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Re: Fibular reduction in birds and its evolution from dinosaurs (free pdf)

The pdf is now available for free.

http: // onlinelibrary.wiley.com/doi/10.1111/evo.12882/epdf

Also, news stories:

Molecular experiment reverses evolution in birds obtaining a
dinosaur-like lower leg

http: // 

http: // www.alphagalileo.org/ViewItem.aspx?ItemId=161171&CultureCode=en

On Wed, Feb 17, 2016 at 9:49 AM, Ben Creisler <bcreisler@gmail.com> wrote:
> Ben Creisler
> bcreisler@gmail.com
> A new paper:
> João Francisco Botelho, Daniel Smith-Paredes, Sergio Soto-Acuña,
> Jingmai O'Connor, Verónica Palma and Alexander Vargas (2016)
> Molecular development of fibular reduction in birds and its evolution
> from dinosaurs.
> Evolution (advance online publication)
> DOI: 10.1111/evo.12882
> http: // onlinelibrary.wiley.com/doi/10.1111/evo.12882/abstract
> Birds have a distally reduced, splinter-like fibula that is shorter
> than the tibia. In embryonic development, both skeletal elements start
> out with similar lengths. We examined molecular markers of cartilage
> differentiation in chicken embryos. We found that the distal end of
> the fibula expresses Indian Hedgehog (IHH), undergoing terminal
> cartilage differentiation, and almost no Parathyroid-related-protein
> (PTHrP), which is required to develop a proliferative growth plate
> (epiphysis). Reduction of the distal fibula may be influenced earlier
> by its close contact with the nearby fibulare, which strongly
> expresses PTHrP. The epiphysis-like fibulare however then separates
> from the fibula, which fails to maintain a distal growth plate, and
> fibular reduction ensues. Experimental downregulation of IHH signaling
> at a post-morphogenetic stage led to a tibia and fibula of equal
> length: The fibula is longer than in controls and fused to the
> fibulare, while the tibia is shorter and bent. We propose that the
> presence of a distal fibular epiphysis may constrain greater growth in
> the tibia. Accordingly, many Mesozoic birds show a fibula that has
> lost its distal epiphysis, but remains almost as long as the tibia,
> suggesting that loss of the fibulare preceded and allowed subsequent
> evolution of great fibulo-tibial disparity.