The Pubic Bones Are The Difference

Dinosaurs are divided into two major categories, Saurischia (lizard-hipped) and Ornithischia (bird-hipped), based on the orientation of the pubis bone.

The Saurischia dinosaurs include theropods (velociraptors are theropods), and theropod footprints are the most common type of fossil footprints. Theropods were typically carnivorous and walked on two legs.

T-Rex is a Saurischia as are the huge plant-eating long-necked sauropods. Although most fossil tracks were made by Saurischia dinosaurs, we will not be spending much time with T-Rex. There are few T-Rex footprints. Most theropod tracks are thought to have been made by other types of dinosaurs such as Coelurosauria.

The Ornithischia dinosaurs were mainly herbivores and include the ornithopod dinosaurs that most likely made the other type of fossil footprint we'll be looking at. Some ornithischian dinosaurs walked on all fours, and some walked on two legs in a similar way to theropods. And some, at times walked on two legs, and sometimes on four legs. This category includes well-known dinosaurs such as Triceratops and the Stegosaurs.

Image credit: AdmiralHood, modified to combine both images into a single image and add text, CC License.

Theropod Dinosaur Tracks

The majority of the dinosaur tracks we'll be looking at were made by theropods. In the above image there are two theropods. The smaller dinosaur in the foreground is a Coelophysis. Some experts say that a similar dinosaur made the smaller three-toed tracks, known as grallator tacks, that you'll see our museum.

The larger dinosaur is a Dilophosaurus. The experts at Dinosaur State Park (Rocky Hill, CT) have proposed this as the dinosaur that made the larger tracks, called eubronties tracks. On the other hand other experts say all of the tracks were made by the same type of dinosaur, just different sizes (juvenile, young adult, and adult). So there are some disagreements. Confused? The answer is that no one knows for sure which theropod made the tracks. The best we can say is that certain three-toed tracks were made by a theropod dinosaur. That's why fossil dinosaur tracks use a different naming system, grallator and eubronties for example, than is used for naming dinosaurs. (There is no grallator nor eubronties dinosaur.)

Ornithopod Dinosaur Tracks

The other type of track we'll be looking at was made by a bipedal, herbivorous, orthopod dinosaur. However, some say it may have been a thyreophoran ornithischian similar to a Scutellosaurus. No one knows for sure, and Scutellosaurus does not seem to have been large enough for some of the tracks that have been found. So we're going to go with just a generic orthopod as the most likely trackmaker.

Photo: Coelophysis photographed in the Dickinson (ND) Museum Center. Dilophosaurus photographed in Dinosaur State Park (CT)

Sauropod (Long Neck) Dinosaurs

One of the most famous types of dinosaurs are the long-neck sauropods. We do not have Sauropod footprints in the museum. They are difficult to come by and not very interesting to look at. Many times they simply look like a round hole in the ground. In most cases a trackway (a trail of dinosaur footprints) is needed for the impressions to be identified as sauropod footprints.

Image credit: KoprX, modified to make legend readable and add title, CC License.

Sauropod Tracks

The photograph above shows sauropod footprints. As I said, they look like a circular hole in the ground. These tracks are from in the Paluxy River near Glen Rose, TX. In this picture the larger hole was made by a rear foot and the smaller hole is a front foot. The photo in the upper left corner shows part of an exhibit at Dinosaur Valley State Park (Paluxy River) showing sauropod foot bones in a sauropod track. In some cases the toes will leave impressions.

Next - How Tracks Are Made   Dinosaurs in Our Museum