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Author Topic: Mangroves  (Read 13475 times)
hardlec
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« on: February 01, 2008, 04:28:25 PM »

In Brackish waters around the world, there are “mangrove” swamps.  These are photogenic for “b” movies, where the gators and other critters munch on the victims.

In reality these are fairly complex ecosystems with a variety of prey and predators.  The Mangrove roots provide cover from the larger predators but are spacious enough to hold a fair-sized fish. (There is a lot more to things than this, but this will do for a start.)

A long-necked predator or the approximate dimensions of a plesiosaur might be well adapted to such an area, as the long neck and “narrow” head can get in where other predators can’t.  There are other reasons why the basic shape of a Plesiosaur might work well in this environment.

But:  Speculation aside, how would someone test this as a “hypothesis?”

It is hard to place a fossil in ecological context.  It can be done, but a lot of things have to happen “right.”  Is there any data on the Plesiosaur’s ecology?  Have people simply assumed deep water and not looked for plant life nearby?  It is also likely that supporting or opposing evidence simply doesn’t exist.

I know some work is being done on stomach contents.  Does any of this contraindicate a “mangrove swamp” environment? 
« Last Edit: February 28, 2008, 12:27:29 PM by richardforrest » Logged
Squalicorax
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« Reply #1 on: February 01, 2008, 09:07:04 PM »

I know nothing about these studies, however one way to test the hypothesis would be to look at the animals' anatomy.
Mangroves swamps usually have long, narrow branches, true. However, a long neck by itself isn't neccessarily indicative of a lifestyle in these systems. Still, if sharks could have prowled Eocene mangroves, its entirley possible that small plesiosaurs may have as well...
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Mike
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« Reply #2 on: February 01, 2008, 09:27:20 PM »

Hardlec,
Although I know of no fossil evidence that would preclude plesiosaurs from living or feeding in or around the edges of the Mesozoic equivalent of a mangrove swamp, I think that a long, relatively inflexible neck would be a hindrance for navigating in a highly congested and very complicated environment...

Unfortunately most people continue to view plesiosaurs as they were portrayed by almost all of the early artists... with a long, snake-like neck... Charles Knight probably did one of the more extreme versions...
http://www.oceansofkansas.com/images2/knight3.jpg

...and as late as 1943, Sam Welles, one of the leading plesiosaur experts at the time, published drawings (fig. 10) of the extremes of movement that he envisioned for elasmosaur necks:

Welles, S. P. 1943. Elasmosaurid plesiosaurs with a description of the new material from California and Colorado. University of California Memoirs 13:125-254. figs.1-37., pls.12-29.

Although we are still learning about how plesiosaurs swam... (imagine driving your car while sitting at the end of a boom that extended 15-20 feet in front of the front wheels - e.g. steering and propulsion -  I'd love to see some one do a 'flight simulator' program on an elasmosaur).  I think it is a pretty safe bet that elasmosaurs were relatively slow moving and had a fairly large "turning radius"... something much more suited for open water than the narrow confines of a tree root congested swamp.

Also, please note that due to "global warming" during the Late Cretaceous.. the Earth was pretty much a water world... with the surface about 85 percent covered by oceans (compared with 71% today)... Lots of shallow open water that would have be great habitat for a fish eater...

My two cents.

Mike
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Anthony
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« Reply #3 on: February 02, 2008, 04:17:42 AM »

The real question here is: is there fossil evidence for mangrove type swamps at all?

Plesiosaur remains, both elasmosaur and polycotylid have been found mixed with dinosaur and champsosaur material, but what does that really tell us?
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hardlec
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« Reply #4 on: February 29, 2008, 03:33:32 AM »

The neck of a giraffe is not very flexible, it is used to help eat leaves high in the trees.  The long neck enable the creature to get its mouth to were the food is. If the Plesiosaur is a large, slow predator, an ability to poke its head into mangrove root systems ed. al. is a big advantage.  My "vision" is not a head and neck that twine in and out, but something that can push its head into places were other predators can't go.

It is too slow to run prey down; not able to strike like a snake (i.e. ambush.)  This leaves stalking prey, or doing some form of grazing or scavenging.

Somehow, stalking prey in a pelagic environment seems close to absurd.  There is no cover or concealment, I doubt a long neck will be of much value here.  Now:  there is the possibility that the small head on a long neck is able to sneak up on prey, but my credulity wanes.

This leaves another option:  The plesiosaur feeds on shellfish in shallow water.  It is able to "tilt" up to breath and "tilt" down to feed with minimal swimming up or down.  It can stand on its tail to "spot" which may or may not be of value locating food, but surely valuable. 

So a plesiosaur is sort of like a swan or a goose.  It feeds on bottom dwelling creatures, I'm thinking shellfish, but crabs and lobsters would fit as well.  Swans have flexible necks, but Plesiosaurs much less so.  They can do the same thing, only in a different way.  There may be a small forest of plesiosaur tails sticking out of the water as they dip their heads down, quite a picture, that.

Maybe the plesiosaur is a sea-going scavenger, like a buzzard.  It's long neck allows it to get its head into the body cavity of dead creatures.  Flexibility is not needed.  This can take place in a mangrove "swamp" as easy as anywhere else.

I do know that a lot more "public" work has been done on paleolithic creatures that their ecologies. 



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Mike
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« Reply #5 on: March 01, 2008, 06:51:32 PM »

RE: Maybe the plesiosaur is a sea-going scavenger, like a buzzard.  It's long neck allows it to get its head into the body cavity of dead creatures.  Flexibility is not needed.  This can take place in a mangrove "swamp" as easy as anywhere else.

I do know that a lot more "public" work has been done on paleolithic creatures that their ecologies.

=====================================
Not to rain on your parade here, but there is no evidence to support the idea that plesiosaurs were scavengers... they simply do not have the kind of teeth that would be useful for tearing pieces off of (or out of) dead animals. Would they eat a dead fish floating on the surface?  Possibly... but mostly they were active predators that used their mouth full of interlocking teeth to capture living prey (small fish and cephalopods)..

Mike
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william583
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« Reply #6 on: March 31, 2010, 05:03:01 AM »

Hello,
This is nice. But I think in the way you define the topic, it is good but not in the way it should be.. You start it good and cover all the things but in the middle you leave the actual topic and did not focus on the specific topic you started.. But over all its good. And I am a student and did different ……………. These are good but taught as well. Hope more topics will be discuss from your side. Have a good day.


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