So caution should be taken when using bone fusion and bone texture, and we may need to histologically reevaluate many prehistoric reptile specimens whose maturity was assumed based on said indicators. Thankfully, paleontology evolves new methods over time to help with that. 9/9

But now it really does seem like bone fusion and bone texture aren’t consistent indicators of immaturity anymore. This is huge, since before histology became more widespread, I recall those two features being commonly used to indicate maturity in extinct reptiles. 8/9

Additionally, the Cleveland skull being mature helps show that we seem to not understand extinct reptile growth as much as we thought we did. The unfused bones and rough bone texture seemed to indicate immaturity. 7/9

So we actually do have a juvenile T. rex. It’s publicly accessible and has been repeatedly studied. So much for the “where are the juvenile T. rex?” argument, lol. 6/9

However, this is a BIG MIGHT! Additional histological studies are needed to check its maturity and age at death. It’s very possible that I’m wrong.

Still, since Thomas is a subadult, it’s possible that “Dinotyrannus” was actually a juvenile at death. 5/9

This also could mean that “Dinotyrannus” (middle specimen) might be less mature than we thought. Previous studies found that it was 14 years old at death, but considering the size disparity between it and Thomas (~18 year old subadult), it might actually be younger than 14. 4/9

Contrary to what I said months ago, Thomas (large individual on the left) is not an adult and was actually immature (likely a subadult) at death. This is despite being much, much larger than the adult Cleveland skull. 3/9

For context, it is more mature than all three of these LACM growth series specimens (or at least the left two since the rightmost one is too incomplete to do histology on and probably undiagnostic). 2/9 bsky.app/profile/milo...

Could you please elaborate on what you mean by that? I am curious.

The unfused bones and rough bone texture of the holotype really seemed to indicate immaturity. But now that it’s turned out to be mature, it seems like bone fusion and bone texture are too inconsistent to use as reliable maturity indicators anymore.

I’d say that the Nano holotype being mature shows that we really don’t understand extinct reptile growth as much as we thought we did.

Edit: I meant to say that I *read* Griffin’s SVP 2024 *abstract.* I never attended any SVP conference. Sorry for the poor wording there.

The fact that the holotype was mature shows that we still don’t understand extinct reptile growth as much as we thought.

Congratulations to Christopher Griffin and his team on the paper! 5/5