As is the case with the sciences, truths are constantly being tested with evidence that may challenge its notions; biology is no such stranger to these constant challenges, as the sheer scope of classifying every organism that’s ever lived on this planet is truly a gargantuan task. This also wouldn’t be the first time a reclassification of an animal into a new genus has been reported here before; an ancient beetle was reclassified just last August 10, and was renamed after famous naturalist David Attenborough.
This time around, the new study deals with something far larger than just a beetle. Published in the journal Canadian Journal of Earth Sciences, a team of researchers reclassified a species of mosasaur—previously assigned to the genus Platecarpus—and has instead been placed in a genus it shares with just one other species: Ectenosaurus. This reclassified find gained the new name of Ectenosaurus everhartorum. (Mosasaurs are mostly known for representing some of the apex predators of the seas during the Cretaceous period, and have been depicted in modern media such as in the Jurassic World movies.)
E. everhartorum was identified from a set of fragmentary fossils, a couple of skull and jaw pieces plus other bones located behind the skull, and was actually gathered some half a century ago back in the 1970s. As with other mosasaur fossils whose initial identifications proved difficult, they were assigned into the Platecarpus genus. Now, nearly 50 years later, the fossil stored at the Sternberg Museum of Natural History (SMNH) in Fort Hays State University, Kansas, found a new lease on life.
According to study co-author and University of Cincinnati vertebrate paleontologist Takuya Konishi, E. everhartorum’s skull measured at an estimated 0.6 m (2 ft) long, and had a narrow and elongated snout. This, along with other skull features such as a notch at the back of the lower jaw, gave them the sign to reclassify it with its sole companion in the Ectenosaurus genus, said Konishi. It should also be noted, however, that E. everhartorum’s fossil was determined to be about half a million to a million years younger than the E. clidastoides fossil specimen.
The fossil of E. everhartorum was found in western Kansas, alongside other mosasaurs like Tylosaurus. This initially comes as a surprise, as the state of Kansas is landlocked. As it turns out, around the time of the early to late Cretaceous period, there existed a vast body of water that cut between what was then continental North America. This vast inland sea, referred to as the Western Interior Seaway, separated North America into two major islands: Laramidia to the west (the current west coast of the United States of America and Canada), and Appalachia to the east (the current east coast). Fossils and other relevant remains from the areas previously underwater revealed a world rife with animals and other forms of wildlife; this included a plethora of ancient aquatic reptilian predators, like plesiosaurs (long-necked sea reptiles that may have influenced the current depiction of the mythological Loch Ness monster) and the aforementioned mosasaurs.
Future studies aim to explore other parts of E. everhartorum, possibly exposing other features of its skeleton to truly classify the enigmatic animal. Another point of inquiry for Konishi and the team was the fact that the Ectenosaurus genus has been poorly represented in the fossil record across western Kansas, while hundreds of Platecarpus specimens had been identified from nearby sites.
References
- de Lazaro, E. (2021, August 30). New Mosasaur Species Uncovered in Kansas. Sci-News. Retrieved September 28, 2021, from http://www.sci-news.com/paleontology/ectenosaurus-everhartorum-10012.html
- Weisberger, M. (2021, September 10). An 18-foot-long sea monster ruled the ancient ocean that once covered Kansas. Live Science. Retrieved September 28, 2021, from https://www.livescience.com/mosasaur-18-foot-monster.html
- Konishi, T., Jiménez-Huidobro, P., & Caldwell, M. W. (2018). The smallest-known neonate individual of Tylosaurus (Mosasauridae, tylosaurinae) sheds new light on the tylosaurine rostrum and heterochrony. Journal of Vertebrate Paleontology, 38(5), e1510835. https://doi.org/10.1080/02724634.2018.1510835
- Roberts, L. N. R., & Kirschbaum, M. A. (1995). Paleogeography and the late cretaceous of the western interior of middle north america; coal distribution and sediment accumulation (USGS Numbered Series No. 1561; Professional Paper). http://pubs.er.usgs.gov/publication/pp1561
- Sampson, S. D., Loewen, M. A., Farke, A. A., Roberts, E. M., Forster, C. A., Smith, J. A., & Titus, A. L. (09 22, 10). New horned dinosaurs from utah provide evidence for intracontinental dinosaur endemism. PLOS ONE, 5(9), e12292. https://doi.org/10.1371/journal.pone.0012292
- Willman, A. J., Konishi, T., & Caldwell, M. W. (2021). A new species of Ectenosaurus (Mosasauridae: Plioplatecarpinae) from western Kansas, USA, reveals a novel suite of osteological characters for the genus1. Canadian Journal of Earth Sciences, 58(9), 741–755. https://doi.org/10.1139/cjes-2020-0175
