Enlarge / Artist's conception of the newly found species. (credit: Matheus Fernandes)

It was relatively small in comparison to the giants that would follow it later in Earth’s history. With a hip height of approximately 0.3 meters (about a foot) and a length of perhaps a meter (roughly three feet), this ancient reptile existed long before the evolution of the pterosaurs most of us recognize.

Its most striking features are its skull and hands, two body parts that rarely survive fossilization among similar animals this old. The skull consists of a raptorial-like beak without teeth, while its forelimbs end in long fingers with scimitar-like claws. These two surprising features are among many revelations in a paper published Wednesday in Nature.

Venetoraptor gassenae is the name of this new species of lagerpetid, a type of pterosaur precursor that lived about 230 million years ago in Brazil. Named for the district of Vale Vêneto in the same municipality in which the fossil was found—and for the plundering it might have done with its beak and claws ("raptor" is Latin for "plunderer")—it is also named to honor Valserina Maria Bulegon Gassen. Although not a paleontologist herself, the authors note that she is “one of the main people responsible for the CAPPA/UFSM ” (the Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria), a paleontological research support center).

Enlarge / It takes careful study and the right kind of bones to determine how something like this breathed. (credit: Tito Aureliano et. al. )

Somewhere in Earth’s past, some branches on the tree of life adopted a body plan that made breathing and cooling down considerably more efficient than how mammalian bodies like ours do it. This development might not seem like much on the surface, until you consider that it may have ultimately enabled some of the largest dinosaurs this planet has ever known. It was so successful that it was maintained by three different groups of extinct species and continues to exist today in the living descendants of dinosaurs.

Because lungs don’t usually survive fossilization, one might wonder how scientists are able to ascertain anything about the breathing capabilities of extinct species. The answer lies within their bones.

In a suite of papers published in late 2022 and early 2023 , paleontologists examined fossil microstructure within some of the earliest known dinosaurs to determine just how early parts of this system evolved.

Enlarge / The two skeletons are completely intertwined. (credit: Gang Han)

A new fossil described this week captures two intertwined animals caught in a life-or-death struggle right before both were entombed in a volcanic event. Published in Scientific Reports this Tuesday, the fossil doesn’t capture one dinosaur attacking another—rather, the predator in this case is a smaller mammal known as Repenomamus robustus, and it died with its teeth clamped upon the herbivorous Psittacosaurus lujiatunensis , a dinosaur three times its size.

Gut contents from a Repenomamus fossil described in 2005 prove this same mammalian species ate very young and considerably smaller Psittacosaurus . But the remarkable fossil revealed today is the first evidence of any Cretaceous mammal attacking a larger dinosaur. It’s an astounding snapshot of ancient behavior, challenging previous assumptions of predator/prey dynamics millions of years ago.

A final struggle

These two species in the fossil couldn’t be more different. Psittacosaurus is a type of bipedal ceratopsian dinosaur—an early relative of dinosaurs such as Triceratops—with a large beak-like snout and spiky tail bristles. This was a herd animal, and it's the most commonly found fossil in the Lujiatun Member of the Lower Cretaceous Yixian Formation of China. This particular Psittacosaurus was approximately 6.5–10 years old when it died.

Enlarge / That blue tube is actually a very close relative of vertebrates. (credit: Gerard Soury )

Beneath the waves, there are strange, almost alien creatures that raise questions about the evolution of life on Earth and our own earliest origins. The answers might be hiding in tunicates .

Tunicates are filter-feeding invertebrates that include sea squirts and salps. The more common ascidiacean species are sessile and attach to rocks or the seafloor, while the appendicularian species swim freely. Yet all of them spawn as larvae that vaguely resemble tadpoles. Motile tunicates tend to grow into something that looks like a larger version of the larva. The others eventually faceplant onto a surface and absorb their own tails while morphing into a sessile, tubelike form with two siphons.

Despite all this weirdness, there is now strong evidence that tunicates are the closest relatives to vertebrates, but a mystery still surrounds them. How did they evolve, and what did they evolve from? A 500 million-year-old fossil is now telling us more about the evolution of these peculiar life forms.

Enlarge / Artist's reconstruction of the shark as it once lived. (credit: Klug et. al. )

Sharks are largely cartilaginous, a body structure that often doesn’t survive fossilization. But in a paper published in the Swiss Journal of Paleontology, scientists describe an entirely new species of primitive shark from the Late Devonian period, a time when they were just beginning to proliferate in ancient oceans.

The team found several exceptionally well-preserved fossils that include soft tissues such as scales, musculature, digestive tract, liver, and blood vessel imprints. Also preserved: the species’ most distinct feature, widely separated nasal organs, somewhat akin to those on today’s hammerhead sharks. The find suggests that sharks’ finely tuned sense of smell, the subject of urban legends, was already being selected for just as these predators were becoming established.

A key time and a rare find

Christian Klug is the lead author and curator of the Paleontological Institute and Museum at Zurich University. He explained the significance of the Devonian period in the oceans’ history, when life was flourishing and an evolutionary arms race was in full swing. “With increasing competition among predators inhabiting the water column, the entire organism was selected for more efficiency,” he explained. “This affected swimming abilities, feeding apparatus, but also the sensory systems, which are essential to detect prey, to orient themselves in space, and to escape from even larger predators such as the huge placoderm Dunkleosteus and the equally large shark Ctenacanthus .”

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.