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Cary Woodruff @doublebeam.bsky.social · 14h

hamoni: in honor of Bob Harmon. Bob was the former head of the MOR lab and field program, and he was the best field mentor I've ever had. I learned so much from Bob, and I am the crew chief I am today thanks to his tutelage. Thank you Bob, for everything.
(📷 by A. Bailleul)

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Cary Woodruff @doublebeam.bsky.social · 14h

Now, on to the name: Brontotholus, which means Thunder Dome. Yes, a bit of a nod to the classic sauropod named "Brontosaurus", but primarily in homage to the classic 1985 film Mad Max Beyond Thunderdome.

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Cary Woodruff @doublebeam.bsky.social · 14h

But while there was no support for such a relationship between these 3, given the stratigraphic distribution & time between these Two Med specimens, we suggest that there *might* be a case for anagenesis within this new species (ex T. horridus -> T. prorsus).

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Cary Woodruff @doublebeam.bsky.social · 14h

Long story short, we found that these Two Med domes constituted a novel genus, and that this taxon was phylogenetically not close to either Stegoceras *OR* Pachycephalosaurus. So, no anagenetic relationship between these three.

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Cary Woodruff @doublebeam.bsky.social · 14h

Fast forward MANY YEARS later, & one of my dissertation chapters was to describe this Two Med dome (& 4 others) with my academic 'parents' - Dave Evans and Jack Horner, and 'committee uncle' Mark Goodwin.

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Cary Woodruff @doublebeam.bsky.social · 14h

Horner et al (1992) proposed that a dome from the Two Medicine Fm was an anagenetic intermediate between the stratigraphically older Stegoceras & the younger Pachycephalosaurus. & given our understanding of their taxonomy at the time, that wasn't a crazy hypothesis.

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Cary Woodruff @doublebeam.bsky.social · 14h

Barring debate, the case for anagenesis in these proposed lineages has mixed support: present in tyrannosaurids and ceratopsians, less so in the hadrosaurs. But one lineage from the 1992 paper had yet to be tested: Pachycephalosauria.

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Cary Woodruff @doublebeam.bsky.social · 14h

In 1992, Horner et al published a landmark paper that examined the regression/transgression of the Western Interior Seaway in regards to dino evolution, and postulated that many NA dino lineages underwent a not-controversial-at-all-process (he said facetiously) called anagenesis.

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Cary Woodruff @doublebeam.bsky.social · 14h

Pachycephalosaurs are mostly known from the Late Cretaceous (save Zavacephale from the Early Cret.), & there are many taxa known from NA formations like the Judith, Dinosaur Park, Oldman, & Hell Creek Formations. But none from the Judithian ~coeval Two Medicine Fm. Until now...

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Cary Woodruff @doublebeam.bsky.social · 14h

Let's start with the paper:
(I also put it on ResearchGate)
The first pachycephalosaurid from the Late Cretaceous Two Medicine Formation: effects of the Western Interior Seaway on North American pachycephalosaurid evolution.
doi: doi.org/10.1093/zool...

Validate User

doi.org

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Cary Woodruff @doublebeam.bsky.social · 14h

For #FossilFriday, it's a *NEW PACHYCEPHALOSAURID*(!), and a project that is very near and dear to my heart. Let's welcome #Brontotholus_harmoni!

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Reposted by Cary Woodruff

Prof Susie Maidment @tweetisaurus.bsky.social · 15h

After we published the new specimen of #Spicomellus a few weeks ago, we were contacted by George Blasing, who said he'd bought some on the commercial market, and wanted to return it to Morocco. It arrived last week. Thanks George for doing the right thing in the name of science!

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Cary Woodruff @doublebeam.bsky.social · 1d

Thanks!

Cary Woodruff @doublebeam.bsky.social · 23d

Chinzo & Lindsay were gracious enough to host me for a day last year to see this remarkable specimen in person, and as gorgeous as the photos are, they pale in comparison to the actual fossil 🤩

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Cary Woodruff @doublebeam.bsky.social · 23d

#Zavacephale is SUPER important for our understanding of pachycephalosaur evolution! Some parts look pretty derived, others pretty basal, and there are so many parts of the skeleton that provide crucial details of the evolution of this bizarre dino clade.

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Cary Woodruff @doublebeam.bsky.social · 23d

And the link to the paper:
Tsogtbaatar Chinzorig, Ryuji Takasaki, Junki Yoshida, Ryan T. Tucker, Batsaikhan Buyantegsh, Buuvei Mainbayar, Khishigjav Tsogtbaatar & Lindsay E. Zanno (2025)
A domed pachycephalosaur from the early Cretaceous of Mongolia
www.nature.com/articles/s41...

A domed pachycephalosaur from the early Cretaceous of Mongolia - Nature

The pachycephalosaurian Zavacephale rinpoche, from the Early Cretaceous of Mongolia, provides crucial insights into the early evolution of dome-headed dinosaurs, including the development of the front...

doi.org

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Cary Woodruff @doublebeam.bsky.social · 23d

#ZAVACEPHALE IS FINALLY OUT! 🥳 Our first definitive Early Cretaceous pachycephalosaur! (~15 my older than the previous oldest pachycephalosaurs) And the first hand material for the clade! I can't tell y'all how much of a pleasure it was to review this paper! ☺️