the newly discovered “mummy zone”<\/a> will redefine what we know about T. rex, inside and out.<\/p>\n\u201cAll I\u2019ll say is we don’t see scales,\u201d he said.<\/p>\n
![\"An](\"https:\/\/www.newsbeep.com\/us\/wp-content\/uploads\/2026\/09\/T-rex-model-9.19.26.jpg\")
An animatronic Tyrannosaurus rex on display at the Natural History Museum in London, England. The new insights from the exceptional skeleton of “Rex Junior” are poised to change what paleontologists thought about how T. rex looked when it was alive during the Late Cretaceous Period, 67 million years ago. The Big Block<\/p>\n
Sereno encountered Rex Junior at the top of a hill near Newcastle in the 1990s. It eroded out of the Lance Formation, a 67-million-year-old layer of rock dating to the end of the Late Cretaceous Period, when T. rex and Triceratops roamed Wyoming.<\/p>\n
This T. rex wasn\u2019t so much excavated as wrapped up and hauled off the Zerbst Ranch. The Zerbsts have been assisting paleontologists with that for generations.<\/p>\n
William Zerbst helped paleontologist Charles Sternberg excavate a mummified Edmontosaurus from the ranch in 1910. His son, Leonard, encouraged paleontologists to explore the ranch his entire life, leading to the discovery of spectacular Triceratops specimens and other Edmontosaurus mummies.<\/p>\n
That\u2019s how Sereno zeroed in on \u201cthe big block.\u201d<\/p>\n
\u201cI worked on the Zerbst Ranch and got to know the family quite well,\u201d he said. \u201cThey know the land, as many ranchers do, and they knew there was something in a big block on the top of a hill.\u201d<\/p>\n
Kristen Zerbst, Leonard\u2019s daughter, mentioned the block to Sereno. It wasn\u2019t a new discovery, as the family had been finding broken scraps of fossilized bone lying beside it for decades.<\/p>\n
\u201cI found an interview with Leonard Zerbst where he talked about the dinosaur at the top of a hill,\u201d Sereno said. “It was from 1952.”<\/p>\n
Other paleontologists had visited the mysterious block over the years, thinking it might contain another mummified Edmontosaurus. Sereno was the first one tenacious enough to recover it, and what an effort it was.<\/p>\n
It Could Only Be<\/p>\n
In the early 1990s, Sereno brought graduate and high school students from Chicago to eastern Wyoming for a field trip. Once they got situated on the Zerbst Ranch, thanks to the hospitality of the Zerbst family, their first day was spent reaching the big block.<\/p>\n
\u201cI’m charging ahead, because I\u2019ve got a lot of energy, while trying to get the undergrads to move their butts up the hill,\u201d he said.<\/p>\n
Once he reached the big block, Sereno picked up a few fossil-containing pieces scattered around it. In an instant, he knew it was something unique. <\/p>\n
\u201cI could see a cross-section of two little bones, and two more little bones, and two more little bones,\u201d he said. \u201cI understood it was a T. rex. It could only be a T. rex.\u201d<\/p>\n
More important, Sereno recognized he was looking at bones that had never been found intact in any other T. rex skeleton.<\/p>\n
\u201cThose little bones were gastralia, part of the stomach ribs, and they were in place,\u201d he said. \u201cI could see a line connecting them in the sediment.\u201d<\/p>\n
With these clues, Sereno deduced that the big block could contain the articulated skeleton of a T. rex. There was no question it was going back with him to Chicago.<\/p>\n
I Haul The U-Haul<\/p>\n
Because the rock of the block was impossibly hard, the entire block was removed intact. Once again, the Zerbsts lent a hand \u2014 and several hundred horsepower.<\/p>\n
\u201cThe main concretion was over 5,000 pounds, with several subsidiary pieces that weighed around 2,000 pounds,\u201d Sereno said. \u201cWe wrapped them in plaster, put some wood on them, and Kristen’s husband, Chad, lifted them with a backhoe.\u201d<\/p>\n
Since Sereno didn\u2019t have a vehicle with enough space and torque to get the block out of the field, he improvised by renting a 17-foot U-Haul truck.<\/p>\n
