DinosaurTheory Introduction and Evidence Summary

Millions of years ago, dinosaurs grew to be over three times larger than the terrestrial animals of today. Nearly all young children are fascinated by the enormous size of dinosaurs, and yet when they go to school, they are informed that - according to experts - there is nothing odd about dinosaurs being so large. According to paleontologists, dinosaurs had numerous adaptations that made them much lighter and stronger, and this is what allowed them to grow so large. The paleontologists’ claims are in science textbooks, repeated by science teachers, echoed in the media, and even provided by artificial intelligence if students ask. What children - and everyone else - are not being told is how Galileo’s Square-Cube Law - the simple physics concept that explains how size matters - clarifies what is wrong with the paleontologists’ dismissal of the paradox of how dinosaurs grew so large.

From the moment scientists first recognized that dinosaurs previously roamed the Earth, paleontologists have struggled to explain how dinosaurs grew so incredibly large. That has not changed. What has changed is the degree to which paleontologists shape the narratives presented through media and institutions, leading to their explanations dominating public discussion.

Despite Galileo’s Square-Cube Law being one of the most fundamental concepts in science, the vast majority of people - including teachers, scientists, and engineers - have never even heard of it. At most, students may vaguely recall being told that size matters, but that statement has little meaning unless they are also taught Galileo’s Square-Cube Law, which explains precisely how size matters. Of the few students that learn the implications of this law, many of these students soon realize that the explanations given by paleontologists appear inadequate for explaining how dinosaurs grew to be three times the size of modern terrestrial animals. Instead of being an easy-to-understand lesson, students are being forced to decide whether Galileo or the paleontologists are correct; it is an incongruity that creates an embarrassing burden for their teachers. Because paleontologists downplay the significance of size and refuse to acknowledge their struggles in solving the large dinosaurs' paradox, they are effectively censoring the teaching of Galileo’s Square-Cube Law.

It is difficult to overstate how much this holds back the advancement of science. Understanding how size matters is a concept fundamental to nearly every major scientific discipline, including biology, chemistry, physics, astronomy, geology, and numerous others. Because Galileo’s Square-Cube Law is mostly left out of science education, students struggle to make sense of numerous scientific concepts that depend on understanding how size influences the natural world.

And that is not all. Beyond the exceptionally large dinosaurs, there are several other related scientific paradoxes associated with the Mesozoic era that paleontologists have failed to solve. Like the large dinosaur’s paradox, instead of acknowledging their struggle, paleontologists mislead the public by claiming that these are settled issues.

The purpose of this discussion is not merely to criticize, but to clear the public’s mind of incorrect beliefs so that a fresh start can be made in the search for solutions to these longstanding Mesozoic era paradoxes.

DinosaurTheory is a science website that presents evidence-based arguments explaining how the dinosaurs were able to grow so large. The solution to the large dinosaurs’ paradox is also the solution to numerous other paradoxes associated with the Mesozoic era, such as the flying pterosaurs, large flying birds, and the unusual Mesozoic climate. Along the way in explaining this evidence, DinosaurTheory also explains numerous scientific concepts, such as Galileo’s Square-Cube Law, how airplanes and flying vertebrates fly, and how the moons and planets of our solar system evolved.

There are those who reason well, but they are greatly outnumbered by those who reason badly.

Real Scientists Solve Problems

The Puzzle

Nearly every scientist encounters anomalies they cannot explain. What should we make of this? While science deniers use such events to reject science entirely, authoritarian scientists can be just as wrong in denying these paradoxes to preserve their image of being infallible. Neither extreme advances science. Instead, science progresses when science-minded people are curious about these puzzling paradoxes, ask questions, and, when possible, investigate the problems and find solutions.

A foundational assumption of science is that we exist in a rational reality governed by consistent laws. This assumption gives us confidence in our attempts to understand the workings of the natural world and has proven remarkably successful. Believing that reality is intelligible encourages scientists to persist in solving difficult problems. It is this perspective - that the natural world ultimately makes sense and that apparent paradoxes have underlying explanations - that gives curious scientists the fortitude to push on to find answers.

