Enlarge / Mammoth tusks collected at Wrangel Island, where some of the samples tested for hormones originated. (credit: Alexei Tikhonov)

Musth, a time of heightened testosterone levels and aggression in male elephants related to reproduction, has now been identified in woolly mammoth tusks. Remarkably, this is the first time hormones have been seen in the extant or the extinct. And it opens up an exciting new field of paleontology that the team behind the discovery calls ‘palaeoendocrinology’—the study of hormones in ancient species.

A paper published on Wednesday in Nature describes that work, in which an international team of scientists studied African elephant and woolly mammoth tusks. Elephants and woolly mammoths are distantly related, and both belong to a group of animals known as proboscideans.

Testing tusks

Michael Cherney is the lead author and research affiliate at the University of Michigan Museum of Paleontology. He said his team started by testing elephant tusks. “We wanted to start with something that provided the best chance of recovering data, because we didn’t know that we’d see any,” Cherney told Ars in a video interview. Nobody knew for sure whether hormonal signatures existed in modern elephant tusks prior to this study, but the team was able to identify testosterone in the tusks.

Enlarge / Fossil of Tullimonstrum gregarium ("Tully's common monster"). Its discovery in the 1950s sparked a long-running scientific debate as to whether the creature should be classed as a vertebrate or invertebrate. (credit: Ghedoghedo/CC BY-SA 3.0 )

The state fossil of Illinois is a strange creature with stalked eyes and a long nose-like appendage with teeth, dubbed the " Tully monster ." Specimens typically measure just 15 centimeters (about 6 inches), but the tiny creatures sparked a major decadeslong scientific debate over whether they should be classed as vertebrates or invertebrates. That mystery may now have been solved, according to a team of Japanese scientists who claim their 3D scans of a generous sampling of fossils rule out the vertebrate hypothesis. They described their findings in a recent paper published in the journal Nature.

The fossil gets its name ( Tullimonstrum gregarium , or "Tully's common monster") from Francis Tully, an amateur fossil collector who discovered the specimen in 1955 while scouring the Mazon Creek fossil beds in Illinois—the only site where Tully monster fossils have been found. He had never seen anything like this "torpedo"-shaped fossil and brought it to paleontologists at the Field Museum of Natural History in Chicago for identification. But the paleontologists there couldn't figure out how to classify it.

While it might resemble a slug at first glance, Tully monster fossils have several unique features, most notably an elongated, flexible proboscis (long nose with teeth) and outward-protruding eyes on stalks, similar to those of a hammerhead shark. Tully has been compared to gastropods (slugs and snails), conodonts (an extinct group of jawless vertebrates), polychaetes (segmented marine worms), nemerteans (ribbon worms), and nectocarids (a squid-like Cambrian organism) in the ensuing decades. If it was a vertebrate, then the Tully monster would fill a critical gap in evolutionary history, connecting jawless fish (such as lampreys and hagfish) to jawed fish.

Enlarge / A sea turtle of the sort found in the Paja Formation. (credit: Wikimedia Commons )

Roughly 130 million years ago, in an area within what is now central Colombia, the ocean was filled with a diversity of species unseen today. Within that water swam several massive apex predators that are the stuff of nightmares. These marine reptiles could reach lengths of 2 to 10 meters (about 6 to 32 feet), some with enormous mouths filled with teeth, others with relatively small heads (also filled with teeth) attached to long, snake-like necks.

These giants shared the ocean with countless smaller species, many of them predators themselves. These included ichthyosaurs—dolphin-like reptiles—as well as turtles, fish, ammonites, crabs, mollusks, sharks, and at least one species of crocodyliform .

Allowing all these creatures to thrive must have required a flourishing ecosystem at all levels. Thanks to discoveries in what’s called the Paja Formation, a treasure trove where fossils are abundantly and exquisitely preserved, researchers are now beginning to figure out how the ecosystem supported so many apex predators. And they may find hints of how it flourished so soon after a mass extinction brought the Jurassic to a close.

Enlarge / The Oregon pterosaur Bennettazhia oregonensis , with 4 meter wingspan, reconstructed independently in seagull colors by Midiaou Diallo and reproduced with permission. (credit: Midiaou Diallo)

A single fossil toe is all we have of the ‘ Mitchell ornithopod ,’ the nickname of the first early Cretaceous dinosaur fossil found in Oregon in 2018. Ornithopods were enormous herbivores such as duck-billed dinosaurs and iguanodons, and Gregory J. Retallack, lead author of that discovery, wanted to find more of its skeleton. Three years later, he returned to the site, aided by over 80 volunteers who helped excavate in more detail.

No further ornithopod bones—indeed, no substantial dinosaur bones of any kind—were retrieved after two weeks of digging. It was, he said, “a failure” in that regard. What they found instead was a complete mess, a jumble of the remains of land-based and aquatic animals. And lots and lots of guano.

That came from extinct flying reptiles, known collectively as pterosaurs, and suggests these animals may have flocked together on the cliffs above the coast of Oregon.

Enlarge (credit: Royal Tyrrell Museum of Palaeontology)

Borealopelta mitchelli found its way back into the sunlight in 2017, millions of years after it had died. This armored dinosaur is so magnificently preserved that we can see what it looked like in life. Almost the entire animal—the skin, the armor that coats its skin, the spikes along its side, most of its body and feet, even its face—survived fossilization. It is, according to Dr. Donald Henderson, curator of dinosaurs at the Royal Tyrrell Museum, a one-in-a-billion find.

