Dinosaurs in La Rioja – “The dinosaurs ran at 45 km per hour”, Pablo Navarro

There are few traces in the world of running dinosaurs, like in La Rioja. There, by analyzing their tracks, researcher Pablo Navarro was able to calculate how fast the fastest dinosaurs on Earth were.

We now know something more about some of the fastest two-legged carnivorous dinosaurs from the Early Cretaceous (between 145 and 100 million years old), known as theropods, thanks to a study conducted by University of La Rioja researcher, Pablo Navarro Lorbés.

According to the discovery, these animals roamed what is now known as La Rioja, and could reach 45 kilometers per hour, making them the third fastest of their species.

Recreation of a Carcharodontosaurus fleeing investigation of their fossilized footprints. Source: Francesc Gasco

In the article, published in Scientific Reports of the Nature groupScientists from the Complutense University of Madrid, the University of the Basque Country, the National University of Río Negro in Argentina and the Center for Paleontological Interpretation of La Rioja also collaborated.

The fossil footprints analyzed, or also called ichnites, are located in two deposits in the municipality of Igea, in La Rioja. One, La Torre 6A, contains five footprints and the other, La Torre 6B, seven. All three fingers and longer.

Pablo Navarro on the left, at the excavation site. Source: University of La Rioja

Many still wonder what would have happened if dinosaurs hadn’t gone extinct, even if it was necessary for humans to arise. Years ago, some theories claimed that they disappeared due to volcanic activity, but others pointed to the great Cretaceous extinction caused by a large asteroid that killed 75% of lives during that period.

This last hypothesis was confirmed by a team at Yale University last year. in your report, showed that the cause of the disappearance was due to an asteroid and for no other reason, as the volcanic eruptions occurred much earlier.

What does the study carried out by the University of La Rioja consist of?

The study focused on the analysis of two traces of La Rioja. When we first looked at them, we already saw that they could be dinosaur tracks running through the distance between the tracks. We used a series of formulas that are applied in these cases to calculate the speeds of the dinosaurs when they were walking on that surface and the results returned very high speeds.

The second part of the work was to compare these results, both with other tracks published around the world, and with the estimated velocities that these animals could reach, calculated in other studies using biomechanical models.

“Although the speeds are much slower, we would be talking about the fastest predators in your ecosystem, like a cheetah”

The results showed that the tracks we measured match very well with the estimated velocities for dinosaurs of this type and size. There are few traces in the world of running dinosaurs.

How are these formulas you used?

What these formulas do is relate the height to the hip that these animals would have, which we calculate from the length of each neck. There are some ratios that allow us to estimate hip height thanks to these lengths and then we put that hip height in relation to stride distance.

The stride distance is the distance between two consecutive lanes on the same foot, that is, the distance between two consecutive lanes on the right, for example.

Thanks to this relationship, we can calculate the speed that the animal carried in each step it took. We can even graph the evolution of speed along the trail.

dinosaur footprint

One of the remains of the La Torre 6A site. 10 cm scale. Source: Pablo Navarro Lorbés

How big are these theropods?

The size we calculated for these animals would be a hip height between 1.1 and 1.4 meters, which in the total height of the animal could be between 1.5 and 2 meters. The length would be about 4 to 5 meters from the muzzle to the tip of the sole.

In the article they reflect that, in addition to being fast, they were also agile, right?

Yes, they could run at 45 kilometers an hour and are between the third and fourth fastest in the world. There are two lanes that are a few kilometers faster up to 55 kilometers per hour, what happens is that the speed of the fastest lane is calculated with only two lanes and you have to jump with a tweezers. These two fastest trails are from Utah, and there is another trail from Texas that was posted in the 1980s, with approximately the same speed.

In the area of ​​La Rioja, the animals walked over muddy sediments that, when the water level rose, were buried by new sediments, allowing their conservation.

On one of our trails, in the last few steps we see a change of direction with a small change in speed at one point, and then it recovers again. The change of direction is to the left. Being able to maneuver and change direction at these speeds indicates that they were very agile animals, they could maneuver quite efficiently.

