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Re: Tinamous: living dinosaurs



First of all, tinamous ARE ratites despite their size and flying ability, so 
there is no reason to assume that their brooding habits were independently 
acquired. 

Paternal-only brooding for dinosaurs IS  pure speculation as (to my knowledge) 
we have no evidence that the animals found in brooding positions (are there 
more than one?) were males. Do we have any evidence for male brooding other 
than the presence of large nests for troodontids etc?  Do we have any evidence 
(other than large clutch size, again) that clutches represent multiple female 
layings?

Ronald Orenstein 
1825 Shady Creek Court
Mississauga, ON
Canada L5L 3W2

On 2011-06-27, at 12:40 PM, Jason Brougham <jaseb@amnh.org> wrote:

> Yes, of course, we might well expect a radiation of diverse brooding 
> strategies among Dinosauria, as so many millions of years went by and so many 
> specialized lineages diverged.
> 
> There may even be a sample bias, also, for those taxa that nested on the 
> ground on floodplains. I w=myself wouldn't be at all surprised if we find one 
> day an alvarezsaur female seated atop one or two very large eggs, for example.
> 
> But, nonetheless, we have several samples of non - avian maniraptoran nests 
> and they are consistent in the features of large numbers of eggs in the 
> clutches and males brooding them alone.
> 
> Also, I'm not clear from your e-mail if you are suggesting that Tinamous 
> evolved paternal - only brooding independently of ratites (since tinamous are 
> not large and flightless)?
> 
> Let me put it this way: if you HAD to reconstruct the brooding of a non - 
> avian maniraptoran now, wouldn't it be safest to go with the paternal - only 
> brooding model? Anything else would be pure speculation.
> 
> In other words, isn't it most parsimonious to assume that the brooding 
> strategy held in common by Troodon, oviraptorids, (possibly Gobipteryx), 
> tinamous and ratites is a synapomorphy, rather than a strategy that was 
> independently converged upon four times? It certainly could have been 
> independently derived, but that just requires more assumptions and thus is 
> less parsimonious.
> 
> Cheers
> -Jason
> 
> On Jun 24, 2011, at 11:35 AM, Ronald Orenstein wrote:
> 
>> I would be very nervous about doing this.  We have no idea if paternal care 
>> is a 
>> basal character or simply a common feature (symplesiomorph?) of ratites.  
>> Ratites are still neornithine birds, and there is a lot of intervening 
>> evolution 
>> between them and maniraptorians.  I would be reluctant to assume that any 
>> behavioural characteristic of ratites not associated with large size or 
>> flightlessness is any more likely to be a basal feature than  the 
>> behavioural 
>> characteristics of any other ground-living bird (such as a lyrebird, for 
>> example!).
>> 
>> Ronald Orenstein
>> 1825 Shady Creek Court
>> Mississauga, ON L5L 3W2
>> Canada
>> ronorenstein.blogspot.com
>> 
>> 
>> 
>> ----- Original Message ----
>> From: Jason Brougham <jaseb@amnh.org>
>> To: dinosaur@usc.edu
>> Sent: Fri, June 24, 2011 10:17:27 AM
>> Subject: Tinamous: living dinosaurs
>> 
>> I put up a  new blog post about Tinamous, and how they are underexploited
>> as models for extrapolations about the biology of extinct maniraptorans.
>> Since their egg brooding behavior is comparable to Troodon and
>> oviraptorids, can we infer that the behavior between the father and the
>> chicks was the same also?
>> 
>> http://web.me.com/jasonbrougham/Site/Blog/Entries/2011/6/18_Tinamous__Living_dinosaurs.html
>> 
>> 
>> 
>> Jason Brougham
>> Senior Principal Preparator
>> Department of Exhibition
>> American Museum of Natural History
>> 81st Street at Central Park West
>> 212 496 3544
>> jaseb@amnh.org
> 
> Jason Brougham
> Senior Principal Preparator
> American Museum of Natural History
> jaseb@amnh.org
> (212) 496 3544
> 
>