New Zealand paleontologists have discovered a partial skeleton. platypterygoid ichthyosaur It dates back to the Cretaceous period.
a pair of Platypterygius sp. Image credit: Dmitry Bogdanov / CC BY 3.0.
“Ichthyosaurs are a clade of secondary aquatic marine reptiles that lived in the oceans for much of the Mesozoic, first appearing in the Early Triassic and eventually becoming part of the Cenomanian.'' It became extinct at the Turonian border.”
“Cretaceous ichthyosaurs were once thought to be a group with low diversity and disparity, the result of a long-term decline since the Jurassic.”
“However, recent studies have produced a growing body of evidence that Cretaceous ichthyosaurs were much more diverse than previously thought.”
“Ichthyosaur fossils were first recorded in New Zealand by von Haast in 1861 from Pott Mountain in the central South Island,” they added.
“Over the next 150 years, ichthyosaur fossil material was recovered from the Triassic, Jurassic, and Cretaceous periods.”
The new New Zealand ichthyosaur was discovered in the Coverham area at the northern end of the Waiau Toa/Clarence Valley.
The specimen is a disarticulated partial skeleton preserved in a tubercle.
Its origins date back to 98 million years ago during the Cretaceous period, about 4 million years before ichthyosaurs finally became extinct.
“This material comes from the condensate that was discovered.” on site “It lies within the Swale Silt Formation of the Split Rock Formation, a siliciclastic unit deposited during the Cenomanian period and found throughout southern Marlborough and northernmost Canterbury on New Zealand's South Island,” the paleontologists said.
“All Cretaceous ichthyosaur material ever described in New Zealand comes from the North Island.”
This specimen is the most completely preserved ichthyosaur known from New Zealand.
It has a well-preserved pelvis and dorsal fin, adding to the known data set of these elements, which are poorly preserved in Cretaceous species.
“Although the specimen is too fragmentary to be formally named, this taxon has an extremely reduced basioccipital extracondylar area, a scapula with a prominent acromion process and a strap-like scapular shaft, and A complete left pelvic girdle with an elongated depression “located on the anteroproximal aspect of the ischium” is shown, the researchers said.
They suggest that it is a late-diverging member of the platypterygian ichthyosaurs and is closely related to East Gondwanan species. Platypterygius australis and many European Cretaceous ichthyosaurs.
However, it appears to be unrelated to the Cretaceous ichthyosaurs of western Gondwana, suggesting potential regionalism in the Cretaceous ichthyosaur populations of Gondwana.
“New Zealand ichthyosaurs add to the known diversity of Gondwanan-Cretaceous ichthyosaurs, and suggest that ichthyosaur populations were distributed regionally, rather than internationally, near the margins of Cretaceous Gondwana. “This may indicate that,” the scientists concluded.
of findings will appear in Journal of Vertebrate Paleontology.
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George R.A. Young others. A platyptera ichthyosaur from the Cenomanian region of central New Zealand. Journal of Vertebrate Paleontologypublished online October 30, 2024. doi: 10.1080/02724634.2024.2408391
Source: www.sci.news
