A High-Resolution Growth Series of Tyrannosaurus rex

[AlexSciChannel]

For those of you who don't know Thomas Carr published a paper describing Tyrannosaurus rex growth in high resolution. The paper is below. 

A high-resolution growth series of Tyrannosaurus rex obtained from multiple lines of evidence

 

 

And what does this mean for Nanotyrannus?

[Pemphix]

13 hours ago, AlexSciChannel said:

And what does this mean for Nanotyrannus?

Nothing much i would say...

[DD1991]

On 6/5/2020 at 9:26 AM, Pemphix said:

Nothing much i would say...

Tom Carr argued in a 1999 paper published in the Journal of Vertebrate Palaeontology that Nanotyrannus is merely a juvenile T. rex, and most paleontologists (except Larson) have come to agree with Carr. In particular, characters that Larson (2013) cites to support his view that Nanotyrannus is valid are also found in a Tarbosaurus bataar juvenile described by Tsuihiji et al. (2011) (see pre-print by Chan-gyu Yun) as well as Daspletosaurus horneri and one isolated tyrannosaur quadratojugal (CMN 57080). Also, an SVP 2018 abstract by Burnham and colleagues reports that a juvenile T. rex specimen (KUVP 156375) found in Montana has the same maxillary count as adult T. rex (12 maxillary teeth), unlike the count of 15-16 maxillary teeth in the Nanotyrannus holotype and “Jane”. Because of the difference between KUVP 156375 and Jane in the maxillary tooth count despite both specimens being juvenile, KUVP 156375, when described will provide further proof that Nanotyrannus is a juvenile T. rex because it is the first juvenile T. rex specimen to demonstrate a decrease in the number of maxillary teeth as T. rex matured. Also note that Carr infers the undescribed juvenile T. rex specimen RSM 2347.1 to be older than LACM 28471 and but younger than "Jane" and LACM 23845.

 

That said, despite individual variation among T. rex juvenile specimens, Carr's paper reaffirms his long-standing view of Nanotyrannus as a juvenile T. rex. In particular a pneumatic foramen on the quadratojugal is widespread among tyrannosaurines, and it is clear that juvenile tyrannosaurine specimens have morphological traits similar to those of albertosaurines.

 

Burnham, Atkins-Weltman, and Jevnikar, 2018. A new juvenile Tyrannosaurus rex from the Hell CreekFormation of eastern Montana provides insights into cranial and dental ontogeny. SVP 78th annual meeting, Albuquerque, New Mexico, p. 99. (see http://vertpaleo.org/Annual-Meeting/Annual-Meeting-Home/SVP-2018-program-book-V4-FINAL-with-covers-9-24-18.aspx)

[DD1991]

Did you know that T. rex specimens LACM 28471 and LACM 23845 were originally classified as holotypes of new taxa, Stygivenator molnari and Dinotyrannus megagracilis, but were eventually recognized as belonging to T. rex?

[Pemphix]

I think there are two different opinions about that topic.

That papers supports one of these thesis.