As we transition into the fall, I thought it would be fun to reminisce on one of my favorite summer vacations.
One of the best adventures of my life occurred one summer when my family and I spent a week in western Colorado. During two of those days, we joined a dinosaur dig. It was very hot and dirty. Insects swarmed us, the nearest porta-potty was a half mile away – and I never had more fun in my life!
The paleontologist in charge of the dig, Jim Kirkland, told us where to dig and what to do. The area we dug in was a vast bone bed dating to about 150 million years ago, during the late Jurassic (one of the three time periods during which dinosaurs lived). Many dinosaurs had died, perhaps in a flood, and had their bodies swept into this huge heap. Their bones were all jumbled together. Diggers in that area have found bones from Brachiosaurus, Stegosaurus, Allosaurus, Apatosaurus, and other Jurassic dinosaurs. We would not get to keep any bones we found. They would stay with the paleontologists for study, as they should.
The rock was crumbly, like flaky pastry, and easily removed with just our hands. We searched through it and then discarded the rock into plastic bins. It’s not always easy to tell what’s rock and what’s bone, but at this site the rock was a light brown and the bones much darker brown, almost black. We moved a lot of rock before we saw anything. (Caption: That’s my husband, John, in striped shirt, my son, Patrick, in red cap, and Jim Kirkland in cowboy hat.)
That thrill, though, when you see a bone that’s been buried for 150 million years is not like anything else. It was definitely worth the hours of digging. I felt awed and elated and also a little humble. I’m a tiny speck in this universe. You know, we also spent two days white water rafting while we were in Colorado, but digging up dinosaur bones was more exhilarating!
During those two days digging I only found three bones, but one of them in particular interested Dr. Kirkland (in red shirt at left; me in blue). It looked like a piece of armor from an armored dinosaur, but at that point no one had ever found an armored dinosaur in Jurassic rock. Further excavation after I left produced more of that dinosaur, and it turned out to be just what Dr. Kirkland suspected: an armored dinosaur, the first ever found from the Jurassic Period. He named it Mymoorapelta and wrote to me about it. He also put out a press release, and I got my picture on the front page of the local newspaper!
Dr. Kirkland is now the state paleontologist of Utah.
Mymoorapelta is a nodosaur, which means, among other things, that it doesn’t have a club at the end of its tail. It was one of the earliest armored dinosaurs ever to have lived, and, at 9.8 feet long, one of the smallest. It ate mostly plants that grew low to the ground, such as ferns, cycads, and conifers. Its teeth were small and leaf-shaped. Scientists can’t say for sure, but it is likely that it lived in herds.
I will leave you with this question: If you found a new dinosaur, what would you name it? Please let me know in the comment section.
I don’t know who makes up the names for groups of animals: a herd of cows, a pack of wolves, or a litter of kittens. Some of the group names are funny: a business of ferrets, a kettle of hawks, a bloat of hippopotami, a shiver of sharks, a stench of skunks, and an ambush of tigers. But whoever makes up those names certainly got it right for Tyrannosaurus. A group of them is called a terror of tyrannosaurs. Several species of dinosaur fall into the category of tyrannosaur, such as Albertosaurus, Gorgosaurus, and Daspletosaurus. The most famous, of course, is Tyrannosaurus rex. All of them are among the largest meat-eating creatures that ever lived.
Scientists don’t know whether or not Tyrannosaurus lived or travelled in groups. There are only two clues that could help with this. Sometimes paleontologists find bonebeds that contain many dinosaurs of the same kind that all died at the same time. That might happen if a flash flood killed a large herd of animals. For example, in Alberta, Canada, thousands of bones of the dinosaur Centrosaurus were found in a bonebed measuring about 1 ½ square miles. This is strong evidence that centrosaurs travelled in large groups. Dinosaur bonebeds for Protoceratops, Avimimus, Pinacosaurus, Edmontosaurus, and others have been found. But no bonebeds of Tyrannosaurus or any other tyrannosaur have ever been discovered.
The other evidence of animals living or travelling in groups is footprints. Often just one, single footprint is found. Other times a trackway is found, showing the progress of a single dinosaur.
