A swimming theropod Nathan E. Rogers
Posted on 04/12/2013 4:05:42 AM PDT by SunkenCiv
New evidence suggests some two-legged dinos were strong swimmers.
Most people still have a very last-century idea of what dinosaurs were like. No, T. rex didn't stand upright; lots of dinos were actually feathered, not leathery; and they may have been killed by a comet, not an asteroid. Now there's some new research to further muddle your mental image: Some of those clumsy-looking land dinosaurs, like the early tyrannosaur, may have actually been strong swimmers. Scott Persons, a researcher at the University of Alberta, examined fossilized claw marks on a river bottom in China's Szechuan Province. Persons found that the scratches, which cover a distance of nearly 50 feet, suggest coordinated left-right, left-right paddling.
"What we have are scratches left by the tips of a two-legged dinosaur's feet," Persons says. "The dinosaur's claw marks show it was swimming along in this river and just its tippy toes were touching bottom."
The claw marks were probably left by a carnivorous theropod dinosaur that stood just over 3 feet at the hip -- possibly an early tyrannosaur or a Sinocalliopteryx, Persons says.
The study appeared April 8 in the journal Chinese Science Bulletin.
(Excerpt) Read more at popsci.com ...
A swimming theropod Nathan E. Rogers
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| GGG managers are SunkenCiv, StayAt HomeMother & Ernest_at_the_Beach | |
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On Monday I had Friday on my mind. |
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glad I know that
Makes sense ... Thanks SunkenCiv. Also explains some fossilization recovered.
They are still here, we just call them chickens now..../s
Hard to out “doggy-paddle” a tsunami.
I'm a theropod, I'm in water up to my neck (per the picture) and I'm swimming along, my feet occasionally making contact with the bottom of the river, leaving some footprints for posterity.
Can someone please explain to me the mechanism whereby the footprints stay in the mud, the river eventually ceases to flow, the water that was the river evaporates (how long does that take?)-- throughout all of this, the mud still hangs on to the precious imprint of my footprints -- then, the mud bakes in the sunlight and eventually becomes rock, and millions of years later people look at the rock and say "Aha! This was once mud, about 8 ft underwater, and a theropod stepped on it and left a footprint!"
I've been in rivers, streams, lakes, and ponds. I have stepped in mud. I have left footprints. They last less than a minute. Not a single one of my footprints in an underwater environment has yet become a fossil. What am I doing wrong?
You don't weigh a gazillion pounds? ;-)
Neat !
The key to most fossilization is burial prior to disturbing or eradicating what is to be fossilized, be it body parts, impressions, trackways, etc. In most cases, these sorts of impressions/fossils occur in the mud flats along the sides of river, or in shallow, very slow flow waterways (hence the mud, not sand) or lakes. These were most likely in fine-grained mud, indicting slow to no flow in the water, and were not disturbed (i.e. washed away) prior to burial by an influx of new sediment (i.e. there was a flood, carrying with new sediment to cover the old sediments and anything in or on the surface).
So, most likely these were in some sort of shallow oxbow lake adjacent to a river, or were in a lake bed that was fed by a stream/river. The drag marks on the bed of the lake or river were covered over with sediment prior to being washed away or eradicated by other mechanisms.
Trace fossils are actually quite common in some sediments, particularly in ocean sediments.
Beaver: 
Dog:
Elephant:
Lizard:
Horse:
Alligator:
First thing I thought when I saw the photo.. head down, nostrils just clearing the waterline.
How did they ever learn the theropod's name?
It was engraved on his Thuitcase.
The Texas area was one big shallow sea or swamp back in those days
There is film of Komodo dragons swimming in the sea between islands.
Also film with elephants, bears and snakes swimming. If it has lungs to fill with air, it can swim.
Can anyone think of a mammal or reptile that CAN’T swim—at least for short distances.
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