\u201cWhen we pushed it into the back of the U-Haul, the flaps went right down to the ground,\u201d he said. \u201cWith 7,000 pounds in the back, and realizing the tires could blow within 50 yards of driving down the gravel road, I got in the cab and started driving.\u201d<\/p>\n
Sereno turned onto the highway at a modest 45 mph. After checking the tires to ensure the truck could handle the load, he bumped it up to 60 mph for the 988-mile trek back to Chicago.<\/p>\n
\u201cI don’t think that U-Haul was ever quite the same,\u201d he said.<\/p>\n
Perfect<\/p>\n
Once the big block was back at the University of Chicago, the laborious process of preparing the specimen began. Rex Junior didn\u2019t give up its secrets easily.<\/p>\n
\u201cIt\u2019s the hardest rock we’ve ever encountered,\u201d Sereno said. \u201cEvery once in a while, the bones of something will attract the groundwater in such a way that an ironstone concretion forms around them. It\u2019s just about the hardest rock I think I’ve ever seen.\u201d<\/p>\n
Millimeter by millimeter, the ironstone was etched away, and the fossilized skeleton slowly revealed. It was immediately worth every laborious inch of struggle.<\/p>\n
The first big revelation was the articulated right arm. Every bone was there, from the long, thin scapula to the very tips of the claws, perfectly articulated as they would have been when Rex Junior was alive.<\/p>\n
\u201cIt was the only complete T. rex hand and forearm ever found,\u201d Sereno said. \u201cEvery single bone, in place outside of the ribcage. I was totally shocked.\u201d<\/p>\n
As of 2026, the preparation of Rex Junior continues. The primary 5,000-pound concretion has been mostly prepared on one side, revealing the right arm and most of the ribcage.<\/p>\n
\u201cIt looks like we\u2019ve got both arms, the torso, and the base of the neck,\u201d Sereno said. \u201cThere are five or six small blocks that fit into it, and you can see the knee coming up to the chest, so we\u2019re probably going to get most of the (right) leg.\u201d<\/p>\n
What about the tail and the highly coveted skull?<\/p>\n
\u201cUnfortunately, those have been lost to erosion,\u201d Sereno said. \u201cThose weathered away through doubtless centuries, and probably a millennium of time. That block had been weathering for centuries before we got to it.\u201d<\/p>\n
It\u2019s unfortunate that time decapitated this dinosaur, he said, but Rex Junior doesn\u2019t need a pretty face to be one of the best T. rex specimens ever found.<\/p>\n
No Wishful Thinking<\/p>\n
As Rex Junior’s preparation continued, another first was revealed: An articulated furcula, better known as \u201cthe wishbone,\u201d was found attached to the shoulder at the midline of the body, right where it should be.<\/p>\n
That discovery had an immediate impact, leading to the world\u2019s most famous T. rex getting a somewhat extreme makeover.<\/p>\n
Sue the T. rex, found in South Dakota a few years before Rex Junior, had a litigious journey before ending up at Chicago\u2019s Field Museum of Natural History in 1997.<\/p>\n
Sue remains the most complete T. rex ever found, with over 90% of its skeleton recovered.<\/p>\n
\u201cSue was quite complete, and, very fortunately, there have been even more T. rex skeletons that they’ve been able to piece together to know what they looked like,\u201d he said. \u201cBut they did make a mistake with Sue.\u201d<\/p>\n
When Sue was excavated and sold at auction, nobody knew she had a wishbone, too. The U-shaped bone was thought to be one of her stomach ribs until it was \u201crediscovered.\u201d<\/p>\n
\u00a0When the world-famous T. rex was remounted for a new display at the Field Museum, she got some scientifically accurate beauty tips from Rex Junior.<\/p>\n
\u201cWhen they originally mounted Sue, she was barrel-chested,\u201d Sereno said. \u201cT. rex is a big animal, around 50 feet long, so you want to give it a little bit of a barrel-shaped chest.\u201d<\/p>\n
Despite the inclination of generations of paleontologists to make T. rex barrel-chested, the articulated shoulders and wishbone of Rex Junior revealed something different.<\/p>\n
