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Re: Dinosaur speeds



>Date: Thu, 20 Jan 2000 12:27:35 +0000
>From: "Adrian Thomas" <adrian.thomas@zoology.oxford.ac.uk>
>Greetings,
>Anyone know of references to trackway analyses that suggest dinosaur speeds
>higher than Alexander's classic 1 - 3m/s (human walking speed) based on
>dimensional analyses and Froude numbers (Steve?).

Yes. In 1981 Jim Farlow (Nature 294:747-748) published what (AFAIK) is still the fastest known running dinosaur track, estimated at 11.9 meters/second. I don't know where the Acrocanthosaur-like tracks
were published as "25 mph" (ca. 11m/s). The Kayenta theropod tracks published by Welles (1971, in Plateau 44:37-28; also see Paul 1988:138-139) do not show "40mph" (ca. 18m/s) motion, from what I can tell. With a stride length of ~2m, foot length ~0.5m (hip ht ~2m), according to Thulborn's (1990, Dinosaur Tracks p. 291) formula they are estimated at ~5m/s (~11m/s), still not too slow and almost certainly a running gait. That is assuming that Paul's drawing of the track is accurate enough to take measurements from.

Of course, all of these trackway speed estimate formulae have their bugbears; at Berkeley we've tried using Alexander's equation to estimate speeds of elephants whose actual velocities we rigorously measured (up to 4.1 m/s). Generally it overestimates by about 2x, sometimes almost 3x; it almost never underestimates. I find the qualitative conclusions of these estimates more compelling than the quantitative estimates; the faster tracks clearly show a running gait and the slower ones show a walking gait. However, I don't trust relative stride length [= stride length/ hip ht] as a conclusive indicator of gait. We had elephants walking at a 2.8 RSL which according to Thulborn should be a trot (trot= 2.0 to 2.9 RSL); it was not even close. (we presented this stuff at SICB, and I know others have recently made similar conclusions)

There are no published tracks of large theropods, ornithopods, or sauropods that show anything but a walk (again AFAIK, contrary refs are welcome), but of course I do not extrapolate from that to say that running was impossible or that the speeds are maximal.

Cheers,
John


==================
John R. Hutchinson
Department of Integrative Biology Phone: (510) 643-2109
3060 Valley Life Sciences Bldg. Fax: (510) 642-1822
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