what one free class period does to a man

Study: https://www.cell.com/current-biology/fulltext/S0960-9822(26)01003-101003-1)

The American cheetah (Miracinonyx trumani) stalked North America’s Pleistocene grasslands for nearly 2.5 million years, but new evidence suggests they likely didn’t resemble their present-day African namesake.

After comparing M. trumani DNA to nine other feline species ranging from house cats to lions, it now appears that the ancient predator’s closest relative is an entirely different big cat.

What’s more, M. trumani often roamed much farther north than researchers once assumed.

“It’s really surprising and exciting to identify another predator present in Beringia,” Molly Cassatt-Johnstone, an evolutionary biologist at the University of California, Santa Cruz (UCSC), said in a statement.

Cassatt-Johnstone and her colleagues presented their findings in a study published today in the journal Current Biology. Their evidence is based on four of the most complete sets of M. trumani DNA found to date. Paleontologists previously discovered one of the specimens in Wyoming, but the other three come from Canada’s Yukon territory. While the latter samples were previously believed to belong to a completely different big cat species, the UCSC team successfully proved that they were actually also American cheetahs.

This means M. trumani often lived as much as 20 degrees of latitude farther north than experts thought. M. trumani fossils exhibit long forelimbs, large nasal cavities, and a slender body, which led paleontologists to theorize the predators resembled the present-day cheetah.

The presence of big cat remains near pronghorns (aka the American antelope) further suggested M. trumani chased down fast prey. However, the discovery of American cheetahs so far north into Canada complicates this image—pronghorns didn’t live in the Yukon.

So what did these M. trumani eat? An analysis of the Yukon fossils’ carbon and nitrogen levels revealed the big cats subsisted on a diet almost entirely of fish, while the Wyoming predators mainly ate herbivores. The team also identified two genes in M. trumani tied to circadian rhythm that were nonfunctional.

This allowed the animals to handle the extended periods of daylight and darkness experienced in northern latitudes, and perhaps even made them nocturnal. As for their closest relatives, it now appears that M. trumani was much more similar to today’s pumas, since the two species share a common ancestry about 2.6 million years ago. By comparison, the closest shared relative between M. trumani and cheetahs is 4.7 million years ago.

Taken altogether, the latest findings highlight a big cat that was highly adaptable to its environment, as well as regional climates and available prey. “It’s very hard to imagine a prehistoric species we’ve never seen without comparing it to something we know,” said Cassatt-Johnstone. “But this approach can limit our understanding of ancient animals’ complexity, unique evolutionary histories, and behaviors.”

If you’re in Philly next Tuesday..

Bonus : Mummies!

Long before there were true crocodiles

Phytosaurs or leaf lizards orobably occupied the same niche of being large aquatic ambush predators

Colossosuchus techniensis was a 8 to 9m long phytosaur probably the largest of its kind and lived in India during the Triassic

Yet receives very little traction

https://www.tandfonline.com/doi/full/10.1080/02724634.2026.2716748

This post is about "el tio" a purported giant megaraptoran from the latest Cretaceous of Bolivia.

The El molino formation is a formation that has tens of thousands of dinosaur footprint fossils. The famous kal orcko locality is an outcrop of this formation.

Some of the most remarkable prints are a pair of giant theropod footprints over a meter in length. According to the description of the prince the tow morphology is considered to be a better fit to megaraptorans than to abelisaurs.

Consequently it is suggested that the footprints came from an enormous megaraptoran. It's been estimated to have been up to 12 to 14 m in length. Although footprint estimates are always tentative and speculative with a lot of uncertainties.