The large dinosaurs’ paradox is actually just one of numerous scientific paradoxes involving the Mesozoic era. Besides exceptionally large dinosaurs, there were the giant flying reptiles known as pterosaurs. Today, not a single species of reptile is capable of flight, yet during the Mesozoic era, pterosaurs grew to become the largest creatures that ever flew. In addition to these massive flying reptiles, enormous birds filled the skies - birds that were several times heavier than the largest flying birds today. Moreover, unlike most modern large birds, which typically require exceptionally large wings to fly, these huge Mesozoic birds were able to fly with only relatively small wings. Beyond the oddity of these extremely large vertebrates, the Mesozoic climate was noticeably different: throughout the era, Earth had a nearly uniform, mild temperate climate across its entire surface, with no ice at either the South or North Pole.

Throughout the history of paleontology, instead of seeing the big picture - that something was fundamentally different about Earth during the Mesozoic era - paleontologists have focused on explaining away anomalies instead of understanding their significance. These explanations tend to be weak in terms of evidence and reasoning, and are therefore often challenged. Yet each time an explanation fails, paleontologists simply replaced it with another one that is just as questionable; like playing a game of whack-a-mole, paleontologists refuse to acknowledge that there is something wrong with their core belief.

DinosaurTheory contends that the immense sizes of dinosaurs, pterosaurs, and flying birds of the Mesozoic era are paradoxes only for paleontologists who refuse to challenge their core assumption: that Earth’s ancient environment was essentially the same as today’s. If this assumption is challenged, these paradoxes are resolved. Furthermore, rather than viewing these anomalies as problems to be explained away, we should see them as clues that lead to a better understanding of how Earth was different during the Mesozoic era. When examined collectively, these lines of evidence point to a simple, elegant, and scientifically sound solution.

In addition to explaining a few key scientific concepts, what follows is a list of major scientific paradoxes of the Mesozoic era. Think of them as clues. Read them carefully. With confidence that reality is rational, enjoy applying logic to help solve one of the greatest puzzles of our time. At the end of the list, a link will take you to the proposed solution.

Can you solve the puzzle of the gigantic terrestrial animals of the Mesozoic era?

Scientific Paradoxes and Questions

1. Does Size Matter?

How is it that the significance of size is not clear to everyone? Is it because many simple objects - like rocks - can be extremely large or small without any noticeable change in their properties? Is it because science fiction movies often depict animals at unrealistic sizes, either as terrifying giants or as people shrunk to the size of an ant? Or perhaps it is the preexistence of gigantic dinosaurs that leads us to question whether size truly matters?

To be clear, size most definitely matters, and Galileo’s Square-Cube Law explains how. The square-cube law states that area increases as the square of a scaling factor, while volume increases as the cube. This means that the ratio of volume to area becomes larger as objects increase in size, and this change affects their properties.

One consequence of objects being larger is that they have a larger volume-to-area ratio and as a consequence of this – within the presence of a gravitational field – these large objects are under greater stress: force per unit area. If an object is too large, it is likely to break.

For example, suppose a person builds a two-foot-high sandcastle at the beach. They then decide to scale it up to three times its height. Unfortunately, midway through constructing the six-foot-high version, it will likely crumble because the stress within the structure is three times greater.

While a crumbling sandcastle is only a minor disappointment, a general lack of understanding of how size affects the properties of objects can have serious consequences - especially when engineers fail to account for how increasing size can make structures more fragile. And this is only one of the many ways that size influences the behavior of objects. Understanding the significance of size provides powerful insight into how nature works.

2. Large Dinosaurs Paradox

Currently, African elephants and giraffes represent the upper limits of size and height that terrestrial animals can achieve in today’s environment, constrained by factors such as bone strength, muscle strength, blood pressure, and possibly gravitational respiratory stress. Yet during the Mesozoic era, 65 to 245 million years ago, the largest dinosaurs grew to nearly three times the height and at least fifteen to thirty times more massive than these modern animals. Species such as Argentinosaurus, Brachiosaurus, and Patagotitan mayorum reached lengths exceeding 30 meters, over 12 meters in height, and weights of at least 70 metric tons.

