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RE: Tinamous: living dinosaurs
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.
Jaime A. Headden
The Bite Stuff (site v2)
"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
> Date: Mon, 27 Jun 2011 14:09:20 -0400
> From: firstname.lastname@example.org
> To: email@example.com
> CC: firstname.lastname@example.org
> 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.
> > Ronald Orenstein
> > 1825 Shady Creek Court
> > Mississauga, ON
> > Canada L5L 3W2
> > On 2011-06-27, at 12:40 PM, Jason Brougham <email@example.com> 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 <firstname.lastname@example.org>
> >>> To: email@example.com
> >>> 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
> >>> firstname.lastname@example.org
> >> Jason Brougham
> >> Senior Principal Preparator
> >> American Museum of Natural History
> >> email@example.com
> >> (212) 496 3544
> Jason Brougham
> Senior Principal Preparator
> American Museum of Natural History
> (212) 496 3544