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Re: tyranno scavenging issues
>The researchers use a speed of about 1.5 km/h as the foraging speed for a
>reptilian tyrannosaur. This is actually reasonable for reptilian energetics,
>and is superior to past studies that try to attribute unsustainably fast
>walking speeds to reptiles. However, the way they estimate a reptilian
>walking speed as a fraction of top speed is spurious. Sustainable walking
>speed is not related to top speed. Tortoises can walk at speeds not much
>lower than those of lizards than can run far faster. It is dependent upon
>aerobic exercise capacity, which is very low in all reptiles of all sizes,
>so a reptilian tyrannosaur would not have been able to forage at speeds
>exceeding 2 km/h.
While I agree that sustainable walking speed is related to aerobic capacity,
the statement that aerobic capacity is low in reptiles of all sizes is false.
While many extant reptiles suffer from a carrier's constraint issue that limits
aerobic endurance (an anatomical issue, not a thermophysiological one), there
are some groups that have found ways around it. Most are scleroglossans (teids,
varanids, scinks). For these animals, assumptions of 1.5 km/hr are far too low.
Auffenberg has observed normal foraging speeds of oras to be 4.8 km/hr, which
is roughly twice as fast as you give them credit for. Along with Auffenberg,
work by Bennet, Garland, Gleeson and others have shown high stamina in a
variety of scleroglossans. So there are a fair amount of exceptions to the low
aerobic reptiles rule.
"I am impressed by the fact that we know less about many modern [reptile] types
than we do of many fossil groups."
- Alfred S. Romer Osteology of the Reptiles