Just when you thought it was safe for Spinosaurus to go back in the water..

[andrewsaurus rex]

A new study portrays Spinosaurus as a wading predator (again) not one that actively swam after prey. More like a stork than on otter.  Of special interest to me, is the statement that Spinosaurus' finned tail is LESS efficient for swimming than the tail of a modern crocodile.


https://www.nationalgeographic.co.uk/science-and-technology/2021/01/did-the-river-monster-spinosaurus-hunt-like-a-stork


The only problem I have with a wading Spinosaurus is its short legs.  Short legs would mean you can't wade into very deep water, which means the fish available to eat will be small and thus more nimble and difficult to catch.  Plus you will need to catch many of them if you're the size of Spinosaurus.  If it had had long legs, it could have waded into much deeper water and have access to larger prey.

The article talks about Spinosaurus catching Onchopristis and Coleocanths.......neither of those are going to be found in the shallow waters Spinosaurus would have been able to wade in.

[andrewsaurus rex]

https://www.livescience.com/spinosaurus-dinosaur-mediocre-swimmer.html

This articles says essentially the same thing as the original one I posted but has a bit more detail.  I can see problems with both predation models for Spinosaurus.   I've never thought it would be a good underwater swimmer with that sail on it's back, which would create a lot of drag and make maneuvering under the water difficult...not useful when pursuing fish.  Alternately, as I said above, if it was merely a wader it would only be able to go out into about 6 feet of water or so, due to its short rear legs and the size of the fish available at that depth would be small and they would be more agile.  A full grown Spino would have to catch very many of them to fill its belly.  And there would not be the big coelacanths and onchopristis available to prey on, in water that shallow, but the first article clearly mentions them as prey, which seems somewhat of a contradiction.

i'm kinda surprised there has been no response to this thread, given the high interest many have in Spinosaurus.  These articles are fairly recent but perhaps this is old news to most?

[stargatedalek]

This seems to be in reference to the same terrible paper from a few months ago. I wouldn't take a word of it seriously.

Plus, plenty of predators that swim after prey are "mediocre swimmers", especially compared to the almost nonsensically powerful tails of crocodiles.

[suspsy]

It should be noted that crocodilians are not pursuit predators in spite of their mighty tails; even they can't match the speed and agility of most fish. Instead, they lie perfectly still and wait for the fish to pass close by. Spinosaurus probably used the same tactic, and its sail might even have helped attract fish by providing a shady area in the water which they would think was safe to gather in. Certain herons employ this tactic by spreading their wings.

[andrewsaurus rex]

that's very interesting.  So I guess it could either be sitting in shallow water or floating on the surface in deeper water, motionless in both cases.  And when a fish gets close enough lunge, propelled by its tail and striking with its long neck. 

That would seem to take both Onchopristis and coelacanths off the menu as both probably would have dwelled in deeper water......unless Spino could swim well enough to catch them on occasion and the lying motionless tactic was just one of its methods of hunting for food....which would make total sense...most predators will go after a variety of prey, depending on the circumstances.  Crocodiles for example hunt fish and other aquatic animals much of the time, but also go after animals that come for a drink or are trying to cross during migrations, during certain times of the year.