Not Just Archaic Remnants: How Southern Ceratosaurs Matched the Tyrannosaur Bite

Abstract

The evolutionary history of theropod dinosaurs has long been framed through the lens of the Northern Hemisphere’s tyrannosaurids, whose massive, bone-crushing skulls represent a pinnacle of predatory adaptation. In contrast, the ceratosaurs of the Southern Hemisphere—specifically the Abelisauridae and Noasauridae—were historically characterized as "archaic" or functionally inferior remnants. However, the 2026 study Southern hemisphere ceratosaurs evolved feeding mechanics paralleling those of Northern hemisphere tyrannosaurids, published in Scientific Reports by Rowe, Cerroni, and Rayfield, fundamentally dismantles this Eurocentric and Laurasian-biased perspective. By employing high-fidelity Finite Element Analysis (FEA) on four key taxa—Ceratosaurus, Carnotaurus, Majungasaurus, and Masiakasaurus—the researchers demonstrated that these southern predators evolved feeding mechanics that rivaled the performance of tyrannosaurids, despite utilizing radically different anatomical strategies. This report provides an exhaustive analysis of these findings, exploring the biomechanical paradoxes of the abelisaurid skull, the specialized precision of noasaurids, and the convergent evolutionary pressures that shape apex predators across separated continents.

1. Introduction: The Bifurcation of the Mesozoic World

To understand the significance of the findings presented by Rowe, Cerroni, and Rayfield ¹, one must first contextualize the biogeographical stage of the Late Cretaceous. Following the fragmentation of the supercontinent Pangea, the dinosaurian world was cleaved into two distinct biological realms. In the north, Laurasia (comprising modern North America, Europe, and Asia) became the domain of the Coelurosauria, a clade that would produce the tyrannosaurids and eventually birds. In the south, Gondwana (South America, Africa, Antarctica, India, and Madagascar) became an isolated evolutionary laboratory dominated by the Ceratosauria.

For decades, the scientific narrative favored the north. Tyrannosaurus rex, with its robust, banana-shaped teeth and fused nasal bones, was championed as the ultimate terrestrial predator, capable of "puncture-pull" feeding strategies that pulverized bone.¹ In comparison, the abelisaurids of the south—with their pug-nosed faces, vestigial arms, and prominent horns—were often viewed as oddities. Their skulls were short and tall, leading to hypotheses that they possessed weak bites suited only for soft prey, or that they relied on neck-driven "hatchet" strikes to compensate for weak jaws.²

The research by Rowe et al. (2026) challenges this "inferiority" paradigm using quantitative physics. By subjecting the skulls of southern ceratosaurs to the same digital crash-tests used on tyrannosaurs, they revealed a stunning case of convergent evolution. The study posits that the "structural constraints" of being a giant predator forced both lineages—tyrannosaurs and abelisaurids—along similar mechanical paths, even if their starting anatomies were vastly different.¹

1.1 The Ceratosaurian Lineage

The study focused on four genera that encapsulate the evolutionary breadth of the Ceratosauria:

• Ceratosaurus (Late Jurassic): The ancestral baseline.

• Carnotaurus (Late Cretaceous, Argentina): The cursorial giant with cranial horns.

• Majungasaurus (Late Cretaceous, Madagascar): The robust, cannibalistic apex predator.

• Masiakasaurus (Late Cretaceous, Madagascar): The small-bodied, buck-toothed specialist.

By analyzing this phylogenetic spread, the authors were able to trace the biomechanical evolution of the clade from its generalized Jurassic origins to its highly specialized Cretaceous terminuses.¹

2. Methodology: The Digital Resurrection of Forces

The conclusions drawn by Rowe et al. are grounded in Finite Element Analysis (FEA), a method borrowed from civil and aerospace engineering. In traditional paleontology, functional morphology was qualitative; a scientist might look at a thick bone and describe it as "strong." FEA makes this quantitative, calculating exactly how strong a structure is in Newtons and Pascals.

2.1 From Fossil to Mesh

The process begins with the digitization of fossil material. The skulls of Ceratosaurus, Carnotaurus, Majungasaurus, and Masiakasaurus were subjected to Computed Tomography (CT) scanning and surface scanning.¹

• CT Scanning: This is critical for abelisaurids like Majungasaurus because their skulls are not solid bone. They are permeated by complex systems of air-filled sinuses (pneumaticity). A surface scan would treat the skull as a solid block, vastly overestimating its strength. CT scans reveal the internal struts and hollows, allowing for a biologically accurate model.³

• Reconstruction: Fossil skulls are rarely perfect. They are often crushed or distorted by millions of years of geological pressure. The researchers digitally "retro-deformed" these models, correcting for taphonomic distortion to restore the skull's original life-shape.

