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

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



Dann Pigdon <dannj@alphalink.com.au> wrote:

> That's all fine and dandy *after* you have acquired massive muscles and 
> claws, but I wonder how
> often myrmecophages actually make it past the 'hump' between having no 
> digging specialisations
> but fast locomotion, and developing highly specialised digging equipment that 
> can also compensate
> for the reduced locomotor abilities.



Good point.  Anteaters (vermilinguans) may have gotten over this
'hump' by evolving their specializations in the trees, relatively safe
from predators.  Arboreality seems to be basal for the Vermilingua,
with the terrestriality (and large size) of the giant anteater being
derived (Gaudin & Branham, 1998).  In fact, arboreality might well be
primitive for the entire Pilosa (anteaters + sloths) given the
arboreal nature of the three-toed sloths (Bradypodidae), a group which
has been recovered in a basal position relative to all remaining
sloths.


But to return to your point - this wouldn't be relevant to the
aardwolf or aardvark, both of which appear to have evolved their
myrmecophagous adaptations on terra firma (this is true even if the
tubulidentates evolved from arboreal ancestors).  In the absence of
some form of armor (as developed by armadillos, echidnas and
pangolins) or enlarged and highly formidable foreclaws (as in the
giant anteater), a large myrmecophagous mammal is very vulnerable on
the ground, and there is a cost associated with specialized fossorial
forelimbs in the reduction of terrestrial mobility.




Cheers

Tim