Megalosaurus

About Megalosaurus

Characteristics of Megalosaurus

Megalosaurus was a large carnivorous dinosaur that reigned at the top of the ecosystem in Europe during the Middle Jurassic. According to recent research, the largest individuals are estimated to have reached about 9m in length and weighed over 1 ton.

They had a sturdy, muscular build. Their disproportionately huge heads were lined with dagger-like teeth bearing 18 to 20 minute serrations per centimeter, allowing them to efficiently slice through the flesh and tendons of their prey. Also, although their forelimbs were short, they are thought to have been robust and played a role in forcefully holding down prey during close-quarters hunting.

From the study of their skeletons, it is known that Megalosaurus had an efficient respiratory system called the "air sac system," similar to that of modern birds. Combined with strong hind legs, it was a bipedal dinosaur capable of active movement. It is presumed that Megalosaurus mainly fed on long-necked sauropods and armored thyreophorans.

The First Dinosaur: Opening the Door from Theology to Modern Paleontology

Megalosaurus is the first dinosaur in history to be scientifically described and given a valid name. The history of its discovery was also the process by which humanity came to understand the concept of "extinct giant animals."

The oldest fossil record of Megalosaurus dates back to the 17th century. In 1676, a part of a giant femur was discovered in an English quarry, and naturalist Robert Plot published an illustration of a dinosaur bone for the first time in history. However, because the concept that organisms could go extinct did not exist at the time, Plot interpreted it as the remains of a "giant who perished in the Great Flood" from the Bible. This is an event that shows how bound academic hypotheses of the time were to a theological worldview.

Later, in 1797, physician Sir Christopher Pegge discovered a fossilized lower jaw of a carnivore, which was handed over to William Buckland, a professor of geology at Oxford University. Buckland proceeded with the analysis with the advice of French comparative anatomist Georges Cuvier, and named and announced it as "Megalosaurus (great lizard)" at the Geological Society of London in 1824. This is the birth of the "first dinosaur" based on modern paleontology.

However, it is said that Buckland himself had a profound conflict with Christian doctrine over the fact that a "pure carnivore" was discovered from a stratum long before humans existed. Later, in 1842, Richard Owen proposed the taxonomic group "Dinosauria." The discovery of Megalosaurus had a massive impact on society at the time, and it was even depicted as an ancient monster at the beginning of Charles Dickens' 1852 novel "Bleak House."

Changes in Reconstructed Images and Escape from the "Wastebasket Taxon"

The academic reconstruction of Megalosaurus, the "first dinosaur," has changed significantly over the past 200 years through three main stages, directly reflecting the paradigm shifts in dinosaur research.

In the 1st period (1820s), it was depicted as a "giant amphibious lizard" with its limbs sprawled out to the sides, crawling on its belly, like a giant modern monitor lizard.
In the 2nd period (mid-19th century), Owen's research revealed that its legs extended straight down from its body, changing its appearance to a "heavy, quadrupedal animal that stood upright like a rhinoceros or a bear." In reconstructions of this period, it was once thought to have a "hump on its back," but this was a misidentification caused by mistakenly attributing the vertebrae of another theropod (Altispinax) to Megalosaurus.
And in the 3rd period (late 19th century to present), with the discovery of complete dinosaur skeletons in North America, the image of it as an "active bipedal animal" that we know today was finally established.

Also, Megalosaurus had a historical problem of being treated as a "wastebasket taxon" for a long time. From the 19th to the 20th century, fossils of large theropods of unknown origin found all over the world were easily thrown into the genus Megalosaurus without detailed verification. As a result, Megalosaurus became a "chimera" where the features of dinosaurs from various eras were mixed up, making its true form unknown.

This confusion was brought to an end by a drastic reassessment study conducted by paleontologist Roger Benson and others in the 21st century. They strictly redefined the name Megalosaurus by limiting it to only reliable specimens, such as the initially described lower jaw fragment (lectotype). With this, Megalosaurus was freed from the curse of being a wastebasket taxon that lasted for over a century, and was resurrected as a scientifically useful unique entity once again.