Re: Chicago Tribune article about Jane the juvenile T. rex exhibit at the Burpee Museum

[Phil Bigelow <bigelowp@juno.com>]

Thanks for a great summary!

Tibia paleontologist
or not tibia one.
That is the question.

<pb>
--

On Wed, 29 Jun 2005 17:29:54 -0500 Sarah Werning <swerning@gmail.com>
writes:
> If they used the same element used to estimate Sue's age (Erickson,
> 2004), it would have been the fibula.
> 
> In answer to the question from your previous email ("Why doesn't 
> the
> tibia bone in dinosaurs get remodeled with increasing age?"), the
> tibia does get remodelled with age, but apparently in some dinos, 
> the
> fibula does not. In most long bones, the older LAGs/rings (the ones
> closer to the center of the bone) are lost when the bone is 
> remodelled
> and also as the medullary cavity expands. The fibula has the 
> advantage
> of no medullary cavity, so in tyrannosaurs (which do not remodel 
> their
> fibulae), one can count the earlier rings that are lost to the
> expanding medullary cavity and remodelling that happens in the 
> larger
> long bones like the femur and tibia, making it a good choice for 
> age
> determination (It also has the practical advantage of a much 
> smaller
> diameter, which means you can fit the whole cross section on one
> slide!).
> 
> It is worth mentioning that in other dinosaurs (such as 
> Tenontosaurus,
> the ornithopod whose bone histology and growth I'm looking at for 
> my
> MS thesis), the fibula undergoes early, extensive remodelling and 
> is
> completely useless for determining age by LAG counts. For 
> Tenonto's,
> the best bone for estimating age by number of LAGs is the tibia, 
> but
> because of the reasons mentioned above, you have to do a bit of
> back-calculation to arrive at the animal's approximate age at 
> death.
> Another complication is that different elements will have different
> numbers of LAGs (as in Maiasaura - see Horner et al, 2000). In
> Tenontosaurus, the tibia consistently has the highest number of 
> LAGs
> of all the long bones, and the femur will usually have the same, 
> one
> or two fewer LAGs. I do not know how much the number of LAGs varies 
> by
> element in theropods, though.
> 
> Hope this helps,
> Sarah
> 
> 
> Sarah Werning
> Graduate Student, Department of Zoology
> University of Oklahoma
> 730 Van Vleet Oval, Room 314
> Norman, OK   73019
> swerning@ou.edu
> 
> 
> On 6/28/05, Phil Bigelow <bigelowp@juno.com> wrote:
> > 
> > I think I meant to write "fibula".
> > 
> > <pb>
> > 
> > On Tue, 28 Jun 2005 09:41:53 +0000 (pd) Phil Bigelow 
> <bigelowp@juno.com>
> > writes:
> > 
> > > That [analysis of growth rings] would probably be on the tibia, 
> right?
> > BTW:  Why doesn't the
> > > tibia
> > > bone in dinosaurs get remodeled with increasing age?
> > >
> > >
> > > <pb>
> > > --
> > >
> > >
> > >
> > >
> > >
> > 
> > 
> >
> 
>