\u201cThis specimen shows the furcula sits right in between on the crest of the coracoids, connected to the scapulae, just like it does in a modern bird,\u201d Sereno said. \u201cEverything joins together at the midline.\u201d<\/p>\n
That articulation makes the chest of T. rex much slimmer. The remounted skeleton of Sue reflects this discovery from Rex Junior \u2014 almost.<\/p>\n
\u201cRemounting is a big, expensive procedure, and they’ve got it almost right,\u201d Sereno said. \u201cIt’s certainly a lot closer than it once was.\u201d<\/p>\n
Buried Alive And Mummified<\/p>\n
In October 2025, Sereno and several other paleontologists published a paper on the newly discovered \u201cmummy zone\u201d in western North America. It\u2019s an unusually thick section of the Lance Formation that was predisposed to pristinely preserving dinosaur bodies<\/p>\n
Rex Junior is a mummified dinosaur skeleton. It was found at the top of the mummy zone that also produced other mummified dinosaurs from eastern Wyoming, including several Edmontosaurus from the Zerbst Ranch.<\/p>\n
However, simply calling Rex Junior \u201cmummified\u201d isn\u2019t doing the specimen justice, from Sereno\u2019s perspective.<\/p>\n
What immediately stood out to him was that Rex Junior was three-dimensionally preserved. None of the articulated bones are squashed, distorted, or scattered.<\/p>\n
It was like the dinosaur went to sleep, completely undisturbed.<\/p>\n
\u201cIt\u2019s a particularly interesting case because (the body) does not look dried,\u201d Sereno said. \u201cThe mummies that we described in the paper look dried, like they\u2019d been exposed for several days or weeks before being covered by a flood. (Rex Junior) doesn\u2019t look like that.\u201d<\/p>\n
Sereno noted that Rex Junior isn\u2019t just three-dimensionally preserved \u2013 it\u2019s perfectly three-dimensionally preserved. The articulated arm, in particular, is preserved in what he called \u201ca lifelike position.\u201d<\/p>\n
This is one instance where Sereno said \u201clifelike\u201d is unnatural.<\/p>\n
\u201cWhen you die as a carcass, there’s skin sagging. The hands are pulled up in a deathlike pose. The body dries out like beef jerky. I think the position of the hands and ribs is too natural. It\u2019s preserved in a lifelike position.\u201d<\/p>\n
That\u2019s exactly what Sereno speculates might have happened. Rex Junior couldn\u2019t be buried as a carcass, because the dinosaur wasn\u2019t dead when it was buried.<\/p>\n
\u201cI personally believe that it was buried alive in a flood,\u201d he said. \u201cI don’t think it was a carcass. This looks like it was breathing when it was suddenly buried, like it didn\u2019t have a chance to escape.\u201d<\/p>\n
No Scales<\/p>\n
Sereno has additional clues supporting the \u201cburied alive\u201d theory, along with other incredible insights revealed by Rex Junior. Those will have to wait for the in-progress publication that will bring Rex Junior into the international limelight.<\/p>\n
Ongoing work is focusing on preparing the remaining ironstone concretion blocks while exposing more of the primary block. An unexpected find was a well-preserved tree trunk, pressed against the dinosaur\u2019s chest.<\/p>\n
Sereno did give one big hint about another revelation from Rex Junior that could change T. rex forever.<\/p>\n
Modern scientists accept that there is an unbroken evolutionary lineage between prehistoric dinosaurs and modern birds. Rather than being closely related to each other, today\u2019s birds are all on a surviving branch of the dinosaur family tree.<\/p>\n
Fossils found and reexamined over the last 30 years have revealed that many non-avian dinosaurs, like Velociraptor, were covered in feathers or feather-like integuments.<\/p>\n
Because Wyoming\u2019s mummified dinosaurs are covered with skin impressions, the same might be expected for a mummified T. rex from Wyoming\u2019s mummy zone.<\/p>\n