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The traces of the change of course seem to me the most beautiful of these two places. You can see very well how the footprint varies because the animal, instead of just running in a straight line, is printing the lateralized footprint, pushing to one side to move.

What are the characteristics of these dinosaurs? What current animal could we compare it to?

Theropods are carnivorous animals that, living in these ecosystems, moved in search of food. With the data we have, we can’t say exactly what they were doing, but the possibilities are similar to those of a current animal that runs when trying to catch prey or flee from danger. Although the size seems very large, they are medium-sized theropod animals, so there would be larger ones in their ecosystem that would pose a threat to them. Although the speeds are much slower, we would be talking about the fastest predators in your ecosystem. For example, today you would be a cheetah, a relatively fast hunter.

What is the process like until you find this kind of discovery?

These traces were discovered in places where they are found in the 80’s, and in one of the traces there were already some traces discovered. At a nearby location, two footprints were found quite far apart, with a footprint in the middle, and it was proposed that it could be something similar.

So, at the beginning of the year, what we did was a field campaign in which we cleared the deposits and found three more tracks in the case of the deposit that had only two tracks, and one more track in the other. After cleaning the entire site, we did what is normally done now, photographing the site to generate three-dimensional models that allowed us to work remotely, as the team of authors is from different places. This allowed us to work on these measurements from La Rioja, the Basque Country and even Argentina.

dinosaur footprints 2

Fieldwork at La Torre 6A. Source: Alberto Labrador

Why is the Cameros Basin, between Soria, Burgos and La Rioja an area that stands out for dinosaur footprint sites?

From what was seen in other studies, the existing environmental and geological conditions were very favorable to the conservation of footprints. In the area of ​​La Rioja, with a large area of ​​lakes that would rise and fall to the water level, it would allow animals to walk on muddy sediments in times of low water level that, when the water level rose again, they would be buried by new sediments allowing its conservation.

Furthermore, in the Cameros Basin area, geological processes sink very slowly, allowing them to be filled with successive layers of sediment. In the Cameros Basin it is estimated that there may be up to 5,000 meters of sediment accumulation, now part of them has already been lost due to erosion.

dinosaur footprints 3

Creative reconstruction of a carnivorous dinosaur running through sediment in a lake. Source: Pablo Navarro Lorbés

How did you feel when your work was recognized by one of the most important scientific journals in the world?

It was a surprise. We thought we had some interesting work on our hands and decided to submit it to the Scientific Reports of the Nature group. The first surprise we had is that the criticisms they made of us, let’s say, were very mild. Since the article was definitely accepted, what surprised us is that the magazine itself found it a very interesting article and distributed it to the press. It has spread much more than we expected and the truth is that it is an important satisfaction that reaches all the media in the world.

Some months ago, China researchers found a number of structures similar to chromatin, or strands of DNA, and to proteins in the fossil remains of a 125-million-year-old dinosaur. Do you think it’s possible for reality to overtake fiction and we’ll see a Jurassic Park in a little while?

At the moment I think it’s complicated because these remnants of DNA that were found are so fragmented that from then on it will be difficult to encode the entire genetic code of these animals. But hey, if the world of paleontology is teaching us anything, it’s that it surprises us with new discoveries that we thought were impossible.

If there’s one thing all paleontologists would like to see, it’s seeing these animals alive. They are the animals that are the subject of our study, so let’s wait and see what happens.

Finally, do you think there will be more discoveries in the not too distant future? Maybe new species of dinosaurs or will we learn more about some already known ones?

One of the things we found most interesting about footprints is that while we can’t identify specific species of dinosaurs, what they allow us to study is part of their behavior. Traits are still “fossilized” behaviors, and behavior is one of the hardest things to study about these animals with bones alone. They teach us a lot about their biology and anatomy, but little about their behavior. Footprints help fill in this information. In the future, we hope to continue providing new data on how dinosaurs lived and behaved.

REFERENCES

Fast-running theropod tracks from the early Cretaceous of La Rioja, Spain

In the death of dinosaurs, it all came down to the asteroid – not the volcanoes

Nuclear preservation in Jehol dinosaur cartilage Caudipteryx

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