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RE: Size limits



-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of JAMES ARONIS
>Argentinosaurus isn't even the largest found to date. There is as yet, an unamed sauropod found in Argentina about 2 years
>ago that estimates put at over 160ft. in length.
 
Length estimates are horrendously unuseful for dealing with questions of biological meaningful size (aka mass), particularly for taxa such as sauropods which exhibit a lot of variation of tail length (and, to a lesser degree, neck length).  As for the Argentine sauropod, which actual bones are known, and what are their measurements, so that they can be compared to Argentinosaurus, Argyrosaurus, Paralititan, and the like.
 
>As far as individuals in the over 25% size larger are concerned, it is highly
>unlikely. Argentinosaurus is already in blue whale territiory when it comes to its estimated weight, finding a specimen much
>over 100 tons would be a miracle of biological engineering.
 
Not necessarily.  Bone and muscle are pretty darn tough, and we honestly don't know yet if it is mechanical stresses which would generate the size "cealing" for land-living animals.  Other ecological factors (including but not restricted to nutrient intake, home range size, thermal regulation, growth, reproductive factors) may produce a limit at a smaller size than mechanical ones.  Carrano and Janis have already suggested something along these lines for the limiting factor in sizes of terrestrial placental mammals (in that case, gestation period).  Jim Farlow has done some theroetical work suggesting that feeding range (and its inverse, population density) might be a major limiting factor in theropod body size.
 

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742      
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796

"Thomas R. Holtz, Jr." wrote:

The chances that the known specimen of Argentinosaurus is the largest individual that ever lived is vanishingly small: there are almost certainly larger individuals out there in the fossil record.  My suspicion is that we are nearing the plateau of land animal size in Argentinosaurus, but that there might well be taxa which are 25-50% larger still to be found.  
 
                 Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796
-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of Jan Grönvik
Sent: Wednesday, June 13, 2001 2:09 AM
To: Dinosaur Mailing List
Subject: Size limits
 
I would like to know if you think that Argentinosaurus  reached the upper size limit for a terrestrial animal or if you think that we can espect even bigger finds in the future?  Jan Grönvik, Sweden