A new tale of Protohadros

Protohadros byrdi is a species of dinosaur known only from the Dallas-Fort Worth area, making it a very unique fossil for the region. It was originally discovered in 1994 by an amateur fossil hunter, Gary Byrd, who worked with Southern Methodist University to excavate the remains from a highway road cut in the town of Flower Mound. It was described from a partial skull and other scant skeletal material by Jason Head in 1998 and named for its discoverer (hence the specific title byrdi). A reconstruction of the skull is now on display at the Perot Museum in Dallas.

 

Originally it was thought that Protohadros was an early member of the Hadrosauridae, a family also known as the "duck-billed" dinosaurs. Subsequent work has shown that it is actually more primitive, belonging to the larger group of "almost-duck-bills" we call the Hadrosauroidea. I know, the name's a mouth full, but what it means is that this animal does not quite have all the skeletal features found in the true hadrosaurids. It is instead a close cousin. But Protohadros is important because it helps us understand how this group was evolving prior to the emergence of the true hadrosaurids.

A lot of progress has been made in understanding the evolution of the Hadrosauroidea since 1998, but we still have relatively little evidence from North America, except for several new species described from the west and one new species from Alabama. With only a skull, the exact relationship between Protohadros and these other almost-duck-bills is difficult to nail down. New material we have discovered at the AAS has significantly filled in what the rest of Protohadros' body looked like.

 

We have parts of the limbs, ribs, hips, shoulders, backbone, and tail (see what I did there with the title--it's a pun!). Not only that but much of the material comes from smaller individuals that must have been young, perhaps juveniles or subadults. Compared to the original material, bones from the AAS are almost identical but 30% to 50% smaller.

 

The lower jaw (dentary) from the AAS (top) and the original skull (bottom).

We know they frequently fell prey to the large crocodiles that lived in the area because of croc bite marks on many of the bones. We discuss those a bit more in a previous lab note.

 

Fossils found all over the Dallas-Fort Worth area most likely all come from Protohadros, and some of these remains are HUGE. What does all this mean? Protohadros was like a Cretaceous cow, probably a common animal existing in large herds and one of its main defenses against the crocs and theropod predators was to get big. How big? Maybe 25-30 ft. So, what does the body of Protohadros look like? Something like this:

 

Artwork by Tracy Ford

I want to take this moment to highlight one of our supporters, Billings Productions, for their generous contribution to this campaign! They are a local company that specializes in creating educational animatronic displays. A few years ago we were asked to look at their new animatronic Protohadros, which they have in part based on some of our work. It gives you an idea what an impressive animal Protohadros was in life. It's amazingly life like! This model now tours the United States educating about this unique dinosaur that is found only in Texas.

 

One of the versions being ridden by long-time AAS volunteer Art. This color scheme is based in part on original artwork of the AAS specimen.

 

Another version at the Milwaukee County Zoo this past summer.

--Chris