The largest modern terrestrial animals are pushing the limits of how large they can be. If they were to grow significantly larger, their bones would most likely break. If elephants were much larger there is a real possibility that their muscles would not be strong enough to lift themselves up off the ground. Hence, we should wonder how it was possible for dinosaurs to be about three times larger than modern terrestrial animals.

Paleontologists have proposed various explanations for how these exceptionally large animals could function on land. Initially, many of the bipedal dinosaurs were mounted in museums as though they walked on four legs. To account for the largest dinosaurs - the sauropods - paleontologists suggested that they spent most of their time partially or fully submerged in water so that the buoyancy of water supported most of their weight. Now, paleontologists argue that dinosaurs were significantly lighter due to having hollow bones.

The proposed hypothesis of dinosaurs having hollow bones actually makes an initial problem worse. As just explained in the previous section, the larger the object, the greater the stress, and so larger animals require much thicker bones so that their bones do not break as a consequence of the increased stress. Claiming that dinosaurs had hollow bones would have only a marginal effect on reducing a dinosaurs’ weight, but this would substantially increase the stress in the bones - making fragile bones even more likely to break.

While paleontologists attempt to solve individual problems associated with larger animals, they ignore the fact that gigantism was widespread among dinosaurs - it was simply normal for many dinosaurs of the Mesozoic era to be much larger than modern terrestrial animals. This fact suggests that the environment of the Mesozoic era was somehow different so as to produce this global gigantism.

3. Tall Dinosaurs' Blood Pressure Paradox

The immense height of some sauropod dinosaurs presents a major physiological paradox: how could these animals pump blood to their head? Using the equation P = ρ g h, where P is the pressure, ρ is the density of blood, g is the acceleration due to gravity, and h is the vertical height, the required systolic blood pressure increases linearly with neck height. For a sauropod with a head 9 meters above its heart, the pressure needed would vastly exceed anything seen in modern animals.

For comparison, giraffes, with a vertical neck height of about 2.5 to 3 meters, have specialized adaptations to sustain blood flow at high pressures. Yet their cardiovascular system already operates at the limit of biological feasibility. The much greater height of sauropods would demand pressures far beyond what thickened arterial walls and powerful hearts could likely achieve. Paleontologists have yet to present a scientifically acceptable explanation that resolves this height paradox.

4. Why Do Dinosaurs Have Their Unique Form?

While much attention is given to the large size of dinosaurs, there is a tendency to overlook their distinctive shape: except for the largest dinosaurs, most dinosaurs have strong tails and much larger rear legs compared to their forelimbs. But why is this the case? What is the reason behind the typical dinosaur form being so different from that of modern terrestrial vertebrates?

With such strong rear legs for propulsion and a powerful tail capable of movement similar to that of aquatic vertebrates - like a crocodile’s - this body shape might have been useful if the dinosaur were constantly moving across a river or shallow lake, provided the water remained at just the right depth.

However, this suggestion raises many questions. While the "shoulder-high water" hypothesis helps visualize the purpose of the strong tail in propelling the animal through a dense fluid, it would be both unlikely and actually impossible for the lake water to remain at the ideal depth for both adult and juvenile dinosaurs of various sizes. Even stating that the water was at shoulder height doesn’t resolve the issue, since the skeletal frame of Edmontosaurus shows its tail positioned above its shoulders. For the tail to function effectively, the animal would need to be fully submerged in this dense fluid. But if the dinosaur were fully submerged, how did it breathe?

Dinosaurs were probably not breathing underwater, and based on the dissimilarity between their feet and those of modern aquatic or semi-aquatic animals, it seems unlikely that they spent much time in the water. But if dinosaurs were not submerged in water, then what conditions would make this body plan advantageous? Why did these dinosaurs have a muscular tail and powerful rear legs?

5. Flying Pterosaurs Paradox

Pterosaurs were giant flying reptiles that coexisted with the dinosaurs. They were the largest flying animals that ever existed. This fact is especially remarkable because flight requires a high level of power output, yet pterosaurs were reptiles - animals known for their low-power, cold-blooded metabolism. Furthermore, the larger the animal, the more difficult it becomes to meet the power demands of flight. In contrast to these large pterosaurs that made flying look easy, there is not a single reptile species today - no matter how small - that is capable of powered flight.

