Hainosaurus or Tylosaurus? The Importance of Good Fossil Preparation
How poor fossil preparation resulted in a case of mistaken identity
Meet Sid
The Miami Museum in Miami, Manitoba is home to a remarkable mosasaur specimen, nicknamed Sid. The fossil was found in a bentonite quarry southwest of Miami in the 1970s. However, with limited resources, Sid's bones initially only underwent minimal conservation efforts.
Skull Buried in Plaster (2023) by Canadian Fossil Discovery CentreCanadian Fossil Discovery Centre
Much of the skull, for example, remained covered in plaster, while other bones were simply placed in a display case in random order.
Research
Despite the lack of fossil preparation, the near-complete specimen caught the attention of Dr. Elizabeth "Betsy" Nicholls, a palaeontologist with the Royal Tyrrell Museum in Alberta, Canada.
Studying both the Miami mosasaur Sid and the CFDC's mosasaur Bruce, Dr. Nicholls established that these specimens belonged to the genus Hainosaurus, naming the new species pembinensis in 1988. She argued that Hainosaurus is separate from the genus Tylosaurus due to a number of significant differences, including a larger number of vertebrae in a specific part of the spine.
The Original Sid Exhibition (2023) by Canadian Fossil Discovery CentreCanadian Fossil Discovery Centre
Incorrect Reconstruction
However, in 2010, Timon S. Bullard & Michael W. Caldwell re-examined the specimen and noticed that some of the vertebrae just behind the rear limb actually belonged to another individual, meaning that it actually had a similar number of vertebrae as other known Tylosaurs.
Tylosaurus (2022) by Canadian Fossil Discovery CentreCanadian Fossil Discovery Centre
Tylosaurus Pembinensis
Given what they learned about these vertebrae, as well as noting that the specimen's other features were not that different from other Tylosaurus, the specimens were rediagnosed as Tylosaurus pembinensis, with Sid being the holotype for the species.
Restoration and Reconstruction
However, the problem of poor conservation still existed, and some important skeletal elements could not be fully described. In 2017, the Miami Museum commissioned Adolfo Cuetara, who is now the executive director of the CFDC, to properly restore and reconstruct this specimen.
Uncovering the Cranial Elements (2023) by Canadian Fossil Discovery CentreCanadian Fossil Discovery Centre
Removing the Plaster
First, the plaster had to be removed from the skeleton so that the palaeontologists could get a good look at all the elements that were present.
Identification
Then, the skeletal elements were laid out for identification and a more thorough restoration.
This is what the atlas (a neckbone) looked like once the plaster was removed and it was properly restored.
Fabrication of Steel Brackets (2023) by Canadian Fossil Discovery CentreCanadian Fossil Discovery Centre
The Steel Frame
To display the skeleton properly, Adolfo Cuetara created a set of steel frames and brackets to hold each bone in its correct orientation.
Mounting the Skeleton
Every bone, from skull to tail to limbs, was mounted on individual steel brackets.
Mounted Skull (2023) by Canadian Fossil Discovery CentreCanadian Fossil Discovery Centre
The Benefits of Restoration
Unlike the original conservation efforts, which left much of the skeleton covered in plaster, mounting the skeleton on steel frames leaves all bones visible to viewers and easily accessible for future research.
Sid the Tylosaurus Pembinensis (2023) by Canadian Fossil Discovery CentreCanadian Fossil Discovery Centre
Sid in Detail
The exhibit was also updated with an illustration by palaeoartist Arturo De Miguel, which depicts the Tylosaurus pembinensis in its natural habitat.
The Sid Exhibit - Panorama (2023) by Canadian Fossil Discovery CentreCanadian Fossil Discovery Centre
Restoration Complete
The finished product can be seen in this impressive display at the Miami Museum. The CFDC, meanwhile, continues to focus on restoration to make fossils more accessible to the public and researchers alike.
Visit the Miami Museum to learn more about Sid! R.M of Thompson - The Miami Museum (rmofthompson.com)
Nicholls, E. L. (1988) Marine vertebrates of the Pembina member of the Pierre Shale (Campanian, upper cretaceous) of Manitoba and their significance to the biogeography of the Western Interior Seaway. University of Calgary, Calgary, AB. doi:10.11575/PRISM/11742.
Bullard, Timon S. & Caldwell, Michael W. (2010) Redescription and rediagnosis of the tylosaurine mosasaur Hainosaurus pembinensis Nicholls, 1988, as Tylosaurus pembinensis (Nicholls, 1988). Journal of Vertebrate Paleontology, 30:2, 416-426.
