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

RE: Troodon/Orodromeus hypothesis



>   We've spent some time talking about various durophages, including
> ovophages. One thing that should be kept in mind here is that to predate
> an egg, you need one primary thing: a way to break the eggshell. Crushing
> teeth, or slicing teeth, or an apparatus that can do so (dropping the egg,
> using a rock, swallowing and slicing within the mouth/throat, etc.). The
> troodontid hatchlings in question lack any of these features, and moreover
> none of them have teeth thicker than the eggshell in question. Their
> proximity to the eggs of a nest filled with oviraptorids implies 2 is
> improbable if not impossible;

Norell et al., (Science, vol. 266, no 5186, Nov 4, 1994, pg. 779) wrote
"the possibility that the dromaeosaurids (-sic, later found to be
troodontids)... were predators on the the oviraptorid eggs or
hatchlings,... cannot be discounted". Of course I agree that the hatchling
Troodontids were unlikely to break the eggs. But that's not to say they
didn't mistakenly try. I think I've seen films of juvenile foxes gnawing
on eggs but failing to break them. Moreover, the troodontids could have
been attracted to the eggs in order to snatch the chorioallantoic
membranes upon hatching. So I think that your use of the word "impossible"
was overstated.

this leaves 1 and 3. I doubt, based on the
> jaw anatomy, that troodontids destroyed or opened eggs orally, although
> they could have eaten the neonates post-hatching, so I doubt the inverse
> of 1, but at the same time the evidence of nests of troodontids in NA at
> least implies 3 is not correct (but this is based on negative evidence).
> Nest parasitism is curious, be we've little data to indicate that,

Well, if you are suggesting that, since some Troodontids were not nest
parasites, that Byronosaurus was most likely not a nest parasite, I agree
that that is supported, but the evidence is by no means decisive. We must
acknowledge that an archosaur family, such as the Cuculidae, can contain
both parasitic and nest - building members. I believe that some ducks are
even opportunistic nest parasites, so that the same species will rear
their young if they have to, but will dump them in other nests if they
can.


> especially as Bever and Norell indicate that the associated eggshells are
> oviraptorid, of the same type found with the oviraptorid embryo.

Do you have a reference on that? In the Bever, Norell paper I  can only
find a mention that two small pieces of eggshell adhere to the right
rostral region, but no mention of the nature or origin of the eggshell.
But in Norell et al., 1994, they do mention that the outer, convex,
surface of the eggshell contacts the rostrum, implying that the egg did
not enclose the skull when it was deposited.

> Varricchio et al. document troodontid eggshell, and show it to be
> extremely different from that of oviraptorids, thus confusing the
> association as parasitic (the eggshells associated with the skulls as
> evidence the neonates were hatched in the nest) rather than predatory (the
> oviraptorids dumping the neonates into the nest). I would implicity, as
> Bever and Norell do (tangentially, as this same nest produced the
> oviraptorid embryo), support 1.

Overall I'd say that's perfectly plausible, but I do urge consideration of
the complexity of the situation.


>
> 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: Fri, 13 May 2011 02:01:02 -0400
>> From: jaseb@amnh.org
>> To: dinosaur@usc.edu
>> Subject: Troodon/Orodromeus hypothesis
>>
>> Hi everyone,
>>
>> I was reading about Paleocene Lithornithids tonight and I came up with a
>> new hypothesis about Orodromeus remains in Troodon nests.
>>
>> Please check it out at my blog (below) and I'd appreciate any feedback,
>> further references, and criticism.
>>
>> In particular, does anyone know what other vertebrate remains are found
>> in
>> the nests besides Orodromeus?
>>
>> http://web.me.com/jasonbrougham/Site/Blog/Entries/2011/5/12_Vertebrate_remains_in_dinosaur_nests.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
Department of Exhibition
American Museum of Natural History
81st Street at Central Park West
212 496 3544
jaseb@amnh.org