Dimetrodon

## Physiology

### Description

Large mammal-like predatory reptile with a large sail on its back and different kinds of teeth

### Attributes

Large sail on back; different types of teeth; mammal-like traits

## Biography

### Locations

Europe, North America

***Dimetrodon*** (name meaning "*Two Measures of Teeth*") is a genus of synapsids that originated during the Early Permian era in what is now North America and Europe. A carnivorous, non-therapsid mammal-like reptile measuring over 4 meters long, weighing over 250 kg, and arguably the apex predator of its time, its recognizable feature is the large fin-like sail on its back.

One of the primary creatures needed for the park, in the Series 1 episode "**Sail Backs**", a single female named Scarlet-Eye was brought to the park from Early Permian Germany, 280 million years ago, along with several other individuals, including one other female. Scarlet-Eye was given her named due to the red spot on her right eye which she got during a fight with another female. The team manage to also rescue her eggs so they incubated so they can hatch.

## Facts

### Era & Discovery

*Dimetrodon* lived in North America and Europe during the Early Permian era to Early Triassic period from 295 to 270 million years ago. Among the apex predator of its day for 25 million years, it lived alongside animals like *Edaphosaurus* and *Seymoria*.

First discovered by Edward Drinker Cope in 1877, fossils of *Dimetrodon* have been found in North America and Europe as well as significant discovery of *Dimetrodon* footprints in southern New Mexico by Jerry MacDonald. In addition, *Dimetrodon* was not a dinosaur, despite being often incorrectly classed with them over the years. Rather, it is classified as a pelycosaur. Nevertheless, since its discovery, *Dimetrodon* has become one of the most well-known prehistoric animals in the world.

### Physical Attributes

Among the largest and apex predators of its day and said to have been the biggest enemy of *Edaphosaurus*, *Dimetrodon* was a large, quadrupedal synapsid, notable for its very large spinal sail. Measuring between 1.8 to 4.5 meters (6 to 15 feet) in length and weigh between 28 and 250 kg (60 and 550 lb), *Dimetrodon* was the size of an alligator or a big cat. It walked on four side-sprawling legs like a crocodile and had a large tail. *Dimetrodon* may have moved in a manner similar to present-day lizards. As a non-therapsid synapsid, *Dimetrodon* was distantly related to modern mammals.

As well as their sheer size and power, *Dimetrodon* had a killer edge. As a protomammal, its blunt-snouted head was equipped with with very powerful jaws equipped with large, specially evolved teeth, hence their name, which gave it a bone-crushing bite force. Their serrated canines cut and slice flesh while their incisors shear off chunks of flesh, allowing *Dimetrodon* to shear meat into smaller pieces for easier ingestion. These 'two-measure teeth' eventually gave rise to the various kinds of teeth present in modern mammals. Though even humans have inherited these same form of meat-eating teeth, we use a smaller version in our mouths today. Additionally, similar to Komodo dragons, *Dimetrodon* had a deadly amount of microbes and bacteria in their mouths, enough that even if a bitten animal were to get away alive, they would suffer massive infection which would be crippling and, in a a human's case, slow but fatal.

#### Sail

The most distinctive characteristic of *Dimetrodon* was the spectacular sail on its back (other pelycosaurs such as *Edaphosaurus* also have this trait). The sail, which was dense with blood vessels, was probably used to regulate body temperature; the surface area would allow it to warm up or cool off more efficiently. This adaption was important because it would give the animal more time to hunt prey. The sail may also have been used in mating rituals and to warn off other predators. The sail was supported by neural spines, each one sprouting from an individual vertebra. Bramwell and Fellget (1973) calculate that a 200 kg *Dimetrodon* would heat up from 26 °C to 32° 205 minutes without a sail and in only 80 minutes with a sail. However, some other studies indicate it made a poor heat loss object.

### Behavior & Traits

*Dimetrodon* was a formidable and aggressive carnivore in its day, preying on even their own kind. *Dimetrodon* was also observed to apparently have a loose social structure, easily fighting rivals in the pursuit of food and being quick to cannibalism. Nevertheless, being cold-blooded, *Dimetrodon* would also gather in large numbers early during the day to bask and warm up under the sun, with their sails serving as heat regulators. In this state, they were slow, sluggish and disinterested. But when *Dimetrodon* took interest in prey and became active, they could give disturbing bursts of speed and agility.

While *Dimetrodon* was more than capable of taking on fully-grown, adult *Edaphosaurus*, pregnant female *Dimetrodon* about to give birth would hunt smaller prey (such as an adolescent *Edaphosaurus*) in order to avoid getting injured. Once the female selected her target, she would erupt from her ambush position and perform a mach charge in order to break the herd up and expose defenseless prey. Upon making her kill, the pregnant female *Dimetrodon* would need to eat enough food to last her for the egg's entire incubation, which took a period of roughly seven months. In order to increase their offsprings chances of survival, *Dimetrodon* evolved a basic form of parental care: guarding her eggs. However, male *Dimetrodon* have been known to have taken the female's kill. Rather than defending her kill, she would willingly leave it to the males, who are said to have been highly aggressive. Whether eating in a group or eating alone, by the time *Dimetrodon* was finished with its meal, the only things left of a carcass would be bones. In comparison to lions today, which were able to eat 70% of a carcass, *Dimetrodon* ate 90%. However, they only ate intestines upon shaking the waste inside a carcass. Therefore, dung was something *Dimetrodon* couldn't stomach.

When the female *Dimetrodon* had finished her meal, she would return to her nest, which was made entirely of earth and wood. Once digging a deep burrow, she lay her eggs and cover them carefully. Needing to constantly monitor the temperature of the nest (which was vital for *Dimetrodon* hatchlings even before they were born), the female would either add more layers if the eggs got too cold or remove layers if too warm, otherwise, the unborn hatchlings would die. Either way, once done, the females would assume their guard duty for the long seven months. Because of this, the females would grow weaker over the course of the eggs incubation due to lack of food and water. Nevertheless, mother *Dimetrodon* were fiercely protective of the eggs and no matter how weak they were, they would attack anything going near the nest, whether that would be an egg-thieving amphibian or even another *Dimetrodon* (even if it was other females desperate to lay their own eggs). If allowed, the invading mother *Dimetrodon* would kill the incubating eggs already inside.

Once the eggs hatched, rather than nurture their young, female *Dimetrodon* would abandon them. They would need to save themselves via finding food.