Ask anyone to picture what an “underwater reptile” looks like and they’d be likely to bring up images of crocodiles and alligators waiting for their next prey with their eyes slightly above the waterline. After all, these animals are among those that we have left of the massive reptiles that once roamed our planet.
Some images that may not come up in people’s minds, though, are those of dolphins. These creatures seem to be the poster child for “friendly sea dwellers,” mostly due to the anecdotal stories of these animals guiding, or sometimes even outright returning lost humans out at sea to the nearest shore. These animals have been around for millions of years, and they likely evolved from land-dwelling mammals.
Get a photo of a skeleton of a dolphin and place it near the fossil of an ancient marine reptile called an ichthyosaur, however, and the lines start to get blurry. This particularly ancient marine reptile was given a name which literally translates to “fish lizard,” and for a pretty good reason: they scoured the vast seas through much of the Mesozoic Era, also known as the Age of Dinosaurs.
One ichthyosaur, in particular, is making waves in the paleontological world. Published in the journal Science, this particular study found ichthyosaur fossils atop the Augusta Mountains of Nevada. The new find, named Cymbospondylus youngorum, may have been a “fish reptile” that grew to immense sizes pretty quickly, which may have made it one of the largest animals around during its heyday.
The ichthyosaur C. youngorum was dated to be around 246 million years old, which places it at the early Triassic period—just some three million years after the very first ichthyosaur relatives were thought to have first entered the ancient Triassic oceans. Among the parts of the skeleton found were its 2-m (6.6-ft) long skull, parts of its backbone, shoulder, and parts of one of its flipper arms.
Given the size of its skull, this particular specimen of C. youngorum would have grown to about 17 m (55 ft) in length—a massive size for a marine animal, considering it lived just some 5 million years after the Great Dying, or the Permian-Triassic extinction event, which wiped out around 81% of all marine life and some 70% of all terrestrial life.
Additionally, given the short three (3) million years of geologic time since the first ichthyosaurs splashed onto the scene, the time it took this particular family of marine reptiles to achieve giant sizes—a process called gigantism—was particularly rapid. The scientists who worked on the study say that this may have been due to the explosion of prey animals right after the Great Dying, which gave ichthyosaurs like C. youngorum plenty of food that can be used to grow to such large sizes.
Said the Natural History Museum of Los Angeles County’s (NHM) Associate Curator of Mammalogy (Marine Mammals) Dr. Jorge Velez-Juarbe in a statement from the NHM website: “This discovery and the results of our study highlight how different groups of marine tetrapods evolved body sizes of epic proportions under somewhat similar circumstances, but at surprisingly different rates. Moving forward, with the dataset we’ve compiled and analytical methods we’ve tested, we can start thinking about including other groups of secondarily aquatic vertebrates to understand this aspect of their evolutionary history.”
(For more related news, read further on how Kansas was once home to a vicious sea creature that was recently reclassified.)
References
- Geggel, L. (2021, December 23). 55-foot-long Triassic sea monster discovered in Nevada. LiveScience. https://www.livescience.com/ichthyosaurs-grew-to-big-sizes-fast
- Hayden, T. (n.d.). Earth’s first giant | natural history museum. Natural History Museum of Los Angeles County. Retrieved 7 January 2022, from https://nhm.org/stories/earths-first-giant
- Irving, M. (2022, January 4). Colossal marine skull reveals Earth’s earliest known giant animal. New Atlas. https://newatlas.com/biology/ichthyosaur-earth-earliest-giant-animal/
- Sander, P. M., Griebeler, E. M., Klein, N., Juarbe, J. V., Wintrich, T., Revell, L. J., & Schmitz, L. (2021). Early giant reveals faster evolution of large body size in ichthyosaurs than in cetaceans. Science. https://doi.org/10.1126/science.abf5787