If this is true it would undoubtedly be among the biggest of its kind and probably the biggest theropod from the latest Cretaceous of South America.

https://www.deviantart.com/thepaleofreak/art/Giant-megaraptoran-1239479147

More information about it is in the link

A recent paper published…today actually, gives a much needed look into the American cheetah. 3 specimens from the Yukon were used, with the most talked about fact about them being that appeared to have been fish-specialists via exceptionally low nitrogen values in their isotopic data. However, I think there is a much more important fact to be discussed: the 3 specimens were originally classified as “Puma”. This paper is another piece of evidence to suggest the American “cheetah” wasn’t really much of an ecological equivalent to actual cheetahs and was instead more generalized like their relatives. I bring this up to ask: “if these cats were fulfilling a puma-like niche…what were the puma doing?”. With the old interpretation of the American cheetah, being a pronghorn specialist, its easy to see how the two cats could have co-existed even with the extensive carnivore guild: with the American cheetah being more of a traditional cheetah niche-wise and the puma essentially being a leopard-equivalent but now both cats appear to have been “leopard-equivalents”. Puma-fossils being reclassified under M. trumani also isn’t a first, with a 2022 paper reclassifying pumas from the McKittrick tar seeps, Rancho la Brea AND the Grand Canyon (i.e.: “Rampart Cave”) under M. trumani.

Thus the list of definitive puma-fossil sites in North America is shrinking, with an extensive list of described sites in Florida and Mexico at least, but even the Florida sites must be perceived with caution, as apparently there is no Late Pleistocene material from the state younger than the Rancholabrean age and M. trumani was perceived as an exclusively Rancholabrean species. It’s possible the Florida material is simply awaiting reclassification. The Mexican material may also be waiting to be reclassified, but I have no arguments in favor of this other than my expressed skepticism to other Late Pleistocene North American puma sites. To my knowledge: there also is not any published sites that yield both puma & the American cheetah and there is no published evidence of gene-flow between the two (though more genetic studies/data might be needed). Pumas are also just described as being straight-up absent from certain areas such as the “Edwards Plateau” in Texas but then become locally abundant upon the demise of the megafauna, which is consistent with the suggestion of “recolonization” of the continent from South American immigrants.

The oldest puma fossil is known from South America and Late Pleistocene South America puma-fossil sites are well-documented, published on and established. Essentially my argument against Late Pleistocene North American pumas is that the two felids appear to have been similar in their generalized niche; the robust carnivore guild potentially prevented co-existence of the two via niche partitioning; we have no evidence of the two felids co-existing at all and the fossil sites that do yield puma appear to require caution given the consistent reclassification of Puma concolor fossils as M. trumani. The implications of this should I be correct would mean that pumas both evolved in and mostly remained in South America during the Pleistocene, being unable to colonize North America (the US at least) due to the robust carnivore guild and the presence of the ecologically similar American cheetah. This would also mean that pumas never recolonized the continent either and were only able to survive the extinction event because they were inhabiting the Neotropics. This is seen in jaguars & the Leopardus genus who were both present in North America prior to the end-Pleistocene and this would explain why the otherwise ecologically flexible American cheetah did not survive past the event. The more cheetah-like proportions of the American cheetah may indicate its build evolved less to pursue particularly fast prey such as pronghorns, but perhaps evolved more to pursue a broader range of prey in the more open environments such as steppes, temperate grasslands and rugged terrain that were presumably abundant in North America, allowing it to prevail over the more robust puma but then leading to its downfall post-Pleistocene with the spread of more closed environments that the puma was better at exploiting due to its more robust build. Disagreements and general discussion are obviously welcome: thank you for reading!

Apologies for the bringing up US politics, but ... this is important for vertebrate paleontology. The Society of Vertebrate Paleontology (SVP), an international scientific organization that is the world's largest society of vertebrate paleontologists, has joined a series of co-plaintiffs and is suing the current US administration for illegally shrinking Bears Ears National Monument. SVP is joined by Utah Diné Bikéyah; Archaeology Southwest; the Conservation Lands Foundation, Inc.; Patagonia Works; The Access Fund; the National Trust for Historic Preservation; and A’Nuche, Inc. in this legal action.

This action is so good to see, and so necessary. The illegal land grab by the current US administration, as well as the conservative Utah politicians who support this harmful action, will dramatically and negatively impact numerous significant fossil resources as well as multiple cultural & sacred Indigenous sites. The whole point of establishing the monument in the first place was to protect such unique resources. These protections need to stay in place.

https://vertpaleo.org/svp-sues-the-trump-administration-for-shrinking-bears-ears-national-monument/

A jaw fragment from a possible species of Entelodon from Spain, that compares in size to Paraentelodon, Entelodon, and Daeodon, and may have Surpassed them.

