More than 110 million years ago, a lumbering 1,300-kilogram, armour-plated dinosaur ate its last meal, died, and was washed out to sea in what is now northern Alberta. This ancient beast then sank onto its thorny back, churning up mud in the seabed that entombed it — until its fossilized body was discovered in a mine near Fort McMurray in 2011.

Since then, researchers at the Royal Tyrrell Museum of Palaeontology in Drumheller, Alta., Brandon University, and the University of Saskatchewan (USask) have been working to unlock the extremely well-preserved nodosaur’s many secrets — including what this large armoured dinosaur (a type of ankylosaur) actually ate for its last meal.

“The finding of the actual preserved stomach contents from a dinosaur is extraordinarily rare, and this stomach recovered from the mummified nodosaur by the museum team is by far the best-preserved dinosaur stomach ever found to date,” said USask geologist Jim Basinger, a member of the team that analyzed the dinosaur’s stomach contents, a distinct mass about the size of a soccer ball.

“When people see this stunning fossil and are told that we know what its last meal was because its stomach was so well preserved inside the skeleton, it will almost bring the beast back to life for them, providing a glimpse of how the animal actually carried out its daily activities, where it lived, and what its preferred food was.”

There has been lots of speculation about what dinosaurs ate, but very little known. In a just-published article in Royal Society Open Science, the team led by Royal Tyrrell Museum palaeontologist Caleb Brown and Brandon University biologist David Greenwood provides detailed and definitive evidence of the diet of large, plant-eating dinosaurs — something that has not been known conclusively for any herbivorous dinosaur until now.

“This new study changes what we know about the diet of large herbivorous dinosaurs,” said Brown. “Our findings are also remarkable for what they can tell us about the animal’s interaction with its environment, details we don’t usually get just from the dinosaur skeleton.”

Previous studies had shown evidence of seeds and twigs in the gut but these studies offered no information as to the kinds of plants that had been eaten. While tooth and jaw shape, plant availability and digestibility have fuelled considerable speculation, the specific plants herbivorous dinosaurs consumed has been largely a mystery.

So what was the last meal of Borealopelta markmitchelli (which means “northern shield” and recognizes Mark Mitchell, the museum technician who spent more than five years carefully exposing the skin and bones of the dinosaur from the fossilized marine rock)?

“The last meal of our dinosaur was mostly fern leaves — 88 per cent chewed leaf material and seven per cent stems and twigs,” said Greenwood, who is also a USask adjunct professor.

“When we examined thin sections of the stomach contents under a microscope, we were shocked to see beautifully preserved and concentrated plant material. In marine rocks we almost never see such superb preservation of leaves, including the microscopic, spore-producing sporangia of ferns.”

Team members Basinger, Greenwood and Brandon University graduate student Jessica Kalyniuk compared the stomach contents with food plants known to be available from the study of fossil leaves from the same period in the region. They found that the dinosaur was a picky eater, choosing to eat particular ferns (leptosporangiate, the largest group of ferns today) over others, and not eating many cycad and conifer leaves common to the Early Cretaceous landscape.

Specifically, the team identified 48 palynomorphs (microfossils like pollen and spores) including moss or liverwort, 26 clubmosses and ferns, 13 gymnosperms (mostly conifers), and two angiosperms (flowering plants).

“Also, there is considerable charcoal in the stomach from burnt plant fragments, indicating that the animal was browsing in a recently burned area and was taking advantage of a recent fire and the flush of ferns that frequently emerges on a burned landscape,” said Greenwood.

“This adaptation to a fire ecology is new information. Like large herbivores alive today such as moose and deer, and elephants in Africa, these nodosaurs by their feeding would have shaped the vegetation on the landscape, possibly maintaining more open areas by their grazing.”

The team also found gastroliths, or gizzard stones, generally swallowed by animals such as herbivorous dinosaurs and today’s birds such as geese to aid digestion.

