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Re: Jeholornis and enantiornithines had one functioning ovary like modern birds

No more than the fact that they retained teeth, the loss of which is
also usually seen as a flight-related, weight reducing adaptation. It
does suggest that if basal paravians were volant, they were not as
well adapted for flight as avialans, but that would have been the
working hypothesis anyway.

On the other hand, this could be seen as support for the hypothesis
that basal avialans themselves were volant, which is not universally


On Mon, Mar 18, 2013 at 3:36 AM, Tim Williams <tijawi@gmail.com> wrote:
>> Xiaoting Zheng, Jingmai O’Connor, Fritz Huchzermeyer, Xiaoli Wang, Yan
>> Wang, Min Wang & Zhonghe Zhou (2013)
>> Preservation of ovarian follicles reveals early evolution of avian
>> reproductive behaviour.
>> Nature (advance online publication)
>> doi:10.1038/nature11985
>> http://www.nature.com/nature/journal/vaop/ncurrent/full/nature11985.html
> "Why living birds lost the right ovary and oviduct is unclear,
> but the most common hypothesis suggests that this was related to the
> need to reduce weight in flight during the reproductive season, the
> female having to carry only a single egg inside rather than two..."
> Troodontids had two functional oviducts (Varicchio et al., 1997).  So
> did oviraptorosaurs (Sato et al., 2005)
> If the loss of a functional right oviduct is indeed a flight-related
> feature...  does this undermine the hypothesis that terrestrial
> deinonychosaurs and oviraptorosaurs were secondarily flightless?
> Cheers
> Tim