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

Re: Alvarezsaur spurs (was Re: dino-lice)

Picid tongues are supported by an extremely elongate hyoid apparatus. I would 
expect that if alvarezsaurids had a protrusible tongue the hyoid would show 
specialization to that effect - are hyoid elements known for the group?

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

On 2011-05-03, at 2:09 AM, Augusto Haro <augustoharo@gmail.com> wrote:

> Perhaps conservation of canines until developing powerful arms with
> large claws is a way an anteater can protect itself. Phylogenetically,
> conservation of canines makes sense, overall if descending from a
> clade where the canines were much used. At least, there is an
> intraspecific struggle selective force acting for their conservation,
> in absence of other weapon. I once saw a video with an aardvark trying
> to bite a cheetah which was trying to play with it. I suppose that
> although biting will not be great thing against a larger hyena, lion
> or leopard, it may at least diminish the list of predators, because
> the similarly sized jackal and Cape badger would likely go for it if
> this defense was not present (as far as I was able to observe, no
> matter how courageous they are, mammalian carnivores do not prey on
> other carnivores not smaller than they one-on-one, probably because
> they have canines similar in effect to their own).
> Returning to the question of mymecophagy and cursoriality, I think
> they are not exclusive, as shown by Proteles, and also the canid
> Otocyon, but this is constrained because most myrmecophages today are
> quadrupedal mammals, where you cannot specialize the forelimb for
> myrmecophagy in the sense of anteaters or pholidotans while keeping
> being a cursor. When termites go around without need to break their
> nests, a cursor may perfectly feed upon them. The limbs of cursors are
> energy-saving because of their longer stride and lesser weight
> distally, requiring less force to be moved forwards, so can easily be
> used for an energy-saving myrmecophage. It seems that the inactivity
> of the specialized Proteles has more to do with the inactivity of the
> termites themselves. Likely, if the termites were less seasonally
> variable in activity, or active during a larger part of the day, the
> aardwolf would be a similarly more active animal.
> Now, turning back to alvarezsaurs, they may have simply specialized
> their forelimb without need to lose their hindlimb cursorial
> adaptations (as many said). Thus, lack of cursoriality in most
> myrmecophagous mammals can be explained because of the adaptation of
> the forelimb, instead of metabolic rate constraints. Now, if
> alvarezsaurids were capable of preying upon termites in their nests,
> thanks to their forelimbs, they may have likely enjoyed this food
> during a larger part of the year, overall accepting the calid
> conditions loved by termites were more common in the Mesozoic.
> Other thing: there are birds, like picids, which have a long, sticky
> tongue to grab insects. This seems to make them more similar to their
> mammalian myrmecophagous counterparts. Tubular mouths are less common
> outside mammals because there are no cheeks (oh, well, except for
> seahorses and curculionids). We may say it was difficult for
> alvarezsaurs to have had a tubular mouth because of phylogenetic
> constraints.