This week, the scientific paper announcing the discovery of a new megaraptor from South America was published.  The dinosaur has been named Joaquinraptor casali and it is probably the geologically youngest member of the Megataptoridae described to date.  In the media release there were several field photographs of the Joaquinraptor casali bones.  We were not able to use them all in our blog post about this new theropod. However, we wanted to share them with our readers, so we created a second article.

Joaquinraptor casali bones in the field (2019) shown with a skeletal reconstruction. Known fossil material is highlighted in blue. The photograph shows fossils of the new megaraptor dinosaur species Joaquinraptor casali in the quarry, laying in the positions they had laid for approximately 67 million years. A dentary, teeth, ribs, and several other bones are visible. Picture credit: Marcelo Luna, Laboratorio de Paleontología de Vertebrados Dr Rubén Martínez, Universidad Nacional de la Patagonia San Juan Bosco.

Picture credit: Marcelo Luna, Laboratorio de Paleontología de Vertebrados Dr Rubén Martínez, Universidad Nacional de la Patagonia San Juan Bosco

To read Everything Dinosaur’s earlier blog post about the discovery of Joaquinraptor: A New Species of Megaraptor from Patagonia.

Joaquinraptor casali Bones Photographed

When visitors view dinosaur fossils in a museum they appear, smooth, free from cracks and clean. The Joaquinraptor casali bones photographed at the dig site look different. Skilled technicians spend many hours preparing each fossil for display. They carefully remove rock, repair breaks, and restore missing areas. As a result, the finished fossils look polished and ready for study or exhibition. However, this final appearance is very different from how the bones first look when they are carefully excavated in the field.

Fossils of the new megaraptor species Joaquinraptor casali in the quarry. Picture credit: Marcelo Luna, Laboratorio de Paleontología de Vertebrados Dr Rubén Martínez, Universidad Nacional de la Patagonia San Juan Bosco.

Picture credit: Marcelo Luna, Laboratorio de Paleontología de Vertebrados Dr Rubén Martínez, Universidad Nacional de la Patagonia San Juan Bosco

The picture (above) shows the jumble of fossil bones in the quarry.  The field team take care to extract the fossils. In addition, they map their precise location and gather data on the fossil matrix.

Fragile Bones and Delicate Work in the Field

At the quarry, the Joaquinraptor casali bones are fragile, fragmented, and often extremely difficult to expose. Field team members work slowly with small tools to expose each piece. Dirt, dust, and natural cracks make the fossils appear rough and incomplete. Only after careful cleaning and conservation do these remains reveal their true form. This process highlights the remarkable journey from excavation site to museum gallery.

Mike from Everything Dinosaur commented:

“The media release we received contained some incredible photographs of the quarry.  We wanted to highlight the care and dedication it takes to extract fossils in the field.  Moreover, the fossil material comes from the uppermost part of the Lago Colhué Huapi Formation.  These field photographs are significant as the strata is most likely late Maastrichtian.  This suggests that Joaquinraptor lived close to the Cretaceous/Palaeogene boundary.  Therefore, the Megaraptoridae persisted until the end of the Age of Dinosaurs.”

Everything Dinosaur acknowledges the assistance of a media release from the Carnegie Museum of Natural History in the compilation of this article.

The scientific paper: “Latest Cretaceous megaraptorid theropod dinosaur sheds light on megaraptoran evolution and palaeobiology” by Lucio M. Ibiricu, Matthew C. Lamanna, Bruno N. Alvarez, Ignacio A. Cerda, Julieta L. Caglianone, Noelia V. Cardozo, Marcelo Luna and Rubén D. Martínez published in Nature Communications.

The award-winning Everything Dinosaur website: Dinosaur and Prehistoric Animal Models.