Smart News | December 16, 2024 8:00 a.m.

The Top Ten Dinosaur Discoveries of 2024

From the realization that paleontologists still haven’t found the biggest dinosaurs to the unearthing of a small burrowing dino, the year has been marked by awe-inspiring finds

Paleontologists made discoveries about a wide variety of dinosaurs over the past 12 months. Illustration by Emily Lankiewicz / See full caption at bottom of article

Riley Black

Science Correspondent

Another year is coming to a close, and, just like last year, scientists have made an amazing number of dinosaur discoveries. Experts have continued to name new species and reveal previously unknown details of dinosaur lives at a rapid pace, allowing us to envision the Mesozoic world in ever more detail.

Paleontologists have published dozens of new dinosaur papers this year, each adding to what we know about the terrible lizards. Researchers have found tiny long-necks, trackways made by flapping raptors and more. What follows is just a small sampling of this year’s most surprising and informative finds, touching everything from dinosaur social lives to as-yet-undiscovered giants.

The biggest dinosaurs will take millennia to find

Giant T Rex — Even familiar dinosaurs like *Tyrannosaurus rex* may have had giant-sized individuals whose fossils await future discovery. Mark Witton

How big a dinosaur was is always a hot topic in paleontology, whether it’s the biggest species or the largest member of a particular species. Given the incomplete nature of the fossil record and the way dinosaurs lived, however, it’s unlikely that paleontologists have found the largest individuals of any given species. Using Tyrannosaurus rex as a model, paleontologists have estimated that much more massive dinosaurs are still awaiting discovery.

Paleontologists have certainly found some big T. rex, about 40 feet long and estimated to be about nine tons. But by modeling a virtual T. rex population, using information from modern alligators to outline variation between individuals and growth, a new Ecology and Evolution study anticipates that some T. rex were likely up to 70 percent more massive than any found so far. These giants were very rare, in the 99.99th percentile of body size for the species, and may take hundreds if not thousands of years to uncover based on the current rate of fossil searches.

While the study focused primarily on T. rex, the same principles hold for dinosaurs in general. Experts have certainly found some big dinosaurs, but the most exceptional giants have not yet been found.

Flapping tracks

Small Flapping Dinosaur — Fossil tracks found in South Korea were likely made by a small, flapping dinosaur. Julius Csotonyi

Dinosaur tracks are fossilized behavior. Each footstep represents an actual moment in the dinosaur’s life, affected by how it was moving. And while paleontologists have found trackways made by running dinosaurs before, this year paleontologists described a trackway made by a dinosaur that was flapping as it ran.

Detailed in the Proceedings of the National Academy of Sciences, the Cretaceous trackway was made by a two-toed dinosaur like Microraptor. The spacing between the tracks indicates the dinosaur was moving at high speed, but it seemed to be moving even faster than expected if the dinosaur was just propelling itself with its legs alone. The little raptor was likely flapping as it kicked with its feet, even though experts aren’t sure if the dinosaur was trying to take off, land, run up an incline or something else. Nevertheless, the tracks indicate that flapping wings could be as important to running as long, strong legs.

Stegosaurs used their spikes to intimidate

*Miragaia* had a very spiky tail but swung it to intimidate rather than pierce muscle and bone. Connor Ashbridge CC BY-SA 4.0

The spiky tails of stegosaurs are some of the best-known dinosaur weapons. Previous research on species like the spiky Kentrosaurus has indicated that some of these dinosaurs were capable of piercing bone with their tail swings. But not all stegosaurs used their tails the same way. A study of the long-necked stegosaur Miragaia indicates some may have relied more on intimidation than direct strikes.

In a study of Miragaia published in the Italian Journal of Paleontology and Stratigraphy, researchers virtually modeled the tail of the stegosaur and its range of motion. The dinosaur definitely had a fast and potentially dangerous swing, but its tail vertebrae were not well-suited to the stresses of potential impacts. Miragaia likely swung its tail to drive off predators, and perhaps cause rivals to back down, rather than trying to strike potential threats.

A new burrowing dinosaur

The small dinosaur *Fona* likely made burrows. Jorge Gonzalez

Dinosaurs didn’t just walk the Earth during the Mesozoic. They also burrowed into it. Since 2007, paleontologists have known that some small, beaked, herbivorous dinosaurs created underground dens. A new dinosaur found in eastern Utah now pushes back the age of the earliest burrowing dinosaurs and hints that some of its relatives dug into the ground, too.

Revealed earlier this year in the Anatomical Record, the small dinosaur is named Fona. The dinosaur is known from several skeletons that are remarkably complete compared with other dinosaurs known from the same Early Cretaceous rocks. Bolstered by skeletal clues related to digging, paleontologists think that Fona could burrow into the ground and was sometimes preserved in its dens. The relationship of the dinosaur to later species that seem to show burrowing adaptations, such as Thescelosaurus from the same habitat as Triceratops, suggests that these small dinosaurs evolved to be burrowers through the Cretaceous.

Ants farmed fungus after dino demise

Adding a discovery to this list that doesn’t directly involve dinosaurs might seem strange, but new findings about when ants began to farm fungus have added significant detail to the mass extinction that wiped out all the non-avian dinosaurs. Reported in Science earlier this year, entomologists discovered that fungus-farming ants began their close relationship with their food in the immediate aftermath of the asteroid-triggered mass extinction that ended the Cretaceous 66 million years ago.