“We also know that based on how well-preserved both the plant fragments and animal itself are, the animal’s death and burial must have followed shortly after the last meal,” said Brown. “Plants give us a much better idea of season than animals, and they indicate that the last meal and the animal’s death and burial all happened in the late spring to mid-summer.”

“Taken together, these findings enable us to make inferences about the ecology of the animal, including how selective it was in choosing which plants to eat and how it may have exploited forest fire regrowth. It will also assist in understanding of dinosaur digestion and physiology.”

Borealopelta markmitchelli, discovered during mining operations at the Suncor Millennium open pit mine north of Fort McMurray, has been on display at the Royal Tyrrell Museum since 2017. The main chunk of the stomach mass is on display with the skeleton.

Other members of the team include museum scientists Donald Henderson and Dennis Braman, and Brandon University research associate and USask alumna Cathy Greenwood.

Research continues on Borealopelta markmitchelli — the best fossil of a nodosaur ever found — to learn more about its environment and behaviour while it was alive. Student Kalyniuk is currently expanding her work on fossil plants of this age to better understand the composition of the forests in which it lived. Many of the fossils she will examine are in Basinger’ collections at USask.

The research was funded by Canada Foundation for Innovation, Research Manitoba, Natural Sciences and Engineering Research Council of Canada, National Geographic Society, Royal Tyrrell Museum Cooperating Society, and Suncor Canada, as well as in-kind support from Olympus Canada.

Reference:
Caleb M. Brown, David R. Greenwood, Jessica E. Kalyniuk, Dennis R. Braman, Donald M. Henderson, Cathy L. Greenwood, James F. Basinger. Dietary palaeoecology of an Early Cretaceous armoured dinosaur (Ornithischia; Nodosauridae) based on floral analysis of stomach contents. Royal Society Open Science, 2020; 7 (6): 200305 DOI: 10.1098/rsos.200305

Note: The above post is reprinted from materials provided by University of Saskatchewan.

Palaeontologists from St Petersburg University have been the first to study in detail the structure of the brain and blood vessels in the skull of the ankylosaur Bissektipelta archibaldi, an herbivorous dinosaur somewhat similar in appearance to a modern armadillo. Scientists produced the first three-dimensional computer reconstruction of a dinosaur endocast made in Russia,a digital cast of its braincase. It made it possible to determine that ankylosaurs, and Bissektipelta in particular, were capable of cooling their brains, had an extremely developed sense of smell, and heard low-frequency sounds. However, their brains were one and a half times smaller than that of modern animals of the same size.

Ankylosaurs appeared on Earth in the middle of the Jurassic—about 160 million years ago—and existed until the end of the dinosaur era, which ended 65 million years ago. These herbivorous animals were somewhat reminiscent of modern turtles or armadillos, were covered with thick armour, and sometimes even had a bony club on the tail. The researchers became interested in the uniquely preserved remains of ankylosaurs from Uzbekistan. Although these fossils have been known for 20 years, only now have the scientists had an opportunity to study the specimens from the inside using cutting-edge methods.

During the study, the palaeontologists examined three fragments of fossil skulls of the ankylosaur Bissektipelta archibaldi. They were found during a series of international expeditions URBAC (Uzbek / Russian / British / American / Canadian Joint Paleontological Expeditions) in the late 1990s and early 2000s at the Dzharakuduk locality in the Central Kyzylkum Desert, Uzbekistan. The scientists emphasise that it is unique, in that numerous remains of representatives of ~90-million-year-old fauna can be found there. These include dinosaurs, pterosaurs, crocodiles, birds, mammals and other vertebrates.

“This is really one of the richest locations in the world. The fauna of Dzharakuduk now has more than 100 species of ancient vertebrates,” said Pavel Skutschas, associate professor at St Petersburg University and an expert in Mesozoic vertebrates. “Of course, such a diversity of life would not have been found without large-scale field studies. A series of nine URBAC expeditions, undertaken from 1997 to 2006, pooled together the efforts of palaeontologists from many countries in the search for the bones of ancient animals.”

