Nomen conservandum?

[Loon]

I was thinking about times when two or more species have been found to be synonymous, but one name has become relatively well-known enough to become the official species name. I know something like this happened with tyrannosauridae, but other than that, I can't recall any other instances. It's bound to have happened, though.

Update: turns out I'm thinking of nomen conservandum.

[andrewsaurus rex]

scientifically, the first name given takes precedence, whether it's well known or not.  One example is Brontosaurus and Apatosaurus.   When they were thought to be the same, the name Brontosaurus was dropped because Apatosaurus was used first.  However, I believe Bronto is back as it is now considered a valid genus.  However, there are lots of examples where the first name gets used and the, perhaps more popular name, goes by the wayside.

T rex was first called Dynamosaurus, but that got lost in history.  I believe Barnum Brown first wanted to call T rex, Epispondylus or something like that but Osborn overruled him and coined Tyrannosaurus Rex.

[Loon]

A @andrewsaurus I should have been clear, but I do know that. The brontosaurus business doesn't necessarily fall into what I'm asking. I'm thinking of instances where that rule is broken for one reason or another to keep the more popular name.

Also, I believe the other name for tyrannosaurus was Deinodon, which the family tyrannosauridae was originally named after, but I may be wrong.

Edit: I actually found the name for this phenomenon: nomen conservandum

[andrewsaurus rex]

ah ok.  Well, Dynamosaurus may apply because i think a fossil found before Brown made his discovery was later found to be a T rex and had been named Dynamosaurus.  But by then Tyrannosaurus Rex was so popular Dynamosaurus was just left forgotten about.

And the original name for T Rex was Manospondylus Gigas.  I looked it up.

[Loon]

A @andrewsaurus yeah, you're right, I forgot about manospondylus. Weird, considering it's a fairly catchy name. So, yeah, I guess tyrannosaurus counts then.

[andrewsaurus rex]

well i don't think Mandospondylus was ever official.  It was proposed by Brown, but Osborn didn't like it and made the official name Tyrannosaurus. 

Dynamosaurus was an official name before Tyrannosaurus though and should have had priority.  But Tyrannosaurus was so popular that Dynanosaurus was left forgotten.  Back then the rules weren't enforced as rigidly as they are today.  It was the wild west of fossil hunting.

[Leyster]

Manospondylus (which was used by Cope), Bathygnathus ecc. are nomina oblita = not used as valid name since 1900. This applies for modern species name, too. Deinodon cannot be distinguished among Tyrannosaurids (since it's from the Judith River, it's either Daspletosaurus or Gorgosaurus), so it's a nomen dubium.

[Halichoeres]

Manospondylus (which was used by Cope), Bathygnathus ecc. are nomina oblita = not used as valid name since 1900. This applies for modern species name, too. Deinodon cannot be distinguished among Tyrannosaurids (since it's from the Judith River, it's either Daspletosaurus or Gorgosaurus), so it's a nomen dubium.

Yep, Bathygnathus being suppressed in favor of the later name Dimetrodon is the most prominent example that I can think of.