2.2 The Physics of the Bite

Once the geometry was established, the researchers created a "mesh"—a 3D grid composed of millions of tiny tetrahedrons. Each tetrahedron was assigned the material properties of bone (elasticity, density).

• Muscle Mapping: The team reconstructed the jaw adductor muscles (the muscles that close the mouth) based on osteological correlates—rough patches on the fossil bone where muscle tendons would have attached in life.

• Biting Scenarios: The models were then subjected to virtual bite forces. The study simulated bites at different points along the tooth row (anterior, middle, posterior) to understand how the skull behaved during different phases of feeding.¹

The output of these simulations is a map of Von Mises stress. This metric combines the complex forces of tension, compression, and shear into a single scalar value that predicts the likelihood of material failure. High stress (represented by "hot" colors like red and white) indicates areas where the bone is under maximum load; low stress (blue) indicates areas of relative safety or over-engineering.

3. The Biomechanics of the Abelisaurid Giants

The central finding of the study concerns the large-bodied abelisaurids, Carnotaurus and Majungasaurus. Previous hypotheses suggested that the extremely short, deep skulls of these animals were adaptations to reduce stress, effectively making the skull a rigid block. The FEA results, however, paint a more complex and violent picture.

3.1 High Stress and Structural Constraints

Contrary to the "stress-minimization" hypothesis, the FEA models revealed that the skulls of large abelisaurids experienced high magnitudes of stress during biting.¹ When scaled to the same size, the abelisaurid skulls showed stress patterns comparable to, or even exceeding, those of generalized tetanurans.

This seemingly counter-intuitive result—that a "reinforced" skull is highly stressed—actually parallels findings in Tyrannosaurus rex. As theropods evolved into multi-ton giants, the force generated by their jaw muscles increased cubically (muscle mass is a volume), while the strength of their skull bones increased only squarely (bone strength is related to cross-sectional area). This is the Square-Cube Law in action.

• The Implication: Carnotaurus and Majungasaurus did not evolve short skulls to make biting "easy" or low-stress. They evolved short skulls to survive the immense forces their own muscles generated. The shortening of the rostrum reduced the lever arm of the bite, increasing mechanical advantage, but the bone itself was still pushed to its structural limits.¹

3.2 Majungasaurus: The Mechanics of the Clamp

Majungasaurus crenatissimus is the quintessential abelisaurid "bruiser." The FEA results for this taxon provide strong support for the "bite-and-hold" feeding hypothesis.¹

• Fused Nasals: Unlike most theropods, the nasal bones of Majungasaurus are fused together and thickened. The FEA showed that stress accumulated heavily in the dorsal part of the snout during biting. The fusion of the nasals prevented the bones from shearing apart under these loads, effectively turning the snout into a single, rigid unit.³

• Pneumatic Struts: The CT scans revealed that the thickened nasals were not solid but filled with air sinuses supported by bony struts, similar to the ossicones of giraffes. The biomechanical analysis suggests this structure maximized strength-to-weight ratio, allowing the head to remain maneuverable despite its rigidity.³

The high stress observed in the Majungasaurus skull is consistent with a predator that latches onto large, struggling prey (such as the sauropod Rapetosaurus) and maintains its grip despite the prey's attempts to shake it off. The skull was designed not to be impervious to stress, but to manage it just well enough to secure a kill.

3.3 Carnotaurus: Speed and Shock Absorption

Carnotaurus sastrei presents a different biomechanical profile. While its cranium was robust, the study highlighted the mandible (lower jaw) as a key differentiator.

• Mandibular Flexibility: The FEA indicated that the Carnotaurus mandible experienced distinct stress distribution patterns that hint at a degree of flexibility or kineticism.¹

• The "Hatchet" Validity: The combination of a highly rigid upper skull and a potentially shock-absorbing lower jaw supports the "hatchet bite" or "slash-and-bite" theory. In this model, Carnotaurus would use its neck to drive the teeth of the upper jaw into prey like a pickaxe. The lower jaw would then close rapidly to secure the flesh. The flexibility of the mandible would prevent it from snapping if the prey moved violently during the initial strike.²

3.4 The Myth of Functional Ornamentation

One of the most visually striking features of ceratosaurs is their cranial ornamentation: the nasal horn of Ceratosaurus, the bull-like brow horns of Carnotaurus, and the frontal boss of Majungasaurus. For years, paleontologists speculated that these structures served a mechanical function, perhaps buttressing the skull against the shock of impact or distributing bite forces.