The material that was collected at that time comprises dozens of fragments of skulls and skeletons, and hundreds of thousands of isolated bones. Scientists still use them in their research and say that will provide studies for many years to come. At present, the three fragments of fossil ankylosaur braincases from Uzbekistan are stored at the Zoological Institute of the Russian Academy of Sciences. However, they have been temporarily transferred for research to the Department of Vertebrate Zoology at St Petersburg University.

Ankylosaurs lived on our planet for 100 million years

“Thanks to the development of computed tomography (CT) over the past 15 to 20 years, palaeontologists are able to learn more and more about the dinosaur brain and its structure,” said Ivan Kuzmin, the lead author of the article and a doctoral student at St Petersburg University.

“We decided to re-describe Bissektipelta archibaldi, and we managed to clarify its place on the phylogenetic tree of ankylosaurs. A 3-D reconstruction of the endocast of its brain cavity was made using CT. It is important to understand that the digital ‘cast’ of the braincase is not the brain itself. It is necessary to study it carefully to understand how big the actual brain was, where its parts were, how the vessels and nerves were housed.”

After meticulous work that lasted for three years, the scientists determined that a considerable part of the brain of Bissektipelta archibaldi was occupied by olfactory bulbs—about 60% of the size of the cerebral hemispheres. Bissektipelta likely had an extremely developed sense of smell, which probably helped it to look for food, the opposite sex, and to feel the approach of predators in time. It was of vital importance to know about any danger in advance because ankylosaurs had such heavy armor and a clumsy figure. The olfaction of ankylosaurs can even be compared with the olfaction of the famous predator Tyrannosaurus rex. Its olfactory bulbs were even larger, as they occupied about 65-70% of the size of the large hemispheres.

“Another interesting skill of the ankylosaur that we learned about is the ability to cool its brains in the literal sense,” said Ivan Kuzmin. “The network of veins and arteries in its braincase turned out to be very complicated: They did not go in a single direction, but constantly communicated with each other, like a system of railway tracks. The blood could have flowed in different directions and been redistributed, while maintaining the optimal brain temperature of the animal. For example, if the top of an ankylosaur’s head became warm, the vessels quickly diverted the warm blood and created a screening effect—as if a dinosaur put a sun hat on. Moreover, the endocranial vasculature of ankylosaurs turned out to be somewhat more like the vessels of present-day lizards than that of the closer extant relatives of dinosaurs—crocodiles or birds.”

Another important conclusion concerns the hearing of Bissektipelta archibaldi. The palaeontologists managed to examine the inner ear of the ancient animal. Its anatomy suggests the frequency of sounds that the ankylosaur could hear. The range turned out to have been from about 300 to 3,000 hertz—present-day crocodiles hear in the same range. These are quite low frequencies that correspond to the relatively large size of ankylosaurs. The larger the present-day animals are, the more low-frequency sounds they make and hear. The palaeontologists suggested that, during evolution, ankylosaurs increased in size, so later forms perceived sounds of even lower frequencies.

“Present-day animal species are characterized by a certain brain-body size relationship,” explained Ivan Kuzmin. “If you look at dinosaurs, then ankylosaurs and their closest relatives (stegosaurs) were almost outsiders. The mass of their brain turned out to be at least half less than what we would expect, based on a comparison with present-day animals. It was about 26.5 grams for a three-meter Bissektipelta. Its brain size can be compared with two walnuts. Nevertheless, ankylosaurs existed on the planet for 100 million years. They were quite successful in terms of evolution. However, judging by the size of their olfactory bulbs, they sniffed a little faster than they thought.”

At the next stage of their research, the scientists would like to study the fossil braincases of other species of ankylosaurs in order to test the hypotheses expressed in the paper. Additionally, the palaeontologists continue to use computed tomography and are currently working with digital endocranial casts of hadrosaurs—duck-billed dinosaurs whose remains were found at the same locality in Uzbekistan.

The research is published in Biological Communications.

Note: The above post is reprinted from materials provided by St. Petersburg State University.