Re: Swimming dinosaurs

["M.A.Whyte" <M.A.Whyte@sheffield.ac.uk>]

Martin Lockley has argued in his book 'Tracking Dinosaurs' that all 
the tracks interpreted as having been made by swimming dinosaurs have 
either been misinterpreted (e.g. undertracks etc. of walking 
dinosaurs) or were made by crocodiles.

Mike Romano and I have been studying vertebrate tracks from the 
middle Jurassic of Yorkshire, England.  These include a distinctive 
tridactyl form in which the toe marks are parallel rather than 
radiating and the foot appears to have swept through rather 
than rested on the sediment. This suggests that they were made by a 
bouyant animal.  Only left and right prints of one limb (?hind) 
pair are known and these are generally close to the midline of 
trackways.  In one trackway the prints are offset showing that the 
animal was swimming obliquely across a current and being swept 
downstream by it.  The spacing of prints indicates an asymmetrical 
galloping swimming stroke (the dinopaddle) which suggests that the 
other limb (?fore) pair were being used in the swimming even though 
they, being apparently shorter, did not impinge on the sediment.  The 
associated sequence contains a variety of walking tracks of bipedal 
and quadrupedal dinosaurs and at the moment our preferred 
interpretation is that the swimmer is also a dinosaur.  But.....

All the best,

Martin Whyte.