Prehistoric Wild: Life in the Mesozoic

Below the Beasts (212 MYA)

Los Colorados Formation, Argentina, 212 Million Years Ago

It is early morning, and the sun casts its golden glare from a pale gray sky. Darker gray clouds drift through the air, casting a shadow off the late dawn radiance. The mix of shade and solar gleam projects onto what is now South America.

At this time, the land of Argentina rests at the lower west edge of the supercontinent of Pangea. Many of the major continental shifts that would split and contort the great landmass have yet to occur. Thus, the only form of high elevation is a series of smooth hills. Although this area is where the Andes mountains will one day be, no signs of them are present as they won't form until far in the future.

Below and between the hills is a system of crisscrossing rivers and streams. Waters carried in them flow in and out of lakes and ponds scattered between. The sounds of rabbles, ripples, burbles, and trickles emanate from them as clear liquid gently travels through them.

Surrounding these bodies of water is a plethora of plant life. Much of it is familiar to modern-day such as the many ferns, seed ferns, and conifer trees. The latter has yet to take a form recognized today, having a more primitive appearance. One plant, dicroidium, appears like a sycamore tree but is a type of seed plant ancestral to many modern gymnosperms.

One form of greenery is almost alien in appearance, like nothing humankind has ever witnessed. Their trunks are tall, slender, and upright with a crown of narrow-needle-like leaves arranged in a spiral pattern around the base. Resting at the top of each of these trunks are cone-like structure akin to what's seen on cycad plants, yet these plants, called pleuromeia, are unrelated. It's actually an ancestor of smaller, grass-like plants called quillworts.

Such an abundance of plant life is a rare sight outside of the more fluvial parts of this area. With temperatures of up to 86 degrees Fahrenheit common in the Triassic, this land has become hot and arid. Even here by the streams, the ground beneath the plants is brown, dry, and covered in small, gray pebbles.

Despite such scorched conditions, life continues to thrive in abundance. The smallest and most plentiful forms are the many dragonflies and damselflies. In varying numbers, they zoom above and hover around the plentiful rivers. The sounds of their rapid wing flaps and stridulations fill the air around these bodies of water.

These insects are the most familiar of the animals present here. This runs in contrast to the other creatures that reside here. Much of this fauna is scarcely like anything alive today.

Drinking from and stalking the streams are the occasional Neoaetosauroides. They're 10-foot-long, flat-bodied animals with bony plates on their tops and underbellies. This mosaic of meticulously interlocked armor creates a nearly impenetrable shield over their back and flanks. These fortress-like bodies are supported by four stout, powerful limbs, each ending in clawed feet. Such claws are sharp and strong, serving them well at digging. Smaller versions of their bony plates decorate their long, muscular tails. Resting on its short neck is a small head and a blunt, slightly upturned snout. Their jaws are equipped with sharp, leaf-shaped teeth, well-suited for gripping their prey such as insects and small lizards, but also for shredding vegetation like ferns. This runs in contrast with other members of the aetosaur order which are normally solely herbivorous, despite being evolutionary offshoots of crocodilians. Much of their scaly skin is primarily reddish brown except for their tan underbellies.

Hanging around the vegetation are herds of Coloradisaurus. These are early members of the prosauropods, a clade of dinosaurs that will one day give rise to long-necked sauropods like Brontosaurus and Brachiosaurus. At up to 10 feet in length, they're a small fraction of the gigantic sizes their descendants will eventually reach.