looks just like your avatar!

I just hope this and the duelling dino 'Nano' end up in the right hands and get the proper investigative treatment by all parties like Jane did and then we can start drawing some real conclusions. I'm actually open minded to anything as you have to be in the world of dinosaur knowledge where the unexpected is always lurking round the corner. What's the story in America anyway with museums bidding for significant or scientifically important specimens as opposed to receiving donations?

I know The Natural history museum seldom purchases new specimens, Sophie the Stegosaurus being an exception, and I imagine this presentation at Tuscon is a sales pitch as much as anything but its kind of frustrating to imagine these items ending up as an ornamental show piece in some Hollywood star's mansion.

[fossilking]

Hi Frank thanks for stopping by the show had I not been so busy we could of open the case so you could get some good images of Baby Bob's skull material. Sorry can't let you have a tooth but might be-able to get you a cast someday. The largest rooted tooth from the Baby Bob T.rex site is 4.25" posted in the far right photo in the center. I'll post some skull material if you'd like?

I truly believe we have the smoking gun and should set the record straight once and for all. Once you see it in person you'll know that this is no nano everything about it screams tyrannosaurus rex, I mean just look at those teeth that's just another feature. We changed a lot of minds last weekend!

Like to hear thought's from others..

[Troodon]

Glad to see you on the forum, thanks for posting the additional images and photos. I enjoyed seeing the material and appreciate that you made it available to the general public. I can believe that it left Nano skeptics in a quandary.

The teeth are awesome and the closeup with the serrations going around the tip says Rex. Are replicas going to be made available of the skull or teeth?

Bob in the end if it can be studied and published its will speak for itself and finally end the debate. I hope that everything works out that places it in the right institution for that to happen.

[The Amateur Paleontologist]

Finally hard evidence of juvenile Tyrannosaurus rex! Has a paper been written on it?

[Troodon]

It's still in private hands, needs to be sold to a museum to get that paper written.