cj227
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Post by cj227 on Oct 9, 2023 18:41:07 GMT 5
Is there any record of a Late Maastrichtian polycotylid? It seems that there was a faunal turnover between the Early and Late Maastrichtian that resulted in the disappearance of these (usually) relatively short-necked plesiosaurs, the last one having been Sulcusuchus from the Early Maastrichtian of Argentina. References: Fischer, Valentin, et al. "The evolutionary history of polycotylid plesiosaurians." Royal Society open science 5.3 (2018): 172177. O’Gorman, José P., and Rodolfo A. Coria. "A new elasmosaurid specimen from the upper Maastrichtian of Antarctica: new evidence of a monophyletic group of Weddellian elasmosaurids." Alcheringa: An Australasian Journal of Palaeontology 41.2 (2017): 240-249. Otero, Rodrigo A., et al. "New elasmosaurids (Plesiosauria, Sauropterygia) from the Late Cretaceous of the Magallanes Basin, Chilean Patagonia: Evidence of a faunal turnover during the Maastrichtian along the Weddellian Biogeographic Province."
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cj227
Junior Member Rank 1
Posts: 7
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Post by cj227 on Oct 11, 2023 19:17:30 GMT 5
Apparently there is a Rarosaurus singularis, from the late Maastrichtian of Jordan that was published in 2009. Almost no one has heard of it because it was described in the obscure book "Fossils of the Harrana Fauna and the Adjacent Areas" by Hani F. Kaddumi. Wikipedia only has a page about it in Italian. Here is the description's translation:
"All that is known about this animal is the fossil of the front part of a skull , very well preserved and including some teeth . The fossil, about twenty centimeters long, is extremely elongated and the surface of the bones is finely sculpted with a large number of tiny holes and grooves. The teeth are not very long, circular in section, conical in shape and relatively thin. The first tooth of the lower jaw protrudes far forward.
From comparison with fossils of other similar forms, it is assumed that Rarosaurus was a small plesiosaur, perhaps three meters long, with a short neck and an extremely elongated and thin skull. The legs, as in all plesiosaurs, were transformed into fin-like structures."
As far as I know, the Harrana marine reptile fauna was dominated by mosasaurs (no surprise here).
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Post by Infinity Blade on Oct 12, 2023 2:22:21 GMT 5
Apparently there is a Rarosaurus singularis, from the late Maastrichtian of Jordan that was published in 2009. Almost no one has heard of it because it was described in the obscure book "Fossils of the Harrana Fauna and the Adjacent Areas" by Hani F. Kaddumi. Wikipedia only has a page about it in Italian. Here is the description's translation: "All that is known about this animal is the fossil of the front part of a skull , very well preserved and including some teeth . The fossil, about twenty centimeters long, is extremely elongated and the surface of the bones is finely sculpted with a large number of tiny holes and grooves. The teeth are not very long, circular in section, conical in shape and relatively thin. The first tooth of the lower jaw protrudes far forward. From comparison with fossils of other similar forms, it is assumed that Rarosaurus was a small plesiosaur, perhaps three meters long, with a short neck and an extremely elongated and thin skull. The legs, as in all plesiosaurs, were transformed into fin-like structures." As far as I know, the Harrana marine reptile fauna was dominated by mosasaurs (no surprise here). Man, what a name. Seems like it was pretty rare lol. But on a serious note, this is some really interesting stuff. I'm not too knowledgable on polycotylids, but I wonder why they apparently seem to have become so rare by the late Maastrichtian. Were mosasaurs pushing them out or what?
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cj227
Junior Member Rank 1
Posts: 7
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Post by cj227 on Oct 12, 2023 4:43:07 GMT 5
Man, what a name. Seems like it was pretty rare lol. But on a serious note, this is some really interesting stuff. I'm not too knowledgable on polycotylids, but I wonder why they apparently seem to have become so rare by the late Maastrichtian. Were mosasaurs pushing them out or what? It's difficult to attribute a clade's decline and/or extinction to competition, but mosasaurs certainly benefited from their gradual disappearance. By the early Maastrichtian, after all, the highly derived Plotosaurus was present in both sides of the Pacific, for example, and even Mosasaurus itself is quite derived, having the second most piscine flippers after Plotosaurus. They also benefited from the demise of Cretoxyrhina.
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