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RE: T. rex's vision as SUPPORT for scavenging activitiy...



Don Ohmes wrote:

Any candidates for the role of volant scavenger(s) co-existing with T. rex?

A scavenging lifestyle was suggested for _Quetzalcoatlus_ back in the 1970's, when this flying beastie was first described. But as I learned from Darren Naish's blog...


http://darrennaish.blogspot.com/2006/04/why-azhdarchids-were-giant-storks_03.html

... the evidence to support a scavenger lifestyle for _Qutzalcoatlus_ and other azhdarchids is very weak.

I'd bet dollars to donuts that one day a Mesozoic bird (probably an enantiornithean) turns up with characters consistent with specialist scavenging.

Considering the sheer bulk of many dinosaur carcasses around in the Jurassic and Cretaceous, scavenging seems like too good a niche to pass up. Of course, it helps to have a strong digestive system.

IF there is the presence of a population of volant scavengers, then timely visual cues (eg, circling vultures) to any local large animal death exist, and are detectable from distances up to 40 miles in an open environment.

AFAIK, nobody has suggested that tyrannosaurs could fly. Apart from George Olshevsky, that is. :-)


Cheers

Tim








Don







From: don ohmes <d_ohmes@yahoo.com>
Reply-To: don ohmes <d_ohmes@yahoo.com>
To: dinosaur@usc.edu
Subject: T. rex's vision as SUPPORT for scavenging activitiy...
Date: Mon, 03 Jul 2006 13:13:37 -0700 (PDT)

In my opinion-- obligate scavenger is not the most probable lifestyle for T. rex, and there are strong arguments for a top predator lifestyle, as well some against the obligate scavenger hypothesis. That said, there is no doubt that the ability to scavenge/co-opt fortuitous mortalities in the local large animal population is potentially advantageous for top predators.

The ability to detect fortuitous mortality in a timely fashion is obviously critically important to efficient utilization of such resources, and any sense used for detection is therefore subject to strong directional selection. IF there is the presence of a population of volant scavengers, then timely visual cues (eg, circling vultures) to any local large animal death exist, and are detectable from distances up to 40 miles in an open environment.

Given the large size of resource animals extant in the Cretaceous, a relatively large time window for utilization would exist. An open environment, very large animals, and volant scavengers seems like an ideal recipe for evolving keen (ie, long-range) daytime vision in a large terrestrial predator.

I don't know if this has been addressed before, in print. If it has, sorry about the lack of reference.