Dino Debate: Apatosaurus or Brontosaurus?

by Eileen Neary

Assistant Project Manager

As a kid, one of the scariest movies I ever saw was Jurassic Park. I remember lying awake in bed at night, listening to the sound of a giant T. rex stomping down trees in my backyard. Sure, it was just the sound of the new dishwasher, but I didn’t know that until I confessed to my parents what I’d heard.

Before Jurassic Park, all I knew of dinosaurs came from The Land Before Time movie series. I wasn’t really sure what kinds of dinosaurs any of the characters were, though my older brother quickly pointed out which was obviously a pterodactyl (not that he pronounced it correctly). It wasn’t until later on in life that I heard about how the brontosaurus character should really be called an apatosaurus, so Littlefoot was officially the latter. Of course, I didn’t think much of it.

But the real story of the bronto-apato debate is much more complicated than I ever thought. In the 1970s, researchers from the Carnegie Museum of Natural History determined that the brontosaurus skeleton displayed in a museum was actually “wearing” the wrong head, and that it belonged to a different dinosaur. They figured that the skeleton was supposed to have an apatosaurus head. News agencies then reported that the brontosaurus never even existed.

But things were convoluted long before then. Back in the late 1800s, a paleontologist named Othniel Charles Marsh discovered two fossils, and believing them to be different genera (or potentially wanting them to be two different genera, as the conspiracy goes), named the first one Apatosaurus and the second Brontosaurus. Then in 1903, competing paleontologist Elmer Riggs determined that Marsh was mistaken about their differences. He claimed that the smaller skeleton was just a young apatosaurus, and that both skeletons were of the same genus. As a result, the genus Brontosaurus dissolved—since, you know, finder’s keepers—or “the rules of scientific nomenclature” as they say. The genus Apatosaurus came first, so Apatosaurus it would be.

But it looks like ol’ Elmer Riggs made a mistake too. The brontosaurus fossils are, it seems, different enough from apatosaurus fossils to warrant their own genus. Lead author of a new 2015 study on these two fossils, Emanuel Tschopp, notes that “Brontosaurus can be distinguished from Apatosaurus most easily by its neck, which is higher and less wide. . . . Apatosaurus is even more extreme than Brontosaurus.”

Tschopp and his team believe the two genera are truly much more different than originally thought. However, it’s not quite as easy as changing the name in some books. To determine a genus’s restoration, an organization called the International Commission on Zoological Nomenclature has to agree. All members have to be elected in. The 27 current members represent 19 countries. Together, they make determinations that are accepted by scientists worldwide.

But then, scientists are always double- and triple-checking each other’s work. Maybe there is more to the bronto-apato debate still to come. All I know is that as long as one doesn’t come stomping through my backyard, they can have whatever name the scientists want.

Did You Know?

In our August 2014 blog “Those Are Some Funky Chickens: Feathered Dinosaurs Rule the Roost,” we mistakenly called the apatosaurus and the brontosaurus the same animal when we said “Apatosaurus (a.k.a. Brontosaurus).” We should have said “formerly Brontosaurus,” since that is what would have been accurate at the time. Of course, now, the time for “a.k.a.” is over!