Saturday, October 15, 2011

Why extinct dinosaurs keep getting bigger!

Tyrannosaurus rex, a theropod from the Late Cr...Image via Wikipedia
I sometimes ply for blog ideas.  Today I found two articles about well known dinosaurs, both of which are now officially considered physically bigger than they were several years ago.

These include the Tyrannosaurus Rex which is now thought to be 30% heavier, and a species of giant pterosaur, wingspan has been increased to 7 meters. 
Pterosaurs on the South BankImage by Ben Rimmer via Flickr

Why is it that these sizes have been changed after knowing of the species for so long? 

There can be only one logical explanation.  A conspiracy!  The government thinks people will go nuts, just scared out of their minds, if we know how big the dinosaurs were all at once.  And if you believe that, than I have a bridge for sale at a great discount for you!

DinosaursImage by CameliaTWU via Flickr

The real reason why this happens, according to my great wisdom, is the scarcity of the fossil record.  Pretend some future race had found the fossils of 20 humans.  Then they took the largest of these sets (some of which were fossils of men, women, and children) and decided that the largest set represented the maximum size of a human being.  What are the chances that they actually found the largest set that has existed.  Virtually nil.  As more bones are uncovered, occasionally a larger specimen will be found, and the "maximum size" will be increased. 

It is a very conservative approach in science that is praiseworthy in terms of not overstating the actual sizes of dinosaurs, but, it will virtually always be corrected multiple times over the years.  I have two better ideas. 
LAS VEGAS - SEPTEMBER 30:  Enya Kim from the N...Image by Getty Images via @daylife
First, and the most fun, is to simply state the best size.  For example, if you think that it would be cool if the dinosaur was way bigger, than just say that it's way bigger.  Then life size replicas could be absolutely huge.  Like the sabretooth tigers in the movie 10,000 BC.  Or Clifford the red dog. 

Second, and less fun, would be take the theorized measurements of all the fossils of a species that have been found so far, and place them on a standard bell curve.  You should end up with most fossils in the average range, some in the small range, and some in the large range.  The 99.5% number will give you a size, and that will be the maximum size of the creature. 
DinosaurImage by Richard Elzey via Flickr

Advantages: Changes in the number over time will be smaller, providing more continuity and less need to revise textbooks etc.  Also, this will produce larger maximum sizes almost invariably for dinosaurs.  And bigger sizes are always cooler.

Disadvantages: Occasionally, some of the dinosaurs will be found to be smaller in reality than was previously hypothesized.  The very small number of fossils, varied ages and genders, and questions of fossils being the same or different species may make a bell curve impossible in a lot of cases.  Also, since the size of a creature based on a usually very incomplete fossil takes into account many educated guesses (the new T-rex weight is based on soft tissue measurements using crocodile and bird soft tissue averages), the "size" of any specific dinosaur fossil may change, which will then change the bell curve produced by its previous placement. 
Dinosaurs, Crystal PalaceImage by Pete Reed via Flickr

Still, at the end of the day, I think it's worth it, when possible, to use statistical averages to provide a more realistic and credible claim to the maximum size of extinct animals. 

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