Istiorachis, new sail-back styracosternan from Lower Cretaceous of Isle of Wight (free pdf)

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

A new paper:

Free pdf:

Istiorachis macarthurae gen. et sp. nov.

 
Jeremy A. F. Lockwood, David M. Martill & Susannah C. R. Maidment (2025)
The origins of neural spine elongation in iguanodontian dinosaurs and the osteology of a new sail-back styracosternan (Dinosauria, Ornithischia) from the Lower Cretaceous Wealden Group of England
Papers in Palaeontology 11(4): e70034
doi: https://doi.org/10.1002/spp2.70034
https://onlinelibrary.wiley.com/doi/10.1002/spp2.70034

Free pdf:
https://onlinelibrary.wiley.com/doi/epdf/10.1002/spp2.70034


The Wealden Group of southern England was deposited during the late Berriasian to early Aptian interval. It records a critical time in the development of iguanodontian dinosaur diversity, which increased from low levels during the Jurassic to higher levels in the Aptian and Albian. A new iguanodontian dinosaur, Istiorachis macarthurae gen. et sp. nov. from the Wessex Formation (Wealden Group) of the Isle of Wight, exhibits hyperelongation of the dorsal and caudal neural spines, suggesting that it possessed a possible sail structure. Ancestral state reconstruction for the relative height of dorsal neural spines in iguanodontians demonstrates that modest elongation began with Ankylopollexia in the Late Jurassic and elongation became established during the Berriasian stage of the Early Cretaceous, albeit with widely disparate values. Hyperelongation of neural spines occurred more sporadically throughout the Cretaceous, being recorded most often in the Barremian and early Aptian. Possible explanations for neural spine elongation in Ankylopollexia include biomechanical advantage, perhaps related to greater mass and a locomotory shift towards quadrupedalism, and visual signalling driven either by sexual selection or species recognition, or both. The function of elongate neural spines was probably pluralistic and differed in different taxa. No single explanation fully supports the variation seen throughout the Cretaceous.

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News:

New sail-backed dinosaur species unearthed on the Isle of Wight.

https://www.nhm.ac.uk/discover/news/2025/august/new-sail-backed-dinosaur-species-unearthed-isle-of-wight.html

https://www.theguardian.com/science/2025/aug/22/new-species-of-dinosaur-with-eye-catching-sail-discovered-on-isle-of-wight

[Gregory Paul]

Do any know if the following late Maastrichtian small tyrannosaur specimens have nicknames, or if not that the name of the collector? 

UCRC V1

UCMP 84133

FNMH PR2411 

HRS 08

HRS 15001

KU 155809

RSM P2347.1 

GSPaul

[Franco Sancarlo]

HRS 08 if you mean the Tyrannosaurid from the Lance is known as "Zuri specimen" and collected by Zuri Franco in my knowledge 

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[Matthew McLain]

The HRS08 specimen you're talking about is nicknamed "Zuri". The specimen was disarticulated, and each bone was given its own specimen number. The maxilla is numbered HRS08438 (https://fossil.swau.edu/link/Public/Browse/Specimen/HRS08438), but there is also a quadratojugal (HRS08440), a splenial (HRS08443), a pterygoid (HRS08444), two jugals (HRS08458 and HRS08502), a dentary (HRS08486), two prearticulars (HRS08495 and HRS08564), a lacrimal (HRS08496), an ectopterygoid (HRS08498), a surangular (HRS08510), two quadrates (HRS08600 and HRS08614), a frontal (HRS08607), and some postcranial elements (vertebrae, ribs, fragmentary ilium, etc.). All of the elements are photographed, and 3D models can be downloaded from that site.

HRS15001 is a manual claw. It does not have a name but was collected by the same person the "Zuri" specimen was named after: Zuri Franco (https://fossil.swau.edu/link/Public/Browse/Specimen/HRS15001).

Have a great day,

Matt

Matthew McLain 

Chair of the Department of Biological and Physical Sciences

Associate Professor of Biology and Geology

The Master's University, Santa Clarita, CA

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[Deinonychus47]

If HRS 08 and FNMH PR2411 are tyrannosaur specimens, I have been unable to find any information about them.

Can you tell me more about them?

Thanks.

[Gregory Paul]

They are in https://www.mapress.com/mz/article/view/mesozoic.2.2.1 

and refs therein. 

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[Gregory Paul]

Rozhdestvensky (A.K. (1965) Growth changes in Asian dinosaurs and some problems of 

        their taxonomy. Paleontologicheskii Zhurnal, 1965, 95–109) has been assigned credit for being the first to propose that the future Nanotyrannus is a juvenile Tyrannosaurus.

But did he actually do that? 

I wonder because in the English version (https://reptilis.net/DML/2020Dec/pdfo9xDkFG82J.pdf) it looks like translator Dale Russell may have added the suggestion as a footnote, it not being in the text. I do not have access to the original Russian (which I cannot read anyhow) article so I cannot check.   

Might anyone be able to elucidate on this matter? 

GSPaul

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

The Russian Nanotyrannus Wikipedia article cites the Russian version of the 1965 paper. This would seem to support that the original Russian version suggested the skull was a juvenile Tyrannosaurus. I'll see if I can find the Russian paper online somewhere such as the Geokniga website.

https://ru.wikipedia.org/wiki/%D0%9D%D0%B0%D0%BD%D0%BE%D1%82%D0%B8%D1%80%D0%B0%D0%BD%D0%BD%D1%83%D1%81

(Online translation)

The validity of Nanotyrannus can only be finally resolved after the femur BMRP 2002.4.1 ("Jane") is examined, which may prove to be either another representative of the genus or a juvenile individual of Tyrannosaurus. An examination of two skeletons from the Hell Creek Formation that were used to argue for the genus Nanotyrannus (Jane and Peaty ( tibia BMRP 2006.4.4)) showed that they were juvenile individuals of Tyrannosaurus, aged 13 and 15 years. This result supports the interpretation of the skull CMNH 7541 as a juvenile T. rex [ 5 ] , proposed by the Soviet paleontologist A.K. Rozhdestvensky in 1965 [ 19 ].

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[Deinonychus47]

Cool. Thanks.

Sent from the all new AOL app for iOS

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[Jerry Harris]

Here's the original Russian paper.

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

Thanks for the Russian pdf. Comparing the two, Russell's translation of Footnote 6 on page 106 of the Russian text appears accurate. 

Russell's version:

*Similar relationships are observed between Tyrannosaurus rex and Gorgosaurus lancensis (Gilmore, 1946), and it is therefore possible that the latter species is a young individual of the former. The remains of both species come from the Hell Creek (Lance) Formation of Montana. 

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[Gregory Paul]

Yep, this settles it. 

GSPaul

https://groups.google.com/d/msgid/DinosaurMailingGroup/5b169e1b-903c-484d-8941-7fdd1d35eba9n%40googlegroups.com

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