Paleontologists have proposed various hypotheses to explain how giant pterosaurs could have flown, often attributing extraordinary capabilities to these animals. Common claims include reduced body mass, unusually strong bones and muscles, exceptionally high metabolic rates, and the ability to launch themselves into the sky with a single leap. However, these proposals remain largely speculative, as they are not supported by quantitative analysis or empirical evidence.

A key difficulty in evaluating whether an animal or aircraft can fly is that, until recently, there was no clear, accessible theoretical framework with corresponding equations for determining the minimum requirements for flight. Several variables must be considered when determining whether something can fly: the flyer’s weight, wingspan, power output, aerodynamic form, static and dynamic balance, and the density of the surrounding air are among the most critical. The explanations offered by paleontologists fall far short of addressing these requirements. Nothing in flight physics, aircraft design, or experiments with RC models of pterosaurs supports the idea that a reptile the size of a small recreational airplane could fly in present-day atmospheric conditions.

6. The Enormous Flying Birds of the Mesozoic Era Are Not Dinosaurs

For many years, paleontologists struggled to classify a number of large fossil species that possessed wings and numerous other bird-like features. Interpreting them as large flying birds presents a clear physical difficulty: their size and relatively small wings appear inconsistent with the aerodynamic and power requirements for flight under present-day atmospheric conditions. Paleontologists now classified these bird-like creatures as being feathered dinosaurs.

Since introducing this classification, paleontologists have emphasized how easily feathers could have evolved in dinosaurs, yet they have failed to provide a rational explanation for why supposedly grounded animals would evolve wings or asymmetric flight feathers - features closely associated with flight. Considering the many features they share with flying birds, we must consider the possibility that these feathered dinosaurs were either large flying feathered dinosaurs or simply large flying birds.

With skepticism, one might still wonder whether these winged, feathered animals were actually flightless birds - perhaps like ostriches, which are thought to have evolved from flying ancestors and later lost the ability to fly. While this is a plausible possibility, the available evidence indicates otherwise. The wings of Cretaceous birds were far more developed than the vestigial wings of ostriches and, most importantly, were equipped with asymmetric flight feathers - structures strongly associated with aerodynamic function.

Once we accept the most likely possibility that these were large flying birds, it becomes difficult to believe that the Mesozoic environment was similar to the present, as this conclusion follows from how easily these animals could fly. Due to the Square-Cube Law, modern flying birds are limited in size. Yet Cretaceous birds were at least three times larger than the largest flying birds today and, unlike modern flyers - which typically require disproportionately large wings - appear to have required only modest wings. These features indicate that flight was relatively easy for such large animals, implying that the Mesozoic environment must have differed in a way that made this possible.

The apparent ease with which extremely large Cretaceous birds were capable of flight corroborates with the widely accepted view that pterosaurs of the same period were also effective fliers. Under present-day atmospheric conditions, the large size of these Cretaceous birds and pterosaurs would have made flight impossible. Yet during the Mesozoic - particularly the late Cretaceous - these animals became the largest fliers of all time, coexisting at a time when dinosaurs were also exceptionally large.

7. Nearly Uniform Global Climate Paradox

Today, we experience significant temperature variations due to factors such as day and night, latitude, altitude, and seasons. However, this was not always the case. During the Mesozoic era - the age of dinosaurs - temperature variations were far less extreme. Lower latitudes were not excessively hot, nor were the polar regions excessively cold. Most notably, there was little to no glaciation at the poles. Fossil evidence, including dinosaur remains and temperate vegetation found in high-latitude regions, supports the idea of a globally uniform - or nearly uniform - balmy climate during the Mesozoic era.

Looking further back in time to the Pennsylvanian and Permian periods, extensive glaciation indicates a return to a cooler, icehouse climate. Going back even further, however, ice largely disappears again, and climates shift toward a greenhouse state, similar to that of the Mesozoic. These alternating climate regimes are commonly referred to as “icehouse” and “greenhouse” states.