In a devastated world rife with decomposing organic material, fungus spread during the “impact winter” following the asteroid strike. Ants that survived the initial heat pulse began feeding on the fungus, but also defending it from other creatures. So began a partnership in which ants would evolve their own form of agriculture seen in species like leafcutter ants today, which intentionally cultivate fungus to feed themselves.

Dinosaurs hung out in age-segregated groups

A skull of *Hypacrosaurus stebingeri*, collected in Glacier County, Montana Tim Evanson / FunkMonk via Wikipedia under CC By-SA 2.0

Paleontologists have been fascinated by dinosaur social lives for decades. Despite the interest, however, direct evidence on whether dinosaurs lived by themselves or in social groups has been difficult to obtain. A growing body of evidence hints that dinosaurs were not wholly solitary or gregarious over the course of their lives, but rather behaved differently at different ages. A new study of the hadrosaur Hypacrosaurus underscores the shift in our understanding.

Published in Palaeogeography, Palaeoclimatology, Palaeoecology, the study focused on Hypacrosaurus bonebeds in Montana and Alberta for insight into the social lives of the dinosaurs. The age and the distribution of the bones indicates that Hypacrosaurus stayed in juvenile herds until they were about 4 years old, at which time they joined multigenerational herds. Paleontologists know that dinosaurs reached sexual maturity and began reproducing before they reached their full adult size, and so, the researchers propose, the 4-year-old Hypacrosaurus might have been joining the multigenerational herds as they began breeding.

Small dinosaurs still await discovery

Paleontologists have been exploring the Hell Creek Formation of western North America for over a century, turning up fossil after fossil of T. rex, Triceratops, Edmontosaurus and other big dinosaurs. Smaller dinosaurs that lived in the same habitat are more elusive, however, and are still being found. Early this year, paleontologists named one such turkey-sized dinosaur related to a larger species known as the “chicken from hell.”

Named Eoneophron infernalis, the little dinosaur is principally known from a partial right leg. The anatomy of the bones, as well as the dinosaur’s age at death, helped distinguish it as a new species rather than a juvenile of a bigger one. The critter was one of three parrot-like dinosaurs that lived in the same environments about 67 million years ago, indicating that these dinosaurs survived alongside each other by evolving different sizes and, likely, diets. The find also indicates that there are still small dinosaur discoveries to be made in even the best-known of fossil hunting grounds.

Dinosaurs ate their way to success

Dinosaurs Eating Plants — Dinosaurs didn’t start to get big until climate shifts allowed plants the animals craved to spread. Marcin Ambrozik

What allowed dinosaurs to become so successful in the Jurassic? The answer, paleontologists have proposed, has to do with what they ate.

Fossils of dinosaur feces, gut contents and regurgitated material document what dinosaurs were actually eating in the distant past. Hundreds of such fossils found between the Late Triassic and Early Jurassic rocks of Poland, prior to and just after 200 million years ago, record what dinosaurs were eating during the early chapters of their evolution. The emerging picture, paleontologists reported in Nature, is that dinosaur ancestors were omnivorous animals that ate beetles, leaves and a little bit of everything. As the first true dinosaurs emerged, some remained omnivorous, while early predecessors of the Allosaurus and T. rex lineage began to hunt insects and fish. Climate change toward the end of the Triassic provided a new glut of food that herbivorous dinosaurs, such as the ancestors of Apatosaurus, began to dine on. As the plant-eaters became larger, so did the carnivores, and a broad array of impressive reptiles emerged that thrived through the Jurassic and Cretaceous.

A new tyrannosaur family emerges

Paleontologists have discovered a glut of new tyrannosaur species during the last 20 years. New species have turned up from Alaska to Mexico, an entire menagerie of tyrant carnivores that lived between 66 million and 80 million years ago. A new species from Mexico, in particular, is revealing a novel subgroup of lanky, leggy tyrants from the southern parts of North America.

Named Labocania aguillonae in Fossil Studies, the tyrannosaur prowled what’s now Mexico about 73 million years ago. It more closely resembles other tyrannosaur species found in New Mexico and Utah, representing a group of tyrant dinosaurs that diversified in southern North America while two different subgroups, represented by Daspletosaurus and Albertosaurus, lived side by side in the northern part of the continent. Rather than being just one main lineage of tyrannosaurs before T. rex, at least three roamed the Earth.

A tiny titanosaur

The long-necked *Titanomachya* was about ten times smaller than its giant relatives. Gabriel Díaz Yantén

If titanosaurs are known for anything, it’s being gigantic. The group of long-necked dinosaurs included the biggest land-dwelling animals of all time, exceeding 100 feet in length and weighing more than 70 tons. But not all titanosaurs were titanic. Named this year, Titanomachya was about the size of a cow.

Described earlier this year in Historical Biology, the new dinosaur was found in the 70-million-year-old rocks of Patagonia. It was uncovered as experts have tried to better understand the Late Cretaceous in South America, and researchers found it within the same geologic formation where the famous horned carnivore Carnotaurus was discovered. Perhaps the carnivore would have given Titanomachya reason to fear, as the herbivore was ten times smaller than its giant relatives like Patagotitan.

Main Image Caption: Illustration by Emily Lankiewicz / Julius Csotonyi / Jorge Gonzalez / Mark Witton / Marcin Ambrozik / Zubin Erik Dutta / Atkins-Weltman et al., 2024, PLOS One, CC-BY 4.0 / Gabriel Díaz Yantén

Riley Black | | READ MORE

Riley Black is the author of The Last Days of the Dinosaurs and many other books. She is a science correspondent for Smithsonian magazine covering fossils and natural history, and she writes about the prehistoric past for a variety of publications.