Revision of dinosaur fossil: "You can do a lot more with a skeleton with today’s knowledge"

In the 1970s, scientists discovered the 175 million-year-old fossil of long-necked dinosaur Patagosaurus fariasi in Patagonia, Argentina. In 1979 and 1986, the early Jurassic dinosaur was described, and now Utrecht palaeontologist Femke Holwerda and her colleagues have thoroughly revised the fossil description with today’s technology and knowledge. This taxonomic revision is the basis for answering new questions: how fast did Patagosaurus grow, and how did the dinosaur walk? We spoke to Holwerda about the new description, which was recently published in Geodiversitas.

What were you able to research now, that wasn’t possible in the 1970s?

“Nowadays, we don't often do classical taxonomic studies anymore, in which you describe one animal in a paper. Nevertheless, it is important to describe a fossil as thoroughly as possible before you can run all the ‘sexy’ state of the art analyses on it. This time, we examined the bones more thoroughly with better high-res cameras, and were able to look into the vertebrae with a CT scan. This allowed us to see that Patagosaurus had internal air sacs in its vertebrae, to keep their skeleton as light as possible. Also, more long-necked dinosaurs have been found since the 1970s, so we can now better compare the different fossils.”

(Text continues after image)

CT-scan waar op de luchtzakken in de ruggenwervels van patagosaurus zichtbaar zijn
The CT scan of the vertebrae shows air sacs (blue) that keep the skeleton light. Source: Holwerda et al. 2021

How does Patagosaurus compare to other long-necks?

“Patagosaurus is not as big as its younger cousin Patagotitan, the largest land animal ever, but they do share certain base characteristics. Those air sacs or 'pneumatic features' in its vertebrae were more common in long-necked dinosaurs in the Late Jurassic and Cretaceous. Now you see a similar characteristic in birds: birds’ bones are filled with air, and their skeletons are therefore very light. In these early dinosaurs, the skeleton is still very strong, in order to carry their massive weight. In further evolved cousins of Patagosaurus, you also find these air sacs in the vertebrae of the tail and ribs.”

Earlier you said that you can now do new analyses on the skeleton. What will you investigate?

“At the moment we are exploring how skeletons of long-necked dinosaurs changed during the Jurassic with a so-called morphometric analysis, for which we can make good use of Patagosaurus’ femurs. In the future, we can use a biomechanical analysis to see how the dinosaur walked, and how fast, as was done earlier this year for T-rex. I myself find it interesting to find out how fast Patagosaurus grew. It was a huge beast, and we think these long-necked dinosaurs filled a similar niche in their ecosystem as elephants and giraffes do now. Those mammals are so big that birds settle on their backs, maybe that's what happened to Patagosaurus and small pterosaurs in the past!"

Reconstructie van patagosaurus, met drie kleine pterosaurussen op de rug.
Reconstruction of Patagosaurus by Joschua Knüppe. The dinosaur likely filled a niche in their ecosystems as elephants and giraffes do now, where smaller animals settled on their backs.

Publication

Holwerda, F., Rauhut, O.W.M., Pol, D., 2021. — Osteological revision of the holotype of the Middle Jurassic sauropod dinosaur Patagosaurus fariasi Bonaparte, 1979 (Sauropoda: Cetiosauridae). Geodiversitas 43 (16): 575 - 643. https://doi.org/10.5252/geodiversitas2021v43a16.

The study was published in the journal Geodiversitas by Royal Tyrrell Museum and Utrecht University researcher Femke Holwerda, in collaboration with the Argentine researcher Diego Pol (MEF, Trelew) and the German researcher Oliver Rauhut (SNSB-BSPG, Munich).