The Rowe et al. (2026) study definitively refutes this hypothesis.¹

• Stress Trajectories: The FEA simulations showed that stress did not flow through the horns or bosses in a way that relieved load from the rest of the skull. In fact, the horns often remained relatively stress-free or accumulated stress in ways unrelated to feeding stability.

• Display Structures: The lack of mechanical utility confirms that these features were almost certainly the products of sexual selection. They were visual signals for species recognition, mating displays, or intraspecific combat (head-shoving), rather than tools for predation. The "rugged" look of the abelisaurid face was a billboard, not a helmet.

4. The Precision of Masiakasaurus: A Noasaurid Case Study

While the giants tell a story of raw power, the inclusion of the small-bodied noasaurid Masiakasaurus knopfleri reveals the incredible versatility of the ceratosaurian design. Living alongside Majungasaurus in the Maevarano Formation, Masiakasaurus was a wolf-sized predator with a bizarre dental arrangement: its anterior teeth projected forward (procumbent), resembling the teeth of a shrew or lemur.¹

4.1 Stress Isolation and Mechanics

The FEA results for Masiakasaurus were markedly different from the abelisaurids.

• Lowest Overall Stress: The skull of Masiakasaurus experienced the lowest peak stresses of all the taxa modeled.¹

• The Function of Procumbency: The simulation revealed the genius of the procumbent teeth. When force was applied to the tips of these forward-facing teeth (simulating the grasping of a small object), the stress was directed axially along the length of the tooth and into the strong symphysis of the jaw. This orientation isolated the rest of the mandible from bending forces.

• Bending Moments: If Masiakasaurus had vertical teeth at the front of its jaw, grasping a struggling prey item would create a large "bending moment" (torque) that could snap the delicate jaw. By angling the teeth forward, the animal converted that dangerous torque into safer compressive force.¹

4.2 Ecological Niche Partitioning

These biomechanical findings provide a physical basis for understanding the ecology of Late Cretaceous Madagascar. The ecosystem was prone to severe, catastrophic droughts, forcing predators to compete for dwindling resources.

• The Generalist vs. The Specialist: Majungasaurus was the heavy-duty generalist, capable of processing carcasses and hunting large dinosaurs. Masiakasaurus, with its precision-grip bite, was a specialist.

• Dietary Inference: The low-stress, high-precision mechanics suggest Masiakasaurus fed on small, agile prey that required catching rather than crushing—fish, invertebrates, lizards, and mammals.¹ This confirms that the two theropods engaged in strict niche partitioning, allowing them to coexist by exploiting completely different segments of the food web.

5. Comparative Evolution: Gondwana vs. Laurasia

The overarching theme of the Rowe et al. paper is the concept of parallel evolution. The study demonstrates that the evolution of "apex predator" mechanics is not random but governed by universal physical laws.

5.1 The Tyrannosaurid Comparison

In the Northern Hemisphere, tyrannosaurids achieved apex status through:

• Massive Size: Increasing body mass to dominate other predators.

• Cranial Reinforcement: Deepening the snout and fusing the nasals to resist bite forces.

• Puncture-Pull: Evolving thick teeth to crush bone.

5.2 The Abelisaurid Response

In the Southern Hemisphere, abelisaurids faced similar pressures (large titanosaur prey, competition) and achieved a similar status through:

• Massive Size: Though generally smaller than T. rex, forms like Carnotaurus reached 1.5 - 2 tons.

• Cranial Restructuring: Drastic shortening of the skull to increase mechanical advantage.

• Bite-and-Hold: Evolving locking jaws and powerful necks to subdue prey.

The study concludes that these are two solutions to the same equation. The "structural constraints" of biology limit the number of ways a bipedal reptile can become a giant hyper-carnivore. Both lineages converged on high-stress, reinforced skulls because that is the only way to break the bones of a multi-ton herbivore.¹

5.3 Divergence in the Details

However, the parallel is not perfect. The study highlights that while the goals were the same, the tools differed.

• Forelimbs: Tyrannosaurs retained small but functional arms. Abelisaurids abandoned them entirely, reducing them to vestigial nubs. This placed even more evolutionary pressure on the abelisaurid skull, as it became the sole organ of manipulation and predation.

