Jurassic Age

The Herbivores: Songs, Crests and Gigantism For herbivores, the mating season centered on visual and auditory displays. Living in herds, competition was fierce. Visual Display: Many dinosaurs, such as the ancestors of Stegosaurus or Huayangosaurus, likely used their plates or spines. Scientists believe these plates were filled with blood vessels; during mating season, they could have "pumped" blood into them to change color, turning red or bright to attract females or intimidate rivals. Power Struggles: Sauropods (long necks) did not use their necks to butt heads like giraffes (it would be very dangerous for their spines), but they probably used their size to push each other or cracked their tails like whips to produce sonic booms that could be heard for miles. Mass Nesting: They used to congregate in large, safe areas. They dug holes in the ground, laid dozens of eggs, and in some groups, stayed nearby to protect the area from small predators. Carnivores: Dances, Scars, and Gifts For predators like Allosaurus or Ceratosaurus, mating was a much more tense and potentially dangerous affair. Theropod Courtship: It is believed that males performed rhythmic movements or "dances" similar to those of modern birds. Fossil sites have been found with "scratch" marks in the ground, suggesting that males vigorously scratched the earth to demonstrate their vigor to females. Colorful Crests: Jurassic carnivores often had bony crests above their eyes (like Allosaurus) or horns (like Ceratosaurus). During mating season, these structures were likely covered in brightly colored keratin (blue, orange, or red) to indicate health and sexual maturity. Scars of Love: It is common to find fossils of large carnivores with bite marks on their snouts that have healed.

Unlike modern carnivores that tend to specialize, these predators were opportunistic: Young Sauropods: Attacking a 15-meter adult was suicidal, so they focused on young or sick individuals. Thyreophorans (Armored): They tried to flip dinosaurs like Huayangosaurus over to reach their soft underbelly, avoiding the back plates. Carrion: They had no problem taking advantage of a fresh carcass if another carnivore had already done the dirty work.

1. Ceratosaurs Although Ceratosaurus nasicornis is most famous from 150 million years ago, its ancestors were already patrolling the Middle Jurassic. Characteristics: They are distinguished by the horn on their snout and a row of small bony plates (osteoderms) along their back. Hunting style: They had proportionally very long teeth for their size. It is believed that they could hunt aquatic or terrestrial prey, being more flexible in their diet than other large carnivores.
2. Allosaurus (The first "Lions of the Jurassic") 170 million years ago, allosauroids were at their peak. A close relative from that time is Piatnitzkysaurus. Characteristics: They possessed bony crests above their eyes. Their arms were robust and ended in three sharp claws. Attack tactic: They used their jaw like an "axe." Instead of a crushing bite (like the T-Rex), they delivered quick, downward blows to cause their prey to bleed out.
3. Torvosaurus and the Megalosaurids In the Middle Jurassic, the Megalosaurids (the Torvosaurus family) were the true kings in terms of brute power. Torvosaurus: It is one of the most massive carnivores of the Jurassic period. It was more robust and heavier than Allosaurus. Characteristics: Elongated skulls and bodies designed for strength. They were the "heavyweights" who were not afraid to confront young or wounded sauropods.

Conifers: Trees similar to modern pines, araucarias, and cypresses. They were the primary energy source for large sauropods. Their needles were hard, but highly nutritious if the animal had a suitable digestive system. Cycads: Plants that look like palm trees but are not. They had thick trunks and hard, leathery leaves. Ginkgos: Trees with fan-shaped leaves that were very common at that time. Ferns and horsetails: These covered the ground in wetlands. Lower herbivores, such as Scelidosaurus, depended on these plants, which grew near rivers and lakes.

Vegetarian Giants: Herbivorous Species At this point in the Jurassic, sauropod dinosaurs (the long-necked ones) already dominated the landscape, but they had not yet reached the titanic sizes that we would see at the end of the period (like Diplodocus).

1. Sauropodomorphs and Early Sauropods Patagosaurus: One of the most famous representatives of this era in South America. It measured about 14 meters long. Its neck allowed it to reach foliage that other herbivores could not touch. Cetiosaurus: Common in what is now Europe and Africa. Although not as sophisticated as its later relatives, it was a massive plant processor that relied on fermentation in its enormous stomach to digest fiber.
2. Thyreophorans (Armored) Huayangosaurus: An early ancestor of stegosaurs. Unlike more famous models, this one had smaller spines and plates, and its head was slightly taller, indicating that it fed on medium-height shrubs. Scelidosaurus: An armored herbivore that walked mostly on all fours, specializing in eating low, tough plants close to the ground.
3. Early Ornithopods They were smaller, more agile animals, and often bipedal. They had no strong defenses, so their strategy was to eat quickly and flee.

Around 170 million years ago, we find ourselves in the Middle Jurassic, specifically in the Bajocian epoch. The world was a warm, humid, and green place, where the continents were still very close together, forming the supercontinent Pangaea, which was beginning to break apart.