Paleontologists in New Zealand have discovered a partial skeleton of platypterygiid ichthyosaur relationship to the Cretaceous interval.
A pair of Platypterygius sp. Image credit score rating: Dmitry Bogdanov / CC BY 3.0.
“Ichthyosaurs have been a clade of secondarily aquatic marine reptiles that inhabited the seas for lots of the Mesozoic Interval, first displaying throughout the Early Triassic sooner than their last extinction on the Cenomanian-Turonian boundary,” acknowledged School of Canterbury paleontologist George Youthful and his colleagues.
“Cretaceous ichthyosaurs have been as quickly as thought of a gaggle with low vary and disparity ensuing from a long-term decline as a result of the Jurassic.”
“Nonetheless, newest work has produced a rising physique of proof that Cretaceous ichthyosaurs have been far more numerous than beforehand thought.”
“Ichthyosaur fossils have been first recorded in New Zealand by von Haast in 1861 from Mt Potts throughout the central South Island,” they added.
“Over the subsequent 150 years, fossil supplies of ichthyosaurs has been recovered from the Triassic, Jurassic, and Cretaceous.”
The model new New Zealand ichthyosaur was found throughout the Coverham area on the northern end of the Waiau Toa/Clarence valley.
The specimen is a disarticulated partial skeleton preserved inside a concretion.
It dates once more 98 million years up to now to the Cretaceous interval — roughly 4 million years sooner than the last word extinction of the ichthyosaurs.
“The material derives from a concretion that was found on website contained in the Swale Siltstone Member of the Break up Rock Formation, a siliciclastic unit deposited in the middle of the Cenomanian age and situated all by way of southern Marlborough and northernmost Canterbury throughout the New Zealand’s South Island,” the paleontologists acknowledged.
“All of New Zealand’s beforehand described Cretaceous ichthyosaur supplies comes from the North Island.”
The specimen might be probably the most totally preserved specific particular person ichthyosaur recognized from New Zealand.
It possesses a well-preserved pelvis and hindfin which have added to the recognized dataset of these elements which are so rarely preserved in Cretaceous species.
“Whereas the specimen is simply too fragmentary to formally determine, this taxon reveals an extreme low cost of the basioccipital extracondylar area, a scapula with a excellent acromion course of and a strap-like scapula shaft, along with a complete left pelvic girdle with an elongated despair on the anteroproximal face of the ischiopubis,” the researchers acknowledged.
They suggest that it is a late branching member of the platypterygiid ichthyosaurs, rigorously related to an Japanese Gondwanan species known as Platypterygius australis and to many European Cretaceous ichthyosaurs.
Nonetheless, it appears to be unrelated to the Cretaceous ichthyosaurs of Western Gondwana, suggesting potential regionalism amongst the Gondwanan Cretaceous ichthyosaur populations.
“The model new New Zealand ichthyosaur offers to the recognized vary of Gondwanan Cretaceous ichthyosaurs and can suggest a regionalized reasonably than cosmopolitan distribution of ichthyosaur populations throughout the margin of Cretaceous Gondwana,” the scientists conlcuded.
The findings appear throughout the Journal of Vertebrate Paleontology.
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George R.A. Youthful et al. A platypterygiid ichthyosaur from the Cenomanian of central New Zealand. Journal of Vertebrate Paleontologyprinted on-line October 30, 2024; doi: 10.1080/02724634.2024.2408391