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Re: Dinosaur lactation?




It's an interesting concept, but all of his examples of lactating birds are 
well within Neognathae. Thus it seems more parsimonious to assume that this was 
a trait that only a few bird groups evolved rather than a holdover from 
dinosaurian ancestry. 

It also would have been nice if the author had cited caecilians and some 
cockroaches as well, if for no other reason than to round out the parental 
feeding examples.


Jason




>________________________________
> From: Ben Creisler <bcreisler@gmail.com>
>To: dinosaur@usc.edu 
>Sent: Thursday, 17 January 2013 12:28 PM
>Subject: Dinosaur lactation?
> 
>From: Ben Creisler
>bcreisler@gmail.com
>
>A new paper not mentioned yet:
>
>Paul L. Else (2013)
>Dinosaur lactation?
>Journal of Experimental Biology 216: 347-351
>doi: 10.1242/jeb.065383
>http://jeb.biologists.org/content/216/3/347.abstract
>
>
>Lactation is a process associated with mammals, yet a number of birds
>feed their newly hatched young on secretions analogous to the milk of
>mammals. These secretions are produced from various sections (crop
>organ, oesophageal lining and proventriculus) of the upper digestive
>tract and possess similar levels of fat and protein, as well as added
>carotenoids, antibodies and, in the case of pigeons and doves,
>epidermal growth factor. Parental care in avian species has been
>proposed to originate from dinosaurs. This study examines the
>possibility that some dinosaurs used secretory feeding to increase the
>rate of growth of their young, estimated to be similar to that of
>present day birds and mammals. Dinosaur ‘lactation’ could also have
>facilitated immune responses as well as extending parental protection
>as a result of feeding newly hatched young in nest environments. While
>the arguments for dinosaur lactation are somewhat generic, a case
>study for lactation in herbivorous site-nesting dinosaurs is
>presented. It is proposes that secretory feeding could have been used
>to bridge the gap between hatching and establishment of the normal
>diet in some dinosaurs.