[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: Tinamous: living dinosaurs



My understanding (quick research) indicates most research on rate of loss is 
based on what are essentially domesticated fowl, which lay year-round, and are 
used to study medullary gain/loss highs, lowns, and means, but not for total 
periods of absence. Any help by other readers would be useful.

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)


----------------------------------------
> Subject: Re: Tinamous: living dinosaurs
> From: jaseb@amnh.org
> Date: Thu, 30 Jun 2011 12:01:18 -0400
> CC: dinosaur@usc.edu
> To: qi_leong@hotmail.com
>
> Jaime,
>
> Well, the entire issue then is the length of time required for the complete 
> and total erasure of any trace of medullary bone. I would encourage you to 
> research the rates of medullary bone resorption in ratites and crocodilians 
> to get some data on the question.
>
> The Varricchio paper acknowledges that medullary bone is not found in every 
> species of archosaur, and discusses their reasoning.
>
> -Jason
>
>
> On Jun 30, 2011, at 11:47 AM, Jaime Headden wrote:
>
> >
> > Quick argument:
> >
> > If we assert that medullary bone is reabsorbed soon after laying, as it 
> > only persists during the laying period, then a post-laying brooding female 
> > should not retain medullary bone. Then, if we assert that nests that 
> > contain well-developed embryos, which may or may not be close to hatching, 
> > that the laying animal is well out of the laying period, we should not find 
> > medullary bone if the brooder was female. I would then conclude that in a 
> > nest with well-developed embryos, the associated nester could be either 
> > male or female, and the association or not of the actual layer(s) would be 
> > unknown.
> >
> > I may be wrong in some of my assertions, so please correct me if I am.
> >
> > 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)
> >
> >
> > ----------------------------------------
> >> Date: Mon, 27 Jun 2011 14:09:20 -0400
> >> From: jaseb@amnh.org
> >> To: ron.orenstein@rogers.com
> >> CC: dinosaur@usc.edu
> >> Subject: Re: Tinamous: living dinosaurs
> >>
> >>
> >> On Jun 27, 2011, at 1:25 PM, Dr Ronald Orenstein wrote:
> >>
> >>> 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.
> >>
> >> I was not aware of that. When you say ARE, which phylogentic 
> >> hypothesis/taxonomy are you referring to? Tinamous are usually classified 
> >> in their own Order, Tinamiformes, distinct from the Ratitae, aren't they? 
> >> Hackett et al. (Science 320 (2008) did nest tinamous within the 
> >> "Struthioniformes", but they refer to the Paleognathae as "ratites and 
> >> tinamous". Other phylogenies, such as Dyke & Van Tuinen, Zoological 
> >> Journal of the Linnean Society 141 (2004), found tinamous to be more 
> >> primitive than any ratite. Also, I thought that the term "ratite" refers 
> >> to the reduced, raft - like, sternum found in the flightless paleognathous 
> >> birds. Perhaps you are using ratite interchangeably with Paleognathae, and 
> >> perhaps you reject the traditional clade "ratite" because it is (probably) 
> >> paraphyletic.
> >>>
> >>> 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?
> >>
> >> Paternal only brooding is supported by multiple specimens, strong 
> >> statistical correlations, and bone histology. Troodon, Oviraptor, and 
> >> Citipati adults have been found in association with their nests. 
> >> Varricchio et al. Science 322 (2008) studied 8 specimens of adult 
> >> non-avian maniraptorans found in association with nests. Not one showed 
> >> evidence of having medullary bone or resorption cavities, as have been 
> >> reported in Tyrannosaurus, Tenontosaurus, Allosaurus and Syntarsus 
> >> previously. When the authors looked at clutch volume to adult body mass 
> >> proportions within extant archosaurs they found that clutches as large as 
> >> those found with Troodon and the oviraptorids correlate strongly with male 
> >> - only care within extant archosaurs. The large clutches (up to 30 eggs) 
> >> are likely polygamous because, put bluntly, this egg volume probably could 
> >> not fit inside the body of a single female Troodon.
> >>
> >> http://www.sciencemag.org/content/322/5909/1826.full.pdf
> >>
> >>
> >>>
> >>> 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
> >>>>
> >>>>
> >>
> >> Jason Brougham
> >> Senior Principal Preparator
> >> American Museum of Natural History
> >> jaseb@amnh.org
> >> (212) 496 3544
> >>
> >>
> >
>
> Jason Brougham
> Senior Principal Preparator
> American Museum of Natural History
> jaseb@amnh.org
> (212) 496 3544
>
>