Paleontologists in New Zealand have found a partial skeleton of platypterygiid ichthyosaur courting to the Cretaceous interval.
A pair of Platypterygius sp. Picture credit score: Dmitry Bogdanov / CC BY 3.0.
“Ichthyosaurs had been a clade of secondarily aquatic marine reptiles that inhabited the seas for a lot of the Mesozoic Period, first showing within the Early Triassic earlier than their final extinction on the Cenomanian-Turonian boundary,” stated College of Canterbury paleontologist George Younger and his colleagues.
“Cretaceous ichthyosaurs had been as soon as considered a gaggle with low variety and disparity ensuing from a long-term decline for the reason that Jurassic.”
“Nonetheless, latest work has produced a rising physique of proof that Cretaceous ichthyosaurs had been way more numerous than beforehand thought.”
“Ichthyosaur fossils had been first recorded in New Zealand by von Haast in 1861 from Mt Potts within the central South Island,” they added.
“Over the next 150 years, fossil materials of ichthyosaurs has been recovered from the Triassic, Jurassic, and Cretaceous.”
The brand new New Zealand ichthyosaur was discovered within the Coverham space on the northern finish of the Waiau Toa/Clarence valley.
The specimen is a disarticulated partial skeleton preserved inside a concretion.
It dates again 98 million years in the past to the Cretaceous interval — roughly 4 million years earlier than the ultimate extinction of the ichthyosaurs.
“The fabric derives from a concretion that was discovered in situ inside the Swale Siltstone Member of the Break up Rock Formation, a siliciclastic unit deposited in the course of the Cenomanian age and located all through southern Marlborough and northernmost Canterbury within the New Zealand’s South Island,” the paleontologists stated.
“All of New Zealand’s beforehand described Cretaceous ichthyosaur materials comes from the North Island.”
The specimen is essentially the most fully preserved particular person ichthyosaur identified from New Zealand.
It possesses a well-preserved pelvis and hindfin which have added to the identified dataset of those components that are so hardly ever preserved in Cretaceous species.
“While the specimen is just too fragmentary to formally identify, this taxon exhibits an excessive discount of the basioccipital extracondylar space, a scapula with a distinguished acromion course of and a strap-like scapula shaft, in addition to an entire left pelvic girdle with an elongated despair on the anteroproximal face of the ischiopubis,” the researchers stated.
They recommend that it’s a late branching member of the platypterygiid ichthyosaurs, carefully associated to an Japanese Gondwanan species known as Platypterygius australis and to many European Cretaceous ichthyosaurs.
Nonetheless, it seems to be unrelated to the Cretaceous ichthyosaurs of Western Gondwana, suggesting potential regionalism amongst the Gondwanan Cretaceous ichthyosaur populations.
“The brand new New Zealand ichthyosaur provides to the identified variety of Gondwanan Cretaceous ichthyosaurs and will recommend a regionalized slightly than cosmopolitan distribution of ichthyosaur populations across the margin of Cretaceous Gondwana,” the scientists conlcuded.
The findings seem within the Journal of Vertebrate Paleontology.
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George R.A. Younger et al. A platypterygiid ichthyosaur from the Cenomanian of central New Zealand. Journal of Vertebrate Paleontology, revealed on-line October 30, 2024; doi: 10.1080/02724634.2024.2408391