\u201cWe have an extraordinary chance, with a mummy of the largest predator to grace the face of the earth, to understand more about its body position and, maybe, its integument,\u201d Sereno said.<\/p>\n
Sereno isn\u2019t revealing anything about what has or hasn\u2019t been found on or around Rex Junior’s fossils. He did confirm that there are some spots they\u2019re studying with great interest, for what might or might not be there.<\/p>\n
\u201cI\u2019m not going to let slip the secret, but I’ll say this: there are no scales,\u201d he said.<\/p>\n
The Triumvirate<\/p>\n
Sereno is working on new research that he hopes to publish in early 2027, focusing exclusively on dinosaurs from the mummy zone on the Zerbst Ranch.<\/p>\n
It takes a lot for someone like Sereno, who\u2019s traveled around the world to find several new, one-of-a-kind dinosaurs, to get excited.<\/p>\n
That said, he\u2019s really excited about what\u2019s coming. The research will include new insights on Wyoming\u2019s state dinosaur, Triceratops.<\/p>\n
\u201cWe\u2019re working on another dinosaur mummy that the Zerbsts found 150 feet away from this one,\u201d he said. \u201cIt\u2019s going to be an incredible discovery once it hits the newsstands.\u201d<\/p>\n
That specimen, \u201cLane,\u201d is on display at the Houston Museum of Natural History in Texas. In addition to being one of the most complete Triceratops ever found, the fossils were recovered with enormous skin impressions.<\/p>\n
\u201cWe\u2019re giving Triceratops a facelift early next year,\u201d he said. \u201cIt\u2019s going to be wild.\u201d<\/p>\n
With Rex Junior, Lane, and the mummified Edmontosaurus specimens, Sereno has \u201cthe triumvirate\u201d of Late Cretaceous dinosaurs, all collected from the Zerbst Ranch.<\/p>\n
Such discoveries, and the rigorous research and review to get them ready for publication, take time and tenacity. That\u2019s what led Sereno to Rex Junior in the 1990s, and what could lead to a whole-new view of T. rex.<\/p>\n
\u201cScience works like a breadcrumb trail,\u201d he said. \u201c(Rex Junior) was like a red flag. It was there for a century, and the story is only now being understood. It takes a while for these stories to come out, but if you\u2019re dogged, you can do it.\u201d<\/p>\n
That\u2019s what makes Rex Junior even more remarkable. Sereno said he is \u201cvery, very, extraordinarily lucky\u201d to have a T. rex, let alone one as perfectly preserved, to study and share with the world.<\/p>\n
\u201cYou\u2019ll hear geologists say the fossil record is 59 seconds of boredom and 1 second of action,\u201d Sereno said. \u201cWhat’s preserved in the fossil record is that 1 second of action, and that\u2019s what we\u2019re looking at with this T. rex.\u201d<\/p>\n
All this is possible, in no small part, to the ongoing legacy and enthusiasm of the Zerbst family. Five generations of Zerbsts have opened their hearts and homes to science, and the riches from their ranch are poised to change T. rex, Triceratops, and other dinosaurs forever.<\/p>\n
\u201cWe\u2019ve got the triumvirate of Triceratops, Edmontosaurus, and Tyrannosaurus from the Zerbst Ranch, and they’re all giving us new information about what these animals were like when they were alive,\u201d Sereno said.<\/p>\n
Andrew Rossi can be reached at arossi@cowboystatedaily.com<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"A partial but perfect Tyrannosaurus rex skeleton from eastern Wyoming is poised to upend everything the world thought…\n","protected":false},"author":2,"featured_media":854586,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[32],"tags":[79],"class_list":["post-854585","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/854585","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=854585"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/854585\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/854586"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=854585"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=854585"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=854585"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}