Ptychodus: a Mesozoic shark fossil stolen and recovered

The formerly enigmatic shark genus, Ptychodus,
was previously known from sometimes isolated and sometimes arranged teeth (Fig 2) found world-wide in Early to Late Cretaceous sediments.

Now on display at the Texas Through Time museum
is the most complete Ptychodus Mesozoic shark skeleton (Figs 1,2). Recovered from the Buda Formation in Uvalde, Texas, the articulated specimen includes soft tissue.

This fossil also has an interesting backstory.

Figure 1. Ptychodus fossil on display at the Texas Through Time museum. ” data-image-caption=”

Figure 1. Ptychodus fossil on display at the Texas Through Time museum.

” data-medium-file=”https://pterosaurheresies.files.wordpress.com/2024/03/ptychodus.ondisplay588.jpg?w=300″ data-large-file=”https://pterosaurheresies.files.wordpress.com/2024/03/ptychodus.ondisplay588.jpg?w=584″ class=”size-full wp-image-84976″ src=”https://pterosaurheresies.files.wordpress.com/2024/03/ptychodus.ondisplay588.jpg” alt=”Figure 1. Ptychodus fossil on display at the Texas Through Time museum.” width=”584″ height=”389″ srcset=”https://pterosaurheresies.files.wordpress.com/2024/03/ptychodus.ondisplay588.jpg?w=584&h=389 584w, https://pterosaurheresies.files.wordpress.com/2024/03/ptychodus.ondisplay588.jpg?w=150&h=100 150w, https://pterosaurheresies.files.wordpress.com/2024/03/ptychodus.ondisplay588.jpg?w=300&h=200 300w, https://pterosaurheresies.files.wordpress.com/2024/03/ptychodus.ondisplay588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />

Figure 1. Ptychodus fossil on display at the Texas Through Time museum. The largest Ptychodus specimens have been estimated to reach 33 feet (10m) in length.

Outside the September 2019 Denver Gem and Mineral Show
this shark fossil, along with several other specimens, all packed inside a 20-foot trailer were stolen from the hotel parking lot. That story is chronicled here and abbreviated below.

The trailer and fossils
were owned by Thomas Lindgren, owner of GeoDecor “Exceptional fossils, minerals, and meteorites for interior designers, collectors, and museums.” According to their website: “Green River Formation fossils are a mainstay of GeoDecor’s offerings.“ The company has a showroom in Tucson, Arizona, USA. Their website currently features a free-standing Stegosaurus skeleton for sale.

The DPS (Dallas Paleontological Society)
was in talks to get the Ptychodus fossil into the Perot (Museum of Nature and Science, according to sources. Evidently they were unsuccessful in those talks.

Figure 1. Ptychodus fossil in situ. Frame 3 shows a reconstruction from the crushed elements. ” data-image-caption=”

Figure 1. Ptychodus fossil in situ. Frame 3 shows a reconstruction from the crushed elements.

” data-medium-file=”https://pterosaurheresies.files.wordpress.com/2023/06/ptychodus_insitu588.gif?w=126″ data-large-file=”https://pterosaurheresies.files.wordpress.com/2023/06/ptychodus_insitu588.gif?w=431″ class=”wp-image-78980″ src=”https://pterosaurheresies.files.wordpress.com/2023/06/ptychodus_insitu588.gif” alt=”Figure 2. Ptychodus fossil in situ. DGS colors added here. Frame 3 shows a reconstruction from the crushed elements.” width=”588″ height=”1398″ srcset=”https://pterosaurheresies.files.wordpress.com/2023/06/ptychodus_insitu588.gif 588w, https://pterosaurheresies.files.wordpress.com/2023/06/ptychodus_insitu588.gif?w=63&h=150 63w, https://pterosaurheresies.files.wordpress.com/2023/06/ptychodus_insitu588.gif?w=126&h=300 126w” sizes=”(max-width: 588px) 100vw, 588px” />

Figure 2. Ptychodus fossil in situ. DGS colors added here. Frame 3 shows a reconstruction from the crushed elements.

According tokdvr.com
“The 20-foot, silver-toned trailer held, among other fossils, a 92-million-year-old fossil shark specimen valued at $50,000 that was scheduled to be purchased by a museum. ‘The theft of the fossil shark is particularly heartbreaking because a museum was counting on adding it to their collection,’ GeoDecor president Thomas Lindgren said. ‘Its high value is based on the fact that shark skeletons rarely fossilize because they are composed of cartilage; hence the $50,000 value.‘”

According to Wikipedia,
“Ptychodus was a large shark, previously estimated at 10 meters (33 feet) long based on extrapolation from tooth. Ptychodus had a massive arrangement of crushing plate teeth. A Ptychodus jaw contains many teeth, up to 550 teeth, 220 of which are on the lower jaw and 260 in the upper jaw. These teeth were very large as well—Paleontologists believe that the largest tooth plate measured 55 centimeters in length and 45 centimeters in width.“

“Ptychodus teeth have long been identified as palates of Diodon, or porcupinefish (Osteichthyes, Diodontidae), well-known for their ability to inflate their bodies in defense. At the beginning of the 19th century, several authors including Swiss paleontologist Louis Agassiz eventually demonstrated the affinities of Ptychodus teeth with those of elasmobranchs (rays and sharks).“

Bivalves and ammonites are example of shelled invertebrates that were likely prey for Ptychodus and its crushing teeth.

From The Fossil Forum, Jan 12, 2020:
“According to Roger Farish at Wednesday night’s DPS meeting, over a week ago the trailer was spotted sitting in the middle of a farmer’s field. When police investigated they found that it was being used to store the thief’s miscellaneous stuff, with all of the intact fossils pushed to the side. I suppose he thought that it would be a great storage trailer, and didn’t pay much mind to the thousands of dollars worth of fossils inside.”

“Roger said that the DPS and Perot museum are now back on track to get the $50,000 raised to buy the Ptychodus marginalis specimen from the dealer and get it into the Perot’s permanent collection for study and display. It is the only known nearly complete Ptychodus. Roger thinks it is from the Eagle Ford, but on geological maps the quarry the specimen came from is shown in the Buda formation.“

When Jambura and Kriwet 2020 reported,
“Articulated remains of the extinct shark Ptychodus,” they meant, “two large shark vertebrae from the Santonian (Upper Cretaceous) of Spain“.

When added to the LRT
Cretaceous Ptychodus nested with Carcharodon, the extant great white shark.

References
Agassiz L 1835. Rapport sur les poissons fossiles découverts depuis la publication de la troisième livraison. In Feuilleton additionel sur les Recherches sur les poissons fossiles. Quatrième livraison(Janvier 1835). Imprimerie de Petitpierre et Prince(text), Neuchatel, pp. 39- 64.
Jambura PL and Kriwet J 2020. Articulated remains of the extinct shark Ptychodus (Elasmobranchii, Ptychodontidae) from the Upper Cretaceous of Spain provide insights into gigantism, growth rate and life history of ptychodontid sharks https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7176087/

wiki/Ptychodus
perotmuseum.org/
geodecor.com/
kdvr.com/news/local/trailer-stolen-at-aurora-hotel/
denverpost.com/2019/09/10/fossils-aurora-stolen/