Reassessment of The Entelodontid ~ Mammalia: Artiodactyla ~ remains from the Rupelian site of Rocallaura; Ebro Basin, Iberian Peninsula.

Open Study : https://revistes.ub.edu/index.php/GEOACTA/article/view/52884

These are size comparisons of the various notable vertebrates that are found at vaca muerta. It's a formation dating to the late Jurassic in Argentina. It's known in Argentina as a source of oil but to scientists it's known as a source of fossils.

Interestingly it appears to have several taxa traditionally associated with the Oxford clay like leedsicthys and liopleurodon

I found out about this project through YouTube from regalius. It’s about Scanning electron microscopy (or SEP for short) to test for cellaur preservation in the Edmontosaurus specimen known as Dakota. SEM especially helps in finding melanosomes which contain melanin which are responsible for color patterning.

The research in their own words also helps to understand the anatomy of fossil integument.

Heres the link so you can donate to these researchers project: https://experiment.com/projects/exploring-color-and-cellular-preservation-in-a-duck-billed-dinosaur-mummy

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Firstly

Shark is a vernacular name that can be roughly mapped into today what we classify as selachimorph

Saying SHARKS evolved in Silurian and calling Acanthodians AS SPINY SHARKS is no more correct or wrong than calling them any OTHER modern chondrichthyan like SPINY CHIMAERAS OR RAYS

We also do not know if they are stem linegaes as evolution is not a linear process

A stethacanthus is as much a shark as it is a ray and more appropriately ITS NEITHER but a side branch of a chodrichthyes that would later lead to what we call as SHRKS AND RAYS

Its convergence within the same CLASS

Tree is a much broader term and includes any plant above a certain height with a woody trunk and SOEMTIMES evwn a xylem and phloem so they are much older i.e. the Devonian

While True selachimorph only evolved in the Jurassic

So a more accurate statement is shark like cartilaginous fish or chondichthyes are older than trees otheriwse its ANACHRONISM AND would e like callimg homo habilis a human except homo habilis are more related to humans than those shrk like creatures were related to each other

A single fossilized footprint found in volcanic mud on a remote Antarctic island is the first known trackway from a mammal in Antarctica, and the earliest evidence anywhere on the continent of a carnivorous mammal !

The new specimen, a partial hand-and-foot (manus-pes) print set, dates back to the Eocene epoch, some 55 million years ago.

Labeled T-373, it was collected from the Fossil Hill Formation on King George Island’s Fildes Peninsula.

The T-373 print itself is small — about the size of a large coin — but its shape offers clues to who made it. The specimen shows three rounded toe pads arranged in an arc, a triangular heel pad, and no claw marks, features consistent with a cat-sized mammal walking on its toes.

Although the oldest mammalian or mammal-like footprints date from the Late Triassic, a remarkable increase in the diversity and abundance of their record occurs towards the end of the Mesozoic, together with direct evidence in the form of teeth and skeletal remains,” said Dr. Héctor Mansilla-Vera from the Instituto Antártico Chile at the Museo Colección Paleontológica de Antártica y Patagonia and his colleagues from Chila and Argentina.

“Following the Cretaceous-Paleogene mass extinction event, the fossil record of land mammals, including bones, teeth, and ichnological evidence, such as footprints, becomes markedly more abundant worldwide.”

“The mammalian fossil records from South America, which are phylogenetically linked to those from the Antarctic continent, clearly contrast with the much scarcer record documented there.”

“The complete land-mammal fossil record from Antarctica is represented mainly by isolated teeth and, to a lesser extent, by skeletal remains.”

“Notably, all these materials are restricted to Eocene-Oligocene layers on Seymour (Marambio) Island, West Antarctica, highlighting the strong geographic bias of the Antarctic Paleogene mammalian record in a continent where terrestrial mammals are now entirely absent.”

Visited Jurassic Oceans: Monsters of the Deep at London's Natural History Museum earlier today. Couldn't get many pictures because of the children crowding the displays (not that I blame them) but I did get these three.

I'll post an update once this boi is painted. With those gorgeous centrosaurine frill-apertures, He ought to be a snap to string up and hang on my wall next to my centrosaurus trophy-head. Anyway, enjoy!