Fungasaurus and the Three-Fingered T. rex

It's been a while since I've gotten nit-picky with a piece of sloppy journalism. I've kind of missed it, to be honest. If you're getting paid to write this stuff, get it right. And often, following up on something that sounds a bit shady leads to some new knowledge, which is a spiffy thing.

For instance, this article contains some small problems that would have been solved with basic fact-checking or additional clarification. The story concerns the Highlands Prehistoric Museum, run by Jerry Jacene, who runs a fossil recreation business called The Prehistoric Exhibits Company in the same space. The museum had a "soft opening" on Saturday, April 17, after moving from Cookeville, TN to Kingsport, TN. When reading the article, three things immediately popped out at me:

1. The stale old mistake of calling pterosaurs "flying dinosaurs." It's possible that the article is referring to birds, of course, but it's relatively rare for that phrase to be used in that way. It's almost always a misidentification of a pterosaur.
2. Something called "fungasaurus." Googling the word leads to either the article itself or references to a video game character.
3. A three-fingered Tyrannosaurus rex

Here's the twist. Number three is basically true. I had not heard of it, and investigating the claim has been a lot of fun. Here's what I've learned.

The T. rex display at the HPM is a restoration of the Fort Peck Rex, the first specimen found that preserves a "third digit" on the hand. The Fort Peck Rex was unearthed in 1997 by a team led by J. Keith Rigby of Notre Dame University, and was also the subject of one of those messy battles over who has rights to the fossils: the property owner or science. The specimen was then subjected to years of study, and it has popped up occasionally on the Dinosaur Mailing List, where paleontologists and other dinosaur researchers engage in debate over matters mesozoic. At the 2007 meeting of the Geological Society of America, a presentation was given about the specimen by paleontologists from Fort Peck Paleontology, Inc.

Fort Peck Rex reconstruction at the Maryland Science Center. Photo by arborwin, via flickr

Calling the Fort Peck Rex "three fingered" is a bit of an exaggeration. It's not as if paleoartists are going to revert back to the practice of giving T. rex a more Allosaurus-like, three-fingered hand, as they had before good T. rex forelimbs were discovered in the latter half of the last century. The bone is actually a metacarpal, not a true digit, and is about the size of a human finger. It had no condyle, or knuckle, and didn't have phalanges connected to it. It wasn't a jointed "finger." Further examination of the third metacarpal in this and other T. rex specimens reveals that it appears to have had some use in life, as it's rather knobby, suggesting it had been injured and healed. [UPDATE: A kind commenter clarified, as I should have, that the metacarpal would have been "contained" within the hand, and not an extremity poking out of it. It's likely that the injury that may have occured to it was incidental, and not because it was specifically being used for something.]

Peck's Rex also provides further evidence that those widely derided arms of the T. rex didn't just flop uselessly. The left arm shows signs of having a bad muscle tear, either due to repeated stress or a struggle in which it essentially was pulled in a "tug of war" between its owner and another animal. I'd like to put forward the entirely reasonable hypothesis that it got stuck in a Mesozoic vending machine.

More:

• Here's the Science Daily article about the Fort Peck Rex from 1997.
• Notre Dame Magazine published an interview with Rigby in 2003.
• Brian Switek wrote about the find at Laelaps, prior to the 2007 GSA Meeting.
• Looking Again at the Forelimb of Tyrannosaurus rex, a chapter by Christine Lipkin and Kenneth Carpenter in the volume Tyrannosaurus rex: The Tyrant King (Indiana University Press), is available at Google books.
• Here's a local PBS interview with Jacene.
• Or maybe you just want to own a replica of the "pinkie."

Back to the really important stuff. What the hell is a fungasaurus?