• Neck Mechanics: The biomechanics of the abelisaurid neck (rigid, robust) versus the tyrannosaur neck (S-shaped, striking) suggests that while both were apex predators, their hunting styles—the "how"—remained distinct. Tyrannosaurs were likely "head-hunters" who struck and pulled; abelisaurids were "grapplers" who bit and shoved.

6. Table of Comparative Biomechanics

The following table summarizes the key biomechanical data points derived from the Rowe et al. (2026) study, contrasting the four ceratosaurian subjects.

Feature	Masiakasaurus	Ceratosaurus	Carnotaurus	Majungasaurus
Family	Noasauridae	Ceratosauridae	Abelisauridae	Abelisauridae
Skull Morphology	Long, low, heterodont	Moderate length, blade-like	Short, deep, horned	Short, broad, fused nasals
Primary Stress Profile	Low Stress (Optimized)	Intermediate	High Stress (Flexible)	High Stress (Rigid)
Anterior Dentition	Procumbent (Forward)	Vertical, Blade-like	Vertical, Slender	Vertical, Conical/Robust
Key Biomechanical Adaptation	Stress Isolation: Procumbent teeth direct force axially, protecting the weak mandible.	Baseline: Standard theropod mechanics; no extreme specialization.	Speed/Shock: Mandible allows for rapid closure; potential shock absorption.	Clamp/Rigidity: Fused nasals resist high loads during prolonged holding.
Ecological Niche	Small-prey specialist (Fish/Inverts)	Generalist Hunter	Cursorial Pursuit Predator	Ambush/Bite-and-Hold Apex
Ornament Function	None prominent	Display (Nasal Horn)	Display (Brow Horns)	Display (Frontal Boss)

7. Implications for Future Research

The publication of this study in Scientific Reports marks a significant step forward in the field of virtual paleontology. It validates the use of FEA as a primary tool for testing evolutionary hypotheses, moving the field beyond "just-so stories" about dinosaur behavior.

7.1 The Validity of "B-Team" Predators

The primary implication is the rehabilitation of the abelisaurid image. They were not "failed" tyrannosaurs; they were a highly successful, biomechanically sophisticated radiation that solved the problems of predation in their own way. The high stresses observed in their skulls are not signs of weakness, but badges of high-performance engineering—evidence that they were pushing their biological materials to the absolute limit in the arms race against the titanosaurs.

7.2 The Mystery of Ceratosaurus

The intermediate position of Ceratosaurus in the study results highlights an interesting evolutionary narrative. As the "jack-of-all-trades," it was successful in the Jurassic. However, as the Cretaceous dawned and prey became more specialized (armored titanosaurs vs. swift ornithopods), the generalist model gave way to the divergent specialists: the heavy-duty abelisaurids and the precision noasaurids.

7.3 Directions for the Future

The authors suggest that future work should integrate these cranial models with post-cranial biomechanics. Understanding how the massive neck muscles of Majungasaurus or the sprinting legs of Carnotaurus integrated with their feeding mechanics will provide a holistic view of these animals as living, moving organisms. Furthermore, applying these methods to juvenile specimens could reveal how feeding niches shifted as these dinosaurs grew from hatchlings to multi-ton adults.⁷

8. Conclusion

The 2026 study by Rowe, Cerroni, and Rayfield is a landmark in the functional analysis of extinct archosaurs. By stripping away the flesh and exposing the physics of the bone, they have revealed that the southern continents were ruled by predators every bit as formidable as the tyrants of the north. From the precision forceps of Masiakasaurus to the crushing clamp of Majungasaurus, the ceratosaurs demonstrate the incredible plasticity of the dinosaurian skull and the relentless drive of evolution to fill every available niche, no matter the structural cost.

Key Takeaways

1. High Stress is High Performance: Large abelisaurids like Majungasaurus operated with high cranial stresses, similar to T. rex, debunking the idea that their skulls were weak.

2. Masiakasaurus was a Surgeon: The bizarre teeth of Masiakasaurus were a sophisticated adaptation for isolating stress, allowing it to act as a precision hunter of small prey.

3. Horns are for Show: Biomechanical analysis confirms that cranial horns and bosses provided no structural benefit during feeding, serving instead as display structures.

4. Convergence is King: The distinct lineages of Laurasia and Gondwana converged on similar "high-input, high-output" feeding strategies to deal with the physics of killing large prey.

Works cited

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