Sometimes there are many footprints, showing the travels of a whole herd. Prior to 2011, only single footprints of tyrannosaurs had been found. Though it’s hard to say for sure which made a footprint, scientists can make educated guesses. The one most confidently attributed to Tyrannosaurus rex was found in Montana in 2007. The Montana footprint was 2 ½ feet long with slender toes, and it was found in the right age of rock for Tyrannosaurus. Also, its toes were correctly positioned for T-rex, so paleontologists are fairly certain they have correctly identified it. But that print doesn’t tell us much about how Tyrannosaurus lived and moved.
Some scientists thought that because they had never found a tyrannosaur bonebed or more than one footprint of a tyrannosaur that Tyrannosaurus was a solitary creature, perhaps only associating with others of its kind for mating. Many of today’s predatory birds, such as eagles and hawks, are largely solitary. That way they don’t have to compete for food. But in 2011 a trackway showing three tyrannosaurs walking together made scientists reconsider the idea of tyrannosaurs as loners.
In the forests of northeastern British Columbia, paleontologists uncovered a series of tracks showing three large dinosaurs walking side by side. A total of seven footprints were found: three from one dinosaur and two from each of the other two, but all the footprints were made at the same time, and they are clearly walking together. The prints are so well preserved that scientists can even see scales on the dinosaurs’ feet. The size of the tracks and the size and positioning of the toes clearly make these tyrannosaur tracks. However, it’s not possible to know which species of tyrannosaur they are from.
McCrea RT, Buckley LG, Farlow JO, Lockley MG, Currie PJ, Matthews NA, et al. (2014) A ‘Terror of Tyrannosaurs’: The First Trackways of Tyrannosaurids and Evidence of Gregariousness and Pathology in Tyrannosauridae. PLoS ONE 9(7): e103613. https://doi.org/10.1371/journal.pone.0103613
The size of the footprints does indicate that the creatures were of a similar age, different scientists estimating perhaps 25, 26, and 29 years old. The size also indicates their approximate height: 7.5 to 9.4 feet tall, measured at the hip. Dinosaur height is usually measured at the hip because most of them didn’t hold their heads at a consistent height. By knowing the height of the animal and measuring how far apart the footprints are, scientists can determine how fast the dinosaurs were going. When scientists did the math for these footprints, they concluded that these three dinosaurs were going 3.9 to 5.2 m.p.h. However, in 2021 researchers from the Netherlands made a computer reconstruction of a Tyrannosaurus walking, and they concluded that its top speed was only about 3 m.p.h. More evidence is needed to figure out how fast a tyrannosaur could walk.
Still the trackways give a tantalizing look at the life of a tyrannosaur, no longer a loner, but a friendly guy who liked to hang out with his terror of friends.
Make up a name for a group of you and your friends. Please put it in the comments below!
Burns, M. E., T. A. Tumanova and Philip J. Currie. “Postcrania of Juvenile Pinacosaurus grangeri (Ornithischia: Ankylosauria) from the Upper Cretaceous Alagteeg Formation, Alag Teeg, Mongolia: Implications for Ontogenetic Allometry in Ankylosaurs.” Journal of Paleontology. 2015. Vol. 89, pp. 168-182. https://pubs.geoscienceworld.org/jpaleontol/ article-abstract/89/1/168/139797/Postcrania-of-juvenile-Pinacosaurus-grangeri.
Evans, D. C., D. A. Eberth, and M. J. Ryan. “Hadrosaurid (Edmontosaurus) Bonebeds from the Horseshoe Canyon Formation (Horsethief Member) at Drumheller, Alberta, Canada: Geology, Preliminary Taphonomy, and Significance.” Canadian Journal of Earth Science. 2015. Vol. 52, pp. 642–654. https://cdnsciencepub.com/doi/pdf/10.1139/cjes-2014-0184?download=true.
McCrea R.T., L.G. Buckley, J.O. Farlow, M.G. Lockley, P.J. Currie, et al. “A ‘Terror of Tyrannosaurs’: The First Trackways of Tyrannosaurids and Evidence of Gregariousness and Pathology in Tyrannosauridae.” 30 July 2014. PLoS ONE Vol. 9, p. 7: e103613. doi:10.1371/ journal.pone.01036
Title Image: Stock photo shows a dinosaur footprint in the ground. Footprints in Texas have been revealed as drought persists. NEENAWAT/GETTY
Dinosaur Lady 
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