Beyond its remarkable preservation, this dinosaur is an important key to understanding aspects of Early Cretaceous ecology, and it shows how this species may have lived within its environment. Since its remains were discovered, scientists have studied its anatomy, its armor, and even what it ate in its last days, uncovering new and unexpected insight into an animal that went extinct approximately 100 million years ago.

Down by the sea

Borealopelta is a nodosaur, a type of four-legged ankylosaur with a straight tail rather than a tail club. Its finding in 2011 in an ancient marine environment was a surprise, as the animal was terrestrial.

Enlarge / Full-color life reconstruction of Edmontosaurus . (credit: Natee Puttapipat/CC-BY 4.0 )

There's rarely time to write about every cool science-y story that comes our way. So this year, we're once again running a special Twelve Days of Christmas series of posts, highlighting one science story that fell through the cracks in 2022, each day from December 25 through January 5. Today: Why dinosaur "mummies" might not be as rare as scientists believed.

Under specific conditions, dinosaur fossils can include exceptionally well-preserved skin—an occurrence long thought to be rare. But the authors of an October paper published in the journal PLoS ONE suggested that these dinosaur "mummies" might be more common than previously believed, based on their analysis of a mummified duck-billed hadrosaur with well-preserved skin that showed unusual telltale signs of scavenging in the form of bite marks.

In this case, the term "mummy" refers to fossils that with well-preserved skin and sometimes other soft tissue. As we've reported previously , most fossils are bone, shells, teeth, and other forms of "hard" tissue, but occasionally rare fossils are discovered that preserve soft tissues like skin, muscles, organs, or even the occasional eyeball. This can tell scientists much about aspects of the biology, ecology, and evolution of such ancient organisms that skeletons alone can't convey.

Enlarge / Diplodocus dinosaur scene from the Jurassic era 3D illustration (credit: Warpaintcobra )

Finding any fossil skin is extraordinary; finding dinosaur skin is that much more rare. So when Tess Gallagher and her mom excavated patches of skin from one of the largest dinosaurs to exist, there was reason for jubilation.

More than a year later, that glee disintegrated—right along with the skin they excavated. But what could have been the end of a sad story was merely the beginning of another exciting chapter, one that could potentially broaden our understanding of how these enormous creatures cooled themselves.

Found and lost

Gallagher, now a paleontologist and paleobiology graduate student at the University of Bristol, and her mother, Lisa Marshall, were part of a team excavating a site called the Mother’s Day Quarry in Montana. The site has produced, among other things, 15 individual Diplodocus juveniles from about 145 million years ago.

Back in 1997, Microsoft's then-CTO, Nathan P. Myhrvold , made headlines when his computer simulations suggested that the enormous tails of sauropods—specifically Apatosaurus —could crack like a bullwhip and break the sound barrier, producing a sonic boom. Paleontologists deemed it an intriguing possibility, although several were skeptical. Now a fresh team of scientists has tackled the issue and built its own simulated model of an Apatosaurus tail. They found no evidence of a sonic boom, according to a new paper published in the journal Scientific Reports. In fact, the maximum speed possible in the new simulations was 10 times slower than the speed of sound in standard air.

While still at Microsoft in the 1990s, Myhrvold—a longtime dinosaur enthusiast—stumbled upon a book by zoologist Robert McNeill Alexander speculating about whether the tails of certain sauropods may have been used like a bullwhip to produce a loud noise as a defensive strategy, a mating call, or other purpose. The structure somewhat resembles a bullwhip, in that each successive vertebra in the tail is roughly 6 percent smaller than its predecessor. It was already well-known in physics circles that the crack of a whip is due to a shock wave, or sonic boom, arising from the speed of the thin tip breaking through the sound barrier.

Myhrvold wanted to put that speculative suggestion to the test, and struck up an email correspondence with paleontologist Philip J. Currie , now at the University of Alberta in Edmonton, Canada. (Fun fact: Currie was one of the inspirations for the Alan Grant character in Jurassic Park .) The two men analyzed fossils, developed computer models, and conducted several computer simulations to test the biomechanics of the sauropod's tail. They also compared those simulations to the mechanics of whips.

Enlarge / The tail clubs of ankylosaur species seem to have been used to bash each other rather than predators. (credit: Henry Sharpe)

New research indicates that the tail clubs on huge armored dinosaurs known as ankylosaurs may have evolved to whack each other rather than deter hungry predators. This is a complete shift from what was previously believed.

Prior to the paper published today in Biology Letters, most scientists looked upon the dinosaur’s tail club, a substantial bony protrusion comprised of two oval-shaped knobs, primarily as a defense against predation. The team behind the new paper argues that this is not necessarily the case. To make their case, they focus on years of ankylosaur research, analysis of the fossil record, and data from an exceptionally well-preserved specimen named Zuul crurivastator .

Zuul’s name, in fact, embraces that previous idea. While "Zuul" references the creature in the original Ghostbusters , the two Latin words that make up its species name are crus (shin or shank) and vastator (destroyer). Hence, the destroyer of shins: a direct reference to where the dinosaur’s club may have struck injured approaching tyrannosaurs or other theropods.