RE: Complete juvenile theropod unveiled in Germany

[Jaime Headden <qi_leong@hotmail.com>]

  Understand that I do not take with Horner's view in this context because the 
actual argument I made was that the juveniles of related but disimilar adult 
taxa can be quite similar, if not impossible to tell apart. This inference is 
made especially clear in various publications assessing the ontogeny of 
hadrosauroids, especially lambeosaurines, as in Brink et al. 2011., which I 
covered (without attribution) here: 
https://qilong.wordpress.com/2011/08/09/o-crest-less-one/ . It is impossible, 
in my view, based on _current_ analysis, to determine the complexity of the 
taxonomy based on juveniles, hatchlings, etc. of virtually any paleontological 
taxon. Due to this, I argue that one should not name taxa on this basis. But 
this does not mean that these taxa _do not exist_, merely that our tools or 
options are not strong enough to differentiate them at the youngest levels.

  Of course, I have no idea what Rauhut et al. have to say, and will wait for 
the paper before saying they cannot make the case their taxon is distinct 
enough.

Brink, K. S., Zelenitsky D. K., Evans, D. C., Therrien, F. & Horner, J. R. 
2011. A sub-adult skull of *Hypacrosaurus stebingeri* (Ornithischia: 
Lambeosaurinae): Anatomy and comparison. _Historical Biology_ 23(1):63-72.

Cheers,

  Jaime A. Headden
  The Bite Stuff (site v2)
  http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
Backs)


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> Date: Thu, 13 Oct 2011 21:39:53 -0700
> From: saint_abyssal@yahoo.com
> To: dinosaur@usc.edu
> Subject: Re: Complete juvenile theropod unveiled in Germany
>
> The possibility that many of our small "coelurosaurs" are actually juveniles 
> of larger non-coelurosaur taxa certainly bolsters Horner's claims that 
> paleontology's current view of dinosaur biodiversity is grossly over-inflated 
> by ontogenetic stages misidentified as distinct taxa. I think I remember 
> David Unwin's pterosaur book describing pterosaur ecosystems as having low 
> taxonomic diversity because juveniles occupied the ecological niches that 
> would otherwise be taken by distinct small species. Maybe theropods had a 
> similar life cycle. Tyrannosaur ontogeny supports the general idea; young 
> tyrannosaurs had sharper more blade-like teeth and more cursorial body types 
> than adult suggesting different prey preferences and therefore different 
> niches. That's not suggesting, of course, that all small theropods were just 
> juveniles of some larger form, and earlier commenters suggesting that the new 
> find is a typical Juravenator-type compsognathid rather than a baby
> megalosaur could turn out right. I'm just musing here.
>
> ~ Abyssal
>