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

RE: Microraptor hanqingi, new species from China.

> Date: Fri, 25 May 2012 11:05:52 +1000
> From: tijawi@gmail.com
> To: dinosaur@usc.edu
> Subject: Re: Microraptor hanqingi, new species from China.
> K Kripchak <saurierlagen1978@gmail.com> wrote:
> > "True" arboreality... If we are leaning toward the notion that "true"
> > arboreality arose with the perching pes, no discussion necessary. It's
> > what I see as those "pseudo"- arboreal or "near" arboreal critters
> > that came before (and were often still around)...
> Archaeopterygids, jeholornithids and many small deinonychosaurs might
> indeed qualify as incipiently arboreal. _Jeholornis_ was found with
> seeds in its stomach. Maybe it scaled trunks to get to the seeds far
> from the ground, then glided back down.
> > Alright... Microraptorans are considered to have been gliders.
> > Confuciusnornithids are considered to have been gliders.
> > Confuciusornithids are considered to have been "true" arboreal because
> > they had a foot morphology that enabled a degree of perching.
> > Therefore, Confuciusornithids... gliders... were climbers (had to get
> > "up" there somehow) and were "true" arboreal since they had perching
> > feet.  Microraptorans... gliders... *may* have been climbers... and
> > they couldn't have been arboreal to any degree since the characters
> > (pleural) they did possess are ambiguous and they lacked the foot
> > morphology to enable perching?
> Something along those lines, yes. But their lack of arboreality in
> these theropods is not just due to the pedal morphology. Their
> overall morphology (limb proportions, degree of motion at the joints)
> is inconsistent with arboreal behavior. Spider monkey, my foot.
> > It's hard not to interpret the perching foot as being the linchpin for
> > arboreality when it is repeatedly referred too during most discussion.
> > Sure, they weren't *perfect* hands, or feet, or ungul geometry, or
> > limb/digit length ratios, or whatever for grasping branches... But why
> > expect animals in transition to have the perfect anything or fully
> > functioning whatevers for behaviors or niches they were in the process
> > of adapting to/being selected for to exploit?
> I agree. Arboreal behavior had to start somewhere. But IMHO it's
> significant that the overall proportions of _Archaeopteryx_,
> _Microraptor_ etc are those of a bipedal, cursorial theropod. They
> all had a long neck, a long tail (although generally shorter than the
> ancestral condition), and long legs for terrestrial locomotion.

Wonder if this is one of the reasons why the birds-are-dino-cousins(not 
descendants) groups decided that it had to be a non-theropodian archosaur
> This brings me to the petrel example. Certain petrels can and do
> roost in trees, in spite of the reduced or absent hallux. The webbed
> feet are capable of gripping branches. My guess is that the anterior
> digits toes wrap over the branch. Cormorants do the same thing, with
> rocks and branches.
> But petrels, as typical for procellariform birds, have bodies built
> for flight and life at sea. They have short necks, short tails and
> short legs. All neornitheans have the benefit of being descended from
> an arboreal, perching bird. Comparing these advanced birds with
> _Archaeopteryx_, _Microraptor_ etc is inappropriate, given just how
> different the bauplans are. It's just as bad as using the juvenile
> hoatzin as an analog for tree-climbing behavior in _Archaeopteryx_.
> Tinamous are known to roost in trees, in spite of the reduced or
> absent hallux. They don't really perch, and use their tarsi to help
> them "sit". But again, although terrestrial, the bauplan is that of
> an advanced modern avian.

 great.  so just find us something sufficiently theropodian.  (a kangaroo, 
perhaps?  wait, they can climb trees too)

> > No, no... I understood what you meant by ambiguous.   "Who or whom"
> > was insinuating that to us, the characters/traits are ambiguous, but
> > if the animal put itself up in a tree, they were anything but.
> If an animal habitually spent its time in trees, then the characters
> wouldn't be ambiguous.
> > Just like everyone else who lays awake critically thinking about this
> > stuff, I'm drawing my own set of conclusions based on our current
> > understandings... not just pulling them out of wishes and desires for
> > coolness. Although arboreal microraptorans are rather cool :-)
> Cool: agreed! But if we're going to put microraptorans in trees, it
> has to be for the right reasons.

 to be the pinata.