Dani Barrera Guevara

@ceratopsyuta So here we run into a problem. Cryptarcus is more closely related to Penta than Chasmo. And the only Chasmo currently is C. belli. Which is different from the OLDER heart-shaped Chasmo, which was previously referred to C. russelli. So how does one refer to it now? Chasmo sp.?

@ceratopsyuta That specimen most closely resembles A. Heart shaped frill Chasmo, previously C. russelli. Chasmo belli is known from a good skull, with a straight posterior bar (G). Stratigraphically higher. Cryptarcus (previously Chasmo russelli) is from high in strat. Campbell et al., 2016

@NatSciChannel @TheRedRaptor65 @JoschuaKnuppe You are on your A-game sharing new papers!

🚨NEW STUDY DROP🚨 This study found that there is a strong possibility turtles survived the KPG extinction by evolving durophagy - the ability to eat tough foods. Those that did not eat hard foods, did not sail through the extinction as easily. 🎨: @JoschuaKnuppe

@Collinson_C @NatSciChannel To be fair, that discussion was a Twitter post with ~30 views.😅 But what I did notice is that they say the Penta clade/lineage is restricted to the south of North America, with Cryptarcus being anomalous. However, Pentaceratops is known from Alberta (Longrich, 2014)!

@Barrerasaurus @NatSciChannel Looks like they didn’t see your discussion of the epi parietals at the embayment and using Lehman’s figures.

🚨NEW STUDY DROP🚨 Chasmosaurus russelli is no more! The species has been assigned to a new genus, Cryptarcus! They found the features that were used to put it in the chasmo genus were not strong enough to keep it there. 🎨: Tuomas Koivurinne

@NatSciChannel Chasmosaurus sp.? Or refer to it as “the lower Dinosaur Park Fm Chasmosaurus”? It appears that the older heart-shaped-frill Chasmosaurus is nameless. Figure 3 and Figure 4F of Campbell et al., 2016.

@Barrerasaurus So would that mean those specimens would have no placement at this time?

@NatSciChannel Discussion in this new paper is dedicated to biogeography, and why a Penta-related chasmo would be found Alberta, when the Penta group is from Southern North America. In 2024, we suggested a latitundal vicariance (not endemism) influenced by seaway transgressions and regressions.

@NatSciChannel In 2024, we suggested CMNFV 8800 was an early member of the Pentaceratops lineage/clade, therefore closer to Pentaceratops than to Chasmosaurus! Today, CMNFV 8800 is described as a new genus, Cryptarcus russelli. And closer to the Penta-clade/lineage. (1/2)

@NatSciChannel In a non-peer reviewed paper by Longrich, he assigns the other C. russeli to Chasmosaurus priscus. However it that manuscript was never formally published. Good to see finally someone distinguish this specimen was closer to Pentaceratops!

The other C. russelli specimens may all belong to a unique species (requiring a new name), the original Chasmosaurus belli species, or all belong to unique genera/species.

@PRECISETHF whooops!

@Barrerasaurus This is arguably a worse fate

@ceratopsyuta I personally think that is the case. But I know that not everyone agrees with this interpretation and hypothesis. This to me is the best explanation for late Campanian - early Maastrichtian Chasmosaurines.

@Barrerasaurus I wonder if the P0 in Regaliceratops could instead be interpreted as a fusion of the left and right P1s, although I realize this may well be an oversimplification on my part.

レガリがトリケラトプス族に置かれるより納得感ある。

@ceratopsyuta Interpretation of these characters -and how they are coded- will affect the outcome of the phylogeny. If one codes Regali with a P0, short rounded frill, small rounded fenestrae, it will come out with the other Triceratopsins…

@ceratopsyuta Both Regali and Anchi have large blade like epiparietals, small round fenestrae, and epiparietals on the dorsal surface of the posterior parietal bar (P1s in Anchi P0 in Regali). The shortening of the squamosals and rounding of the overall frill is a trend seen on both lineages.

🦖Stratigraphic Reassessment of the Mexican Chasmosaurine Coahuilaceratops magnacuerna as the First Diagnostic Dinosaur Remains from the Cerro Huerta Formation.... 👥Daniela Barrera Guevara et al. 🔗Read at: brnw.ch/21x0M4W #Diversity #Ceratopsidae #Maastrichtian

@Deform2022 Oh yeah, I’m aware ! But some people might not… I meant to say IN the diagram. Sometimes these images get spread around, cropped and edited. Where the silhouette gets shared around with vague information. To avoid that, you could include the found elements in the silhouette.

@Barrerasaurus This is the tibia in question, directly from Longrich's lecture:

In wake of the new Kirkland Formation tyrannosaurine specimen, I updated "Denazinosaurus sicarius." There's clearly a Tarbosaurus-sized tyrannosaurine in New Mexico.

@MiloGaillard3 @Elemental93 Identification of the Titano specimen to Pentaceratops predates its plaster reconstruction! Titano wouldn’t be named named until 2011. Its diagnosis based on non reconstructed elements. The specimen is not encased in plaster. But rather, has missing parts restored with plaster.

@MiloGaillard3 @Elemental93 The Titano specimen was first described by Lehman (1998), accepted February, 1998, published September 1998. By October-November, 1998, the specimen was being restored. With the refurbished Oklahoma Museum set to open in 2000. samnoblemuseum.ou.edu/wp-content/upl… doi.org/10.1126/scienc…

Eh. I’d rather not say Titano and Penta are the same and I’d just wait for more information.

@MiloGaillard3 @Elemental93 In the literature, the attribution of the Titano specimen to aff. Pentaceratops sp. has been done considering the known elements (see Supp. Info. of Fowler & Freedman Fowler, 2020). Never has it been considering the reconstructed plaster restorations made to it. (2/2)

@MiloGaillard3 @Elemental93 While the mounted Titano specimen is restored, it has been readily apparent in the literature which elements are present in the specimen and the which have been reconstructed. See Lehman, (1998) and Longrich, (2011). (1/2)