The Evolving Story of Apatosaurus

Have you ever heard of Apatosaurus?  Apatosaurus lived on Earth approximately 150 million years ago in the Jurassic Period. You may better know this dinosaur by the name Brontosaurus. The name Apatosaurus means “deceptive lizard” due to the fact that it resembles many other species and sometimes, apparently, does not resemble itself. The first Apatosaurus fossils were found in 1877 by Othniel Charles Marsh. The full name of this species was Apatosaurus ajax, and later a second species was found called Apatosaurus louisae.

Apatosaurus Fossil RemainsApatosaurus is believed to be one of the largest animals to ever walk on Earth.  Fossil remains have been found in North America from Oklahoma to Utah.  Some fossils suggest that they could reach 75 feet in length. They probably weighed close to 20 tons.  As you probably know, the Earth looked much different 150 million years ago. There were two continents, Laurasia and Gondwanaland. You can go here to see that globe and where Apatosaurus lived on it (although it’s really where Apatosaurus died on it, because the locations are based on fossil findings).  

Brontosaurus is the name given (also by Othniel Charles Marsh) to a specimen found after his first find.  This one  was an older animal and therefore larger.   They have since been found to be the same species so it is appropriate to refer to both of them as Apatosaurus.   It is becoming more and more common to use the name Apatosaurus for both, although some still maintain that Apatosaurus and Brontosaurus are in fact different species.

Fully Grown Apatosaurus DinosuarDue to their large size you might think it would have been hard for Apatosaurus to move around.  Their skeletal structure, with wide paired spines, made their neck very thick and strong and air sacs in their neck made it lighter than it might look. The flexibility of their necks is still highly debated. Some computer models in the 90s suggest that they had very little flexibility, that their neck was stiff and it would have been hard for them to move close to the ground. Some mid-2000s studies suggest that they probably still wouldn’t have been able to move their necks, but could have held them similar to how a swan or flamingo does. And yet later research posits that, by studying ostriches, a very closely related descendant, we can determine that they had a lot of flexibility, due to the presence of soft tissues.

One thing you may not know about Apatosaurus is about their tails. Apatosaurus tails were very long and tapered very thinly. It is thought that its shape resembled a bullwhip and computer simulations have deduced that it actually could have been used as such. If this is the case, it would have made a noise louder than a cannon and could be heard for over 200 miles. Scientists don’t believe that this would have served in any defense capacity, though, and if the Apatosaurus made use of this tactic, it is unclear why.  We have talked about this before but it is worth pointing out again that fossils provide a glimpse into what animals were like or what they could and couldn’t do.  Our theories and ideas evolve the more we study fossils and flesh out what the actual animal was like.  How they defended themselves and how they moved is based on well educated deductions using the fossils and where they were found as clues in light of what we know about modern day animals.

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2 thoughts on “The Evolving Story of Apatosaurus”

  1. Wow, I have never heard about the Apatosaurus bullwhip tail theory. So cool! Indiana Jones, look out, you’ve met your match! I also enjoyed spinning the globe of our 150 million year old world. Great blog!

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