Paleoclimatologists have developed simulations to model past climates, including the Mesozoic, using hypotheses like elevated CO₂ levels and changes in ocean circulation. However, even with extensive adjustments to variables, these models struggle to fully align with the known glaciation history over the past half-billion years. For instance, they often fail to account for the significant glaciations during the Pennsylvanian and Permian periods or accurately reproduce the transitions between icehouse and greenhouse climates. This suggests that the proposed mechanisms driving large-scale climate shifts may be wrong or at least not yet completely understood.

8. What Is the Source of Earth’s or Any Other Planet’s Atmosphere?

Science education can be surprisingly unbalanced. While most people have heard countless times that trace amounts of atmospheric carbon dioxide is the cause of global warming, many would be hard-pressed to identify the chemical compositions of planetary atmospheres - or even to state the composition of Earth’s atmosphere. Likewise, most people have little understanding of where Earth’s atmosphere and oceans came from, how they have changed over time, or how Earth’s atmosphere differs from those of other planets. How can there be meaningful conversations about these issues when there are such large gaps in fundamental knowledge?

The primary source of a terrestrial planet’s atmosphere is volcanic emissions, and the two most common gases released by volcanoes are water vapor and carbon dioxide. On Earth, the water vapor condensed to form the oceans. On Venus and Mars, carbon dioxide accumulated in their atmospheres such that it now makes up over 96% of their atmospheres. So, what happened to the water on Venus and Mars? And what happened to the carbon dioxide on Earth?

9. Why is Earth's Atmosphere So Unique?

In our solar system, planets fall into two broad groups: the relatively small terrestrial planets near the Sun and the much larger outer planets. Physics helps explain this distinction. The outer planets—Jupiter, Saturn, Uranus, and Neptune—have much greater mass and therefore stronger gravity, allowing them to retain even the lightest gases, hydrogen and helium. Combined with their colder temperatures, this enables them to accumulate vast atmospheres composed primarily of these elements.

In contrast, the inner planets, with their lower gravity and higher temperatures, are unable to retain significant amounts of hydrogen and helium. As a result, their atmospheres are composed of heavier gases. For example, Venus and Mars have atmospheres dominated by carbon dioxide, while Mercury has little to no atmosphere at all.

This general pattern appears consistent - except that Earth does not fit it. Unlike its nearest neighbors, Venus and Mars, Earth’s atmosphere is composed primarily of nitrogen and oxygen rather than carbon dioxide. Furthermore, despite being similar in size to Venus, Earth has a much thinner atmosphere. This raises an important question: why is Earth’s atmosphere so different from those of other terrestrial planets?

10. Many Aspects of Our Solar System Are Still Unexplained

Paleontologists are not the only scientists who grapple with difficult questions. Planetary science, despite its many successes, still faces important uncertainties. While current models explain many aspects of Earth’s environment, they do not fully account for why Earth’s atmosphere is so different from those of other planets. There are clearly gaps in our understanding of how the Earth evolved, and by filling in some of these gaps it may be possible to understand why gigantism occurred during the Mesozoic era.

Far from being a completely solved puzzle, our solar system still presents a number of open questions:

• What processes determine the long-term evolution of a planet’s atmosphere?
• What governs the wide variation in densities and compositions among planets and moons?
• Why does Saturn and the other gas giants have rings? How did these rings form?
• Why do some planets and moons remain geologically active while others become inactive?

Progress in science depends on asking difficult questions, refining models, and improving our understanding as new evidence emerges. If new evidence does not support current beliefs, then we need to find the will to question those beliefs rather than dismiss the evidence.

David Esker
M.S. Physics
College Physics Instructor
Resolution of the Large Dinosaur Paradox
Science of Flight Equations
Theory of Planetary Evolution
Author of DinosaurTheory

Science is an ongoing process of discovery. We do not know why our reality exists; we struggle to define what life is; we do not know how the laws of physics came to be or why the physical constants have the values they do. Yet one thing is undeniable: science advances on the assumption that our reality is rational.

Comments, Questions, and Answers

Selected comments and questions are given with the permission of the parties involved.