Exceptionally preserved fossils of an ancient shark that coexisted with dinosaurs have finally revealed what this predator looked like and why it may have gone extinct.
The absolutely incredible discovery of several fully articulated shark fossils from the Late Cretaceous Period, 105 to 72 million years ago, sheds much-needed light on the mysterious shark family tree.
At the fossil deposits of the deposit in Vallecillo, Mexico, paleontologists have made the find of a lifetime: several exceptionally well-preserved fossils of an extinct genus called Ptychodus.
These fossils preserve not only the sharks’ articular bones, but also some of their cartilage structures, the contours of their entire bodies, and possibly even organs. These details reveal how sharks’ teeth and vertebrae fit into the context of their bodies, a new tool for estimating their size and where they fit phylogenetically.
The anatomy of a Ptychodus shark is revealed through its extraordinary fossil. (Vullo et al., Proc. R. Soc. B, 2024)
The fossils finally confirm that the… Ptychodus They are a species of shark that belongs to the Lamniformes family, which also includes great white sharks. The Ptychodus They were smaller than today’s great white sharks and reached a length of 9.7 meters. Their feeding strategy couldn’t have been more different: their teeth consisted of grinding plates that allowed the animals to eat Feast on peeled animals that would otherwise be too difficult to eat.
“Our results support the view that Lamniformes were ecomorphologically very diverse and represented the dominant group of sharks in Cretaceous marine ecosystems,” writes a team of paleontologists led by Romain Vullo from the French National Center for Scientific Research.
“Ptychodus may have fed predominantly on hard-shelled nektonic prey, like ammonites and sea turtlesrather than benthic invertebrates, and its extinction during the Campanian, long before the end-Cretaceous crisis, may be related to competition with the emerging blunt-toothed globidensin and prognathodontin mosasaurs.
Ptychodus fossils have been a mystery since the first fossils of its crushing teeth were found in England in 1729. Most of the remains found in recent centuries were teeth and vertebrae, the only parts of a shark’s skeleton that were made of bone. The rest, the cartilage, usually doesn’t survive long enough to fossilize, leaving much to the imagination.
As fragmentary as they may be, these few remains found around the world offer enough clues to point to the animal that left them.
There are sharks today that use a similar feeding strategy known as durophagy, setting a precedent for such a diet. The relative absence of other remains, despite so many teeth being found in Late Cretaceous fossil sites, confirms that it was probably a cartilaginous skeleton. Furthermore, the few Ptychodus vertebrae we have are consistent with those of other sharks.
Just from the type of remains that sharks typically leave behind, it is not possible to determine with certainty what these sharks looked like. Even our understanding of the famous megalodon is based on a lot of guesswork.
But then we have something like the Vallecillo deposit. A deposit is a type of fossil bed that tends to preserve remains incredibly well, including soft tissue that usually decomposes before the fossilization process can take place. In the Vallecillo deposit, paleontologists found six specimens of Ptychodus, finally revealing the literal form of this ancient predator.
An upper tooth plate of a Ptychodus shark. (Vullo et al., Proc. R. Soc. B, 2024)
None of the fossils came from a particularly large shark, with the longest reaching a total length of just over 2 meters. But more importantly, the fossils showed the sharks in the greatest anatomical detail we’ve ever seen, allowing researchers to extrapolate that anatomy to other recovered teeth and derive a maximum length of 9.7 meters.
We also now know how many vertebrae these sharks had, how big their eye sockets were, how many fins they had, how big their heads were, and what body shape they had. This allowed the researchers to confidently classify the sharks as lamniforms and determine that they could swim at high speeds.
They also had a different body shape than all living durophaga sharks, illustrating how difficult it can be to determine a shark’s morphology based on its teeth alone. In fact, it is possible that Ptychodus was the largest durophagus shark to ever exist, much larger than the largest shark today.
“The tachypelagic ecomorphotype revealed by the newly discovered material from Mexico challenges the widely held view that it is a genus of durophagous organisms Ptychodus “was a group of bottom-dwelling sharks that fed primarily on benthic invertebrates with shells, such as inoceramide mussels,” the researchers write.
“The new evidence suggests that Ptychodus was a fast-swimming open-water predator that fed on well-armored pelagic organisms such as large ammonites and sea turtles, confirming the more active nektonic lifestyle previously suggested based on the morphological features of the centers .” ” Vertebral and placoid scales. We sincerely hope that the miracles will never stop.
REFERENCE
Exceptionally well-preserved shark fossils from Mexico clarify the long-standing mystery surrounding the Cretaceous elasmobranch Ptychodus
